Adding upstream version 1:10.6.11.upstream/1%10.6.11upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

23 files changed, 4080 insertions, 0 deletions

diff --git a/wsrep-lib/wsrep-API/v26/examples/node/CMakeLists.txt b/wsrep-lib/wsrep-API/v26/examples/node/CMakeLists.txt
new file mode 100644
index 00000000..d018afde
--- /dev/null
+++ b/wsrep-lib/wsrep-API/v26/examples/node/CMakeLists.txt
@@ -0,0 +1,26 @@
+# Copyright (c) 2019, Codership Oy. All rights reserved.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; version 2 of the License.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+
+FILE(GLOB SRC
+  "*.h"
+  "*.c"
+  )
+
+ADD_EXECUTABLE(node ${SRC})
+
+TARGET_LINK_LIBRARIES(node wsrep dl pthread)
+
+CONFIGURE_FILE(${CMAKE_CURRENT_SOURCE_DIR}/node.sh
+               ${CMAKE_CURRENT_BINARY_DIR}/node.sh COPYONLY)
diff --git a/wsrep-lib/wsrep-API/v26/examples/node/README.md b/wsrep-lib/wsrep-API/v26/examples/node/README.md
new file mode 100644
index 00000000..4a07c149
--- /dev/null
+++ b/wsrep-lib/wsrep-API/v26/examples/node/README.md
@@ -0,0 +1,81 @@
+# wsrep API node application
+
+## Overview
+
+This is a simple application to demonstrate the usage of wsrep API. It
+deliberately does nothing useful in order to present as concentrated and
+concise API usage as possible.
+
+The program is deliberately written in C to demonstrate the naked API usage.
+For C++ example see a much more advanced integration library at
+https://github.com/codership/wsrep-lib
+
+## High level architecture
+
+Process-wise the program consists of an endless main loop that periodically
+samples and prints performance stats and a configurable number of "master" and
+"slave" threads, with master threads loop executing "transactions" and
+replicating resulting "write sets" and slave threads receiving and processing
+the write sets from other nodes.
+
+Object-wise the program is composed of two main objects: `store` and `wsrep`.
+'store' object contains application "state" and generates and commits changes
+to the state. `wsrep` object contains cluster context and provides interface
+to it. Changes generated by `store` are replicated and certified through
+`wsrep` and then committed to `store`.
+
+## Unit descriptions (in alphabetical order)
+
+#### ctx.h
+A small header to declare the application context structure.
+
+#### log.*
+Implements logging functionality for the application AND
+**a logging callback** for the wsrep provider.
+
+#### main.c
+Defines `main()` routine that initializes storage and wsrep provider, starts
+the worker threads and loops in a statistics collection loop. Even though it is
+not designed to return it still shows the deinitialization order.
+
+#### options.*
+Implements reading configuration options from the command line, does not have
+anything related to wsrep API, but shows which additional parameters must be
+configured for the program to make use of wsrep clustering.
+
+#### socket.*
+Network sockets boilerplate code for setting TCP connections between processes
+(for SST). Has nothing wsrep-related and can be ignored.
+
+#### sst.*
+Defines **SST callbacks** for the wsrep provider and shows how to asynchronously
+implement state snapshot transfer (yes, you don't want to spend eternity in
+callbacks).
+
+#### stats.*
+Implements performance stats collecting function for the main loop. While it is
+an absolutely optional provider functionality, still it shows how to use that.
+
+#### store.*
+Defines the `store` object that pretends to store and modify some data in a
+"transactional" manner. It provides the caller that intends to do a change with
+a *change data* and a *key* for replication and certification.
+
+#### trx.*
+Defines routines to process local and replicated transactions.
+
+#### worker.*
+Implements worker thread pool functinality. Worker threads run routines defined
+in 'trx.*'. Also implements **apply callback** for the wsrep provider.
+
+#### wsrep.*
+Maintains wsrep cluster context: provider instance and cluster membership view.
+While there is little use for the latter in this primitive application, still
+it shows **connected and view callbacks** usage. But mostly, for this
+application its purpose is to initialize the provider, connect to the cluster
+and offer access to initialized provider for other parts of the program.
+
+## Example usage
+```
+./node -f /tmp/galera/0 -v /tmp/galera/0/galera/lib/libgalera_smm.so -o 'pc.weight=2;evs.send_window=2;evs.user_send_window=1;gcache.recover=no' -s 8 -m 16
+```
diff --git a/wsrep-lib/wsrep-API/v26/examples/node/ctx.h b/wsrep-lib/wsrep-API/v26/examples/node/ctx.h
new file mode 100644
index 00000000..01653554
--- /dev/null
+++ b/wsrep-lib/wsrep-API/v26/examples/node/ctx.h
@@ -0,0 +1,34 @@
+/* Copyright (c) 2019, Codership Oy. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ */
+
+/**
+ * @file This unit defines application context for wsrep provider
+ */
+
+#ifndef NODE_CTX_H
+#define NODE_CTX_H
+
+#include "store.h"
+#include "wsrep.h"
+
+struct node_ctx
+{
+    node_wsrep_t*              wsrep;
+    node_store_t*              store;
+    const struct node_options* opts;
+};
+
+#endif /* NODE_CTX_H */
diff --git a/wsrep-lib/wsrep-API/v26/examples/node/log.c b/wsrep-lib/wsrep-API/v26/examples/node/log.c
new file mode 100644
index 00000000..71f4705c
--- /dev/null
+++ b/wsrep-lib/wsrep-API/v26/examples/node/log.c
@@ -0,0 +1,100 @@
+/* Copyright (c) 2019, Codership Oy. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ */
+
+#include "log.h"
+
+#include <stdio.h>    // fprintf(), fflush()
+#include <sys/time.h> // gettimeofday()
+#include <time.h>     // localtime_r()
+#include <stdarg.h>   // va_start(), va_end()
+
+wsrep_log_level_t node_log_max_level = WSREP_LOG_INFO;
+
+static const char* log_level_str[WSREP_LOG_DEBUG + 2] =
+{
+    "FATAL: ",
+    "ERROR: ",
+    " WARN: ",
+    " INFO: ",
+    "DEBUG: ",
+    "XXXXX: "
+};
+
+static inline void
+log_timestamp_and_log(const char* const prefix, // source of msg
+                      int         const severity,
+                      const char* const msg)
+{
+    struct tm      date;
+    struct timeval time;
+
+    gettimeofday(&time, NULL);
+    localtime_r (&time.tv_sec, &date);
+
+    FILE* log_file = stderr;
+    fprintf(log_file,
+            "%04d-%02d-%02d %02d:%02d:%02d.%03d " /* timestamp fmt */
+            "[%s] %s%s\n",                        /* [prefix] severity msg */
+            date.tm_year + 1900, date.tm_mon + 1, date.tm_mday,
+            date.tm_hour, date.tm_min, date.tm_sec,
+            (int)time.tv_usec / 1000,
+            prefix, log_level_str[severity], msg
+        );
+
+    fflush (log_file);
+}
+
+void
+node_log_cb(wsrep_log_level_t const severity, const char* const msg)
+{
+    /* REPLICATION: let provider log messages be prefixed with 'wsrep'*/
+    log_timestamp_and_log("wsrep", severity, msg);
+}
+
+void
+node_log(wsrep_log_level_t const severity,
+         const char*       const file,
+         const char*       const function,
+         int               const line,
+         ...)
+{
+    va_list ap;
+
+    char   string[2048];
+    int    max_string = sizeof(string);
+    char*  str = string;
+
+    /* provide file:func():line info only if debug logging is on */
+    if (NODE_DO_LOG_DEBUG) {
+        int const len = snprintf(str, (size_t)max_string, "%s:%s():%d: ",
+                                 file, function, line);
+        str += len;
+        max_string -= len;
+    }
+
+    va_start(ap, line);
+    {
+        const char* format = va_arg (ap, const char*);
+
+        if (max_string > 0 && NULL != format) {
+            vsnprintf (str, (size_t)max_string, format, ap);
+        }
+    }
+    va_end(ap);
+
+    /* actual logging */
+    log_timestamp_and_log(" node", severity, string);
+}
diff --git a/wsrep-lib/wsrep-API/v26/examples/node/log.h b/wsrep-lib/wsrep-API/v26/examples/node/log.h
new file mode 100644
index 00000000..09404f26
--- /dev/null
+++ b/wsrep-lib/wsrep-API/v26/examples/node/log.h
@@ -0,0 +1,69 @@
+/* Copyright (c) 2019, Codership Oy. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ */
+
+/**
+ * @file This unit defines logging macros for the application and
+ *       a logger callback for the wsrep provider.
+ */
+
+#ifndef NODE_LOG_H
+#define NODE_LOG_H
+
+#include "../../wsrep_api.h"
+
+/**
+ * REPLICATION: a logger callback for wsrep provider
+ */
+extern void
+node_log_cb(wsrep_log_level_t severity, const char* message);
+
+/**
+ * Applicaton log function intended to be used through the macros defined below.
+ * For simplicity it uses log levels defined by wsrep API, but it does not have
+ * to. */
+extern void
+node_log (wsrep_log_level_t level,
+          const char*       file,
+          const char*       function,
+          const int         line,
+          ...);
+
+/**
+ * This variable made global to avoid calling node_log() when debug logging
+ * is disabled. */
+extern wsrep_log_level_t node_log_max_level;
+#define NODE_DO_LOG_DEBUG (WSREP_LOG_DEBUG <= node_log_max_level)
+
+/**
+ * Base logging macro that records current file, function and line number */
+#define NODE_LOG(level, ...)\
+        node_log(level, __FILE__, __func__, __LINE__, __VA_ARGS__, NULL)
+
+/**
+ * @name Logging macros.
+ * Must be implemented as macros to report the location of the code where
+ * they are called.
+ */
+/*@{*/
+#define NODE_FATAL(...) NODE_LOG(WSREP_LOG_FATAL, __VA_ARGS__, NULL)
+#define NODE_ERROR(...) NODE_LOG(WSREP_LOG_ERROR, __VA_ARGS__, NULL)
+#define NODE_WARN(...)  NODE_LOG(WSREP_LOG_WARN,  __VA_ARGS__, NULL)
+#define NODE_INFO(...)  NODE_LOG(WSREP_LOG_INFO,  __VA_ARGS__, NULL)
+#define NODE_DEBUG(...) if (NODE_DO_LOG_DEBUG) \
+    { NODE_LOG(WSREP_LOG_DEBUG, __VA_ARGS__, NULL); }
+/*@}*/
+
+#endif /* NODE_LOG_H */
diff --git a/wsrep-lib/wsrep-API/v26/examples/node/main.c b/wsrep-lib/wsrep-API/v26/examples/node/main.c
new file mode 100644
index 00000000..f3124042
--- /dev/null
+++ b/wsrep-lib/wsrep-API/v26/examples/node/main.c
@@ -0,0 +1,146 @@
+/* Copyright (c) 2019, Codership Oy. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ */
+
+#include "ctx.h"
+#include "log.h"
+#include "options.h"
+#include "stats.h"
+#include "worker.h"
+#include "wsrep.h"
+
+#include <errno.h>
+#include <signal.h> // sigaction()
+#include <string.h> // strerror()
+
+static void
+signal_handler(int const signum)
+{
+    NODE_INFO("Got signal %d. Terminating.", signum);
+}
+
+static void
+install_signal_handler(void)
+{
+    sigset_t sa_mask;
+    sigemptyset(&sa_mask);
+
+    struct sigaction const act =
+    {
+        .sa_handler = signal_handler,
+        .sa_mask    = sa_mask,
+        .sa_flags   = (int)SA_RESETHAND
+    };
+
+    if (sigaction(SIGINT /* Ctrl-C */, &act, NULL))
+    {
+        NODE_INFO("sigaction() failed: %d (%s)", errno, strerror(errno));
+        abort();
+    }
+}
+
+int main(int argc, char* argv[])
+{
+    install_signal_handler();
+
+    struct node_options opts;
+    int err = node_options_read(argc, argv, &opts);
+    if (err)
+    {
+        NODE_FATAL("Failed to read command line opritons: %d (%s)",
+                   err, strerror(err));
+        return err;
+    }
+
+    struct node_ctx node;
+    node.opts = &opts;
+
+    /* REPLICATION: before connecting to cluster we need to initialize our
+     *              storage to know our current position (GTID) */
+    node.store = node_store_open(&opts);
+    if (!node.store)
+    {
+        NODE_FATAL("Failed to open node store");
+        return 1;
+    }
+
+    wsrep_gtid_t current_gtid;
+    node_store_gtid(node.store, &current_gtid);
+
+    /* REPLICATION: complete initialization of application context
+     *              (including provider itself) */
+    node.wsrep = node_wsrep_init(&opts, &current_gtid, &node);
+    if (!node.wsrep)
+    {
+        NODE_FATAL("Failed to initialize wsrep provider");
+        return 1;
+    }
+
+    /* REPLICATION: now we can connect to the cluster and start receiving
+     *              replication events */
+    if (node_wsrep_connect(node.wsrep, opts.address, opts.bootstrap) !=
+        WSREP_OK)
+    {
+        NODE_FATAL("Failed to connect to primary component");
+        return 1;
+    }
+
+    /* REPLICATION: and start processing replicaiton events */
+    struct node_worker_pool* slave_pool =
+        node_worker_start(&node, NODE_WORKER_SLAVE, (size_t)opts.slaves);
+    if (!slave_pool)
+    {
+        NODE_FATAL("Failed to create slave worker pool");
+        return 1;
+    }
+
+    /* REPLICATION: now that replicaton events are being processed we can
+     *              wait to sync with the cluster */
+    if (!node_wsrep_wait_synced(node.wsrep))
+    {
+        NODE_ERROR("Failed to wait fir SYNCED event");
+        return 1;
+    }
+
+    NODE_INFO("Synced with cluster");
+
+    /* REPLICATION: now we can start replicate own events */
+    struct node_worker_pool* master_pool =
+        node_worker_start(&node, NODE_WORKER_MASTER, (size_t)opts.masters);
+    if (opts.masters > 0 && !master_pool)
+    {
+        NODE_FATAL("Failed to create master worker pool");
+        return 1;
+    }
+
+    node_stats_loop(&node, (int)opts.period);
+
+    /* REPLICATON: to shut down we go in the opposite order:
+     *             first  - disconnect from the cluster to signal master threads
+     *                      to exit loop,
+     *             second - join master and slave threads,
+     *             third  - close provider once not in use */
+    node_wsrep_disconnect(node.wsrep);
+
+    node_worker_stop(master_pool);
+    node_worker_stop(slave_pool);
+
+    node_wsrep_close(node.wsrep);
+
+    /* and finally, when the storage can no longer be disturbed, close it */
+    node_store_close(node.store);
+
+    return 0;
+}
diff --git a/wsrep-lib/wsrep-API/v26/examples/node/node.sh b/wsrep-lib/wsrep-API/v26/examples/node/node.sh
new file mode 100755
index 00000000..40e0a498
--- /dev/null
+++ b/wsrep-lib/wsrep-API/v26/examples/node/node.sh
@@ -0,0 +1,40 @@
+#!/bin/sh -eu
+
+NODE_ID=$1
+
+NODE_NAME=${NODE_NAME:-$NODE_ID}
+
+NODE_DIR=${NODE_DIR:-/tmp/node/$NODE_NAME}
+rm -rf $NODE_DIR/*
+mkdir -p $NODE_DIR
+
+NODE_OPT=${NODE_OPT:-}
+
+NODE_HOST=${NODE_HOST:-localhost}
+NODE_PORT=${NODE_PORT:-$((10000 + $NODE_ID))}
+
+NODE_CLIENTS=${NODE_CLIENTS:-1}
+NODE_APPLIERS=${NODE_APPLIERS:-1}
+
+NODE_ADDR=${NODE_ADDR:-}
+
+NODE_BIN=${NODE_BIN:-$(dirname $0)/node}
+
+# convert possible relative path to absolute path
+NODE_PROVIDER=$(realpath $NODE_PROVIDER)
+
+set -x
+
+$NODE_BIN \
+-v "$NODE_PROVIDER" \
+-n "$NODE_NAME" \
+-f "$NODE_DIR" \
+-o "$NODE_OPT" \
+-t "$NODE_HOST" \
+-p $NODE_PORT \
+-s $NODE_APPLIERS \
+-m $NODE_CLIENTS \
+-d 10 \
+-a "$NODE_ADDR"
+
+set +x
diff --git a/wsrep-lib/wsrep-API/v26/examples/node/options.c b/wsrep-lib/wsrep-API/v26/examples/node/options.c
new file mode 100644
index 00000000..0bd08ffb
--- /dev/null
+++ b/wsrep-lib/wsrep-API/v26/examples/node/options.c
@@ -0,0 +1,291 @@
+/* Copyright (c) 2019-2020, Codership Oy. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ */
+
+#include "options.h"
+
+#include <ctype.h>  // isspace()
+#include <errno.h>
+#include <getopt.h>
+#include <stdio.h>
+#include <stdlib.h> // strtol()
+#include <string.h> // strcmp()
+
+/*
+ * getopt_long() declarations begin
+ */
+
+#define OPTS_NA no_argument
+#define OPTS_RA required_argument
+#define OPTS_OA optional_argument
+
+typedef enum opt
+{
+    OPTS_NOOPT     = 0,
+    OPTS_ADDRESS   = 'a',
+    OPTS_BOOTSTRAP = 'b',
+    OPTS_DELAY     = 'd',
+    OPTS_DATA_DIR  = 'f',
+    OPTS_HELP      = 'h',
+    OPTS_PERIOD    = 'i',
+    OPTS_MASTERS   = 'm',
+    OPTS_NAME      = 'n',
+    OPTS_OPTIONS   = 'o',
+    OPTS_BASE_PORT = 'p',
+    OPTS_RECORDS   = 'r',
+    OPTS_SLAVES    = 's',
+    OPTS_BASE_HOST = 't',
+    OPTS_PROVIDER  = 'v',
+    OPTS_WS_SIZE   = 'w',
+    OPTS_OPS       = 'x'
+}
+    opt_t;
+
+static struct option s_opts[] =
+{
+    { "address",   OPTS_RA, NULL, OPTS_ADDRESS   },
+    { "bootstrap", OPTS_NA, NULL, OPTS_BOOTSTRAP },
+    { "delay",     OPTS_RA, NULL, OPTS_DELAY     },
+    { "storage",   OPTS_RA, NULL, OPTS_DATA_DIR  },
+    { "help",      OPTS_NA, NULL, OPTS_HELP      },
+    { "period",    OPTS_RA, NULL, OPTS_PERIOD    },
+    { "masters",   OPTS_RA, NULL, OPTS_MASTERS   },
+    { "name",      OPTS_RA, NULL, OPTS_NAME      },
+    { "options",   OPTS_RA, NULL, OPTS_OPTIONS,  },
+    { "base-port", OPTS_RA, NULL, OPTS_BASE_PORT },
+    { "records",   OPTS_RA, NULL, OPTS_RECORDS   },
+    { "slaves",    OPTS_RA, NULL, OPTS_SLAVES    },
+    { "base-host", OPTS_RA, NULL, OPTS_BASE_HOST },
+    { "provider",  OPTS_RA, NULL, OPTS_PROVIDER  },
+    { "size",      OPTS_RA, NULL, OPTS_WS_SIZE   },
+    { "ops",       OPTS_RA, NULL, OPTS_OPS       },
+    { NULL, 0, NULL, 0 }
+};
+
+static const char* opts_string = "a:d:f:hi:m:n:o:p:r:s:t:v:w:x:";
+
+/*
+ * getopt_long() declarations end
+ */
+
+static const struct node_options opts_defaults =
+{
+    .provider  = "none",
+    .address   = "",
+    .options   = "",
+    .name      = "unnamed",
+    .data_dir  = ".",
+    .base_host = "localhost",
+    .masters   = 0,
+    .slaves    = 1,
+    .ws_size   = 1024,
+    .records   = 1024*1024,
+    .delay     = 0,
+    .base_port = 4567,
+    .period    = 10,
+    .operations= 1,
+    .bootstrap = true
+};
+
+static void
+opts_print_help(FILE* out, const char* prog_name)
+{
+    fprintf(
+        out,
+        "Usage: %s [OPTION...]\n"
+        "\n"
+        "  -h, --help                 this thing.\n"
+        "  -v, --provider=PATH        a path to wsrep provider library file.\n"
+        "  -a, --address=STRING       list of node addresses in the group.\n"
+        "                             If not set the node assumes that it is the first\n"
+        "                             node in the group (default)\n"
+        "  -o, --options=STRING       a string of wsrep provider options.\n"
+        "  -n, --name=STRING          human-readable node name.\n"
+        "  -f, --data-dir=PATH        a directory to save working data in.\n"
+        "                             Should be private to the process.\n"
+        "  -t, --base-host=ADDRESS    address of this node at which other members can\n"
+        "                             connect to it\n"
+        "  -p, --base-port=NUM        base port which the node shall listen for\n"
+        "                             connections from other members. This port will be\n"
+        "                             used for replication, port+1 for IST and port+2\n"
+        "                             for SST. Default: 4567\n"
+        "  -m, --masters=NUM          number of concurrent master workers.\n"
+        "  -s, --slaves=NUM           number of concurrent slave workers.\n"
+        "                             (can't be less than 1)\n"
+        "  -w, --size=NUM             desirable size of the resulting writesets\n"
+        "                             (approximate lower boundary). Default: 1K\n"
+        "  -r, --records=NUM          number of records in the store. Default: 1M\n"
+        "  -x, --ops=NUM              number of operations per transaction. Default: 1\n"
+        "  -d, --delay=NUM            delay in milliseconds between \"commits\"\n"
+        "                             (per master thread).\n"
+        "  -b, --bootstrap            bootstrap the cluster with this node.\n"
+        "                             Default: 'Yes' if --address is not given, 'No'\n"
+        "                             otherwise.\n"
+        "  -i, --period               period in seconds between performance stats output\n"
+        "\n"
+        , prog_name);
+}
+
+static void
+opts_print_config(FILE* out, const struct node_options* opts)
+{
+    fprintf(
+        out,
+        "Continuing with the following configuration:\n"
+        "provider:      %s\n"
+        "address:       %s\n"
+        "options:       %s\n"
+        "name:          %s\n"
+        "data dir:      %s\n"
+        "base addr:     %s:%ld\n"
+        "masters:       %ld\n"
+        "slaves:        %ld\n"
+        "writeset size: %ld bytes\n"
+        "records:       %ld\n"
+        "operations:    %ld\n"
+        "commit delay:  %ld ms\n"
+        "stats period:  %ld s\n"
+        "bootstrap:     %s\n"
+        ,
+        opts->provider, opts->address, opts->options, opts->name, opts->data_dir,
+        opts->base_host, opts->base_port,
+        opts->masters, opts->slaves, opts->ws_size, opts->records,
+        opts->operations,
+        opts->delay, opts->period, opts->bootstrap ? "Yes" : "No"
+        );
+}
+
+static int
+opts_check_conversion(int cond, const char* ptr, int idx)
+{
+    if (!cond || errno || (*ptr != '\0' && !isspace(*ptr)))
+    {
+        fprintf(stderr, "Bad value for %s option.\n", s_opts[idx].name);
+        return EINVAL;
+    }
+    return 0;
+}
+
+int
+node_options_read(int argc, char* argv[], struct node_options* opts)
+{
+    *opts = opts_defaults;
+
+    int   opt = 0;
+    int   opt_idx = 0;
+    char* endptr;
+    int   ret = 0;
+
+    bool address_given   = false;
+    bool bootstrap_given = false;
+
+    while ((opt = getopt_long(argc, argv, opts_string, s_opts, &opt_idx)) != -1)
+    {
+        switch (opt)
+        {
+        case OPTS_ADDRESS:
+            address_given = strcmp(opts->address, optarg);
+            opts->address = optarg;
+            break;
+        case OPTS_BOOTSTRAP:
+            bootstrap_given = true;
+            opts->bootstrap = true;
+            break;
+        case OPTS_DELAY:
+            opts->delay = strtol(optarg, &endptr, 10);
+            if ((ret = opts_check_conversion(opts->delay >= 0, endptr, opt_idx)))
+                goto err;
+            break;
+        case OPTS_DATA_DIR:
+            opts->data_dir = optarg;
+            break;
+        case OPTS_HELP:
+            ret = 1;
+            goto help;
+        case OPTS_PERIOD:
+            opts->period = strtol(optarg, &endptr, 10);
+            if ((ret = opts_check_conversion(opts->period > 0, endptr, opt_idx)))
+                goto err;
+            break;
+        case OPTS_MASTERS:
+            opts->masters = strtol(optarg, &endptr, 10);
+            if ((ret = opts_check_conversion(opts->masters >= 0, endptr,
+                                             opt_idx)))
+                goto err;
+            break;
+        case OPTS_NAME:
+            opts->name = optarg;
+            break;
+        case OPTS_OPTIONS:
+            opts->options = optarg;
+            break;
+        case OPTS_BASE_PORT:
+            opts->base_port = strtol(optarg, &endptr, 10);
+            if ((ret = opts_check_conversion(
+                     opts->base_port > 0 && opts->base_port < 65536,
+                     endptr, opt_idx)))
+                goto err;
+            break;
+        case OPTS_RECORDS:
+            opts->records = strtol(optarg, &endptr, 10);
+            if ((ret = opts_check_conversion(opts->records >= 0, endptr,
+                                             opt_idx)))
+                goto err;
+            break;
+        case OPTS_SLAVES:
+            opts->slaves = strtol(optarg, &endptr, 10);
+            if ((ret = opts_check_conversion(opts->slaves > 0, endptr, opt_idx)))
+                goto err;
+            break;
+        case OPTS_BASE_HOST:
+            opts->base_host = optarg;
+            break;
+        case OPTS_PROVIDER:
+            opts->provider = optarg;
+            break;
+        case OPTS_WS_SIZE:
+            opts->ws_size = strtol(optarg, &endptr, 10);
+            if ((ret = opts_check_conversion(opts->ws_size > 0, endptr,
+                                             opt_idx)))
+                goto err;
+            break;
+        case OPTS_OPS:
+            opts->operations = strtol(optarg, &endptr, 10);
+            if ((ret = opts_check_conversion(opts->operations >= 1, endptr,
+                                             opt_idx)))
+                goto err;
+            break;
+        default:
+            ret = EINVAL;
+        }
+    }
+
+help:
+    if (ret) {
+        opts_print_help(stderr, argv[0]);
+    }
+    else
+    {
+        if (!bootstrap_given)
+        {
+            opts->bootstrap = !address_given;
+        }
+        opts_print_config(stdout, opts);
+        opts->delay  *= 1000;    /* convert to microseconds for usleep() */
+    }
+
+err:
+    return ret;
+}
diff --git a/wsrep-lib/wsrep-API/v26/examples/node/options.h b/wsrep-lib/wsrep-API/v26/examples/node/options.h
new file mode 100644
index 00000000..62172281
--- /dev/null
+++ b/wsrep-lib/wsrep-API/v26/examples/node/options.h
@@ -0,0 +1,48 @@
+/* Copyright (c) 2019-2020, Codership Oy. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ */
+
+/**
+ * @file This unit defines options interface
+ */
+
+#ifndef NODE_OPTIONS_H
+#define NODE_OPTIONS_H
+
+#include <stdbool.h>
+
+struct node_options
+{
+    const char* provider; // path to wsrep provider
+    const char* address;  // wsrep cluster address string
+    const char* options;  // wsrep option string
+    const char* name;     // node name (for logging purposes)
+    const char* data_dir; // name of the storage file
+    const char* base_host;// host own address
+    long        masters;  // number of master threads
+    long        slaves;   // number of slave threads
+    long        ws_size;  // desired writeset size
+    long        records;  // total number of records
+    long        delay;    // delay between commits
+    long        base_port;// base port to use
+    long        period;   // statistics output interval
+    long        operations;// number of "statements" in a "transaction"
+    bool        bootstrap;// bootstrap the cluster with this node
+};
+
+extern int
+node_options_read(int argc, char* argv[], struct node_options* opts);
+
+#endif /* NODE_OPTIONS_H */
diff --git a/wsrep-lib/wsrep-API/v26/examples/node/socket.c b/wsrep-lib/wsrep-API/v26/examples/node/socket.c
new file mode 100644
index 00000000..377abcaf
--- /dev/null
+++ b/wsrep-lib/wsrep-API/v26/examples/node/socket.c
@@ -0,0 +1,304 @@
+/* Copyright (c) 2019, Codership Oy. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ */
+
+#include "socket.h"
+
+#include "log.h"
+
+#include <assert.h>
+#include <ctype.h>      // isspace()
+#include <errno.h>
+#include <limits.h>     // USHRT_MAX
+#include <netdb.h>      // struct addrinfo
+#include <stdio.h>      // snprintf()
+#include <string.h>     // strerror()
+#include <sys/socket.h> // bind(), connect(), accept(), send(), recv()
+
+struct node_socket
+{
+    int fd;
+};
+
+/**
+ * Initializes addrinfo from the separate host address and port arguments
+ *
+ * Requires calling freeaddrinfo() later
+ *
+ * @param[in] host - if NULL, will be initialized for listening
+ * @param[in] port
+ *
+ * @return struct addrinfo* or NULL in case of error
+ */
+static struct addrinfo*
+socket_get_addrinfo2(const char* const host,
+                     uint16_t    const port)
+{
+    struct addrinfo const hints =
+    {
+        .ai_flags     = AI_PASSIVE |   /** will be ignored if host is not NULL */
+                        AI_NUMERICSERV, /** service is a numeric port */
+        .ai_family    = AF_UNSPEC,      /** either IPv4 or IPv6 */
+        .ai_socktype  = SOCK_STREAM,    /** STREAM or DGRAM */
+        .ai_protocol  = 0,
+        .ai_addrlen   = 0,
+        .ai_addr      = NULL,
+        .ai_canonname = NULL,
+        .ai_next      = NULL
+    };
+
+    char service[6];
+    snprintf(service, sizeof(service), "%hu", port);
+
+    struct addrinfo* info;
+    int err = getaddrinfo(host, service, &hints, &info);
+    if (err)
+    {
+        NODE_ERROR("Failed to resolve '%s': %d (%s)",
+                   host, err, gai_strerror(err));
+        return NULL;
+    }
+
+    return info;
+}
+
+/**
+ * Initializes addrinfo from single address and port string
+ * The port is expected to be in numerical form and appended to the host address
+ * via colon.
+ *
+ * Requires calling freeaddrinfo() later
+ *
+ * @param[in] addr full address specification, including port
+ *
+ * @return struct addrinfo* or NULL in case of error
+ */
+static struct addrinfo*
+socket_get_addrinfo1(const char* const addr)
+{
+    int   const addr_len = (int)strlen(addr);
+    char* const addr_buf = strdup(addr);
+    if (!addr_buf)
+    {
+        NODE_ERROR("strdup(%s) failed: %d (%s)", addr, errno, strerror(errno));
+        return NULL;
+    }
+
+    struct addrinfo* res = NULL;
+    long port;
+    char* endptr;
+
+    int i;
+    for (i = addr_len - 1; i >= 0; i--)
+    {
+        if (addr_buf[i] == ':') break;
+    }
+
+    if (addr_buf[i] != ':')
+    {
+        NODE_ERROR("Malformed address:port string: '%s'", addr);
+        goto end;
+    }
+
+    addr_buf[i] = '\0';
+    port = strtol(addr_buf + i + 1, &endptr, 10);
+
+    if (port <= 0 || port > USHRT_MAX || errno ||
+        (*endptr != '\0' && !isspace(*endptr)))
+    {
+        NODE_ERROR("Malformed/invalid port: '%s'. Errno: %d (%s)",
+                   addr_buf + i + 1, errno, strerror(errno));
+        goto end;
+    }
+
+    res = socket_get_addrinfo2(strlen(addr_buf) > 0 ? addr_buf : NULL,
+                               (uint16_t)port);
+end:
+    free(addr_buf);
+    return res;
+}
+
+static struct node_socket*
+socket_create(int const fd)
+{
+    assert(fd > 0);
+
+    struct node_socket* res = calloc(1, sizeof(struct node_socket));
+    if (res)
+    {
+        res->fd = fd;
+    }
+    else
+    {
+        NODE_ERROR("Failed to allocate struct node_socket: %d (%s)",
+                   errno, strerror(errno));
+        close(fd);
+    }
+
+    return res;
+}
+
+/**
+ * Definition of function type with the signature of bind() and connect()
+ */
+typedef int (*socket_act_fun_t) (int                    sfd,
+                                 const struct sockaddr* addr,
+                                 socklen_t              addrlen);
+
+static int
+socket_bind_and_listen(int                    const sfd,
+                       const struct sockaddr* const addr,
+                       socklen_t              const addrlen)
+{
+    int ret = bind(sfd, addr, addrlen);
+
+    if (!ret)
+        ret = listen(sfd, SOMAXCONN);
+
+    return ret;
+}
+
+/**
+ * A "template" method to do the "right thing" with the addrinfo and create a
+ * socket from it. The "right thing" would normally be bind and listen for
+ * a server socket OR connect for a client socket.
+ *
+ * @param[in] info       addrinfo list, swallowed and deallocated
+ * @param[in] action_fun the "right thing" to do on socket and struct sockaddr
+ * @param[in] action_str action description to be printed in the error message
+ * @param[in] orig_host  host address to be pronted in the error message
+ * @param[in] orig_port  port to be printed in the error message, if orig_host
+ *                       string contains the port, this parameter should be 0
+ *
+ * The last three parameters are for diagnostic puposes only. orig_host and
+ * orig_port are supposed to be what were used to obtain addrinfo.
+ *
+ * @return new struct node_socket.
+ */
+static struct node_socket*
+socket_from_addrinfo(struct addrinfo* const info,
+                     socket_act_fun_t const action_fun,
+                     const char*      const action_str,
+                     const char*      const orig_host,
+                     uint16_t         const orig_port)
+{
+    int sfd;
+    int err = 0;
+
+    /* Iterate over addrinfo list and try to apply action_fun on the resulting
+     * socket. Once successful, break loop. */
+    struct addrinfo* addr;
+    for (addr = info; addr != NULL; addr = addr->ai_next)
+    {
+        sfd = socket(addr->ai_family, addr->ai_socktype, addr->ai_protocol);
+        if (sfd == -1)
+        {
+            err = errno;
+            continue;
+        }
+
+        if (action_fun(sfd, addr->ai_addr, addr->ai_addrlen) == 0) break;
+
+        err = errno;
+        close(sfd);
+    }
+
+    freeaddrinfo(info); /* no longer needed */
+
+    if (!addr)
+    {
+        NODE_ERROR("Failed to %s to '%s%s%.0hu': %d (%s)",
+                   action_str,
+                   orig_host ? orig_host : "", orig_port > 0 ? ":" : "",
+                   orig_port > 0 ? orig_port : 0, /* won't be printed if 0 */
+                   err, strerror(err));
+        return NULL;
+    }
+
+    assert(sfd > 0);
+    return socket_create(sfd);
+}
+
+struct node_socket*
+node_socket_listen(const char* const host, uint16_t const port)
+{
+    struct addrinfo* const info = socket_get_addrinfo2(host, port);
+    if (!info) return NULL;
+
+    return socket_from_addrinfo(info, socket_bind_and_listen,
+                                "bind a listening socket", host, port);
+}
+
+struct node_socket*
+node_socket_connect(const char* const addr_str)
+{
+    struct addrinfo* const info = socket_get_addrinfo1(addr_str);
+    if (!info) return NULL;
+
+    return socket_from_addrinfo(info, connect, "connect", addr_str, 0);
+}
+
+struct node_socket*
+node_socket_accept(struct node_socket* socket)
+{
+    int sfd = accept(socket->fd, NULL, NULL);
+
+    if (sfd < 0)
+    {
+        NODE_ERROR("Failed to accept connection: %d (%s)",
+                   errno, strerror(errno));
+        return NULL;
+    }
+
+    return socket_create(sfd);
+}
+
+int
+node_socket_send_bytes(node_socket_t* socket, const void* buf, size_t len)
+{
+    ssize_t const ret = send(socket->fd, buf, len, MSG_NOSIGNAL);
+
+    if (ret != (ssize_t)len)
+    {
+        NODE_ERROR("Failed to send %zu bytes: %d (%s)", errno, strerror(errno));
+        return -1;
+    }
+
+    return 0;
+}
+
+int
+node_socket_recv_bytes(node_socket_t* socket, void* buf, size_t len)
+{
+    ssize_t const ret = recv(socket->fd, buf, len, MSG_WAITALL);
+
+    if (ret != (ssize_t)len)
+    {
+        NODE_ERROR("Failed to recv %zu bytes: %d (%s)", errno, strerror(errno));
+        return -1;
+    }
+
+    return 0;
+}
+
+void
+node_socket_close(node_socket_t* socket)
+{
+    if (!socket) return;
+
+    if (socket->fd > 0) close(socket->fd);
+
+    free(socket);
+}
diff --git a/wsrep-lib/wsrep-API/v26/examples/node/socket.h b/wsrep-lib/wsrep-API/v26/examples/node/socket.h
new file mode 100644
index 00000000..3a77eff3
--- /dev/null
+++ b/wsrep-lib/wsrep-API/v26/examples/node/socket.h
@@ -0,0 +1,72 @@
+/* Copyright (c) 2019, Codership Oy. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ */
+
+/**
+ * @file This unit implements auxiliary networking functions (for SST purposes)
+ *       It has nothing wsrep related and is not of general purpose.
+ */
+
+#ifndef NODE_SOCKET_H
+#define NODE_SOCKET_H
+
+#include <stddef.h> // size_t
+#include <stdint.h> // uint16_t
+
+typedef struct node_socket node_socket_t;
+
+/**
+ * Open listening socket at a given address
+ *
+ * @return listening socket
+ */
+extern node_socket_t*
+node_socket_listen(const char* host, uint16_t port);
+
+/**
+ * Connect to a given address.
+ *
+ * @return connected socket
+ */
+extern node_socket_t*
+node_socket_connect(const char* addr);
+
+/**
+ * Wait for connection on a listening socket
+ * @return connected socket
+ */
+extern node_socket_t*
+node_socket_accept(node_socket_t* s);
+
+/**
+ * Send a given number of bytes
+ * @return 0 or a negative error code
+ */
+extern int
+node_socket_send_bytes(node_socket_t* s, const void* buf, size_t len);
+
+/**
+ * Receive a given number of bytes
+ * @return 0 or a negative error code
+ */
+extern int
+node_socket_recv_bytes(node_socket_t* s, void* buf, size_t len);
+
+/**
+ * Release all recources associated with the socket */
+extern void
+node_socket_close(node_socket_t* s);
+
+#endif /* NODE_SOCKET_H */
diff --git a/wsrep-lib/wsrep-API/v26/examples/node/sst.c b/wsrep-lib/wsrep-API/v26/examples/node/sst.c
new file mode 100644
index 00000000..e93534ef
--- /dev/null
+++ b/wsrep-lib/wsrep-API/v26/examples/node/sst.c
@@ -0,0 +1,372 @@
+/* Copyright (c) 2019, Codership Oy. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ */
+
+#include "sst.h"
+
+#include "ctx.h"
+#include "log.h"
+#include "socket.h"
+
+#include <arpa/inet.h> // htonl()
+#include <assert.h>
+#include <errno.h>
+#include <pthread.h>
+#include <stdio.h>  // snprintf()
+#include <stdlib.h> // abort()
+#include <string.h> // strdup()
+#include <unistd.h> // usleep()
+
+/**
+ * Helper: creates detached thread */
+static int
+sst_create_thread(void* (*thread_routine) (void*),
+                  void* const thread_arg)
+{
+    pthread_t thr;
+    pthread_attr_t attr;
+    int ret = pthread_attr_init(&attr);
+    ret = ret ? ret : pthread_attr_setdetachstate(&attr,PTHREAD_CREATE_DETACHED);
+    ret = ret ? ret : pthread_create(&thr, &attr, thread_routine, thread_arg);
+    return ret;
+}
+
+/**
+ * Helper: creates detached thread and waits for it to call
+ *         sst_sync_with_parent() */
+static void
+sst_create_and_sync(const char*      const role,
+                    pthread_mutex_t* const mtx,
+                    pthread_cond_t*  const cond,
+                    void* (*thread_routine) (void*),
+                    void*            const thread_arg)
+{
+    int ret = pthread_mutex_lock(mtx);
+    if (ret)
+    {
+        NODE_FATAL("Failed to lock %s mutex: %d (%s)", role, ret, strerror(ret));
+        abort();
+    }
+
+    ret = sst_create_thread(thread_routine, thread_arg);
+    if (ret)
+    {
+        NODE_FATAL("Failed to create detached %s thread: %d (%s)",
+                   role, ret, strerror(ret));
+        abort();
+    }
+
+    ret = pthread_cond_wait(cond, mtx);
+    if (ret)
+    {
+        NODE_FATAL("Failed to synchronize with %s thread: %d (%s)",
+                   role, ret, strerror(ret));
+        abort();
+    }
+
+    pthread_mutex_unlock(mtx);
+}
+
+/**
+ * Helper: syncs with parent thread and allows it to continue and return
+ *         asynchronously */
+static void
+sst_sync_with_parent(const char*      role,
+                     pthread_mutex_t* mtx,
+                     pthread_cond_t*  cond)
+{
+    int ret = pthread_mutex_lock(mtx);
+    if (ret)
+    {
+        NODE_FATAL("Failed to lock %s mutex: %d (%s)", role, ret, strerror(ret));
+        abort();
+    }
+
+    NODE_INFO("Initialized %s thread", role);
+
+    pthread_cond_signal(cond);
+    pthread_mutex_unlock(mtx);
+}
+
+static pthread_mutex_t sst_joiner_mtx  = PTHREAD_MUTEX_INITIALIZER;
+static pthread_cond_t  sst_joiner_cond = PTHREAD_COND_INITIALIZER;
+
+struct sst_joiner_ctx
+{
+    struct node_ctx* node;
+    node_socket_t*   socket;
+};
+
+/**
+ * waits for SST completion and signals the provider to continue */
+static void*
+sst_joiner_thread(void* ctx)
+{
+    assert(ctx);
+
+    struct node_ctx* const node   = ((struct sst_joiner_ctx*)ctx)->node;
+    node_socket_t* const   listen = ((struct sst_joiner_ctx*)ctx)->socket;
+    ctx = NULL; /* may be unusable after next statement */
+
+    /* this allows parent callback to return */
+    sst_sync_with_parent("JOINER", &sst_joiner_mtx, &sst_joiner_cond);
+
+    wsrep_gtid_t state_gtid = WSREP_GTID_UNDEFINED;
+    int err = -1;
+
+    /* REPLICATION: wait for donor to connect and send the state snapshot */
+    node_socket_t* const connected = node_socket_accept(listen);
+    if (!connected) goto end;
+
+    uint32_t state_len;
+    err = node_socket_recv_bytes(connected, &state_len, sizeof(state_len));
+    if (err) goto end;
+
+    state_len = ntohl(state_len);
+    if (state_len > 0)
+    {
+        /* REPLICATION: get the state of state_len size */
+        void* state = malloc(state_len);
+        if (state)
+        {
+            err = node_socket_recv_bytes(connected, state, state_len);
+            if (err)
+            {
+                free(state);
+                goto end;
+            }
+
+            /* REPLICATION: install the newly received state. */
+            err = node_store_init_state(node->store, state, state_len);
+            free(state);
+            if (err) goto end;
+        }
+        else
+        {
+            NODE_ERROR("Failed to allocate %zu bytes for state snapshot.",
+                       state_len);
+            err = -ENOMEM;
+            goto end;
+        }
+    }
+    else
+    {
+        /* REPLICATION: it was a bypass, the node will receive missing data via
+         *              IST. It starts with the state it currently has. */
+    }
+
+    /* REPLICATION: find gtid of the received state to report to provider */
+    node_store_gtid(node->store, &state_gtid);
+
+end:
+    assert(err <= 0);
+    node_socket_close(connected);
+    node_socket_close(listen);
+
+    /* REPLICATION: tell provider that SST is received */
+    wsrep_status_t sst_ret;
+    wsrep_t* const wsrep = node_wsrep_provider(node->wsrep);
+    sst_ret = wsrep->sst_received(wsrep, &state_gtid, NULL, err);
+
+    if (WSREP_OK != sst_ret)
+    {
+        NODE_FATAL("Failed to report completion of SST: %d", sst_ret);
+        abort();
+    }
+
+    return NULL;
+}
+
+enum wsrep_cb_status
+node_sst_request_cb (void*   const app_ctx,
+                     void**  const sst_req,
+                     size_t* const sst_req_len)
+{
+    static int const SST_PORT_OFFSET = 2;
+
+    assert(app_ctx);
+    struct node_ctx* const node = app_ctx;
+    const struct node_options* const opts = node->opts;
+
+    char* sst_str = NULL;
+
+    /* REPLICATION: 1. prepare the node to receive SST */
+    uint16_t const sst_port = (uint16_t)(opts->base_port + SST_PORT_OFFSET);
+    size_t const sst_len = strlen(opts->base_host)
+        + 1 /* ':' */ + 5 /* max port len */ + 1 /* \0 */;
+    sst_str = malloc(sst_len);
+    if (!sst_str)
+    {
+        NODE_ERROR("Failed to allocate %zu bytes for SST request", sst_len);
+        goto end;
+    }
+
+    /* write in request the address at which we listen */
+    int ret = snprintf(sst_str, sst_len, "%s:%hu", opts->base_host, sst_port);
+    if (ret < 0 || (size_t)ret >= sst_len)
+    {
+        free(sst_str);
+        sst_str = NULL;
+        NODE_ERROR("Failed to write a SST request");
+        goto end;
+    }
+
+    node_socket_t* const socket = node_socket_listen(NULL, sst_port);
+    if (!socket)
+    {
+        free(sst_str);
+        sst_str = NULL;
+        NODE_ERROR("Failed to listen at %s", sst_str);
+        goto end;
+    }
+
+    /* REPLICATION 2. start the "joiner" thread that will wait for SST and
+     *                report its success to provider, and syncronize with it. */
+    struct sst_joiner_ctx ctx =
+        {
+            .node   = node,
+            .socket = socket
+        };
+    sst_create_and_sync("JOINER", &sst_joiner_mtx, &sst_joiner_cond,
+                        sst_joiner_thread, &ctx);
+
+    NODE_INFO("Waiting for SST at %s", sst_str);
+
+end:
+    if (sst_str)
+    {
+        *sst_req     = sst_str;
+        *sst_req_len = strlen(sst_str) + 1;
+    }
+    else
+    {
+        *sst_req     = NULL;
+        *sst_req_len = 0;
+        return WSREP_CB_FAILURE;
+    }
+
+    /* REPLICATION 3. return SST request to provider */
+    return WSREP_CB_SUCCESS;
+}
+
+static pthread_mutex_t sst_donor_mtx  = PTHREAD_MUTEX_INITIALIZER;
+static pthread_cond_t  sst_donor_cond = PTHREAD_COND_INITIALIZER;
+
+struct sst_donor_ctx
+{
+    wsrep_gtid_t     state;
+    struct node_ctx* node;
+    node_socket_t*   socket;
+    wsrep_bool_t     bypass;
+};
+
+/**
+ * donates SST and signals provider that it is done. */
+static void*
+sst_donor_thread(void* const args)
+{
+    struct sst_donor_ctx const ctx = *(struct sst_donor_ctx*)args;
+
+    int err = 0;
+    const void* state;
+    size_t state_len;
+
+    if (ctx.bypass)
+    {
+        /* REPLICATION: if bypass is true, there is no need to send snapshot,
+         *              just signal the joiner that snapshot is not needed and
+         *              it can proceed to apply IST. We'll do it by sending 0
+         *              for the size of snapshot */
+        state = NULL;
+        state_len = 0;
+    }
+    else
+    {
+        /* REPLICATION: if bypass is false, we need to send a full state snapshot
+         *              Get hold of the state, which is currently just GTID
+         *              NOTICE that while parent is waiting, the store is in a
+         *              quiescent state, provider blocking any modifications. */
+        err = node_store_acquire_state(ctx.node->store, &state, &state_len);
+        if (state_len > UINT32_MAX) err = -ERANGE;
+    }
+
+    /* REPLICATION: after getting hold of the state we can allow parent callback
+     *              to return and the node to resume its normal operation */
+    sst_sync_with_parent("DONOR", &sst_donor_mtx, &sst_donor_cond);
+
+    if (err >= 0)
+    {
+        uint32_t tmp = htonl((uint32_t)state_len);
+        err = node_socket_send_bytes(ctx.socket, &tmp, sizeof(tmp));
+    }
+
+    if (state_len != 0)
+    {
+        if (err >= 0)
+        {
+            assert(state);
+            err = node_socket_send_bytes(ctx.socket, state, state_len);
+        }
+
+        node_store_release_state(ctx.node->store);
+    }
+
+    node_socket_close(ctx.socket);
+
+    /* REPLICATION: signal provider the success of the operation */
+    wsrep_t* const wsrep = node_wsrep_provider(ctx.node->wsrep);
+    wsrep->sst_sent(wsrep, &ctx.state, err);
+
+    return NULL;
+}
+
+enum wsrep_cb_status
+node_sst_donate_cb (void*               const app_ctx,
+                    void*               const recv_ctx,
+                    const wsrep_buf_t*  const str_msg,
+                    const wsrep_gtid_t* const state_id,
+                    const wsrep_buf_t*  const state,
+                    wsrep_bool_t        const bypass)
+{
+    (void)recv_ctx;
+    (void)state;
+
+    struct sst_donor_ctx ctx =
+    {
+        .node   = app_ctx,
+        .state  = *state_id,
+        .bypass = bypass
+    };
+
+    /* we are expecting a human-readable 0-terminated string  */
+    void* p = memchr(str_msg->ptr, '\0', str_msg->len);
+    if (!p)
+    {
+        NODE_ERROR("Received a badly formed State Transfer Request.");
+        /* REPLICATION: in case of a failure we return the status to provider, so
+         *              that the joining node can be notified of it by cluster */
+        return WSREP_CB_FAILURE;
+    }
+
+    const char* addr = str_msg->ptr;
+    ctx.socket = node_socket_connect(addr);
+
+    if (!ctx.socket) return WSREP_CB_FAILURE;
+
+    sst_create_and_sync("DONOR", &sst_donor_mtx, &sst_donor_cond,
+                        sst_donor_thread, &ctx);
+
+    return WSREP_CB_SUCCESS;
+}
diff --git a/wsrep-lib/wsrep-API/v26/examples/node/sst.h b/wsrep-lib/wsrep-API/v26/examples/node/sst.h
new file mode 100644
index 00000000..7006a1b6
--- /dev/null
+++ b/wsrep-lib/wsrep-API/v26/examples/node/sst.h
@@ -0,0 +1,39 @@
+/* Copyright (c) 2019, Codership Oy. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ */
+
+/**
+ * @file This unit defines SST interface
+ */
+
+#ifndef NODE_SST_H
+#define NODE_SST_H
+
+#include "../../wsrep_api.h"
+
+extern enum wsrep_cb_status
+node_sst_request_cb (void*   app_ctx,
+                     void**  sst_req,
+                     size_t* sst_req_len);
+
+extern enum wsrep_cb_status
+node_sst_donate_cb (void*               app_ctx,
+                    void*               recv_ctx,
+                    const wsrep_buf_t*  str_msg,
+                    const wsrep_gtid_t* state_id,
+                    const wsrep_buf_t*  state,
+                    wsrep_bool_t        bypass);
+
+#endif /* NODE_SST_H */
diff --git a/wsrep-lib/wsrep-API/v26/examples/node/stats.c b/wsrep-lib/wsrep-API/v26/examples/node/stats.c
new file mode 100644
index 00000000..4b02240f
--- /dev/null
+++ b/wsrep-lib/wsrep-API/v26/examples/node/stats.c
@@ -0,0 +1,215 @@
+/* Copyright (c) 2019-2020, Codership Oy. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ */
+
+#include "stats.h"
+
+#include "log.h"
+
+#include <assert.h>
+#include <errno.h>
+#include <stdio.h>  // snprintf()
+#include <stdlib.h> // abort()
+#include <string.h> // strcmp()
+#include <unistd.h> // usleep()
+
+enum
+{
+    STATS_REPL_BYTE,
+    STATS_REPL_WS,
+    STATS_RECV_BYTE,
+    STATS_RECV_WS,
+    STATS_TOTAL_BYTE,
+    STATS_TOTAL_WS,
+    STATS_CERT_FAILS,
+    STATS_STORE_FAILS,
+    STATS_FC_PAUSED,
+    STATS_MAX
+};
+
+static const char* const stats_legend[STATS_MAX] =
+{
+    " repl(B/s)",
+    " repl(W/s)",
+    " recv(B/s)",
+    " recv(W/s)",
+    "total(B/s)",
+    "total(W/s)",
+    " cert.fail",
+    " stor.fail",
+    " paused(%)"
+};
+
+/* stats IDs in provider output - provider dependent, here we use Galera's */
+static const char* const galera_ids[STATS_MAX] =
+{
+    "replicated_bytes",       /**<  STATS_REPL_BYTE  */
+    "replicated",             /**<  STATS_REPL_WS    */
+    "received_bytes",         /**<  STATS_RECV_BYTE  */
+    "received",               /**<  STATS_RECV_WS    */
+    "",                       /**<  STATS_TOTAL_BYTE */
+    "",                       /**<  STATS_TOTAL_WS   */
+    "local_cert_failures",    /**<  STATS_CERT_FAILS */
+    "",                       /**<  STATS_STORE_FAILS */
+    "flow_control_paused_ns"  /**<  STATS_FC_PAUSED  */
+};
+
+/* maps local stats IDs to provider stat IDs */
+static int stats_galera_map[STATS_MAX];
+
+/**
+ * Helper to map provider stats to own stats set */
+static void
+stats_establish_mapping(wsrep_t* const wsrep)
+{
+    int const magic_map = -1;
+    size_t i;
+    for (i = 0; i < sizeof(stats_galera_map)/sizeof(stats_galera_map[0]); i++)
+    {
+        stats_galera_map[i] = magic_map; /* initialize map array */
+    }
+
+    struct wsrep_stats_var* const stats = wsrep->stats_get(wsrep);
+
+    /* to compensate for STATS_TOTAL_* and STATS_STORE_FAILS having no
+     * counterparts */
+    int mapped = 3;
+
+    i = 0;
+    while (stats[i].name) /* stats array is terminated by Null name */
+    {
+        int j;
+        for (j = 0; j < STATS_MAX; j++)
+        {
+            if (magic_map == stats_galera_map[j] /* j-th member still unset */
+                &&
+                !strcmp(stats[i].name, galera_ids[j]))
+            {
+                stats_galera_map[j] = (int)i;
+                mapped++;
+                if (STATS_MAX == mapped) /* all mapped */ goto out;
+            }
+        }
+
+        i++;
+    }
+
+out:
+    wsrep->stats_free(wsrep, stats);
+}
+
+static void
+stats_get(node_store_t* const store, wsrep_t* const wsrep, long long stats[])
+{
+    stats[STATS_STORE_FAILS] = node_store_read_view_failures(store);
+
+    struct wsrep_stats_var* const ret = wsrep->stats_get(wsrep);
+    if (!ret)
+    {
+        NODE_FATAL("wsrep::stats_get() call failed.");
+        abort();
+    }
+
+    int i;
+    for (i = 0; i < STATS_MAX; i++)
+    {
+        int j = stats_galera_map[i];
+        if (j >= 0)
+        {
+            assert(WSREP_VAR_INT64 == ret[j].type);
+            stats[i] = ret[j].value._int64;
+        }
+    }
+
+    wsrep->stats_free(wsrep, ret);
+
+    // totals are just sums
+    stats[STATS_TOTAL_BYTE] = stats[STATS_REPL_BYTE] + stats[STATS_RECV_BYTE];
+    stats[STATS_TOTAL_WS  ] = stats[STATS_REPL_WS  ] + stats[STATS_RECV_WS  ];
+}
+
+static void
+stats_print(long long bef[], long long aft[], double period)
+{
+    double rate[STATS_MAX];
+    int i;
+    for (i = 0; i < STATS_MAX; i++)
+    {
+        rate[i] = (double)(aft[i] - bef[i])/period;
+    }
+    rate[STATS_FC_PAUSED] /= 1.0e+07; // nanoseconds to % of seconds
+
+    char   str[256];
+    int    written = 0;
+
+    /* first line write legend */
+    for (i = 0; i < STATS_MAX; i++)
+    {
+        size_t const space_left = sizeof(str) - (size_t)written;
+        written += snprintf(&str[written], space_left, "%s", stats_legend[i]);
+    }
+
+    str[written] = '\n';
+    written++;
+
+    /* second line write values */
+    for (i = 0; i < STATS_MAX; i++)
+    {
+        size_t const space_left = sizeof(str) - (size_t)written;
+        long long const value   = (long long)rate[i];
+        written += snprintf(&str[written], space_left, " %9lld", value);
+    }
+
+    str[written] = '\0';
+
+    /* use logging macro for timestamp */
+    NODE_INFO("\n%s", str);
+}
+
+void
+node_stats_loop(const struct node_ctx* const node, int const period)
+{
+    double     const period_sec  = period;
+    useconds_t const period_usec = (useconds_t)period * 1000000;
+
+    wsrep_t* const wsrep = node_wsrep_provider(node->wsrep);
+    stats_establish_mapping(wsrep);
+
+    long long stats1[STATS_MAX];
+    long long stats2[STATS_MAX];
+
+    stats_get(node->store, wsrep, stats1);
+
+    while (1)
+    {
+        if (usleep(period_usec)) break;
+        stats_get(node->store, wsrep, stats2);
+        stats_print(stats1, stats2, period_sec);
+
+        if (usleep(period_usec)) break;
+        stats_get(node->store, wsrep, stats1);
+        stats_print(stats2, stats1, period_sec);
+    }
+
+    if (EINTR != errno)
+    {
+        NODE_ERROR("Unexpected usleep(%lld) error: %d (%s)",
+                   (long long)period_usec, errno, strerror(errno));
+    }
+    else
+    {
+        /* interrupted by signal */
+    }
+}
diff --git a/wsrep-lib/wsrep-API/v26/examples/node/stats.h b/wsrep-lib/wsrep-API/v26/examples/node/stats.h
new file mode 100644
index 00000000..f7ab7ef4
--- /dev/null
+++ b/wsrep-lib/wsrep-API/v26/examples/node/stats.h
@@ -0,0 +1,35 @@
+/* Copyright (c) 2019, Codership Oy. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ */
+
+/**
+ * @file This unit defines performance statistics loop
+ */
+
+#ifndef NODE_STATS_H
+#define NODE_STATS_H
+
+#include "ctx.h"
+
+/**
+ * Prints out statistics with a given period.
+ *
+ * @param[in] node   node context
+ * @param[in] period in seconds
+ */
+extern void
+node_stats_loop(const struct node_ctx* node, int period);
+
+#endif /* NODE_STATS_H */
diff --git a/wsrep-lib/wsrep-API/v26/examples/node/store.c b/wsrep-lib/wsrep-API/v26/examples/node/store.c
new file mode 100644
index 00000000..1dc2d6c1
--- /dev/null
+++ b/wsrep-lib/wsrep-API/v26/examples/node/store.c
@@ -0,0 +1,1044 @@
+/* Copyright (c) 2019-2020, Codership Oy. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ */
+
+#include "store.h"
+
+#include "log.h"
+
+#include <assert.h>
+#include <errno.h>
+#include <pthread.h>
+#include <stdbool.h>
+#include <stddef.h>   // ptrdiff_t
+#include <stdint.h>   // uintptr_t
+#include <stdlib.h>   // abort()
+#include <string.h>   // memset()
+
+#define DECLARE_SERIALIZE_INT(INTTYPE)                                  \
+    static inline size_t                                                \
+    store_serialize_##INTTYPE(void* const to, INTTYPE##_t const from)   \
+    {                                                                   \
+        memcpy(to, &from, sizeof(from)); /* for simplicity ignore endianness */ \
+        return sizeof(from);                                            \
+    }
+
+DECLARE_SERIALIZE_INT(uint32);
+DECLARE_SERIALIZE_INT(int64);
+
+#define DECLARE_DESERIALIZE_INT(INTTYPE)                                \
+    static inline size_t                                                \
+    store_deserialize_##INTTYPE(INTTYPE##_t* const to, const void* const from) \
+    {                                                                   \
+        memcpy(to, from, sizeof(*to)); /* for simplicity ignore endianness */ \
+        return sizeof(*to);                                             \
+    }
+
+DECLARE_DESERIALIZE_INT(uint32);
+DECLARE_DESERIALIZE_INT(int64);
+
+typedef struct record
+{
+    wsrep_seqno_t version;
+    uint32_t      value;
+    /* this order ensures that there is no padding between the members */
+}
+record_t;
+
+#define STORE_RECORD_SIZE \
+    (sizeof(((record_t*)(NULL))->version) + sizeof(((record_t*)(NULL))->value))
+
+static inline size_t
+store_record_set(void*           const base,
+                 size_t          const index,
+                 const record_t* const record)
+{
+    char* const position = (char*)base + index*STORE_RECORD_SIZE;
+    memcpy(position, record, STORE_RECORD_SIZE);
+    return STORE_RECORD_SIZE;
+}
+
+static inline size_t
+store_record_get(const void*     const base,
+                 size_t          const index,
+                 record_t*       const record)
+{
+    const char* const position = (const char*)base + index*STORE_RECORD_SIZE;
+    memcpy(record, position, STORE_RECORD_SIZE);
+    return STORE_RECORD_SIZE;
+}
+
+static inline bool
+store_record_equal(const record_t* const lhs, const record_t* const rhs)
+{
+    return (lhs->version == rhs->version) && (lhs->value == rhs->value);
+}
+
+/* transaction context */
+struct store_trx_op
+{
+    /* Normally what we'd need for transaction context is the record index and
+     * new record value. Here we also save read view snapshot (rec_from & rec_to)
+     * to
+     * 1. test provider certification correctness if provider supports read view
+     * 2. if not, detect conflicts at a store level. */
+    record_t rec_from;
+    record_t rec_to;
+    uint32_t idx_from;
+    uint32_t idx_to;
+    uint32_t new_value;
+    uint32_t size; /* nominal "size" of operation to manipulate on-the-wire
+                    * writeset size. */
+};
+
+#define STORE_OP_SIZE (STORE_RECORD_SIZE + STORE_RECORD_SIZE +           \
+                       sizeof(((struct store_trx_op*)NULL)->idx_from) +  \
+                       sizeof(((struct store_trx_op*)NULL)->idx_to) +    \
+                       sizeof(((struct store_trx_op*)NULL)->new_value) + \
+                       sizeof(((struct store_trx_op*)NULL)->size))
+
+struct store_trx_ctx
+{
+    wsrep_gtid_t         rv_gtid;
+    size_t               ops_num;
+    struct store_trx_op* ops;
+};
+
+static inline bool
+store_trx_add_op(struct store_trx_ctx* const trx)
+{
+    struct store_trx_op* const new_ops =
+        realloc(trx->ops, sizeof(struct store_trx_op)*(trx->ops_num + 1));
+
+    if (new_ops)
+    {
+        trx->ops = new_ops;
+#ifndef NDEBUG
+        memset(&trx->ops[trx->ops_num], 0, sizeof(*trx->ops));
+#endif
+        trx->ops_num++;
+    }
+
+    return (NULL == new_ops);
+}
+
+struct store_trx_entry
+{
+    bool                 used;
+    struct store_trx_ctx ctx;
+};
+
+typedef wsrep_uuid_t member_t;
+
+struct node_store
+{
+    wsrep_gtid_t    gtid;
+    pthread_mutex_t gtid_mtx;
+    wsrep_trx_id_t  trx_id;
+    pthread_mutex_t trx_id_mtx;
+    char*           snapshot;
+    member_t*       members;
+    void*           records;
+    size_t          op_size;
+    long            read_view_fails;
+    uint32_t        members_num;
+    uint32_t        records_num;
+    uint32_t        entries_mask;
+    bool            read_view_support; // read view support by cluster
+    /* trx pool piggybacked */
+};
+
+node_store_t*
+node_store_open(const struct node_options* const opts)
+{
+    /* make the size of trx pool the next highest power of 2 over the total
+     * number of workers */
+    uint32_t trx_pool_mask = (uint32_t)(opts->masters + opts->slaves);
+    if (trx_pool_mask > 0)
+    {
+        trx_pool_mask -= 1;
+        trx_pool_mask |= trx_pool_mask >> 1;
+        trx_pool_mask |= trx_pool_mask >> 2;
+        trx_pool_mask |= trx_pool_mask >> 4;
+        trx_pool_mask |= trx_pool_mask >> 8;
+        trx_pool_mask |= trx_pool_mask >> 16;
+    }
+    assert(((trx_pool_mask + 1) & trx_pool_mask) == 0); // 2^n - 1
+
+    size_t const desired_op_size = (size_t)(opts->ws_size/opts->operations);
+    size_t const op_size = (desired_op_size > STORE_OP_SIZE ?
+                            desired_op_size : STORE_OP_SIZE);
+
+    /* since the number of workers will never change, we can allocate trx pool
+     * together with the main store struc */
+    size_t const store_alloc_size = sizeof(struct node_store) +
+        /* op_size - additional buffer for op serialization per trx */
+        (sizeof(struct store_trx_entry) + op_size)*(trx_pool_mask + 1);
+
+    struct node_store* const ret = malloc(store_alloc_size);
+
+    if (ret)
+    {
+        memset(ret, 0, store_alloc_size);
+        ret->records = malloc((size_t)opts->records * STORE_RECORD_SIZE);
+
+        if (ret->records)
+        {
+            ret->gtid = WSREP_GTID_UNDEFINED;
+            pthread_mutex_init(&ret->gtid_mtx, NULL);
+            pthread_mutex_init(&ret->trx_id_mtx, NULL);
+            ret->op_size      = op_size;
+            ret->records_num  = (uint32_t)opts->records;
+            ret->entries_mask = trx_pool_mask;
+
+            uint32_t i;
+            for (i = 0; i < ret->records_num; i++)
+            {
+                /* keep state in serialized form for easy snapshotting */
+                struct record const record = { WSREP_SEQNO_UNDEFINED, i };
+                store_record_set(ret->records, i, &record);
+            }
+
+            return ret;
+        }
+        else
+        {
+            free(ret);
+        }
+    }
+
+    return NULL;
+}
+
+void
+node_store_close(struct node_store* const store)
+{
+    assert(store);
+    assert(store->records);
+    pthread_mutex_destroy(&store->gtid_mtx);
+    pthread_mutex_destroy(&store->trx_id_mtx);
+    free(store->records);
+    free(store->members);
+    free(store);
+}
+
+#define STORE_MUTEX_LOCK(mtx)                              \
+    {                                                      \
+        int err = pthread_mutex_lock(mtx);                 \
+        if (err)                                           \
+        {                                                  \
+            NODE_FATAL("Failed to lock " #mtx ": %d (%s)", \
+                       err, strerror(err));                \
+            abort();                                       \
+        }                                                  \
+    }
+
+static inline struct store_trx_entry*
+store_get_trx_entry(struct node_store* const store, wsrep_trx_id_t const trx_id)
+{
+    return (struct store_trx_entry*)
+        ((char*)(store + 1) + (trx_id & store->entries_mask)*
+         (sizeof(struct store_trx_entry) + store->op_size));
+}
+
+static inline struct store_trx_ctx*
+store_get_trx_ctx(struct node_store* const store, wsrep_trx_id_t const trx_id)
+{
+    return &(store_get_trx_entry(store, trx_id)->ctx);
+}
+
+static inline wsrep_trx_id_t
+store_new_trx_id(struct node_store* const store)
+{
+    wsrep_trx_id_t ret;
+    struct store_trx_entry* trx;
+
+    STORE_MUTEX_LOCK(&store->trx_id_mtx);
+
+    do
+    {
+        store->trx_id++;
+        trx = store_get_trx_entry(store, store->trx_id);
+    }
+    while (trx->used);
+    trx->used = true;
+    ret = store->trx_id;
+
+    pthread_mutex_unlock(&store->trx_id_mtx);
+
+    memset(&trx->ctx, 0, sizeof(trx->ctx));
+
+    return ret;
+}
+
+static inline void
+store_free_trx_id(struct node_store* const store, wsrep_trx_id_t const trx_id)
+{
+    struct store_trx_entry* const trx = store_get_trx_entry(store, trx_id);
+    assert(trx->used);
+    free(trx->ctx.ops);
+
+    STORE_MUTEX_LOCK(&store->trx_id_mtx);
+
+    trx->used = false;
+
+    pthread_mutex_unlock(&store->trx_id_mtx);
+}
+
+/**
+ * deserializes membership from snapshot */
+static int
+store_new_members(const char* ptr, const char* const endptr,
+                  uint32_t* const num, member_t** const memb)
+{
+    ptr += store_deserialize_uint32(num, ptr);
+
+    if (*num < 2)
+    {
+        NODE_ERROR("Bogus number of members %u", *num);
+        return -1;
+    }
+
+    int ret = (int)sizeof(*num);
+
+    size_t const msize = sizeof(member_t) * *num;
+    if ((endptr - ptr) < (ptrdiff_t)msize)
+    {
+        NODE_ERROR("State snapshot does not contain all membership: "
+                   "%zd < %zu", endptr - ptr, msize);
+        return -1;
+    }
+
+    *memb = calloc(*num, sizeof(member_t));
+    if (!*memb)
+    {
+        NODE_ERROR("Could not allocate new membership");
+        return -ENOMEM;
+    }
+
+    memcpy(*memb, ptr, msize);
+
+    return ret + (int)msize;
+}
+
+/**
+ * deserializes records from snapshot */
+static int
+store_new_records(const char* ptr, const char* const endptr,
+                  uint32_t* const num, void** const rec)
+{
+    ptr += store_deserialize_uint32(num, ptr);
+
+    int ret = (int)sizeof(*num);
+    if (!*num)
+    {
+        *rec = NULL;
+        return ret;
+    }
+
+    size_t const rsize = STORE_RECORD_SIZE * *num;
+    if ((endptr - ptr) < (ptrdiff_t)rsize)
+    {
+        NODE_ERROR("State snapshot does not contain all records: "
+                   "%zu < %zu", endptr - ptr, rsize);
+        return -1;
+    }
+
+    *rec = malloc(rsize);
+    if (!*rec)
+    {
+        NODE_ERROR("Could not allocate new records");
+        return -ENOMEM;
+    }
+
+    memcpy(*rec, ptr, rsize);
+
+    return ret + (int)rsize;
+}
+
+int
+node_store_init_state(struct node_store*  const store,
+                      const void*         const state,
+                      size_t              const state_len)
+{
+    /* First, deserialize and prepare new state */
+    if (state_len <= sizeof(member_t)*2 /* at least two members */ +
+        WSREP_UUID_STR_LEN + 1 /* : */ + 1 /* seqno */ + 1 /* \0 */)
+    {
+        NODE_ERROR("State snapshot too short: %zu", state_len);
+        return -1;
+    }
+
+    wsrep_gtid_t state_gtid;
+    int ret;
+    ret = wsrep_gtid_scan(state, state_len, &state_gtid);
+    if (ret < 0)
+    {
+        char state_str[WSREP_GTID_STR_LEN + 1] = { 0, };
+        memcpy(state_str, state, sizeof(state_str) - 1);
+        NODE_ERROR("Could not find valid GTID in the received data: %s",
+                    state_str);
+        return -1;
+    }
+
+    ret++; /* \0 */
+    if ((state_len - (size_t)ret) < sizeof(uint32_t))
+    {
+        NODE_ERROR("State snapshot does not contain the number of members");
+        return -1;
+    }
+
+    const char* ptr = ((char*)state);
+    const char* const endptr = ptr + state_len;
+    ptr += ret;
+
+    uint32_t m_num;
+    member_t* new_members;
+    ret = store_new_members(ptr, endptr, &m_num, &new_members);
+    if (ret < 0)
+    {
+        return ret;
+    }
+    ptr += ret;
+
+    bool const read_view_support = ptr[0];
+    ptr += 1;
+
+    uint32_t r_num;
+    void* new_records;
+    ret = store_new_records(ptr, endptr, &r_num, &new_records);
+    if (ret < 0)
+    {
+        free(new_members);
+        return ret;
+    }
+    ptr += ret;
+
+    STORE_MUTEX_LOCK(&store->gtid_mtx);
+
+    /* just a sanity check */
+    if (0 == wsrep_uuid_compare(&state_gtid.uuid, &store->gtid.uuid) &&
+        state_gtid.seqno < store->gtid.seqno)
+    {
+        NODE_ERROR("Received snapshot that is in the past: my seqno %lld,"
+                   " received seqno: %lld",
+                   (long long)store->gtid.seqno, (long long)state_gtid.seqno);
+        free(new_members);
+        free(new_records);
+        ret = -1;
+    }
+    else
+    {
+        free(store->members);
+        store->members_num = m_num;
+        store->members     = new_members;
+        free(store->records);
+        store->records_num = r_num;
+        store->records     = new_records;
+        store->gtid        = state_gtid;
+        store->read_view_support = read_view_support;
+        ret = 0;
+    }
+
+    pthread_mutex_unlock(&store->gtid_mtx);
+
+    return ret;
+}
+
+int
+node_store_acquire_state(node_store_t* const store,
+                         const void**  const state,
+                         size_t*       const state_len)
+{
+    int ret = 0;
+
+    STORE_MUTEX_LOCK(&store->gtid_mtx);
+
+    if (!store->snapshot)
+    {
+        size_t const memb_len = store->members_num * sizeof(member_t);
+        size_t const rec_len  = store->records_num * STORE_RECORD_SIZE;
+        size_t const buf_len  = WSREP_GTID_STR_LEN + 1
+            + sizeof(uint32_t) + memb_len
+            + 1 /* read view support */
+            + sizeof(uint32_t) + rec_len;
+
+        store->snapshot = malloc(buf_len);
+
+        if (store->snapshot)
+        {
+            char* ptr = store->snapshot;
+
+            /* state GTID */
+            ret = wsrep_gtid_print(&store->gtid, ptr, buf_len);
+            if (ret > 0)
+            {
+                NODE_INFO("");
+                assert((size_t)ret < buf_len);
+
+                ptr[ret] = '\0';
+                ret++;
+                ptr += ret;
+                assert((size_t)ret < buf_len);
+
+                /* membership */
+                ptr += store_serialize_uint32(ptr, store->members_num);
+                ret += (int)sizeof(uint32_t);
+                assert((size_t)ret + memb_len < buf_len);
+                memcpy(ptr, store->members, memb_len);
+                ptr += memb_len;
+                ret += (int)memb_len;
+                assert((size_t)ret + sizeof(uint32_t) <= buf_len);
+
+                /* read view support */
+                ptr[0] = store->read_view_support;
+                ptr += 1;
+                ret += 1;
+
+                /* records */
+                ptr += store_serialize_uint32(ptr, store->records_num);
+                ret += (int)sizeof(uint32_t);
+                assert((size_t)ret + rec_len < buf_len);
+                memcpy(ptr, store->records, rec_len);
+                ret += (int)rec_len;
+                assert((size_t)ret <= buf_len);
+            }
+            else
+            {
+                NODE_ERROR("Failed to record GTID: %d (%s)", ret,strerror(-ret));
+                free(store->snapshot);
+                store->snapshot = 0;
+            }
+        }
+        else
+        {
+            NODE_ERROR("Failed to allocate snapshot buffer of size %zu",buf_len);
+            ret = -ENOMEM;
+        }
+    }
+    else
+    {
+        assert(0); /* provider should prevent such situation */
+        ret = -EAGAIN;
+    }
+
+    pthread_mutex_unlock(&store->gtid_mtx);
+
+    if (ret > 0)
+    {
+        NODE_INFO("\n\nPrepared snapshot of %u records\n\n", store->records_num);
+        *state     = store->snapshot;
+        *state_len = (size_t)ret;
+        ret        = 0;
+    }
+
+    return ret;
+}
+
+void
+node_store_release_state(node_store_t* const store)
+{
+    STORE_MUTEX_LOCK(&store->gtid_mtx);
+
+    assert(store->snapshot);
+    free(store->snapshot);
+    store->snapshot = 0;
+
+    pthread_mutex_unlock(&store->gtid_mtx);
+}
+
+int
+node_store_update_membership(struct node_store*       const store,
+                             const wsrep_view_info_t* const v)
+{
+    assert(store);
+    assert(WSREP_VIEW_PRIMARY == v->status);
+        assert(v->memb_num > 0);
+
+    STORE_MUTEX_LOCK(&store->gtid_mtx);
+
+    bool const continuation = v->state_id.seqno == store->gtid.seqno + 1 &&
+        0 == wsrep_uuid_compare(&v->state_id.uuid, &store->gtid.uuid);
+
+    bool const initialization = WSREP_SEQNO_UNDEFINED == store->gtid.seqno &&
+        0 == wsrep_uuid_compare(&WSREP_UUID_UNDEFINED, &store->gtid.uuid);
+
+    if (!(continuation || initialization))
+    {
+        char store_str[WSREP_GTID_STR_LEN + 1] = { 0, };
+        wsrep_gtid_print(&store->gtid, store_str, sizeof(store_str));
+        char view_str[WSREP_GTID_STR_LEN + 1] = { 0, };
+        wsrep_gtid_print(&v->state_id, view_str, sizeof(view_str));
+
+        NODE_FATAL("Attempt to initialize store GTID from incompatible view:\n"
+                   "\tstore: %s\n"
+                   "\tview:  %s",
+                   store_str, view_str);
+        abort();
+    }
+
+    wsrep_uuid_t* const new_members = calloc(sizeof(wsrep_uuid_t),
+                                             (size_t)v->memb_num);
+    if (!new_members)
+    {
+        NODE_FATAL("Could not allocate new members array");
+        abort();
+    }
+
+    int i;
+    for (i = 0; i < v->memb_num; i++)
+    {
+        new_members[i] = v->members[i].id;
+    }
+
+    /* REPLICATION: at this point we should compare old and new memberships and
+     *              rollback all streaming transactions from the partitioned
+     *              members, if any. But we don't support it in this program yet.
+     */
+
+    free(store->members);
+
+    store->members     = new_members;
+    store->members_num = (uint32_t)v->memb_num;
+    store->gtid        = v->state_id;
+    store->read_view_support = (v->capabilities & WSREP_CAP_SNAPSHOT);
+
+    pthread_mutex_unlock(&store->gtid_mtx);
+
+    return 0;
+}
+
+void
+node_store_gtid(struct node_store* const store,
+                wsrep_gtid_t*      const gtid)
+{
+    assert(store);
+
+    STORE_MUTEX_LOCK(&store->gtid_mtx);
+
+    *gtid = store->gtid;
+
+    pthread_mutex_unlock(&store->gtid_mtx);
+}
+
+
+static inline void
+store_serialize_op(void* const buf, const struct store_trx_op* const op)
+{
+    char* ptr = buf;
+    ptr += store_record_set(ptr, 0, &op->rec_from);
+    ptr += store_record_set(ptr, 0, &op->rec_to);
+    ptr += store_serialize_uint32(ptr, op->idx_from);
+    ptr += store_serialize_uint32(ptr, op->idx_to);
+    ptr += store_serialize_uint32(ptr, op->new_value);
+    store_serialize_uint32(ptr, op->size);
+}
+
+static inline void
+store_deserialize_op(struct store_trx_op* const op, const void* const buf)
+{
+    const char* ptr = buf;
+    ptr += store_record_get(ptr, 0, &op->rec_from);
+    ptr += store_record_get(ptr, 0, &op->rec_to);
+    ptr += store_deserialize_uint32(&op->idx_from, ptr);
+    ptr += store_deserialize_uint32(&op->idx_to, ptr);
+    ptr += store_deserialize_uint32(&op->new_value, ptr);
+    store_deserialize_uint32(&op->size, ptr);
+}
+
+static inline void
+store_serialize_gtid(void* const buf, const wsrep_gtid_t* const gtid)
+{
+    char* ptr = buf;
+    memcpy(ptr, &gtid->uuid, sizeof(gtid->uuid));
+    ptr += sizeof(gtid->uuid);
+    store_serialize_int64(ptr, gtid->seqno);
+}
+
+static inline void
+store_deserialize_gtid(wsrep_gtid_t* const gtid, const void* const buf)
+{
+    const char* ptr = buf;
+    memcpy(&gtid->uuid, ptr, sizeof(gtid->uuid));
+    ptr += sizeof(gtid->uuid);
+    store_deserialize_int64(&gtid->seqno, ptr);
+}
+
+#define STORE_GTID_SIZE (sizeof(((wsrep_gtid_t*)(NULL))->uuid) + sizeof(int64_t))
+
+int
+node_store_execute(node_store_t*      const store,
+                   wsrep_t*           const wsrep,
+                   wsrep_ws_handle_t* const ws_handle)
+{
+    assert(store);
+
+    if (0 == ws_handle->trx_id)
+    {
+        assert(sizeof(ws_handle->trx_id) >= sizeof(uintptr_t));
+        ws_handle->trx_id = store_new_trx_id(store);
+    }
+
+    struct store_trx_ctx* trx = store_get_trx_ctx(store, ws_handle->trx_id);
+    if (store_trx_add_op(trx)) return -ENOMEM;
+    struct store_trx_op* const op = &trx->ops[trx->ops_num - 1];
+
+    STORE_MUTEX_LOCK(&store->gtid_mtx);
+
+    if (1 == trx->ops_num)
+    {
+        /* First operation, save ID of the read view of the transaction */
+        trx->rv_gtid = store->gtid;
+    }
+
+    /* Transaction op: copy value from one random record to another... */
+    op->idx_from = (uint32_t)rand() % store->records_num;
+    op->idx_to   = (uint32_t)rand() % store->records_num;
+    store_record_get(store->records, op->idx_from, &op->rec_from);
+    store_record_get(store->records, op->idx_to,   &op->rec_to);
+
+    pthread_mutex_unlock(&store->gtid_mtx);
+
+    wsrep_status_t ret = WSREP_TRX_FAIL;
+
+    if (op->rec_from.version > trx->rv_gtid.seqno ||
+        op->rec_to.version   > trx->rv_gtid.seqno)
+    {
+        /* transaction read view changed, trx needs to be restarted */
+#if 0
+        NODE_INFO("Transaction read view changed: %lld -> %lld, returning %d",
+                  (long long)trx->rv_gtid.seqno,
+                  (long long)(op->rec_from.version > op->rec_to.version ?
+                              op->rec_from.version : op->rec_to.version),
+                  ret);
+#endif
+        goto error;
+    }
+
+    /* Transaction op: ... and modify it somehow, e.g. increment by 1 */
+    op->new_value = op->rec_from.value + 1;
+
+    if (1 == trx->ops_num) // first trx operation
+    {
+        /* REPLICATION: Since this application does not implement record locks,
+         *              it needs to establish read view for each transaction for
+         *              a proper conflict detection and transaction isolation.
+         *              Otherwose we'll need to implement record versioning */
+        if (store->read_view_support)
+        {
+            ret = wsrep->assign_read_view(wsrep, ws_handle, &trx->rv_gtid);
+            if (ret)
+            {
+                NODE_ERROR("wsrep::assign_read_view(%lld) failed: %d",
+                           trx->rv_gtid.seqno, ret);
+                goto error;
+            }
+        }
+
+        /* Record read view in the writeset for debugging purposes */
+        assert(store->op_size > STORE_GTID_SIZE);
+        store_serialize_gtid(trx + 1, &trx->rv_gtid);
+        wsrep_buf_t ws = { .ptr = trx + 1, .len = STORE_GTID_SIZE };
+        ret = wsrep->append_data(wsrep, ws_handle, &ws, 1, WSREP_DATA_ORDERED,
+                                 true);
+        if (ret)
+        {
+            NODE_ERROR("wsrep::append_data(rv_gtid) failed: %d", ret);
+            goto error;
+        }
+    }
+
+    /* REPLICATION: append keys touched by the operation
+     *
+     * NOTE: depending on data access granularity some applications may require
+     *       multipart keys, e.g. <schema>:<table>:<row> in a SQL database.
+     *       Single part keys match hashtables and key-value stores.
+     *       Below we have two different single-part keys which reference two
+     *       different records. */
+    uint32_t    key_val;
+    wsrep_buf_t key_part = { .ptr = &key_val, .len = sizeof(key_val) };
+    wsrep_key_t ws_key   = { .key_parts = &key_part, .key_parts_num = 1 };
+
+    /* REPLICATION: Key 1 - the key of the source, unchanged record */
+    store_serialize_uint32(&key_val, op->idx_from);
+    ret = wsrep->append_key(wsrep, ws_handle,
+                            &ws_key,
+                            1,   /* single key */
+                            WSREP_KEY_REFERENCE,
+                            true /* provider shall make a copy of the key */);
+    if (ret)
+    {
+        NODE_ERROR("wsrep::append_key(REFERENCE) failed: %d", ret);
+        goto error;
+    }
+
+    /* REPLICATION: Key 2 - the key of the record we want to update */
+    store_serialize_uint32(&key_val, op->idx_to);
+    ret = wsrep->append_key(wsrep, ws_handle,
+                            &ws_key,
+                            1,   /* single key */
+                            WSREP_KEY_UPDATE,
+                            true /* provider shall make a copy of the key */);
+    if (ret)
+    {
+        NODE_ERROR("wsrep::append_key(UPDATE) failed: %d", ret);
+        goto error;
+    }
+
+    /* REPLICATION: append transaction operation to the "writeset"
+     *              (WS buffer was allocated together with trx context above) */
+    assert(store->op_size >= STORE_OP_SIZE);
+    assert(store->op_size == (uint32_t)store->op_size);
+    op->size = (uint32_t)store->op_size;
+    store_serialize_op(trx + 1, op);
+    wsrep_buf_t ws = { .ptr = trx + 1, .len = store->op_size };
+    ret = wsrep->append_data(wsrep, ws_handle, &ws, 1, WSREP_DATA_ORDERED, true);
+
+    if (!ret) return 0;
+
+    NODE_ERROR("wsrep::append_data(op) failed: %d", ret);
+
+error:
+    store_free_trx_id(store, ws_handle->trx_id);
+
+    return ret;
+}
+
+int
+node_store_apply(node_store_t*      const store,
+                 wsrep_trx_id_t*    const trx_id,
+                 const wsrep_buf_t* const ws)
+{
+    assert(store);
+    (void)store;
+
+    *trx_id = store_new_trx_id(store);
+    struct store_trx_ctx* const trx = store_get_trx_ctx(store, *trx_id);
+
+    /* prepare trx context for commit */
+    const char* ptr = ws->ptr;
+    size_t left     = ws->len;
+
+    /* at least one operation should be there */
+    assert(left >= STORE_GTID_SIZE + STORE_OP_SIZE);
+
+    if (left >= STORE_GTID_SIZE)
+    {
+        store_deserialize_gtid(&trx->rv_gtid, ptr);
+        left -= STORE_GTID_SIZE;
+        ptr  += STORE_GTID_SIZE;
+    }
+
+    while (left >= STORE_OP_SIZE)
+    {
+        if (store_trx_add_op(trx))
+        {
+            store_free_trx_id(store,*trx_id); /* "rollback": release resources */
+            return -ENOMEM;
+        }
+        struct store_trx_op* const op = &trx->ops[trx->ops_num - 1];
+
+        store_deserialize_op(op, ptr);
+        assert(op->idx_to <= store->records_num);
+
+        left -= op->size;
+        ptr  += op->size;
+    }
+
+    if (left != 0)
+    {
+        NODE_FATAL("Failed to process last (%d/%zu) bytes of the writeset.",
+                   (int)left, ws->len);
+        abort();
+    }
+
+    return 0;
+}
+
+static uint32_t const store_fnv32_seed  = 2166136261;
+
+static inline uint32_t
+store_fnv32a(const void* buf, size_t const len, uint32_t seed)
+{
+    static uint32_t const fnv32_prime = 16777619;
+    const uint8_t* bp = (const uint8_t*)buf;
+    const uint8_t* const be = bp + len;
+
+    while (bp < be)
+    {
+        seed ^= *bp++;
+        seed *= fnv32_prime;
+    }
+
+    return seed;
+}
+
+
+static void
+store_checksum_state(node_store_t* store)
+{
+    uint32_t res = store_fnv32_seed;
+    uint32_t i;
+
+    for (i = 0; i < store->members_num; i++)
+    {
+        res = store_fnv32a(&store->members[i], sizeof(*store->members), res);
+    }
+
+    res = store_fnv32a(store->records, store->records_num * STORE_RECORD_SIZE,
+                       res);
+
+    res = store_fnv32a(&store->gtid.uuid, sizeof(store->gtid.uuid), res);
+
+    wsrep_seqno_t s;
+    store_serialize_int64(&s, store->gtid.seqno);
+    res = store_fnv32a(&s, sizeof(s), res);
+
+    NODE_INFO("\n\n\tSeqno: %lld; state hash: %#010x\n",
+              (long long)store->gtid.seqno, res);
+}
+
+static inline void
+store_update_gtid(node_store_t* const store, const wsrep_gtid_t* ws_gtid)
+{
+    assert(0 == wsrep_uuid_compare(&store->gtid.uuid, &ws_gtid->uuid));
+
+    store->gtid.seqno++;
+
+    if (store->gtid.seqno != ws_gtid->seqno)
+    {
+        NODE_FATAL("Out of order commit: expected %lld, got %lld",
+                   store->gtid.seqno, ws_gtid->seqno);
+        abort();
+    }
+
+    static wsrep_seqno_t const period = 0x000fffff; /* ~1M */
+    if (0 == (store->gtid.seqno & period))
+    {
+        store_checksum_state(store);
+    }
+}
+
+void
+node_store_commit(node_store_t*       const store,
+                  wsrep_trx_id_t      const trx_id,
+                  const wsrep_gtid_t* const ws_gtid)
+{
+    assert(store);
+    assert(trx_id);
+
+    struct store_trx_ctx* const trx = store_get_trx_ctx(store, trx_id);
+
+    bool const check_read_view_snapshot =
+#ifdef NDEBUG
+        !store->read_view_support;
+#else
+    1;
+#endif /* NDEBUG */
+
+    STORE_MUTEX_LOCK(&store->gtid_mtx);
+
+    store_update_gtid(store, ws_gtid);
+
+    /* First loop is to check if we can commit all operations if provider
+     * does not support read view or for debugging puposes */
+    size_t i;
+    if (check_read_view_snapshot)
+    {
+        for (i = 0; i < trx->ops_num; i++)
+        {
+            struct store_trx_op* const op = &trx->ops[i];
+
+            record_t from, to;
+            store_record_get(store->records, op->idx_from, &from);
+            store_record_get(store->records, op->idx_to,   &to);
+
+            if (!store_record_equal(&op->rec_from, &from) ||
+                !store_record_equal(&op->rec_to,   &to))
+            {
+                /* read view changed since transaction was executed,
+                 * can't commit */
+                assert(op->rec_from.version <= from.version);
+                assert(op->rec_to.version <= to.version);
+                if (op->rec_from.version == from.version)
+                    assert(op->rec_from.value == from.value);
+                if (op->rec_to.version == to.version)
+                    assert(op->rec_to.value == to.value);
+                if (store->read_view_support) abort();
+
+                store->read_view_fails++;
+
+                NODE_INFO("Read view changed at commit time, rollback trx");
+
+                goto error;
+            }
+        }
+    }
+
+    /* Second loop is to actually modify the dataset */
+    for (i = 0; i < trx->ops_num; i++)
+    {
+        struct store_trx_op* const op = &trx->ops[i];
+
+        record_t const new_record =
+            { .version = ws_gtid->seqno, .value = op->new_value };
+
+        store_record_set(store->records, op->idx_to, &new_record);
+    }
+
+error:
+    pthread_mutex_unlock(&store->gtid_mtx);
+
+    store_free_trx_id(store, trx_id);
+}
+
+void
+node_store_rollback(node_store_t*  const store,
+                    wsrep_trx_id_t const trx_id)
+{
+    assert(store);
+    assert(trx_id);
+
+    store_free_trx_id(store, trx_id);
+}
+
+void
+node_store_update_gtid(node_store_t*       const store,
+                       const wsrep_gtid_t* const ws_gtid)
+{
+    assert(store);
+
+    STORE_MUTEX_LOCK(&store->gtid_mtx);
+
+    store_update_gtid(store, ws_gtid);
+
+    pthread_mutex_unlock(&store->gtid_mtx);
+}
+
+long
+node_store_read_view_failures(node_store_t* const store)
+{
+    assert(store);
+
+    long ret;
+
+    STORE_MUTEX_LOCK(&store->gtid_mtx);
+
+    ret = store->read_view_fails;;
+
+    pthread_mutex_unlock(&store->gtid_mtx);
+
+    return ret;
+}
diff --git a/wsrep-lib/wsrep-API/v26/examples/node/store.h b/wsrep-lib/wsrep-API/v26/examples/node/store.h
new file mode 100644
index 00000000..51da74d7
--- /dev/null
+++ b/wsrep-lib/wsrep-API/v26/examples/node/store.h
@@ -0,0 +1,125 @@
+/* Copyright (c) 2019-2020, Codership Oy. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ */
+
+/**
+ * @file This unit defines simple "transactional storage engine" interface
+ */
+
+#ifndef NODE_STORE_H
+#define NODE_STORE_H
+
+#include "options.h"
+
+#include "../../wsrep_api.h"
+
+typedef struct node_store node_store_t;
+
+/**
+ * open a store and optionally assocoate a file with it */
+extern node_store_t*
+node_store_open(const struct node_options* opts);
+
+/**
+ * close store and deallocate associated resources */
+extern void
+node_store_close(node_store_t* store);
+
+/**
+ * initialize store with a state */
+extern int
+node_store_init_state(node_store_t* store, const void* state, size_t state_len);
+
+/**
+ * Return a pointer to state snapshot that is guaranteed to be unchanged
+ * until node_store_release_state() is called.
+ *
+ * @param[out] state     pointer to state snapshot
+ * @param[out] state_len soze of state snapshot
+ */
+extern int
+node_store_acquire_state(node_store_t* store,
+                         const void** state, size_t* state_len);
+
+/**
+ * release state */
+extern void
+node_store_release_state(node_store_t* store);
+
+/**
+ * inform store about new membership */
+extern int
+node_store_update_membership(node_store_t* store, const wsrep_view_info_t* v);
+
+/**
+ * get the current GTID (last committed) */
+extern void
+node_store_gtid(node_store_t* store, wsrep_gtid_t* gtid);
+
+/**
+ * execute and prepare local transaction in store and return its key and write
+ * set.
+ *
+ * This operation allocates resources that must be freed with either
+ * node_store_commit() or node_store_rollback()
+ *
+ * @param[in]  wsrep     provider handle
+ * @param[out] ws_handle reference to the resulting write set in the provider
+ */
+extern int
+node_store_execute(node_store_t*      store,
+                   wsrep_t*           wsrep,
+                   wsrep_ws_handle_t* ws_handle);
+
+/**
+ * apply and prepare foreign write set received from replication
+ *
+ * This operation allocates resources that must be freed with either
+ * node_store_commit() or node_store_rollback()
+ *
+ * @param[out] trx_id locally unique transaction ID
+ * @param[in]  ws     foreign transaction write set
+ */
+extern int
+node_store_apply(node_store_t*      store,
+                 wsrep_trx_id_t*    trx_id,
+                 const wsrep_buf_t* ws);
+
+/**
+ * commit prepared transaction identified by trx_id */
+extern void
+node_store_commit(node_store_t*       store,
+                  wsrep_trx_id_t      trx_id,
+                  const wsrep_gtid_t* ws_gtid);
+
+/**
+ * rollback prepared transaction identified by trx_id */
+extern void
+node_store_rollback(node_store_t*  store,
+                    wsrep_trx_id_t trx_id);
+
+/**
+ * update storage GTID for transactions that had to be skipped/rolled back */
+extern void
+node_store_update_gtid(node_store_t*       store,
+                       const wsrep_gtid_t* ws_gtid);
+
+/**
+ * @return the number of store read view snapshot check failures at commit time.
+ *         (should be zero if provider implements assign_read_view() call) */
+extern long
+node_store_read_view_failures(node_store_t* store);
+
+#endif /* NODE_STORE_H */
diff --git a/wsrep-lib/wsrep-API/v26/examples/node/trx.c b/wsrep-lib/wsrep-API/v26/examples/node/trx.c
new file mode 100644
index 00000000..afdcada4
--- /dev/null
+++ b/wsrep-lib/wsrep-API/v26/examples/node/trx.c
@@ -0,0 +1,155 @@
+/* Copyright (c) 2019-2020, Codership Oy. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ */
+
+#include "trx.h"
+#include "log.h"
+
+#include <assert.h>
+#include <errno.h>  // ENOMEM, etc.
+#include <stdbool.h>
+
+wsrep_status_t
+node_trx_execute(node_store_t*   const store,
+                 wsrep_t*        const wsrep,
+                 wsrep_conn_id_t const conn_id,
+                 int                   ops_num)
+{
+    wsrep_status_t cert = WSREP_OK; // for cleanup
+
+    static unsigned int const ws_flags =
+        WSREP_FLAG_TRX_START | WSREP_FLAG_TRX_END; // atomic trx
+    wsrep_trx_meta_t ws_meta;
+    wsrep_status_t ret = WSREP_OK;
+
+    /* prepare simple transaction and obtain a writeset handle for it */
+    wsrep_ws_handle_t ws_handle = { 0, NULL };
+    while (ops_num--)
+    {
+        if (0 != (ret = node_store_execute(store, wsrep, &ws_handle)))
+        {
+#if 0
+            NODE_INFO("master [%d]: node_store_execute() returned %d",
+                      conn_id, ret);
+#endif
+            ret = WSREP_TRX_FAIL;
+            goto cleanup;
+        }
+    }
+
+    /* REPLICATION: (replicate and) certify the writeset (pointed to by
+     *              ws_handle) with the cluster */
+    cert = wsrep->certify(wsrep, conn_id, &ws_handle, ws_flags, &ws_meta);
+
+    if (WSREP_BF_ABORT == cert)
+    {
+        /* REPLICATION: transaction was signaled to abort due to multi-master
+         *              conflict. It must rollback immediately: it blocks
+         *              transaction that was ordered earlier and will never
+         *              be able to enter commit order. */
+        node_store_rollback(store, ws_handle.trx_id);
+    }
+
+    /* REPLICATION: writeset was totally ordered, need to enter commit order */
+    if (ws_meta.gtid.seqno > 0)
+    {
+        ret = wsrep->commit_order_enter(wsrep, &ws_handle, &ws_meta);
+        if (ret)
+        {
+            NODE_ERROR("master [%d]: wsrep::commit_order_enter(%lld) failed: "
+                       "%d", (long long)(ws_meta.gtid.seqno), ret);
+            goto cleanup;
+        }
+
+        /* REPLICATION: inside commit monitor
+         * Note: we commit transaction only if certification succeded */
+        if (WSREP_OK == cert)
+            node_store_commit(store, ws_handle.trx_id, &ws_meta.gtid);
+        else
+            node_store_update_gtid(store, &ws_meta.gtid);
+
+        ret = wsrep->commit_order_leave(wsrep, &ws_handle, &ws_meta, NULL);
+        if (ret)
+        {
+            NODE_ERROR("master [%d]: wsrep::commit_order_leave(%lld) failed: "
+                       "%d", (long long)(ws_meta.gtid.seqno), ret);
+            goto cleanup;
+        }
+    }
+    else
+    {
+        assert(cert);
+    }
+
+cleanup:
+    /* REPLICATION: if wsrep->certify() returned anything else but WSREP_OK
+     *              transaction must roll back. BF aborted trx already did it. */
+    if (cert && WSREP_BF_ABORT != cert)
+        node_store_rollback(store, ws_handle.trx_id);
+
+    /* NOTE: this application follows the approach that resources must be freed
+     *       at the same level where they were allocated, so it is assumed that
+     *       ws_key and ws were deallocated in either commit or rollback calls.*/
+
+    /* REPLICATION: release provider resources associated with the trx */
+    wsrep->release(wsrep, &ws_handle);
+
+    return ret ? ret : cert;
+}
+
+wsrep_status_t
+node_trx_apply(node_store_t*            const store,
+               wsrep_t*                 const wsrep,
+               const wsrep_ws_handle_t* const ws_handle,
+               const wsrep_trx_meta_t*  const ws_meta,
+               const wsrep_buf_t*       const ws)
+{
+    /* no business being here if event was not ordered */
+    assert(ws_meta->gtid.seqno > 0);
+
+    wsrep_trx_id_t trx_id;
+    wsrep_buf_t err_buf = { NULL, 0 };
+    int app_err;
+    if (ws)
+    {
+        app_err = node_store_apply(store, &trx_id, ws);
+        if (app_err)
+        {
+            /* REPLICATION: if applying failed, prepare an error buffer with
+             *              sufficient error specification */
+            err_buf.ptr = &app_err; // suppose error code is enough
+            err_buf.len = sizeof(app_err);
+        }
+    }
+    else /* ws failed certification and should be skipped */
+    {
+        /* just some non-0 code to choose node_store_update_gtid() below */
+        app_err = 1;
+    }
+
+    wsrep_status_t ret;
+    ret = wsrep->commit_order_enter(wsrep, ws_handle, ws_meta);
+    if (ret) {
+        node_store_rollback(store, trx_id);
+        return ret;
+    }
+
+    if (!app_err) node_store_commit(store, trx_id, &ws_meta->gtid);
+    else          node_store_update_gtid(store, &ws_meta->gtid);
+
+    ret = wsrep->commit_order_leave(wsrep, ws_handle, ws_meta, &err_buf);
+
+    return ret;
+}
diff --git a/wsrep-lib/wsrep-API/v26/examples/node/trx.h b/wsrep-lib/wsrep-API/v26/examples/node/trx.h
new file mode 100644
index 00000000..e1d763a1
--- /dev/null
+++ b/wsrep-lib/wsrep-API/v26/examples/node/trx.h
@@ -0,0 +1,50 @@
+/* Copyright (c) 2019-2020, Codership Oy. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ */
+
+/**
+ * @file This unit defines "transaction" interface
+ */
+
+#ifndef NODE_TRX_H
+#define NODE_TRX_H
+
+#include "store.h"
+
+#include "../../wsrep_api.h"
+
+/**
+ * executes and replicates local transaction
+ */
+extern wsrep_status_t
+node_trx_execute(node_store_t*   store,
+                 wsrep_t*        wsrep,
+                 wsrep_conn_id_t conn_id,
+                 int             ops_num);
+
+/**
+ * applies and commits slave write set
+ *
+ * @param ws replicated event writeset. NULL if it failed certification (and so
+ *           must be skipped, but it was ordered, so store GTID must be updated)
+ */
+extern wsrep_status_t
+node_trx_apply(node_store_t*            store,
+               wsrep_t*                 wsrep,
+               const wsrep_ws_handle_t* ws_handle,
+               const wsrep_trx_meta_t*  ws_meta,
+               const wsrep_buf_t*       ws);
+
+#endif /* NODE_TRX_H */
diff --git a/wsrep-lib/wsrep-API/v26/examples/node/worker.c b/wsrep-lib/wsrep-API/v26/examples/node/worker.c
new file mode 100644
index 00000000..e9901ad8
--- /dev/null
+++ b/wsrep-lib/wsrep-API/v26/examples/node/worker.c
@@ -0,0 +1,197 @@
+/* Copyright (c) 2019-2020, Codership Oy. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ */
+
+#include "worker.h"
+
+#include "log.h"
+#include "options.h"
+#include "trx.h"
+#include "wsrep.h"
+
+#include <assert.h>
+#include <pthread.h>
+#include <stdbool.h>
+#include <string.h>  // strerror()
+
+struct node_worker
+{
+    struct node_ctx* node;
+    pthread_t        thread_id;
+    size_t           id;
+    bool             exit;
+};
+
+enum wsrep_cb_status
+node_worker_apply_cb(void*                    const recv_ctx,
+                     const wsrep_ws_handle_t* const ws_handle,
+                     uint32_t                 const ws_flags,
+                     const wsrep_buf_t*       const ws,
+                     const wsrep_trx_meta_t*  const ws_meta,
+                     wsrep_bool_t*            const exit_loop)
+{
+    assert(recv_ctx);
+
+    struct node_worker* const worker = recv_ctx;
+
+    wsrep_status_t const ret = node_trx_apply(
+        worker->node->store,
+        node_wsrep_provider(worker->node->wsrep),
+        ws_handle,
+        ws_meta,
+        ws_flags & WSREP_FLAG_ROLLBACK ? NULL : ws);
+
+    *exit_loop = worker->exit;
+
+    return WSREP_OK == ret ? WSREP_CB_SUCCESS : WSREP_CB_FAILURE;
+}
+
+
+static void*
+worker_slave(void* recv_ctx)
+{
+    struct node_worker* const worker = recv_ctx;
+    wsrep_t* const wsrep = node_wsrep_provider(worker->node->wsrep);
+
+    wsrep_status_t const ret = wsrep->recv(wsrep, worker);
+
+    if (WSREP_OK != ret)
+    {
+        NODE_ERROR("slave worker [%zu] exited with error %d.", worker->id, ret);
+    }
+
+    return NULL;
+}
+
+static void*
+worker_master(void* send_ctx)
+{
+    struct node_worker* const worker = send_ctx;
+    struct node_ctx*    const node   = worker->node;
+    wsrep_t*            const wsrep  = node_wsrep_provider(node->wsrep);
+
+    assert(node->opts->ws_size > 0);
+
+    wsrep_status_t ret;
+
+    do
+    {
+        /* REPLICATION: we should not perform any local writes until the node
+         * is synced with the cluster. */
+        if (!node_wsrep_wait_synced(node->wsrep))
+        {
+            NODE_ERROR("master worker [%zu] failed waiting for SYNCED state.",
+                       worker->id);
+            break;
+        }
+
+        /* REPLICATION: the node is now synced */
+
+        do
+        {
+            ret = node_trx_execute(node->store,
+                                   wsrep,
+                                   worker->id,
+                                   (int)node->opts->operations);
+        }
+        while(WSREP_OK           == ret // success
+              || (WSREP_TRX_FAIL == ret // certification failed, trx rolled back
+                  && (usleep(10000),true)) // retry after short sleep
+            );
+    }
+    while (WSREP_CONN_FAIL == ret); // provider in bad state (e.g. non-Primary)
+
+    return NULL;
+}
+
+struct node_worker_pool
+{
+    size_t             size;      // size of the pool (nu,ber of nodes)
+    struct node_worker worker[1]; // worker context array;
+};
+
+struct node_worker_pool*
+node_worker_start(struct node_ctx*   const ctx,
+                  node_worker_type_t const type,
+                  size_t             const size)
+{
+    assert(ctx);
+
+    if (0 == size) return NULL;
+
+    const char* const type_str = type == NODE_WORKER_SLAVE ? "slave" : "master";
+
+    size_t const alloc_size =
+        sizeof(struct node_worker_pool) +
+        sizeof(struct node_worker) * (size - 1);
+
+    struct node_worker_pool* const ret = malloc(alloc_size);
+
+    if (ret)
+    {
+        void* (* const routine) (void*) =
+            type == NODE_WORKER_SLAVE ? worker_slave : worker_master;
+
+        size_t i;
+        for (i = 0; i < size; i++)
+        {
+            struct node_worker* const worker = &ret->worker[i];
+            worker->node = ctx;
+            worker->id   = i;
+            worker->exit = false;
+
+            int const err = pthread_create(&worker->thread_id,
+                                           NULL,
+                                           routine,
+                                           worker);
+            if (err)
+            {
+                NODE_ERROR("Failed to start %s worker[%zu]: %d (%s)",
+                           type_str, i, err, strerror(err));
+                if (0 == i)
+                {
+                    free(ret);
+                    return NULL;
+                }
+                else
+                {
+                    break; // some threads have started,
+                           // need to return to close them first
+                }
+            }
+        }
+
+        ret->size = i;
+    }
+    else
+    {
+        NODE_ERROR("Failed to allocate %zu bytes for the %s worker pool",
+                   alloc_size, type_str);
+    }
+
+    return ret;
+}
+
+void
+node_worker_stop(struct node_worker_pool* pool)
+{
+    size_t i;
+    for (i = 0; pool && i < pool->size; i++)
+    {
+        pthread_join(pool->worker[i].thread_id, NULL);
+    }
+
+    free(pool);
+}
diff --git a/wsrep-lib/wsrep-API/v26/examples/node/worker.h b/wsrep-lib/wsrep-API/v26/examples/node/worker.h
new file mode 100644
index 00000000..7ae06423
--- /dev/null
+++ b/wsrep-lib/wsrep-API/v26/examples/node/worker.h
@@ -0,0 +1,66 @@
+/* Copyright (c) 2019, Codership Oy. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ */
+
+/**
+ * @file This unit defines worker thread interface
+ */
+
+#ifndef NODE_WORKER_H
+#define NODE_WORKER_H
+
+#include "ctx.h"
+
+#include "../../wsrep_api.h"
+
+/**
+ * REPLICATION: a callback to apply and commit slave replication events */
+extern enum wsrep_cb_status
+node_worker_apply_cb(void*                    recv_ctx,
+                     const wsrep_ws_handle_t* ws_handle,
+                     uint32_t                 ws_flags,
+                     const wsrep_buf_t*       ws,
+                     const wsrep_trx_meta_t*  ws_meta,
+                     wsrep_bool_t*            exit_loop);
+
+typedef enum node_worker_type
+{
+    NODE_WORKER_SLAVE,
+    NODE_WORKER_MASTER
+}
+    node_worker_type_t;
+
+struct node_worker_pool;
+
+/**
+ * Starts the required number of workier threads of a given type
+ *
+ * @param[in] ctx application context
+ * @param[in] type of a worker
+ * @param[in] number of workers
+ *
+ * @return worker pool handle
+ */
+extern struct node_worker_pool*
+node_worker_start(struct node_ctx*   ctx,
+                  node_worker_type_t type,
+                  size_t             number);
+
+/**
+ * Stops workers in a pool and deallocates respective resources */
+extern void
+node_worker_stop(struct node_worker_pool* pool);
+
+#endif /* NODE_WORKER_H */
diff --git a/wsrep-lib/wsrep-API/v26/examples/node/wsrep.c b/wsrep-lib/wsrep-API/v26/examples/node/wsrep.c
new file mode 100644
index 00000000..6cea6d90
--- /dev/null
+++ b/wsrep-lib/wsrep-API/v26/examples/node/wsrep.c
@@ -0,0 +1,479 @@
+/* Copyright (c) 2019, Codership Oy. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ */
+
+#include "wsrep.h"
+
+#include "log.h"
+#include "sst.h"
+#include "store.h"
+#include "worker.h"
+
+#include <assert.h>
+#include <stdio.h>  // snprintf()
+#include <stdlib.h> // abort()
+#include <string.h> // strcasecmp()
+
+struct node_wsrep
+{
+    wsrep_t* instance; // wsrep provider instance
+
+    struct wsrep_view
+    {
+        pthread_mutex_t      mtx;
+        wsrep_gtid_t         state_id;
+        wsrep_view_status_t  status;
+        wsrep_cap_t          capabilities;
+        int                  proto_ver;
+        int                  memb_num;
+        int                  my_idx;
+        wsrep_member_info_t* members;
+    }
+        view;
+
+    struct
+    {
+        pthread_mutex_t mtx;
+        pthread_cond_t  cond;
+        int             value;
+    }
+            synced;
+
+    bool bootstrap; // shall this node bootstrap a primary view?
+};
+
+static struct node_wsrep s_wsrep =
+{
+    .instance = NULL,
+    .view =
+    {
+        .mtx          = PTHREAD_MUTEX_INITIALIZER,
+        .state_id     = {{{ 0, }}, WSREP_SEQNO_UNDEFINED },
+        .status       = WSREP_VIEW_DISCONNECTED,
+        .capabilities = 0,
+        .proto_ver    = -1,
+        .memb_num     = 0,
+        .my_idx       = -1,
+        .members      = NULL
+    },
+    .synced =
+    {
+        .mtx   = PTHREAD_MUTEX_INITIALIZER,
+        .cond  = PTHREAD_COND_INITIALIZER,
+        .value = 0
+    },
+    .bootstrap = false
+};
+
+static const char* wsrep_view_status_str[WSREP_VIEW_MAX] =
+{
+    "PRIMARY",
+    "NON-PRIMARY",
+    "DISCONNECTED"
+};
+
+#define WSREP_CAPABILITIES_MAX ((int)sizeof(wsrep_cap_t) * 8) // bitmask
+static const char* wsrep_capabilities_str[WSREP_CAPABILITIES_MAX] =
+{
+    "MULTI-MASTER",
+    "CERTIFICATION",
+    "PA",
+    "REPLAY",
+    "TOI",
+    "PAUSE",
+    "CAUSAL-READS",
+    "CAUSAL-TRX",
+    "INCREMENTAL",
+    "SESSION-LOCKS",
+    "DISTRIBUTED-LOCKS",
+    "CONSISTENCY-CHECK",
+    "UNORDERED",
+    "ANNOTATION",
+    "PREORDERED",
+    "STREAMING",
+    "SNAPSHOT",
+    "NBO",
+    NULL,
+};
+
+/**
+ * REPLICATION: callback is called by provider when the node connects to group.
+ *              This happens out-of-order, before the node receives a state
+ *              transfer and syncs with the cluster. Unless application requires
+ *              it it can be empty. We however want to know the GTID of the
+ *              group out of order for SST tricks, so we record it out of order.
+ */
+static enum wsrep_cb_status
+wsrep_connected_cb(void*                    const x,
+                   const wsrep_view_info_t* const v)
+{
+    char gtid_str[WSREP_GTID_STR_LEN + 1];
+    wsrep_gtid_print(&v->state_id, gtid_str, sizeof(gtid_str));
+
+    NODE_INFO("connect_cb(): Connected at %s to %s group of %d member(s)",
+              gtid_str, wsrep_view_status_str[v->status], v->memb_num);
+
+    struct node_wsrep* const wsrep = ((struct node_ctx*)x)->wsrep;
+
+    if (pthread_mutex_lock(&wsrep->view.mtx))
+    {
+        NODE_FATAL("Failed to lock VIEW mutex");
+        abort();
+    }
+
+    wsrep->view.state_id = v->state_id;
+
+    pthread_mutex_unlock(&wsrep->view.mtx);
+
+    return WSREP_CB_SUCCESS;
+}
+
+/**
+ * logs view data */
+static void
+wsrep_log_view(const struct wsrep_view* v)
+{
+    char gtid[WSREP_GTID_STR_LEN + 1];
+    wsrep_gtid_print(&v->state_id, gtid, sizeof(gtid));
+    gtid[WSREP_GTID_STR_LEN] = '\0';
+
+    char caps[256];
+    int written = 0;
+    size_t space_left = sizeof(caps);
+    int i;
+    for (i = 0; i < WSREP_CAPABILITIES_MAX && space_left > 0; i++)
+    {
+        wsrep_cap_t const f = 1u << i;
+
+        if (!(f & v->capabilities)) continue;
+
+        if (wsrep_capabilities_str[i])
+        {
+            written += snprintf(&caps[written], space_left, "%s|",
+                                wsrep_capabilities_str[i]);
+        }
+        else
+        {
+            written += snprintf(&caps[written], space_left, "%d|", i);
+        }
+
+        space_left = sizeof(caps) - (size_t)written;
+    }
+    caps[written ? written - 1 : 0] = '\0'; // overwrite last '|'
+
+    char members_list[1024];
+    written = 0;
+    space_left = sizeof(members_list);
+    for (i = 0; i < v->memb_num && space_left > 0; i++)
+    {
+        wsrep_member_info_t* m = &v->members[i];
+        char uuid[WSREP_UUID_STR_LEN + 1];
+        wsrep_uuid_print(&m->id, uuid, sizeof(uuid));
+        uuid[WSREP_UUID_STR_LEN] = '\0';
+
+        written += snprintf(&members_list[written], space_left,
+                            "%s%d: %s '%s' incoming:'%s'\n",
+                            v->my_idx == i ? " * " : "   ", i,
+                            uuid, m->name, m->incoming);
+
+        space_left = sizeof(members_list) - (size_t)written;
+    }
+    members_list[written ? written - 1 : 0] = '\0'; // overwrite the last '\n'
+
+    NODE_INFO(
+        "New view received:\n"
+        "state: %s (%s)\n"
+        "capabilities: %s\n"
+        "protocol version: %d\n"
+        "members(%d)%s%s",
+        gtid, wsrep_view_status_str[v->status],
+        caps,
+        v->proto_ver,
+        v->memb_num, v->memb_num ? ":\n" : "", members_list);
+}
+
+/**
+ * REPLICATION: callback is called when the node needs to process cluster
+ *              view change. The callback is called in "total order isolation",
+ *              so all the preceding replication events will be processed
+ *              strictly before the call and all subsequent - striclty after.
+ */
+static enum wsrep_cb_status
+wsrep_view_cb(void*                    const x,
+              void*                    const r,
+              const wsrep_view_info_t* const v,
+              const char*              const state,
+              size_t                   const state_len)
+{
+    (void)r;
+    (void)state;
+    (void)state_len;
+
+    struct node_ctx* const node = x;
+
+    if (WSREP_VIEW_PRIMARY == v->status)
+    {
+        /* REPLICATION: membership change is a totally ordered event and as such
+         *              should be a part of the state, like changes to the
+         *              database. */
+        int err = node_store_update_membership(node->store, v);
+        if (err)
+        {
+            NODE_FATAL("Failed to update membership in store: %d (%s)",
+                       err, strerror(-err));
+            abort();
+        }
+    }
+
+    enum wsrep_cb_status ret = WSREP_CB_SUCCESS;
+    struct node_wsrep* const wsrep = ((struct node_ctx*)x)->wsrep;
+
+    if (pthread_mutex_lock(&wsrep->view.mtx))
+    {
+        NODE_FATAL("Failed to lock VIEW mutex");
+        abort();
+    }
+
+    /* below we'll just copy the data for future reference (if need be): */
+
+    size_t const memb_size = (size_t)v->memb_num * sizeof(wsrep_member_info_t);
+    void* const tmp = realloc(wsrep->view.members, memb_size);
+    if (memb_size > 0 && !tmp)
+    {
+        NODE_ERROR("Could not allocate memory for a new view: %zu bytes",
+                   memb_size);
+        ret = WSREP_CB_FAILURE;
+        goto cleanup;
+    }
+    else
+    {
+        wsrep->view.members = tmp;
+        if (memb_size) memcpy(wsrep->view.members, &v->members[0], memb_size);
+    }
+
+    wsrep->view.state_id     = v->state_id;
+    wsrep->view.status       = v->status;
+    wsrep->view.capabilities = v->capabilities;
+    wsrep->view.proto_ver    = v->proto_ver;
+    wsrep->view.memb_num     = v->memb_num;
+    wsrep->view.my_idx       = v->my_idx;
+
+    /* and now log the info */
+
+    wsrep_log_view(&wsrep->view);
+
+cleanup:
+    pthread_mutex_unlock(&wsrep->view.mtx);
+
+    return ret;
+}
+
+/**
+ * REPLICATION: callback is called by provider when the node becomes SYNCED */
+static enum wsrep_cb_status
+wsrep_synced_cb(void* const x)
+{
+    struct node_wsrep* const wsrep = ((struct node_ctx*)x)->wsrep;
+
+    if (pthread_mutex_lock(&wsrep->synced.mtx))
+    {
+        NODE_FATAL("Failed to lock SYNCED mutex");
+        abort();
+    }
+
+    if (wsrep->synced.value == 0)
+    {
+        NODE_INFO("become SYNCED");
+        wsrep->synced.value = 1;
+        pthread_cond_broadcast(&wsrep->synced.cond);
+    }
+
+    pthread_mutex_unlock(&wsrep->synced.mtx);
+
+    return WSREP_CB_SUCCESS;
+}
+
+struct node_wsrep*
+node_wsrep_init(const struct node_options* const opts,
+                const wsrep_gtid_t*        const current_gtid,
+                void*                      const app_ctx)
+{
+    if (s_wsrep.instance != NULL) return NULL; // already initialized
+
+    wsrep_status_t err;
+    err = wsrep_load(opts->provider, &s_wsrep.instance, node_log_cb);
+    if (WSREP_OK != err)
+    {
+        if (strcasecmp(opts->provider, WSREP_NONE))
+        {
+            NODE_ERROR("wsrep_load(%s) failed: %s (%d).",
+                       opts->provider, strerror(err), err);
+        }
+        else
+        {
+            NODE_ERROR("Initializing dummy provider failed: %s (%d).",
+                       strerror(err), err);
+        }
+        return NULL;
+    }
+
+    char base_addr[256];
+    snprintf(base_addr, sizeof(base_addr) - 1, "%s:%ld",
+             opts->base_host, opts->base_port);
+
+    struct wsrep_init_args args =
+    {
+        .app_ctx        = app_ctx,
+
+        .node_name      = opts->name,
+        .node_address   = base_addr,
+        .node_incoming  = "",   // we don't accept client connections
+        .data_dir       = opts->data_dir,
+        .options        = opts->options,
+        .proto_ver      = 0,    // this is the first version of the application
+                                // so the first version of the writeset protocol
+        .state_id       = current_gtid,
+        .state          = NULL, // unused
+
+        .logger_cb      = node_log_cb,
+        .connected_cb   = wsrep_connected_cb,
+        .view_cb        = wsrep_view_cb,
+        .synced_cb      = wsrep_synced_cb,
+        .encrypt_cb     = NULL, // not implemented ATM
+
+        .apply_cb       = node_worker_apply_cb,
+        .unordered_cb   = NULL, // not needed now
+
+        .sst_request_cb = node_sst_request_cb,
+        .sst_donate_cb  = node_sst_donate_cb
+    };
+
+    wsrep_t* wsrep = s_wsrep.instance;
+
+    err = wsrep->init(wsrep, &args);
+
+    if (WSREP_OK != err)
+    {
+        NODE_ERROR("wsrep::init() failed: %d, must shutdown", err);
+        node_wsrep_close(&s_wsrep);
+        return NULL;
+    }
+
+    return &s_wsrep;
+}
+
+wsrep_status_t
+node_wsrep_connect(struct node_wsrep* const wsrep,
+                   const char*        const address,
+                   bool               const bootstrap)
+{
+    wsrep->bootstrap = bootstrap;
+    wsrep_status_t err = wsrep->instance->connect(wsrep->instance,
+                                                  "wsrep_cluster",
+                                                  address,
+                                                  NULL,
+                                                  wsrep->bootstrap);
+
+    if (WSREP_OK != err)
+    {
+        NODE_ERROR("wsrep::connect(%s) failed: %d, must shutdown",
+                   address, err);
+        node_wsrep_close(wsrep);
+    }
+
+    return err;
+}
+
+void
+node_wsrep_disconnect(struct node_wsrep* const wsrep)
+{
+    if (pthread_mutex_lock(&wsrep->synced.mtx))
+    {
+        NODE_FATAL("Failed to lock SYNCED mutex");
+        abort();
+    }
+    wsrep->synced.value = -1; /* this will signal master threads to exit */
+    pthread_cond_broadcast(&wsrep->synced.cond);
+    pthread_mutex_unlock(&wsrep->synced.mtx);
+
+    wsrep_status_t const err = wsrep->instance->disconnect(wsrep->instance);
+
+    if (err)
+    {
+        /* REPLICATION: unless connection is not closed, slave threads will
+         *              never return. */
+        NODE_FATAL("Failed to close wsrep connection: %d", err);
+        abort();
+    }
+}
+
+void
+node_wsrep_close(struct node_wsrep* const wsrep)
+{
+    if (pthread_mutex_lock(&wsrep->view.mtx))
+    {
+        NODE_FATAL("Failed to lock VIEW mutex");
+        abort();
+    }
+    assert(0    == wsrep->view.memb_num); // the node must be disconneted
+    assert(NULL == wsrep->view.members);
+    free(wsrep->view.members);
+    wsrep->view.members = NULL;
+    pthread_mutex_unlock(&wsrep->view.mtx);
+
+    wsrep->instance->free(wsrep->instance);
+    wsrep->instance = NULL;
+}
+
+bool
+node_wsrep_wait_synced(struct node_wsrep* const wsrep)
+{
+    if (pthread_mutex_lock(&wsrep->synced.mtx))
+    {
+        NODE_FATAL("Failed to lock SYNCED mutex");
+        abort();
+    }
+
+    while (wsrep->synced.value == 0)
+    {
+        pthread_cond_wait(&wsrep->synced.cond, &wsrep->synced.mtx);
+    }
+
+    bool const ret = wsrep->synced.value > 0;
+
+    pthread_mutex_unlock(&wsrep->synced.mtx);
+
+    return ret;
+}
+
+void
+node_wsrep_connected_gtid(struct node_wsrep* wsrep, wsrep_gtid_t* gtid)
+{
+    if (pthread_mutex_lock(&wsrep->view.mtx))
+    {
+        NODE_FATAL("Failed to lock VIEW mutex");
+        abort();
+    }
+
+    *gtid = wsrep->view.state_id;
+
+    pthread_mutex_unlock(&wsrep->view.mtx);
+}
+
+wsrep_t*
+node_wsrep_provider(struct node_wsrep* wsrep)
+{
+    return wsrep->instance;
+}
diff --git a/wsrep-lib/wsrep-API/v26/examples/node/wsrep.h b/wsrep-lib/wsrep-API/v26/examples/node/wsrep.h
new file mode 100644
index 00000000..75c7eac3
--- /dev/null
+++ b/wsrep-lib/wsrep-API/v26/examples/node/wsrep.h
@@ -0,0 +1,92 @@
+/* Copyright (c) 2019, Codership Oy. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ */
+
+/**
+ * @file This unit defines various helpers to manage wsrep provider
+ */
+
+#ifndef NODE_WSREP_H
+#define NODE_WSREP_H
+
+#include "options.h"
+
+#include "../../wsrep_api.h"
+
+#include <pthread.h>
+#include <stdbool.h>
+
+typedef struct node_wsrep node_wsrep_t;
+
+/**
+ * loads and initializes wsrep provider for further usage
+ *
+ * @param[in] opts         program options
+ * @param[in] current_gtid GTID corresponding to the current node state
+ * @param[in] app_ctx      application context to be passed to callbacks
+ *
+ * @return initialized object pointer
+ */
+extern node_wsrep_t*
+node_wsrep_init(const struct node_options* opts,
+                const wsrep_gtid_t*        current_gtid,
+                void*                      app_ctx);
+
+/**
+ * connects to primary component
+ *
+ * @param[in] wsrep      wsrep context
+ * @param[in] address    address to connect at (provider specific)
+ * @param[in] bootsstrap bootstrap primary component if there's none
+ *
+ * @return wsrep status code
+ */
+extern wsrep_status_t
+node_wsrep_connect(node_wsrep_t* wsrep,
+                   const char*   address,
+                   bool          bootstrap);
+
+/**
+ * disconnects from primary component
+ */
+extern void
+node_wsrep_disconnect(node_wsrep_t* wsrep);
+
+/**
+ * deinitializes and unloads wsrep provider
+ */
+extern void
+node_wsrep_close(node_wsrep_t* wsrep);
+
+/**
+ * waits for the node to become SYNCED
+ *
+ * @return true if node is synced, false in any other event.
+ */
+extern bool
+node_wsrep_wait_synced(node_wsrep_t* wsrep);
+
+/**
+ * @param[in]  wsrep context
+ * @param[out] gtid of the current view */
+extern void
+node_wsrep_connected_gtid(node_wsrep_t* wsrep, wsrep_gtid_t* gtid);
+
+/**
+ * @return wsrep provider instance */
+extern wsrep_t*
+node_wsrep_provider(node_wsrep_t* wsrep);
+
+#endif /* NODE_WSREP_H */