Adding upstream version 1:10.11.6.upstream/1%10.11.6upstream

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

26 files changed, 3476 insertions, 0 deletions

diff --git a/wsrep-lib/dbsim/CMakeLists.txt b/wsrep-lib/dbsim/CMakeLists.txt
new file mode 100644
index 00000000..aee964cd
--- /dev/null
+++ b/wsrep-lib/dbsim/CMakeLists.txt
@@ -0,0 +1,21 @@
+#
+# Copyright (C) 2018 Codership Oy <info@codership.com>
+#
+
+add_executable(dbsim
+  db_client.cpp
+  db_client_service.cpp
+  db_high_priority_service.cpp
+  db_params.cpp
+  db_server.cpp
+  db_server_service.cpp
+  db_server_state.cpp
+  db_simulator.cpp
+  db_storage_engine.cpp
+  db_threads.cpp
+  db_tls.cpp
+  dbsim.cpp
+)
+
+target_link_libraries(dbsim wsrep-lib ${Boost_PROGRAM_OPTIONS_LIBRARY} ${Boost_SYSTEM_LIBRARY} ${Boost_FILESYSTEM_LIBRARY} ${Boost_THREAD_LIBRARY})
+set_property(TARGET dbsim PROPERTY CXX_STANDARD 14)
diff --git a/wsrep-lib/dbsim/db_client.cpp b/wsrep-lib/dbsim/db_client.cpp
new file mode 100644
index 00000000..b5d56d37
--- /dev/null
+++ b/wsrep-lib/dbsim/db_client.cpp
@@ -0,0 +1,195 @@
+/*
+ * Copyright (C) 2018 Codership Oy <info@codership.com>
+ *
+ * This file is part of wsrep-lib.
+ *
+ * Wsrep-lib 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, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Wsrep-lib 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 wsrep-lib.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "db_client.hpp"
+#include "db_server.hpp"
+
+#include "wsrep/logger.hpp"
+
+db::client::client(db::server& server,
+                   wsrep::client_id client_id,
+                   enum wsrep::client_state::mode mode,
+                   const db::params& params)
+    : mutex_()
+    , cond_()
+    , params_(params)
+    , server_(server)
+    , server_state_(server.server_state())
+    , client_state_(mutex_, cond_, server_state_, client_service_, client_id, mode)
+    , client_service_(*this)
+    , se_trx_(server.storage_engine())
+    , data_()
+    , random_device_()
+    , random_engine_(random_device_())
+    , stats_()
+{
+    data_.resize(params.max_data_size);
+}
+
+void db::client::start()
+{
+    client_state_.open(client_state_.id());
+    for (size_t i(0); i < params_.n_transactions; ++i)
+    {
+        run_one_transaction();
+        report_progress(i + 1);
+    }
+    client_state_.close();
+    client_state_.cleanup();
+}
+
+bool db::client::bf_abort(wsrep::seqno seqno)
+{
+    return client_state_.bf_abort(seqno);
+}
+
+////////////////////////////////////////////////////////////////////////////////
+//                              Private                                       //
+////////////////////////////////////////////////////////////////////////////////
+
+template <class F>
+int db::client::client_command(F f)
+{
+    int err(client_state_.before_command());
+    // wsrep::log_debug() << "before_command: " << err;
+    // If err != 0, transaction was BF aborted while client idle
+    if (err == 0)
+    {
+        err = client_state_.before_statement();
+        if (err == 0)
+        {
+            err = f();
+        }
+        client_state_.after_statement();
+    }
+    client_state_.after_command_before_result();
+    if (client_state_.current_error())
+    {
+        // wsrep::log_info() << "Current error";
+        assert(client_state_.transaction().state() ==
+               wsrep::transaction::s_aborted);
+        err = 1;
+    }
+    client_state_.after_command_after_result();
+    // wsrep::log_info() << "client_command(): " << err;
+    return err;
+}
+
+void db::client::run_one_transaction()
+{
+    if (params_.sync_wait)
+    {
+        if (client_state_.sync_wait(5))
+        {
+            throw wsrep::runtime_error("Sync wait failed");
+        }
+    }
+    client_state_.reset_error();
+    int err = client_command(
+        [&]()
+        {
+            // wsrep::log_debug() << "Start transaction";
+            err = client_state_.start_transaction(
+                wsrep::transaction_id(server_.next_transaction_id()));
+            assert(err == 0);
+            se_trx_.start(this);
+            return err;
+        });
+
+    const wsrep::transaction& transaction(
+        client_state_.transaction());
+
+    err = err || client_command(
+        [&]()
+        {
+            // wsrep::log_debug() << "Generate write set";
+            assert(transaction.active());
+            assert(err == 0);
+            std::uniform_int_distribution<size_t> uniform_dist(0, params_.n_rows);
+            const size_t randkey(uniform_dist(random_engine_));
+            ::memcpy(data_.data(), &randkey,
+                     std::min(sizeof(randkey), data_.size()));
+            wsrep::key key(wsrep::key::exclusive);
+            key.append_key_part("dbms", 4);
+            unsigned long long client_key(client_state_.id().get());
+            key.append_key_part(&client_key, sizeof(client_key));
+            key.append_key_part(&randkey, sizeof(randkey));
+            err = client_state_.append_key(key);
+            size_t bytes_to_append(data_.size());
+            if (params_.random_data_size)
+            {
+                bytes_to_append = std::uniform_int_distribution<size_t>(
+                    1, data_.size())(random_engine_);
+            }
+            err = err || client_state_.append_data(
+                wsrep::const_buffer(data_.data(), bytes_to_append));
+            return err;
+        });
+
+    err = err || client_command(
+        [&]()
+        {
+            // wsrep::log_debug() << "Commit";
+            assert(err == 0);
+            if (do_2pc())
+            {
+                err = err || client_state_.before_prepare();
+                err = err || client_state_.after_prepare();
+            }
+            err = err || client_state_.before_commit();
+            if (err == 0) se_trx_.commit(transaction.ws_meta().gtid());
+            err = err || client_state_.ordered_commit();
+            err = err || client_state_.after_commit();
+            if (err)
+            {
+                client_state_.before_rollback();
+                se_trx_.rollback();
+                client_state_.after_rollback();
+            }
+            return err;
+        });
+
+    assert(err ||
+           transaction.state() == wsrep::transaction::s_aborted ||
+           transaction.state() == wsrep::transaction::s_committed);
+    assert(se_trx_.active() == false);
+    assert(transaction.active() == false);
+
+    switch (transaction.state())
+    {
+    case wsrep::transaction::s_committed:
+        ++stats_.commits;
+        break;
+    case wsrep::transaction::s_aborted:
+        ++stats_.rollbacks;
+        break;
+    default:
+        assert(0);
+    }
+}
+
+void db::client::report_progress(size_t i) const
+{
+    if ((i % 1000) == 0)
+    {
+        wsrep::log_info() << "client: " << client_state_.id().get()
+                          << " transactions: " << i
+                          << " " << 100*double(i)/double(params_.n_transactions) << "%";
+    }
+}
diff --git a/wsrep-lib/dbsim/db_client.hpp b/wsrep-lib/dbsim/db_client.hpp
new file mode 100644
index 00000000..5536a449
--- /dev/null
+++ b/wsrep-lib/dbsim/db_client.hpp
@@ -0,0 +1,89 @@
+/*
+ * Copyright (C) 2018 Codership Oy <info@codership.com>
+ *
+ * This file is part of wsrep-lib.
+ *
+ * Wsrep-lib 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, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Wsrep-lib 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 wsrep-lib.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/** @file db_client.hpp */
+
+#ifndef WSREP_DB_CLIENT_HPP
+#define WSREP_DB_CLIENT_HPP
+
+#include "db_server_state.hpp"
+#include "db_storage_engine.hpp"
+#include "db_client_state.hpp"
+#include "db_client_service.hpp"
+#include "db_high_priority_service.hpp"
+
+#include <random>
+
+namespace db
+{
+    class server;
+    class client
+    {
+    public:
+        struct stats
+        {
+            long long commits;
+            long long rollbacks;
+            long long replays;
+            stats()
+                : commits(0)
+                , rollbacks(0)
+                , replays(0)
+            { }
+        };
+        client(db::server&,
+               wsrep::client_id,
+               enum wsrep::client_state::mode,
+               const db::params&);
+        bool bf_abort(wsrep::seqno);
+        const struct stats stats() const { return stats_; }
+        void store_globals()
+        {
+            client_state_.store_globals();
+        }
+        void reset_globals()
+        { }
+        void start();
+        wsrep::client_state& client_state() { return client_state_; }
+        wsrep::client_service& client_service() { return client_service_; }
+        bool do_2pc() const { return false; }
+    private:
+        friend class db::server_state;
+        friend class db::client_service;
+        friend class db::high_priority_service;
+        template <class F> int client_command(F f);
+        void run_one_transaction();
+        void reset_error();
+        void report_progress(size_t) const;
+        wsrep::default_mutex mutex_;
+        wsrep::default_condition_variable cond_;
+        const db::params& params_;
+        db::server& server_;
+        db::server_state& server_state_;
+        db::client_state client_state_;
+        db::client_service client_service_;
+        db::storage_engine::transaction se_trx_;
+        wsrep::mutable_buffer data_;
+        std::random_device random_device_;
+        std::default_random_engine random_engine_;
+        struct stats stats_;
+    };
+}
+
+#endif // WSREP_DB_CLIENT_HPP
diff --git a/wsrep-lib/dbsim/db_client_service.cpp b/wsrep-lib/dbsim/db_client_service.cpp
new file mode 100644
index 00000000..bb40017c
--- /dev/null
+++ b/wsrep-lib/dbsim/db_client_service.cpp
@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) 2018 Codership Oy <info@codership.com>
+ *
+ * This file is part of wsrep-lib.
+ *
+ * Wsrep-lib 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, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Wsrep-lib 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 wsrep-lib.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "db_client_service.hpp"
+#include "db_high_priority_service.hpp"
+#include "db_client.hpp"
+
+#include <cassert>
+
+db::client_service::client_service(db::client& client)
+    : wsrep::client_service()
+    , client_(client)
+    , client_state_(client_.client_state())
+{ }
+
+int db::client_service::bf_rollback()
+{
+    int ret(client_state_.before_rollback());
+    assert(ret == 0);
+    client_.se_trx_.rollback();
+    ret = client_state_.after_rollback();
+    assert(ret == 0);
+    return ret;
+}
+
+enum wsrep::provider::status
+db::client_service::replay()
+{
+    wsrep::high_priority_context high_priority_context(client_state_);
+    db::replayer_service replayer_service(
+        client_.server_, client_);
+    auto ret(client_state_.provider().replay(
+                 client_state_.transaction().ws_handle(),
+                 &replayer_service));
+    if (ret == wsrep::provider::success)
+    {
+        ++client_.stats_.replays;
+    }
+    return ret;
+}
diff --git a/wsrep-lib/dbsim/db_client_service.hpp b/wsrep-lib/dbsim/db_client_service.hpp
new file mode 100644
index 00000000..be6f9ad8
--- /dev/null
+++ b/wsrep-lib/dbsim/db_client_service.hpp
@@ -0,0 +1,98 @@
+/*
+ * Copyright (C) 2018 Codership Oy <info@codership.com>
+ *
+ * This file is part of wsrep-lib.
+ *
+ * Wsrep-lib 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, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Wsrep-lib 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 wsrep-lib.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef WSREP_DB_CLIENT_SERVICE_HPP
+#define WSREP_DB_CLIENT_SERVICE_HPP
+
+#include "wsrep/client_service.hpp"
+#include "wsrep/transaction.hpp"
+
+namespace db
+{
+    class client;
+    class client_state;
+
+    class client_service : public wsrep::client_service
+    {
+    public:
+        client_service(db::client& client);
+
+        bool interrupted(wsrep::unique_lock<wsrep::mutex>&)
+            const override
+        { return false; }
+        void reset_globals() override { }
+        void store_globals() override { }
+        int prepare_data_for_replication() override
+        {
+            return 0;
+        }
+        void cleanup_transaction() override { }
+        size_t bytes_generated() const override
+        {
+            return 0;
+        }
+        bool statement_allowed_for_streaming() const override
+        {
+            return true;
+        }
+        int prepare_fragment_for_replication(wsrep::mutable_buffer&,
+                                             size_t& position) override
+        {
+            position = 0;
+            return 0;
+        }
+        int remove_fragments() override { return 0; }
+        int bf_rollback() override;
+        void will_replay() override { }
+        void signal_replayed() override { }
+        void wait_for_replayers(wsrep::unique_lock<wsrep::mutex>&) override { }
+        enum wsrep::provider::status replay()
+            override;
+
+        enum wsrep::provider::status replay_unordered() override
+        {
+            return wsrep::provider::success;
+        }
+
+        void emergency_shutdown() override { ::abort(); }
+
+        enum wsrep::provider::status commit_by_xid() override
+        {
+            return wsrep::provider::success;
+        }
+
+        bool is_explicit_xa() override
+        {
+            return false;
+        }
+
+        bool is_xa_rollback() override
+        {
+            return false;
+        }
+
+        void debug_sync(const char*) override { }
+        void debug_crash(const char*) override { }
+    private:
+        db::client& client_;
+        wsrep::client_state& client_state_;
+    };
+}
+
+#endif // WSREP_DB_CLIENT_SERVICE_HPP
diff --git a/wsrep-lib/dbsim/db_client_state.hpp b/wsrep-lib/dbsim/db_client_state.hpp
new file mode 100644
index 00000000..a5cf71b2
--- /dev/null
+++ b/wsrep-lib/dbsim/db_client_state.hpp
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2018 Codership Oy <info@codership.com>
+ *
+ * This file is part of wsrep-lib.
+ *
+ * Wsrep-lib 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, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Wsrep-lib 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 wsrep-lib.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef WSREP_DB_CLIENT_CONTEXT_HPP
+#define WSREP_DB_CLIENT_CONTEXT_HPP
+
+#include "wsrep/client_state.hpp"
+#include "db_server_state.hpp"
+
+namespace db
+{
+    class client;
+    class client_state : public wsrep::client_state
+    {
+    public:
+        client_state(wsrep::mutex& mutex,
+                     wsrep::condition_variable& cond,
+                     db::server_state& server_state,
+                     wsrep::client_service& client_service,
+                     const wsrep::client_id& client_id,
+                     enum wsrep::client_state::mode mode)
+            : wsrep::client_state(mutex,
+                                  cond,
+                                  server_state,
+                                  client_service,
+                                  client_id,
+                                  mode)
+        { }
+
+    private:
+        client_state(const client_state&);
+        client_state& operator=(const client_state&);
+    };
+}
+
+#endif // WSREP_DB_CLIENT_CONTEXT
diff --git a/wsrep-lib/dbsim/db_high_priority_service.cpp b/wsrep-lib/dbsim/db_high_priority_service.cpp
new file mode 100644
index 00000000..669fe502
--- /dev/null
+++ b/wsrep-lib/dbsim/db_high_priority_service.cpp
@@ -0,0 +1,137 @@
+/*
+ * Copyright (C) 2018-2019 Codership Oy <info@codership.com>
+ *
+ * This file is part of wsrep-lib.
+ *
+ * Wsrep-lib 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, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Wsrep-lib 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 wsrep-lib.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "db_high_priority_service.hpp"
+#include "db_server.hpp"
+#include "db_client.hpp"
+
+db::high_priority_service::high_priority_service(
+    db::server& server, db::client& client)
+    : wsrep::high_priority_service(server.server_state())
+    , server_(server)
+    , client_(client)
+{ }
+
+int db::high_priority_service::start_transaction(
+    const wsrep::ws_handle& ws_handle,
+    const wsrep::ws_meta& ws_meta)
+{
+    return client_.client_state().start_transaction(ws_handle, ws_meta);
+}
+
+int db::high_priority_service::next_fragment(const wsrep::ws_meta& ws_meta)
+{
+    return client_.client_state().next_fragment(ws_meta);
+}
+
+const wsrep::transaction& db::high_priority_service::transaction() const
+{
+    return client_.client_state().transaction();
+}
+
+int db::high_priority_service::adopt_transaction(const wsrep::transaction&)
+{
+    throw wsrep::not_implemented_error();
+}
+
+int db::high_priority_service::apply_write_set(
+    const wsrep::ws_meta&,
+    const wsrep::const_buffer&,
+    wsrep::mutable_buffer&)
+{
+    client_.se_trx_.start(&client_);
+    client_.se_trx_.apply(client_.client_state().transaction());
+    return 0;
+}
+
+int db::high_priority_service::apply_toi(
+    const wsrep::ws_meta&,
+    const wsrep::const_buffer&,
+    wsrep::mutable_buffer&)
+{
+    throw wsrep::not_implemented_error();
+}
+
+int db::high_priority_service::apply_nbo_begin(
+    const wsrep::ws_meta&,
+    const wsrep::const_buffer&,
+    wsrep::mutable_buffer&)
+{
+    throw wsrep::not_implemented_error();
+}
+
+int db::high_priority_service::commit(const wsrep::ws_handle& ws_handle,
+                                      const wsrep::ws_meta& ws_meta)
+{
+    client_.client_state_.prepare_for_ordering(ws_handle, ws_meta, true);
+    int ret(client_.client_state_.before_commit());
+    if (ret == 0) client_.se_trx_.commit(ws_meta.gtid());
+    ret = ret || client_.client_state_.ordered_commit();
+    ret = ret || client_.client_state_.after_commit();
+    return ret;
+}
+
+int db::high_priority_service::rollback(const wsrep::ws_handle& ws_handle,
+                                        const wsrep::ws_meta& ws_meta)
+{
+    client_.client_state_.prepare_for_ordering(ws_handle, ws_meta, false);
+    int ret(client_.client_state_.before_rollback());
+    assert(ret == 0);
+    client_.se_trx_.rollback();
+    ret = client_.client_state_.after_rollback();
+    assert(ret == 0);
+    return ret;
+}
+
+void db::high_priority_service::adopt_apply_error(wsrep::mutable_buffer& err)
+{
+    client_.client_state_.adopt_apply_error(err);
+}
+
+void db::high_priority_service::after_apply()
+{
+    client_.client_state_.after_applying();
+}
+
+int db::high_priority_service::log_dummy_write_set(
+    const wsrep::ws_handle& ws_handle,
+    const wsrep::ws_meta& ws_meta,
+    wsrep::mutable_buffer& err)
+{
+    int ret(client_.client_state_.start_transaction(ws_handle, ws_meta));
+    assert(ret == 0);
+    if (ws_meta.ordered())
+    {
+        client_.client_state_.adopt_apply_error(err);
+        client_.client_state_.prepare_for_ordering(ws_handle, ws_meta, true);
+        ret = client_.client_state_.before_commit();
+        assert(ret == 0);
+        ret = client_.client_state_.ordered_commit();
+        assert(ret == 0);
+        ret = client_.client_state_.after_commit();
+        assert(ret == 0);
+    }
+    client_.client_state_.after_applying();
+    return ret;
+}
+
+bool db::high_priority_service::is_replaying() const
+{
+    return false;
+}
diff --git a/wsrep-lib/dbsim/db_high_priority_service.hpp b/wsrep-lib/dbsim/db_high_priority_service.hpp
new file mode 100644
index 00000000..d4a80f1b
--- /dev/null
+++ b/wsrep-lib/dbsim/db_high_priority_service.hpp
@@ -0,0 +1,89 @@
+/*
+ * Copyright (C) 2018-2019 Codership Oy <info@codership.com>
+ *
+ * This file is part of wsrep-lib.
+ *
+ * Wsrep-lib 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, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Wsrep-lib 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 wsrep-lib.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef WSREP_DB_HIGH_PRIORITY_SERVICE_HPP
+#define WSREP_DB_HIGH_PRIORITY_SERVICE_HPP
+
+#include "wsrep/high_priority_service.hpp"
+
+namespace db
+{
+    class server;
+    class client;
+    class high_priority_service : public wsrep::high_priority_service
+    {
+    public:
+        high_priority_service(db::server& server, db::client& client);
+        int start_transaction(const wsrep::ws_handle&,
+                              const wsrep::ws_meta&) override;
+        int next_fragment(const wsrep::ws_meta&) override;
+        const wsrep::transaction& transaction() const override;
+        int adopt_transaction(const wsrep::transaction&) override;
+        int apply_write_set(const wsrep::ws_meta&,
+                            const wsrep::const_buffer&,
+                            wsrep::mutable_buffer&) override;
+        int append_fragment_and_commit(
+            const wsrep::ws_handle&,
+            const wsrep::ws_meta&,
+            const wsrep::const_buffer&,
+            const wsrep::xid&) override
+        { return 0; }
+        int remove_fragments(const wsrep::ws_meta&) override
+        { return 0; }
+        int commit(const wsrep::ws_handle&, const wsrep::ws_meta&) override;
+        int rollback(const wsrep::ws_handle&, const wsrep::ws_meta&) override;
+        int apply_toi(const wsrep::ws_meta&, const wsrep::const_buffer&,
+                      wsrep::mutable_buffer&) override;
+        int apply_nbo_begin(const wsrep::ws_meta&, const wsrep::const_buffer&,
+                            wsrep::mutable_buffer&)
+            override;
+        void adopt_apply_error(wsrep::mutable_buffer&) override;
+        virtual void after_apply() override;
+        void store_globals() override { }
+        void reset_globals() override { }
+        void switch_execution_context(wsrep::high_priority_service&) override
+        { }
+        int log_dummy_write_set(const wsrep::ws_handle&,
+                                const wsrep::ws_meta&,
+                                wsrep::mutable_buffer&) override;
+        virtual bool is_replaying() const override;
+        void debug_crash(const char*) override { }
+    private:
+        high_priority_service(const high_priority_service&);
+        high_priority_service& operator=(const high_priority_service&);
+        db::server& server_;
+        db::client& client_;
+    };
+
+    class replayer_service : public db::high_priority_service
+    {
+    public:
+        replayer_service(db::server& server, db::client& client)
+            : db::high_priority_service(server, client)
+        { }
+        // After apply is empty for replayer to keep the transaction
+        // context available for the client session after replaying
+        // is over.
+        void after_apply() override {}
+        bool is_replaying() const override { return true; }
+    };
+
+}
+
+#endif // WSREP_DB_HIGH_PRIORITY_SERVICE_HPP
diff --git a/wsrep-lib/dbsim/db_params.cpp b/wsrep-lib/dbsim/db_params.cpp
new file mode 100644
index 00000000..40433f6c
--- /dev/null
+++ b/wsrep-lib/dbsim/db_params.cpp
@@ -0,0 +1,124 @@
+/*
+ * Copyright (C) 2018 Codership Oy <info@codership.com>
+ *
+ * This file is part of wsrep-lib.
+ *
+ * Wsrep-lib 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, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Wsrep-lib 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 wsrep-lib.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "db_params.hpp"
+
+#include <boost/program_options.hpp>
+#include <iostream>
+#include <stdexcept>
+
+namespace
+{
+    void validate_params(const db::params& params)
+    {
+        std::ostringstream os;
+        if (params.n_servers != params.topology.size())
+        {
+            if (params.topology.size() > 0)
+            {
+                os << "Error: --topology=" << params.topology << " does not "
+                   << "match the number of server --servers="
+                   << params.n_servers << "\n";
+            }
+        }
+        if (os.str().size())
+        {
+            throw std::invalid_argument(os.str());
+        }
+    }
+}
+
+db::params db::parse_args(int argc, char** argv)
+{
+    namespace po = boost::program_options;
+    db::params params;
+    po::options_description desc("Allowed options");
+    desc.add_options()
+        ("help", "produce help message")
+        ("wsrep-provider",
+         po::value<std::string>(&params.wsrep_provider)->required(),
+         "wsrep provider to load")
+        ("wsrep-provider-options",
+         po::value<std::string>(&params.wsrep_provider_options),
+         "wsrep provider options")
+        ("status-file",
+         po::value<std::string>(&params.status_file),
+         "status output file")
+        ("servers", po::value<size_t>(&params.n_servers)->required(),
+         "number of servers to start")
+        ("topology", po::value<std::string>(&params.topology),
+         "replication topology (e.g. mm for multi master, ms for master/slave")
+        ("clients", po::value<size_t>(&params.n_clients)->required(),
+         "number of clients to start per master")
+        ("transactions", po::value<size_t>(&params.n_transactions),
+         "number of transactions run by a client")
+        ("rows", po::value<size_t>(&params.n_rows),
+         "number of rows per table")
+        ("max-data-size", po::value<size_t>(&params.max_data_size),
+         "maximum size of data payload (default 8)")
+        ("random-data-size", po::value<bool>(&params.random_data_size),
+         "randomized payload data size (default 0)")
+        ("alg-freq", po::value<size_t>(&params.alg_freq),
+         "ALG frequency")
+        ("sync-wait", po::value<bool>(&params.sync_wait),
+         "Turn on sync wait for each transaction")
+        ("debug-log-level", po::value<int>(&params.debug_log_level),
+         "debug logging level: 0 - none, 1 - verbose")
+        ("fast-exit", po::value<int>(&params.fast_exit),
+         "exit from simulation without graceful shutdown")
+        ("ti",
+         po::value<int>(&params.thread_instrumentation),
+         "use instrumentation for threads/mutexes/condition variables"
+         "(0 default disabled, 1 total counts, 2 per object)")
+        ("ti-cond-checks",
+         po::value<bool>(&params.cond_checks),
+         "Enable checks for correct condition variable use. "
+         " Effective only if thread-instrumentation is enabled")
+        ("tls-service",
+         po::value<int>(&params.tls_service),
+         "Configure TLS service stubs.\n0 default disabled\n1 enabled\n"
+         "2 enabled with short read/write and renegotiation simulation\n"
+         "3 enabled with error simulation.")
+        ;
+    try
+    {
+        po::variables_map vm;
+        po::store(po::parse_command_line(argc, argv, desc), vm);
+        if (vm.count("help"))
+        {
+            std::cerr << desc << "\n";
+            exit(0);
+        }
+        po::notify(vm);
+        validate_params(params);
+    }
+    catch (const po::error& e)
+    {
+        std::cerr << "Error parsing arguments: " << e.what() << "\n";
+        std::cerr << desc << "\n";
+        exit(1);
+    }
+    catch (...)
+    {
+        std::cerr << "Error parsing arguments\n";
+        std::cerr << desc << "\n";
+        exit(1);
+    }
+    return params;
+}
diff --git a/wsrep-lib/dbsim/db_params.hpp b/wsrep-lib/dbsim/db_params.hpp
new file mode 100644
index 00000000..e5df8062
--- /dev/null
+++ b/wsrep-lib/dbsim/db_params.hpp
@@ -0,0 +1,71 @@
+/*
+ * Copyright (C) 2018 Codership Oy <info@codership.com>
+ *
+ * This file is part of wsrep-lib.
+ *
+ * Wsrep-lib 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, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Wsrep-lib 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 wsrep-lib.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef WSREP_DB_PARAMS_HPP
+#define WSREP_DB_PARAMS_HPP
+
+#include <cstddef>
+#include <string>
+
+namespace db
+{
+    struct params
+    {
+        size_t n_servers;
+        size_t n_clients;
+        size_t n_transactions;
+        size_t n_rows;
+        size_t max_data_size; // Maximum size of write set data payload.
+        bool random_data_size; // If true, randomize data payload size.
+        size_t alg_freq;
+        bool sync_wait;
+        std::string topology;
+        std::string wsrep_provider;
+        std::string wsrep_provider_options;
+        std::string status_file;
+        int debug_log_level;
+        int fast_exit;
+        int thread_instrumentation;
+        bool cond_checks;
+        int tls_service;
+        params()
+            : n_servers(0)
+            , n_clients(0)
+            , n_transactions(0)
+            , n_rows(1000)
+            , max_data_size(8)
+            , random_data_size(false)
+            , alg_freq(0)
+            , sync_wait(false)
+            , topology()
+            , wsrep_provider()
+            , wsrep_provider_options()
+            , status_file("status.json")
+            , debug_log_level(0)
+            , fast_exit(0)
+            , thread_instrumentation()
+            , cond_checks()
+            , tls_service()
+        { }
+    };
+
+    params parse_args(int argc, char** argv);
+}
+
+#endif // WSREP_DB_PARAMS_HPP
diff --git a/wsrep-lib/dbsim/db_server.cpp b/wsrep-lib/dbsim/db_server.cpp
new file mode 100644
index 00000000..a54610d1
--- /dev/null
+++ b/wsrep-lib/dbsim/db_server.cpp
@@ -0,0 +1,167 @@
+/*
+ * Copyright (C) 2018 Codership Oy <info@codership.com>
+ *
+ * This file is part of wsrep-lib.
+ *
+ * Wsrep-lib 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, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Wsrep-lib 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 wsrep-lib.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "db_server.hpp"
+#include "db_server_service.hpp"
+#include "db_high_priority_service.hpp"
+#include "db_client.hpp"
+#include "db_simulator.hpp"
+
+#include "wsrep/logger.hpp"
+
+#include <ostream>
+#include <cstdio>
+
+static wsrep::default_mutex logger_mtx;
+
+static void
+logger_fn(wsrep::log::level l, const char* pfx, const char* msg)
+{
+    wsrep::unique_lock<wsrep::mutex> lock(logger_mtx);
+
+    struct timespec time;
+    clock_gettime(CLOCK_REALTIME, &time);
+
+    time_t const tt(time.tv_sec);
+    struct tm    date;
+    localtime_r(&tt, &date);
+
+    char date_str[85] = { '\0', };
+    snprintf(date_str, sizeof(date_str) - 1,
+             "%04d-%02d-%02d %02d:%02d:%02d.%03d",
+             date.tm_year + 1900, date.tm_mon + 1, date.tm_mday,
+             date.tm_hour, date.tm_min, date.tm_sec, (int)time.tv_nsec/1000000);
+
+    std::cerr << date_str << ' ' << pfx << wsrep::log::to_c_string(l) << ' '
+              << msg << std::endl;
+}
+
+db::server::server(simulator& simulator,
+                   const std::string& name,
+                   const std::string& address)
+    : simulator_(simulator)
+    , storage_engine_(simulator_.params())
+    , mutex_()
+    , cond_()
+    , server_service_(*this)
+    , reporter_(mutex_, name + ".json", 4)
+    , server_state_(server_service_,
+                    name, address, "dbsim_" + name + "_data")
+    , last_client_id_(0)
+    , last_transaction_id_(0)
+    , appliers_()
+    , clients_()
+    , client_threads_()
+{
+    wsrep::log::logger_fn(logger_fn);
+}
+
+void db::server::applier_thread()
+{
+    wsrep::client_id client_id(last_client_id_.fetch_add(1) + 1);
+    db::client applier(*this, client_id,
+                       wsrep::client_state::m_high_priority,
+                       simulator_.params());
+    wsrep::client_state* cc(static_cast<wsrep::client_state*>(
+                                &applier.client_state()));
+    db::high_priority_service hps(*this, applier);
+    cc->open(cc->id());
+    cc->before_command();
+    enum wsrep::provider::status ret(
+        server_state_.provider().run_applier(&hps));
+    wsrep::log_info() << "Applier thread exited with error code " << ret;
+    cc->after_command_before_result();
+    cc->after_command_after_result();
+    cc->close();
+    cc->cleanup();
+}
+
+void db::server::start_applier()
+{
+    wsrep::unique_lock<wsrep::mutex> lock(mutex_);
+    appliers_.push_back(boost::thread(&server::applier_thread, this));
+}
+
+void db::server::stop_applier()
+{
+    wsrep::unique_lock<wsrep::mutex> lock(mutex_);
+    appliers_.front().join();
+    appliers_.erase(appliers_.begin());
+}
+
+
+void db::server::start_clients()
+{
+    size_t n_clients(simulator_.params().n_clients);
+    for (size_t i(0); i < n_clients; ++i)
+    {
+        start_client(i + 1);
+    }
+}
+
+void db::server::stop_clients()
+{
+    for (auto& i : client_threads_)
+    {
+        i.join();
+    }
+    for (const auto& i : clients_)
+    {
+        const struct db::client::stats& stats(i->stats());
+        simulator_.stats_.commits += stats.commits;
+        simulator_.stats_.rollbacks  += stats.rollbacks;
+        simulator_.stats_.replays += stats.replays;
+    }
+}
+
+void db::server::client_thread(const std::shared_ptr<db::client>& client)
+{
+    client->start();
+}
+
+void db::server::start_client(size_t id)
+{
+    auto client(std::make_shared<db::client>(
+                    *this, wsrep::client_id(id),
+                    wsrep::client_state::m_local,
+                    simulator_.params()));
+    clients_.push_back(client);
+    client_threads_.push_back(
+        boost::thread(&db::server::client_thread, this, client));
+}
+
+void db::server::donate_sst(const std::string& req,
+                            const wsrep::gtid& gtid,
+                            bool bypass)
+{
+    simulator_.sst(*this, req, gtid, bypass);
+}
+
+
+wsrep::high_priority_service* db::server::streaming_applier_service()
+{
+    throw wsrep::not_implemented_error();
+}
+
+void db::server::log_state_change(enum wsrep::server_state::state from,
+                                  enum wsrep::server_state::state to)
+{
+    wsrep::log_info() << "State changed " << from << " -> " << to;
+    reporter_.report_state(to);
+}
diff --git a/wsrep-lib/dbsim/db_server.hpp b/wsrep-lib/dbsim/db_server.hpp
new file mode 100644
index 00000000..98b9a837
--- /dev/null
+++ b/wsrep-lib/dbsim/db_server.hpp
@@ -0,0 +1,82 @@
+/*
+ * Copyright (C) 2018 Codership Oy <info@codership.com>
+ *
+ * This file is part of wsrep-lib.
+ *
+ * Wsrep-lib 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, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Wsrep-lib 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 wsrep-lib.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef WSREP_DB_SERVER_HPP
+#define WSREP_DB_SERVER_HPP
+
+#include "wsrep/gtid.hpp"
+#include "wsrep/client_state.hpp"
+#include "wsrep/reporter.hpp"
+
+#include "db_storage_engine.hpp"
+#include "db_server_state.hpp"
+#include "db_server_service.hpp"
+
+#include <boost/thread.hpp>
+
+#include <string>
+#include <memory>
+
+namespace db
+{
+    class simulator;
+    class client;
+    class server
+    {
+    public:
+        server(simulator& simulator,
+               const std::string& name,
+               const std::string& address);
+        void applier_thread();
+        void start_applier();
+        void stop_applier();
+        void start_clients();
+        void stop_clients();
+        void client_thread(const std::shared_ptr<db::client>& client);
+        db::storage_engine& storage_engine() { return storage_engine_; }
+        db::server_state& server_state() { return server_state_; }
+        wsrep::transaction_id next_transaction_id()
+        {
+            return wsrep::transaction_id(last_transaction_id_.fetch_add(1) + 1);
+        }
+        void donate_sst(const std::string&, const  wsrep::gtid&, bool);
+        wsrep::client_state* local_client_state();
+        void release_client_state(wsrep::client_state*);
+        wsrep::high_priority_service* streaming_applier_service();
+        void log_state_change(enum wsrep::server_state::state,
+                              enum wsrep::server_state::state);
+    private:
+        void start_client(size_t id);
+
+        db::simulator& simulator_;
+        db::storage_engine storage_engine_;
+        wsrep::default_mutex mutex_;
+        wsrep::default_condition_variable cond_;
+        db::server_service server_service_;
+        wsrep::reporter reporter_;
+        db::server_state server_state_;
+        std::atomic<size_t> last_client_id_;
+        std::atomic<size_t> last_transaction_id_;
+        std::vector<boost::thread> appliers_;
+        std::vector<std::shared_ptr<db::client>> clients_;
+        std::vector<boost::thread> client_threads_;
+    };
+}
+
+#endif // WSREP_DB_SERVER_HPP
diff --git a/wsrep-lib/dbsim/db_server_service.cpp b/wsrep-lib/dbsim/db_server_service.cpp
new file mode 100644
index 00000000..d9b1cf90
--- /dev/null
+++ b/wsrep-lib/dbsim/db_server_service.cpp
@@ -0,0 +1,169 @@
+/*
+ * Copyright (C) 2018 Codership Oy <info@codership.com>
+ *
+ * This file is part of wsrep-lib.
+ *
+ * Wsrep-lib 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, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Wsrep-lib 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 wsrep-lib.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "db_server_service.hpp"
+#include "db_server.hpp"
+#include "db_storage_service.hpp"
+
+#include "wsrep/logger.hpp"
+#include "wsrep/high_priority_service.hpp"
+
+db::server_service::server_service(db::server& server)
+    : server_(server)
+{ }
+
+wsrep::storage_service* db::server_service::storage_service(
+    wsrep::client_service&)
+{
+    return new db::storage_service();
+}
+
+wsrep::storage_service* db::server_service::storage_service(
+    wsrep::high_priority_service&)
+{
+    return new db::storage_service();
+}
+
+void db::server_service::release_storage_service(
+    wsrep::storage_service* storage_service)
+{
+    delete storage_service;
+}
+
+wsrep::high_priority_service* db::server_service::streaming_applier_service(
+    wsrep::client_service&)
+{
+    return server_.streaming_applier_service();
+}
+
+wsrep::high_priority_service* db::server_service::streaming_applier_service(
+    wsrep::high_priority_service&)
+{
+    return server_.streaming_applier_service();
+}
+
+void db::server_service::release_high_priority_service(
+    wsrep::high_priority_service *high_priority_service)
+{
+    delete high_priority_service;
+}
+
+bool db::server_service::sst_before_init() const
+{
+    return true;
+}
+
+std::string db::server_service::sst_request()
+{
+    std::ostringstream os;
+    os << server_.server_state().name();
+    wsrep::log_info() << "SST request: "
+                      << server_.server_state().name();
+
+    return os.str();
+}
+
+int db::server_service::start_sst(
+    const std::string& request, const wsrep::gtid& gtid, bool bypass)
+{
+    server_.donate_sst(request, gtid, bypass);
+    return 0;
+}
+
+void db::server_service::background_rollback(wsrep::unique_lock<wsrep::mutex>&,
+                                             wsrep::client_state&)
+{
+}
+
+void db::server_service::bootstrap()
+{
+}
+
+void db::server_service::log_message(enum wsrep::log::level level,
+                                     const char* message)
+{
+    wsrep::log(level, server_.server_state().name().c_str()) << message;
+}
+void db::server_service::log_dummy_write_set(
+    wsrep::client_state&, const wsrep::ws_meta& meta)
+{
+    wsrep::log_info() << "Dummy write set: " << meta.seqno();
+}
+
+void db::server_service::log_view(wsrep::high_priority_service*,
+                                  const wsrep::view& v)
+{
+    wsrep::log_info() << "View:\n" << v;
+    server_.storage_engine().store_view(v);
+}
+
+void db::server_service::recover_streaming_appliers(
+    wsrep::client_service&)
+{
+}
+
+void db::server_service::recover_streaming_appliers(
+    wsrep::high_priority_service&)
+{
+}
+
+wsrep::view db::server_service::get_view(wsrep::client_service&,
+                                         const wsrep::id& own_id)
+{
+    wsrep::view stored_view(server_.storage_engine().get_view());
+    int const my_idx(stored_view.member_index(own_id));
+    wsrep::view my_view(
+        stored_view.state_id(),
+        stored_view.view_seqno(),
+        stored_view.status(),
+        stored_view.capabilities(),
+        my_idx,
+        stored_view.protocol_version(),
+        stored_view.members()
+    );
+    return my_view;
+}
+
+wsrep::gtid db::server_service::get_position(wsrep::client_service&)
+{
+    return server_.storage_engine().get_position();
+}
+
+void db::server_service::set_position(wsrep::client_service&,
+                                      const wsrep::gtid& gtid)
+{
+    return server_.storage_engine().store_position(gtid);
+}
+
+void db::server_service::log_state_change(
+    enum wsrep::server_state::state prev_state,
+    enum wsrep::server_state::state current_state)
+{
+    server_.log_state_change(prev_state, current_state);
+}
+
+int db::server_service::wait_committing_transactions(int)
+{
+    throw wsrep::not_implemented_error();
+}
+
+void db::server_service::debug_sync(const char*)
+{
+
+}
diff --git a/wsrep-lib/dbsim/db_server_service.hpp b/wsrep-lib/dbsim/db_server_service.hpp
new file mode 100644
index 00000000..d62ff11f
--- /dev/null
+++ b/wsrep-lib/dbsim/db_server_service.hpp
@@ -0,0 +1,67 @@
+/*
+ * Copyright (C) 2018 Codership Oy <info@codership.com>
+ *
+ * This file is part of wsrep-lib.
+ *
+ * Wsrep-lib 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, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Wsrep-lib 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 wsrep-lib.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef WSREP_DB_SERVER_SERVICE_HPP
+#define WSREP_DB_SERVER_SERVICE_HPP
+
+#include "wsrep/server_service.hpp"
+#include <string>
+
+namespace db
+{
+    class server;
+    class server_service : public wsrep::server_service
+    {
+    public:
+        server_service(db::server& server);
+        wsrep::storage_service* storage_service(wsrep::client_service&) override;
+        wsrep::storage_service* storage_service(wsrep::high_priority_service&) override;
+
+        void release_storage_service(wsrep::storage_service*) override;
+        wsrep::high_priority_service* streaming_applier_service(wsrep::client_service&) override;
+        wsrep::high_priority_service* streaming_applier_service(wsrep::high_priority_service&) override;
+        void release_high_priority_service(wsrep::high_priority_service*) override;
+
+        bool sst_before_init() const override;
+        int start_sst(const std::string&, const wsrep::gtid&, bool) override;
+        std::string sst_request() override;
+        void background_rollback(wsrep::unique_lock<wsrep::mutex>&,
+                                 wsrep::client_state&) override;
+        void bootstrap() override;
+        void log_message(enum wsrep::log::level, const char* message) override;
+        void log_dummy_write_set(wsrep::client_state&, const wsrep::ws_meta&)
+            override;
+        void log_view(wsrep::high_priority_service*,
+                      const wsrep::view&) override;
+        void recover_streaming_appliers(wsrep::client_service&) override;
+        void recover_streaming_appliers(wsrep::high_priority_service&) override;
+        wsrep::view get_view(wsrep::client_service&, const wsrep::id&)
+            override;
+        wsrep::gtid get_position(wsrep::client_service&) override;
+        void set_position(wsrep::client_service&, const wsrep::gtid&) override;
+        void log_state_change(enum wsrep::server_state::state,
+                              enum wsrep::server_state::state) override;
+        int wait_committing_transactions(int) override;
+        void debug_sync(const char*) override;
+    private:
+        db::server& server_;
+    };
+}
+
+#endif // WSREP_DB_SERVER_SERVICE_HPP
diff --git a/wsrep-lib/dbsim/db_server_state.cpp b/wsrep-lib/dbsim/db_server_state.cpp
new file mode 100644
index 00000000..2bc17d29
--- /dev/null
+++ b/wsrep-lib/dbsim/db_server_state.cpp
@@ -0,0 +1,24 @@
+/*
+ * Copyright (C) 2018 Codership Oy <info@codership.com>
+ *
+ * This file is part of wsrep-lib.
+ *
+ * Wsrep-lib 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, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Wsrep-lib 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 wsrep-lib.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "db_server_state.hpp"
+#include "db_server.hpp"
+
+#include "wsrep/logger.hpp"
+
diff --git a/wsrep-lib/dbsim/db_server_state.hpp b/wsrep-lib/dbsim/db_server_state.hpp
new file mode 100644
index 00000000..49d4499e
--- /dev/null
+++ b/wsrep-lib/dbsim/db_server_state.hpp
@@ -0,0 +1,60 @@
+/*
+ * Copyright (C) 2018 Codership Oy <info@codership.com>
+ *
+ * This file is part of wsrep-lib.
+ *
+ * Wsrep-lib 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, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Wsrep-lib 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 wsrep-lib.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef WSREP_DB_SERVER_CONTEXT_HPP
+#define WSREP_DB_SERVER_CONTEXT_HPP
+
+#include "wsrep/server_state.hpp"
+#include "wsrep/server_service.hpp"
+#include "wsrep/client_state.hpp"
+
+#include <atomic>
+
+namespace db
+{
+    class server;
+    class server_state : public wsrep::server_state
+    {
+    public:
+        server_state(wsrep::server_service& server_service,
+                     const std::string& name,
+                     const std::string& address,
+                     const std::string& working_dir)
+            : wsrep::server_state(
+                mutex_,
+                cond_,
+                server_service,
+                nullptr,
+                name,
+                "",
+                address,
+                working_dir,
+                wsrep::gtid::undefined(),
+                1,
+                wsrep::server_state::rm_async)
+            , mutex_()
+            , cond_()
+        { }
+    private:
+        wsrep::default_mutex mutex_;
+        wsrep::default_condition_variable cond_;
+    };
+}
+
+#endif // WSREP_DB_SERVER_CONTEXT_HPP
diff --git a/wsrep-lib/dbsim/db_simulator.cpp b/wsrep-lib/dbsim/db_simulator.cpp
new file mode 100644
index 00000000..97a18187
--- /dev/null
+++ b/wsrep-lib/dbsim/db_simulator.cpp
@@ -0,0 +1,267 @@
+/*
+ * Copyright (C) 2018 Codership Oy <info@codership.com>
+ *
+ * This file is part of wsrep-lib.
+ *
+ * Wsrep-lib 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, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Wsrep-lib 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 wsrep-lib.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "db_simulator.hpp"
+#include "db_client.hpp"
+#include "db_threads.hpp"
+#include "db_tls.hpp"
+
+#include "wsrep/logger.hpp"
+
+#include <boost/filesystem.hpp>
+#include <sstream>
+
+static db::ti thread_instrumentation;
+static db::tls tls_service;
+
+void db::simulator::run()
+{
+    start();
+    stop();
+    std::flush(std::cerr);
+    std::cout << "Results:\n";
+    std::cout << stats() << std::endl;
+    std::cout << db::ti::stats() << std::endl;
+    std::cout << db::tls::stats() << std::endl;
+}
+
+void db::simulator::sst(db::server& server,
+                        const std::string& request,
+                        const wsrep::gtid& gtid,
+                        bool bypass)
+{
+    // The request may contain extra trailing '\0' after it goes
+    // through the provider, strip it first.
+    std::string name(request);
+    name.erase(std::find(name.begin(), name.end(), '\0'), name.end());
+
+    wsrep::unique_lock<wsrep::mutex> lock(mutex_);
+    auto i(servers_.find(name));
+    wsrep::log_info() << "SST request '" << name << "'";
+    if (i == servers_.end())
+    {
+        wsrep::log_error() << "Server " << request << " not found";
+        wsrep::log_info() << "servers:";
+        for (const auto& s : servers_)
+        {
+            wsrep::log_info() << "server: " << s.first;
+        }
+        throw wsrep::runtime_error("Server " + request + " not found");
+    }
+    if (bypass == false)
+    {
+        wsrep::log_info() << "SST "
+                          << server.server_state().name()
+                          << " -> " << request;
+        i->second->storage_engine().store_position(gtid);
+        i->second->storage_engine().store_view(
+            server.storage_engine().get_view());
+    }
+
+    db::client dummy(*(i->second), wsrep::client_id(-1),
+                     wsrep::client_state::m_local, params());
+
+    if (i->second->server_state().sst_received(dummy.client_service(), 0))
+    {
+        throw wsrep::runtime_error("Call to SST received failed");
+    }
+    server.server_state().sst_sent(gtid, 0);
+}
+
+std::string db::simulator::stats() const
+{
+    auto duration(std::chrono::duration<double>(
+                      clients_stop_ - clients_start_).count());
+    long long transactions(stats_.commits + stats_.rollbacks);
+    long long bf_aborts(0);
+    for (const auto& s : servers_)
+    {
+        bf_aborts += s.second->storage_engine().bf_aborts();
+    }
+    std::ostringstream os;
+    os << "Number of transactions: " << transactions
+       << "\n"
+       << "Seconds: " << duration
+       << " \n"
+       << "Transactions per second: " << double(transactions)/double(duration)
+       << "\n"
+       << "BF aborts: "
+       << bf_aborts
+       << "\n"
+       << "Client commits: " << stats_.commits
+       << "\n"
+       << "Client rollbacks: " << stats_.rollbacks
+       << "\n"
+       << "Client replays: " << stats_.replays;
+    return os.str();
+}
+
+////////////////////////////////////////////////////////////////////////////////
+//                              Private                                       //
+////////////////////////////////////////////////////////////////////////////////
+
+void db::simulator::start()
+{
+    thread_instrumentation.level(params_.thread_instrumentation);
+    thread_instrumentation.cond_checks(params_.cond_checks);
+    tls_service.init(params_.tls_service);
+    wsrep::log_info() << "Provider: " << params_.wsrep_provider;
+
+    std::string cluster_address(build_cluster_address());
+    wsrep::log_info() << "Cluster address: " << cluster_address;
+    for (size_t i(0); i < params_.n_servers; ++i)
+    {
+        std::ostringstream name_os;
+        name_os << (i + 1);
+        std::ostringstream id_os;
+        id_os << (i + 1);
+        std::ostringstream address_os;
+        address_os << "127.0.0.1:" << server_port(i);
+        wsrep::id server_id(id_os.str());
+        auto it(servers_.insert(
+                    std::make_pair(
+                        name_os.str(),
+                        std::make_unique<db::server>(
+                            *this,
+                            name_os.str(),
+                            address_os.str()))));
+        if (it.second == false)
+        {
+            throw wsrep::runtime_error("Failed to add server");
+        }
+        boost::filesystem::path dir("dbsim_" + id_os.str() + "_data");
+        boost::filesystem::create_directory(dir);
+
+        db::server& server(*it.first->second);
+        server.server_state().debug_log_level(params_.debug_log_level);
+        std::string server_options(params_.wsrep_provider_options);
+
+        wsrep::provider::services services;
+        services.thread_service = params_.thread_instrumentation
+                                      ? &thread_instrumentation
+                                      : nullptr;
+        services.tls_service = params_.tls_service
+            ? &tls_service
+            : nullptr;
+        if (server.server_state().load_provider(params_.wsrep_provider,
+                                                server_options, services))
+        {
+            throw wsrep::runtime_error("Failed to load provider");
+        }
+        if (server.server_state().connect("sim_cluster", cluster_address, "",
+                                          i == 0))
+        {
+            throw wsrep::runtime_error("Failed to connect");
+        }
+        wsrep::log_debug() << "main: Starting applier";
+        server.start_applier();
+        wsrep::log_debug() << "main: Waiting initializing state";
+        if (server.server_state().wait_until_state(
+                wsrep::server_state::s_initializing))
+        {
+            throw wsrep::runtime_error("Failed to reach initializing state");
+        }
+        wsrep::log_debug() << "main: Calling initialized";
+        server.server_state().initialized();
+        wsrep::log_debug() << "main: Waiting for synced state";
+        if (server.server_state().wait_until_state(
+                wsrep::server_state::s_synced))
+        {
+            throw wsrep::runtime_error("Failed to reach synced state");
+        }
+        wsrep::log_debug() << "main: Server synced";
+    }
+
+    // Start client threads
+    wsrep::log_info() << "####################### Starting client load";
+    clients_start_ = std::chrono::steady_clock::now();
+    size_t index(0);
+    for (auto& i : servers_)
+    {
+        if (params_.topology.size() == 0 || params_.topology[index]  == 'm')
+        {
+            i.second->start_clients();
+        }
+        ++index;
+    }
+}
+
+void db::simulator::stop()
+{
+    for (auto& i : servers_)
+    {
+        db::server& server(*i.second);
+        server.stop_clients();
+    }
+    clients_stop_ = std::chrono::steady_clock::now();
+    wsrep::log_info() << "######## Stats ############";
+    wsrep::log_info()  << stats();
+    std::cout << db::ti::stats() << std::endl;
+    wsrep::log_info() << "######## Stats ############";
+    if (params_.fast_exit)
+    {
+        exit(0);
+    }
+    for (auto& i : servers_)
+    {
+        db::server& server(*i.second);
+        wsrep::log_info() << "Status for server: "
+                          << server.server_state().id();
+        auto status(server.server_state().provider().status());
+        for_each(status.begin(), status.end(),
+                 [](const wsrep::provider::status_variable& sv)
+                 {
+                     wsrep::log_info() << sv.name() << " = " << sv.value();
+                 });
+        server.server_state().disconnect();
+        if (server.server_state().wait_until_state(
+                wsrep::server_state::s_disconnected))
+        {
+            throw wsrep::runtime_error("Failed to reach disconnected state");
+        }
+        server.stop_applier();
+        server.server_state().unload_provider();
+    }
+}
+
+std::string db::simulator::server_port(size_t i) const
+{
+    std::ostringstream os;
+    os << (10000 + (i + 1)*10);
+    return os.str();
+}
+
+std::string db::simulator::build_cluster_address() const
+{
+    std::string ret;
+    if (params_.wsrep_provider.find("galera_smm") != std::string::npos)
+    {
+        ret += "gcomm://";
+    }
+
+    for (size_t i(0); i < params_.n_servers; ++i)
+    {
+        std::ostringstream sa_os;
+        sa_os << "127.0.0.1:";
+        sa_os << server_port(i);
+        ret += sa_os.str();
+        if (i < params_.n_servers - 1) ret += ",";
+    }
+    return ret;
+}
diff --git a/wsrep-lib/dbsim/db_simulator.hpp b/wsrep-lib/dbsim/db_simulator.hpp
new file mode 100644
index 00000000..693645e3
--- /dev/null
+++ b/wsrep-lib/dbsim/db_simulator.hpp
@@ -0,0 +1,81 @@
+/*
+ * Copyright (C) 2018 Codership Oy <info@codership.com>
+ *
+ * This file is part of wsrep-lib.
+ *
+ * Wsrep-lib 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, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Wsrep-lib 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 wsrep-lib.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef WSREP_DB_SIMULATOR_HPP
+#define WSREP_DB_SIMULATOR_HPP
+
+#include "wsrep/gtid.hpp"
+#include "wsrep/mutex.hpp"
+#include "wsrep/lock.hpp"
+
+#include "db_params.hpp"
+#include "db_server.hpp"
+
+#include <memory>
+#include <chrono>
+#include <unordered_set>
+#include <map>
+
+namespace db
+{
+    class server;
+    class simulator
+    {
+    public:
+        simulator(const params& params)
+            : mutex_()
+            , params_(params)
+            , servers_()
+            , clients_start_()
+            , clients_stop_()
+            , stats_()
+        { }
+
+        void run();
+        void sst(db::server&,
+                 const std::string&, const wsrep::gtid&, bool);
+        const db::params& params() const
+        { return params_; }
+        std::string stats() const;
+    private:
+        void start();
+        void stop();
+        std::string server_port(size_t i) const;
+        std::string build_cluster_address() const;
+
+        wsrep::default_mutex mutex_;
+        const db::params& params_;
+        std::map<std::string, std::unique_ptr<db::server>> servers_;
+        std::chrono::time_point<std::chrono::steady_clock> clients_start_;
+        std::chrono::time_point<std::chrono::steady_clock> clients_stop_;
+    public:
+        struct stats
+        {
+            long long commits;
+            long long rollbacks;
+            long long replays;
+            stats()
+                : commits(0)
+                , rollbacks(0)
+                , replays(0)
+            { }
+        } stats_;
+    };
+}
+#endif // WSRE_DB_SIMULATOR_HPP
diff --git a/wsrep-lib/dbsim/db_storage_engine.cpp b/wsrep-lib/dbsim/db_storage_engine.cpp
new file mode 100644
index 00000000..4278b81d
--- /dev/null
+++ b/wsrep-lib/dbsim/db_storage_engine.cpp
@@ -0,0 +1,120 @@
+/*
+ * Copyright (C) 2018 Codership Oy <info@codership.com>
+ *
+ * This file is part of wsrep-lib.
+ *
+ * Wsrep-lib 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, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Wsrep-lib 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 wsrep-lib.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "db_storage_engine.hpp"
+#include "db_client.hpp"
+
+#include <cassert>
+
+void db::storage_engine::transaction::start(db::client* cc)
+{
+    wsrep::unique_lock<wsrep::mutex> lock(se_.mutex_);
+    if (se_.transactions_.insert(cc).second == false)
+    {
+        ::abort();
+    }
+    cc_ = cc;
+}
+
+void db::storage_engine::transaction::apply(
+    const wsrep::transaction& transaction)
+{
+    assert(cc_);
+    se_.bf_abort_some(transaction);
+}
+
+void db::storage_engine::transaction::commit(const wsrep::gtid& gtid)
+{
+    if (cc_)
+    {
+        wsrep::unique_lock<wsrep::mutex> lock(se_.mutex_);
+        se_.transactions_.erase(cc_);
+        se_.store_position(gtid);
+    }
+    cc_ = nullptr;
+}
+
+
+void db::storage_engine::transaction::rollback()
+{
+    if (cc_)
+    {
+        wsrep::unique_lock<wsrep::mutex> lock(se_.mutex_);
+        se_.transactions_.erase(cc_);
+    }
+    cc_ = nullptr;
+}
+
+void db::storage_engine::bf_abort_some(const wsrep::transaction& txc)
+{
+    std::uniform_int_distribution<size_t> uniform_dist(0, alg_freq_);
+    wsrep::unique_lock<wsrep::mutex> lock(mutex_);
+    if (alg_freq_ && uniform_dist(random_engine_) == 0)
+    {
+        if (transactions_.empty() == false)
+        {
+            for (auto victim : transactions_)
+            {
+                wsrep::client_state& cc(victim->client_state());
+                if (cc.mode() == wsrep::client_state::m_local)
+                {
+                    if (victim->bf_abort(txc.seqno()))
+                    {
+                        ++bf_aborts_;
+                    }
+                    break;
+                }
+            }
+        }
+    }
+}
+
+void db::storage_engine::store_position(const wsrep::gtid& gtid)
+{
+    validate_position(gtid);
+    position_ = gtid;
+}
+
+wsrep::gtid db::storage_engine::get_position() const
+{
+    return position_;
+}
+
+void db::storage_engine::store_view(const wsrep::view& view)
+{
+    view_ = view;
+}
+
+wsrep::view db::storage_engine::get_view() const
+{
+    return view_;
+}
+
+void db::storage_engine::validate_position(const wsrep::gtid& gtid) const
+{
+    if (position_.id() == gtid.id() && gtid.seqno() <= position_.seqno())
+    {
+        std::ostringstream os;
+        os << "Invalid position submitted, position seqno "
+           << position_.seqno()
+           << " is greater than submitted seqno "
+           << gtid.seqno();
+        throw wsrep::runtime_error(os.str());
+    }
+}
diff --git a/wsrep-lib/dbsim/db_storage_engine.hpp b/wsrep-lib/dbsim/db_storage_engine.hpp
new file mode 100644
index 00000000..de5080cf
--- /dev/null
+++ b/wsrep-lib/dbsim/db_storage_engine.hpp
@@ -0,0 +1,92 @@
+/*
+ * Copyright (C) 2018 Codership Oy <info@codership.com>
+ *
+ * This file is part of wsrep-lib.
+ *
+ * Wsrep-lib 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, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Wsrep-lib 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 wsrep-lib.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef WSREP_DB_STORAGE_ENGINE_HPP
+#define WSREP_DB_STORAGE_ENGINE_HPP
+
+#include "db_params.hpp"
+
+#include "wsrep/mutex.hpp"
+#include "wsrep/view.hpp"
+#include "wsrep/transaction.hpp"
+
+#include <atomic>
+#include <unordered_set>
+#include <random>
+
+namespace db
+{
+    class client;
+    class storage_engine
+    {
+    public:
+        storage_engine(const params& params)
+            : mutex_()
+            , transactions_()
+            , alg_freq_(params.alg_freq)
+            , bf_aborts_()
+            , position_()
+            , view_()
+            , random_device_()
+            , random_engine_(random_device_())
+        { }
+
+        class transaction
+        {
+        public:
+            transaction(storage_engine& se)
+                : se_(se)
+                , cc_()
+            { }
+            ~transaction()
+            {
+                rollback();
+            }
+            bool active() const { return cc_ != nullptr; }
+            void start(client* cc);
+            void apply(const wsrep::transaction&);
+            void commit(const wsrep::gtid&);
+            void rollback();
+            db::client* client() { return cc_; }
+            transaction(const transaction&) = delete;
+            transaction& operator=(const transaction&) = delete;
+        private:
+            db::storage_engine& se_;
+            db::client* cc_;
+        };
+        void bf_abort_some(const wsrep::transaction& tc);
+        long long bf_aborts() const { return bf_aborts_; }
+        void store_position(const wsrep::gtid& gtid);
+        wsrep::gtid get_position() const;
+        void store_view(const wsrep::view& view);
+        wsrep::view get_view() const;
+    private:
+        void validate_position(const wsrep::gtid& gtid) const;
+        wsrep::default_mutex mutex_;
+        std::unordered_set<db::client*> transactions_;
+        size_t alg_freq_;
+        std::atomic<long long> bf_aborts_;
+        wsrep::gtid position_;
+        wsrep::view view_;
+        std::random_device random_device_;
+        std::default_random_engine random_engine_;
+    };
+}
+
+#endif // WSREP_DB_STORAGE_ENGINE_HPP
diff --git a/wsrep-lib/dbsim/db_storage_service.hpp b/wsrep-lib/dbsim/db_storage_service.hpp
new file mode 100644
index 00000000..839253db
--- /dev/null
+++ b/wsrep-lib/dbsim/db_storage_service.hpp
@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2018 Codership Oy <info@codership.com>
+ *
+ * This file is part of wsrep-lib.
+ *
+ * Wsrep-lib 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, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Wsrep-lib 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 wsrep-lib.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef WSREP_DB_STORAGE_SERVICE_HPP
+#define WSREP_DB_STORAGE_SERVICE_HPP
+
+#include "wsrep/storage_service.hpp"
+#include "wsrep/exception.hpp"
+
+namespace db
+{
+    class storage_service : public wsrep::storage_service
+    {
+        int start_transaction(const wsrep::ws_handle&) override
+        { throw wsrep::not_implemented_error(); }
+        void adopt_transaction(const wsrep::transaction&) override
+        { throw wsrep::not_implemented_error(); }
+        int append_fragment(const wsrep::id&,
+                            wsrep::transaction_id,
+                            int,
+                            const wsrep::const_buffer&,
+                            const wsrep::xid&) override
+        { throw wsrep::not_implemented_error(); }
+        int update_fragment_meta(const wsrep::ws_meta&) override
+        { throw wsrep::not_implemented_error(); }
+        int remove_fragments() override
+        { throw wsrep::not_implemented_error(); }
+        int commit(const wsrep::ws_handle&, const wsrep::ws_meta&) override
+        { throw wsrep::not_implemented_error(); }
+        int rollback(const wsrep::ws_handle&, const wsrep::ws_meta&)
+            override
+        { throw wsrep::not_implemented_error(); }
+        void store_globals() override { }
+        void reset_globals() override { }
+    };
+}
+
+#endif // WSREP_DB_STORAGE_SERVICE_HPP
diff --git a/wsrep-lib/dbsim/db_threads.cpp b/wsrep-lib/dbsim/db_threads.cpp
new file mode 100644
index 00000000..10b580dd
--- /dev/null
+++ b/wsrep-lib/dbsim/db_threads.cpp
@@ -0,0 +1,729 @@
+/*
+ * Copyright (C) 2019 Codership Oy <info@codership.com>
+ *
+ * This file is part of wsrep-lib.
+ *
+ * Wsrep-lib 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, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Wsrep-lib 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 wsrep-lib.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "db_threads.hpp"
+#include "wsrep/compiler.hpp"
+#include "wsrep/logger.hpp"
+
+#include <cassert>
+#include <cstdint>
+#include <pthread.h>
+
+#include <algorithm>
+#include <atomic>
+#include <array>
+#include <chrono>
+#include <map>
+#include <mutex>
+#include <ostream>
+#include <sstream>
+#include <thread>
+#include <unordered_map>
+#include <vector>
+
+extern "C" { static void* start_thread(void* args_ptr); }
+namespace
+{
+    struct ti_obj
+    {
+    };
+    enum ti_opcode
+    {
+        oc_thread_create,
+        oc_thread_destroy,
+        oc_mutex_create,
+        oc_mutex_destroy,
+        oc_mutex_lock,
+        oc_mutex_trylock,
+        oc_mutex_unlock,
+        oc_cond_create,
+        oc_cond_destroy,
+        oc_cond_wait,
+        oc_cond_timedwait,
+        oc_cond_signal,
+        oc_cond_broadcast,
+        oc_max // must be the last
+    };
+
+    static const char* ti_opstring(enum ti_opcode op)
+    {
+        switch (op)
+        {
+        case oc_thread_create: return "thread_create";
+        case oc_thread_destroy: return "thread_destroy";
+        case oc_mutex_create: return "mutex_create";
+        case oc_mutex_destroy: return "mutex_destroy";
+        case oc_mutex_lock: return "mutex_lock";
+        case oc_mutex_trylock: return "mutex_trylock";
+        case oc_mutex_unlock: return "mutex_unlock";
+        case oc_cond_create: return "cond_create";
+        case oc_cond_destroy: return "cond_destroy";
+        case oc_cond_wait: return "cond_wait";
+        case oc_cond_timedwait: return "cond_timedwait";
+        case oc_cond_signal: return "cond_signal";
+        case oc_cond_broadcast: return "cond_broadcast";
+        default: return "unknown";
+        }
+    }
+
+    static std::vector<std::string> key_vec;
+    static std::atomic<int> key_cnt;
+    static std::vector<std::vector<size_t>> ops_map;
+    static std::vector<std::mutex*> ops_map_sync;
+    static struct ops_map_sync_deleter
+    {
+        ~ops_map_sync_deleter()
+        {
+            std::for_each(ops_map_sync.begin(), ops_map_sync.end(),
+                          [](auto entry) { delete entry; });
+        }
+    } ops_map_sync_deleter;
+    static std::array<std::atomic<size_t>, oc_max> total_ops;
+    static std::atomic<size_t> total_allocations;
+    static std::atomic<size_t> mutex_contention;
+    static std::unordered_map<std::string, size_t> mutex_contention_counts;
+    static int op_level;
+    // Check correct condition variable usage:
+    // - Associated mutex must be locked when waiting for cond
+    // - There must be at least one waiter when signalling for condition
+    static bool cond_checks;
+    static inline void cond_check(bool condition, const char* name,
+                                  const char* message)
+    {
+        if (cond_checks && !condition)
+        {
+            wsrep::log_error() << "Condition variable check failed for '"
+                               << name << "': " << message;
+            ::abort();
+        }
+    }
+    static inline int append_key(const char* name, const char* type)
+    {
+
+        key_vec.push_back(std::string(name) + "_" + type);
+        wsrep::log_info() << "Register key " << name << "_" << type
+                          << " with index " << (key_cnt + 1);
+        ops_map.push_back(std::vector<size_t>());
+        ops_map_sync.push_back(new std::mutex());
+        ops_map.back().resize(oc_max);
+        return ++key_cnt;
+    }
+
+    template <class Key> static inline size_t get_key_index(const Key* key)
+    {
+        size_t index(reinterpret_cast<const size_t>(key) - 1);
+        assert(index < key_vec.size());
+        return index;
+    }
+
+    template <class Key>
+    static inline const char* get_key_name(const Key* key)
+    {
+        return key_vec[get_key_index(key)].c_str();
+    }
+
+    static inline const std::string& get_key_name_by_index(size_t index)
+    {
+        assert(index < key_vec.size());
+        return key_vec[index];
+    }
+
+    // Note: Do not refer the obj pointer in this function, it may
+    // have been deleted before the call.
+    template <class Key>
+    static inline void update_ops(const ti_obj* obj,
+                                  const Key* key,
+                                  enum ti_opcode op)
+    {
+        if (op_level < 1)
+            return;
+        total_ops[op] += 1;
+        if (op_level < 2)
+            return;
+        if (false && op == oc_mutex_destroy)
+        {
+            wsrep::log_info() << "thread: " << std::this_thread::get_id()
+                              << " object: " << obj
+                              << ": name: " << get_key_name(key)
+                              << " op: " << ti_opstring(op);
+        }
+
+        std::lock_guard<std::mutex> lock(*ops_map_sync[get_key_index(key)]);
+        ops_map[get_key_index(key)][op] += 1;
+    }
+
+    struct thread_args
+    {
+        void* this_thread;
+        void* (*fn)(void*);
+        void* args;
+    };
+
+    pthread_key_t this_thread_key;
+    struct this_thread_key_initializer
+    {
+        this_thread_key_initializer()
+        {
+            pthread_key_create(&this_thread_key, nullptr);
+        }
+
+        ~this_thread_key_initializer()
+        {
+            pthread_key_delete(this_thread_key);
+        }
+    };
+
+
+    class ti_thread : public ti_obj
+    {
+    public:
+        ti_thread(const wsrep::thread_service::thread_key* key)
+            : key_(key)
+            , th_()
+            , retval_()
+            , detached_()
+        {
+            update_ops(this, key_, oc_thread_create);
+        }
+        ~ti_thread()
+        {
+            update_ops(this, key_, oc_thread_destroy);
+        }
+
+        ti_thread(const ti_thread&) = delete;
+        ti_thread& operator=(const ti_thread&) = delete;
+        int run(void* (*fn)(void *), void* args)
+        {
+            auto ta(new thread_args{this, fn, args});
+            return pthread_create(&th_, nullptr, start_thread, ta);
+        }
+
+        int detach()
+        {
+            detached_ = true;
+            return pthread_detach(th_);
+        }
+
+        int join(void** retval)
+        {
+            return pthread_join(th_, retval);
+        }
+
+        bool detached() const { return detached_; }
+
+        void retval(void* retval) { retval_ = retval; }
+
+        static ti_thread* self()
+        {
+            return reinterpret_cast<ti_thread*>(
+                pthread_getspecific(this_thread_key));
+        }
+
+        int setschedparam(int policy, const struct sched_param* param)
+        {
+            return pthread_setschedparam(th_, policy, param);
+        }
+
+        int getschedparam(int* policy, struct sched_param* param)
+        {
+            return pthread_getschedparam(th_, policy, param);
+        }
+
+        int equal(ti_thread* other)
+        {
+            return pthread_equal(th_, other->th_);
+        }
+    private:
+        const wsrep::thread_service::thread_key* key_;
+        pthread_t th_;
+        void* retval_;
+        bool detached_;
+    };
+
+    class ti_mutex : public ti_obj
+    {
+    public:
+        ti_mutex(const wsrep::thread_service::mutex_key* key, bool inplace)
+            : mutex_(PTHREAD_MUTEX_INITIALIZER)
+            , key_(key)
+            , inplace_(inplace)
+#ifndef NDEBUG
+            , locked_()
+            , owner_()
+#endif // ! NDEBUG
+        {
+            update_ops(this, key_, oc_mutex_create);
+            if (not inplace) total_allocations++;
+        }
+
+        ~ti_mutex() { update_ops(this, key_, oc_mutex_destroy); }
+
+        ti_mutex& operator=(const ti_mutex&) = delete;
+        ti_mutex(const ti_mutex&) = delete;
+
+        int lock()
+        {
+            update_ops(this, key_, oc_mutex_lock);
+            int ret(pthread_mutex_trylock(&mutex_));
+            if (ret == EBUSY)
+            {
+                mutex_contention++;
+                {
+                    std::lock_guard<std::mutex> lock(*ops_map_sync[get_key_index(key_)]);
+                    mutex_contention_counts[get_key_name(key_)] += 1;
+                }
+                ret = pthread_mutex_lock(&mutex_);
+            }
+#ifndef NDEBUG
+            if (ret == 0)
+            {
+                assert(owner_ == std::thread::id());
+                locked_ = true;
+                owner_ = std::this_thread::get_id();
+            }
+#endif // ! NDEBUG
+            return ret;
+        }
+        int trylock()
+        {
+            update_ops(this, key_, oc_mutex_trylock);
+            int ret(pthread_mutex_trylock(&mutex_));
+#ifndef NDEBUG
+            if (ret == 0)
+            {
+                assert(owner_ == std::thread::id());
+                locked_ = true;
+                owner_ = std::this_thread::get_id();
+            }
+#endif // ! NDEBUG
+            return ret;
+        }
+
+        int unlock()
+        {
+            assert(locked_);
+#ifndef NDEBUG
+            assert(owner_ == std::this_thread::get_id());
+            owner_ = std::thread::id();
+#endif // ! NDEBUG
+            // Use temporary object. After mutex is unlocked it may be
+            // destroyed before this update_ops() finishes.
+            auto key(key_);
+            int ret(pthread_mutex_unlock(&mutex_));
+            update_ops(this, key, oc_mutex_unlock);
+            return ret;
+        }
+
+        struct condwait_context
+        {
+#ifndef NDEBUG
+            bool locked;
+            std::thread::id owner;
+#endif // ! NDEBUG
+        };
+
+        condwait_context save_for_condwait()
+        {
+#ifndef NDEBUG
+            return condwait_context{ locked_, owner_ };
+#else
+            return condwait_context{};
+#endif // ! NDEBUG
+        }
+
+        void reset()
+        {
+#ifndef NDEBUG
+            locked_ = false;
+            owner_ = std::thread::id();
+#endif // ! NDEBUG
+        }
+
+        void restore_from_condwait(const condwait_context& ctx WSREP_UNUSED)
+        {
+#ifndef NDEBUG
+            locked_ = ctx.locked;
+            owner_ = ctx.owner;
+#endif // ! NDEBUG
+        }
+
+        pthread_mutex_t* native_handle() { return &mutex_; }
+        const wsrep::thread_service::mutex_key* key() const { return key_; }
+
+        bool inplace() const { return inplace_; }
+    private:
+        pthread_mutex_t mutex_;
+        const wsrep::thread_service::mutex_key* key_;
+        const bool inplace_;
+#ifndef NDEBUG
+        bool locked_;
+        std::atomic<std::thread::id> owner_;
+#endif // ! NDEBU
+    };
+
+    class ti_cond : public ti_obj
+    {
+    public:
+        ti_cond(const wsrep::thread_service::cond_key* key, bool inplace)
+            : cond_(PTHREAD_COND_INITIALIZER)
+            , key_(key)
+            , inplace_(inplace)
+            , waiter_()
+        {
+            update_ops(this, key_, oc_cond_create);
+            if (not inplace) total_allocations++;
+        }
+
+        ~ti_cond() { update_ops(this, key_, oc_cond_destroy); }
+
+        ti_cond& operator=(const ti_cond&) = delete;
+        ti_cond(const ti_cond&) = delete;
+
+        int wait(ti_mutex& mutex)
+        {
+            cond_check(pthread_mutex_trylock(mutex.native_handle()),
+                       get_key_name(key_), "Mutex not locked in cond wait");
+            waiter_ = true;
+            update_ops(this, key_, oc_cond_wait);
+            // update_ops(&mutex, mutex.key(), oc_mutex_unlock);
+            auto condwait_ctx(mutex.save_for_condwait());
+            mutex.reset();
+            int ret(pthread_cond_wait(&cond_, mutex.native_handle()));
+            // update_ops(&mutex, mutex.key(), oc_mutex_lock);
+            mutex.restore_from_condwait(condwait_ctx);
+            waiter_ = false;
+            return ret;
+        }
+
+        int timedwait(ti_mutex& mutex, const struct timespec* ts)
+        {
+            cond_check(pthread_mutex_trylock(mutex.native_handle()),
+                       get_key_name(key_), "Mutex not locked in cond wait");
+            waiter_ = true;
+            update_ops(this, key_, oc_cond_timedwait);
+            // update_ops(&mutex, mutex.key(), oc_mutex_unlock);
+            auto condwait_ctx(mutex.save_for_condwait());
+            mutex.reset();
+            int ret(pthread_cond_timedwait(&cond_, mutex.native_handle(), ts));
+            // update_ops(&mutex, mutex.key(), oc_mutex_lock);
+            mutex.restore_from_condwait(condwait_ctx);
+            waiter_ = false;
+            return ret;
+        }
+
+        int signal()
+        {
+            update_ops(this, key_, oc_cond_signal);
+            cond_check(waiter_, get_key_name(key_),
+                       "Signalling condition variable without waiter");
+            return pthread_cond_signal(&cond_);
+        }
+
+        int broadcast()
+        {
+            update_ops(this, key_, oc_cond_broadcast);
+            return pthread_cond_broadcast(&cond_);
+        }
+
+        bool inplace() const { return inplace_; }
+    private:
+        pthread_cond_t cond_;
+        const wsrep::thread_service::cond_key* key_;
+        const bool inplace_;
+        bool waiter_;
+    };
+}
+
+int db::ti::before_init()
+{
+    wsrep::log_info() << "db::ti::before_init()";
+    return 0;
+}
+
+int db::ti::after_init()
+{
+    wsrep::log_info() << "db::ti::after_init()";
+    return 0;
+}
+
+//////////////////////////////////////////////////////////////////////////////
+//                               Thread                                     //
+//////////////////////////////////////////////////////////////////////////////
+
+extern "C"
+{
+static void* start_thread(void* args_ptr)
+{
+    thread_args* ta(reinterpret_cast<thread_args*>(args_ptr));
+    ti_thread* thread = reinterpret_cast<ti_thread*>(ta->this_thread);
+    pthread_setspecific(this_thread_key, thread);
+    void* (*fn)(void*) = ta->fn;
+    void* args = ta->args;
+    delete ta;
+    void* ret = (*fn)(args);
+    pthread_setspecific(this_thread_key, nullptr);
+    // If we end here the thread returned instead of calling
+    // pthread_exit()
+    if (thread->detached())
+        delete thread;
+    return ret;
+}
+
+WSREP_NORETURN
+static void exit_thread(wsrep::thread_service::thread* thread, void* retval)
+{
+    pthread_setspecific(this_thread_key, nullptr);
+    ti_thread* th(reinterpret_cast<ti_thread*>(thread));
+    th->retval(retval);
+    if (th->detached())
+        delete th;
+    pthread_exit(retval);
+}
+} // extern "C"
+
+db::ti::ti()
+{
+    thread_service::exit = exit_thread;
+}
+
+const wsrep::thread_service::thread_key*
+db::ti::create_thread_key(const char* name) WSREP_NOEXCEPT
+{
+    assert(name);
+    return reinterpret_cast<const wsrep::thread_service::thread_key*>(
+        append_key(name, "thread"));
+}
+
+int db::ti::create_thread(const wsrep::thread_service::thread_key* key,
+                          wsrep::thread_service::thread** thread,
+                          void* (*fn)(void*), void* args) WSREP_NOEXCEPT
+{
+    auto pit(new ti_thread(key));
+    total_allocations++;
+    int ret;
+    if ((ret = pit->run(fn, args)))
+    {
+        delete pit;
+    }
+    else
+    {
+        *thread = reinterpret_cast<wsrep::thread_service::thread*>(pit);
+    }
+    return ret;
+}
+
+int db::ti::detach(wsrep::thread_service::thread* thread) WSREP_NOEXCEPT
+{
+    return reinterpret_cast<ti_thread*>(thread)->detach();
+}
+
+int db::ti::equal(wsrep::thread_service::thread* thread_1,
+                   wsrep::thread_service::thread* thread_2) WSREP_NOEXCEPT
+{
+    return (reinterpret_cast<ti_thread*>(thread_1)->equal(
+                reinterpret_cast<ti_thread*>(thread_2)));
+}
+
+int db::ti::join(wsrep::thread_service::thread* thread, void** retval) WSREP_NOEXCEPT
+{
+    ti_thread* th(reinterpret_cast<ti_thread*>(thread));
+    int ret(th->join(retval));
+    if (not th->detached())
+    {
+        delete th;
+    }
+    return ret;
+}
+
+wsrep::thread_service::thread* db::ti::self() WSREP_NOEXCEPT
+{
+    return reinterpret_cast<wsrep::thread_service::thread*>(ti_thread::self());
+}
+
+int db::ti::setschedparam(wsrep::thread_service::thread* thread,
+                          int policy, const struct sched_param* param) WSREP_NOEXCEPT
+{
+    return reinterpret_cast<ti_thread*>(thread)->setschedparam(policy, param);
+}
+
+int db::ti::getschedparam(wsrep::thread_service::thread* thread,
+                          int* policy, struct sched_param* param) WSREP_NOEXCEPT
+{
+    return reinterpret_cast<ti_thread*>(thread)->getschedparam(policy, param);
+}
+
+//////////////////////////////////////////////////////////////////////////////
+//                                Mutex                                     //
+//////////////////////////////////////////////////////////////////////////////
+
+const wsrep::thread_service::mutex_key*
+db::ti::create_mutex_key(const char* name) WSREP_NOEXCEPT
+{
+    assert(name);
+    return reinterpret_cast<const wsrep::thread_service::mutex_key*>(
+        append_key(name, "mutex"));
+}
+
+wsrep::thread_service::mutex*
+db::ti::init_mutex(const wsrep::thread_service::mutex_key* key, void* memblock,
+                   size_t memblock_size) WSREP_NOEXCEPT
+{
+    return reinterpret_cast<wsrep::thread_service::mutex*>(
+        memblock_size >= sizeof(ti_mutex) ? new (memblock) ti_mutex(key, true)
+                                          : new ti_mutex(key, false));
+}
+
+int db::ti::destroy(wsrep::thread_service::mutex* mutex) WSREP_NOEXCEPT
+{
+    ti_mutex* m(reinterpret_cast<ti_mutex*>(mutex));
+    if (m->inplace())
+    {
+        m->~ti_mutex();
+    }
+    else
+    {
+        delete m;
+    }
+    return 0;
+}
+
+int db::ti::lock(wsrep::thread_service::mutex* mutex) WSREP_NOEXCEPT
+{
+    return reinterpret_cast<ti_mutex*>(mutex)->lock();
+}
+
+int db::ti::trylock(wsrep::thread_service::mutex* mutex) WSREP_NOEXCEPT
+{
+    return reinterpret_cast<ti_mutex*>(mutex)->trylock();
+}
+
+int db::ti::unlock(wsrep::thread_service::mutex* mutex) WSREP_NOEXCEPT
+{
+    return reinterpret_cast<ti_mutex*>(mutex)->unlock();
+}
+
+//////////////////////////////////////////////////////////////////////////////
+//                                Cond                                      //
+//////////////////////////////////////////////////////////////////////////////
+
+const wsrep::thread_service::cond_key* db::ti::create_cond_key(const char* name) WSREP_NOEXCEPT
+{
+    assert(name);
+    return reinterpret_cast<const wsrep::thread_service::cond_key*>(
+        append_key(name, "cond"));
+}
+
+wsrep::thread_service::cond*
+db::ti::init_cond(const wsrep::thread_service::cond_key* key, void* memblock,
+                  size_t memblock_size) WSREP_NOEXCEPT
+{
+    return reinterpret_cast<wsrep::thread_service::cond*>(
+        memblock_size >= sizeof(ti_cond) ? new (memblock) ti_cond(key, true)
+                                         : new ti_cond(key, false));
+}
+
+int db::ti::destroy(wsrep::thread_service::cond* cond) WSREP_NOEXCEPT
+{
+    ti_cond* c(reinterpret_cast<ti_cond*>(cond));
+    if (c->inplace())
+    {
+        c->~ti_cond();
+    }
+    else
+    {
+        delete c;
+    }
+    return 0;
+}
+
+int db::ti::wait(wsrep::thread_service::cond* cond,
+                 wsrep::thread_service::mutex* mutex) WSREP_NOEXCEPT
+{
+    return reinterpret_cast<ti_cond*>(cond)->wait(
+        *reinterpret_cast<ti_mutex*>(mutex));
+}
+
+int db::ti::timedwait(wsrep::thread_service::cond* cond,
+                      wsrep::thread_service::mutex* mutex,
+                      const struct timespec* ts) WSREP_NOEXCEPT
+{
+    return reinterpret_cast<ti_cond*>(cond)->timedwait(
+        *reinterpret_cast<ti_mutex*>(mutex), ts);
+}
+
+int db::ti::signal(wsrep::thread_service::cond* cond) WSREP_NOEXCEPT
+{
+    return reinterpret_cast<ti_cond*>(cond)->signal();
+}
+
+int db::ti::broadcast(wsrep::thread_service::cond* cond) WSREP_NOEXCEPT
+{
+    return reinterpret_cast<ti_cond*>(cond)->broadcast();
+}
+
+void db::ti::level(int level)
+{
+    ::op_level = level;
+}
+
+void db::ti::cond_checks(bool cond_checks)
+{
+    if (cond_checks)
+        wsrep::log_info() << "Enabling condition variable checking";
+    ::cond_checks = cond_checks;
+}
+
+std::string db::ti::stats()
+{
+    std::ostringstream os;
+    os << "Totals:\n";
+    for (size_t i(0); i < total_ops.size(); ++i)
+    {
+        if (total_ops[i] > 0)
+        {
+            os << "  " << ti_opstring(static_cast<enum ti_opcode>(i)) << ": "
+               << total_ops[i] << "\n";
+        }
+    }
+    os << "Total allocations: " << total_allocations << "\n";
+    os << "Mutex contention: " << mutex_contention << "\n";
+    for (auto i : mutex_contention_counts)
+    {
+        os << "  " << i.first << ": " << i.second << "\n";
+    }
+    os << "Per key:\n";
+    std::map<std::string, std::vector<size_t>> sorted;
+    for (size_t i(0); i < ops_map.size(); ++i)
+    {
+        sorted.insert(std::make_pair(get_key_name_by_index(i), ops_map[i]));
+    }
+    for (auto i : sorted)
+    {
+        for (size_t j(0); j < i.second.size(); ++j)
+        {
+            if (i.second[j])
+            {
+                os << "  " << i.first << ": "
+                   << ti_opstring(static_cast<enum ti_opcode>(j)) << ": "
+                   << i.second[j] << "\n";
+            }
+        }
+    }
+    return os.str();
+}
diff --git a/wsrep-lib/dbsim/db_threads.hpp b/wsrep-lib/dbsim/db_threads.hpp
new file mode 100644
index 00000000..32d44c10
--- /dev/null
+++ b/wsrep-lib/dbsim/db_threads.hpp
@@ -0,0 +1,84 @@
+/*
+ * Copyright (C) 2019 Codership Oy <info@codership.com>
+ *
+ * This file is part of wsrep-lib.
+ *
+ * Wsrep-lib 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, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Wsrep-lib 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 wsrep-lib.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef WSREP_DB_THREADS_HPP
+#define WSREP_DB_THREADS_HPP
+
+#include "wsrep/thread_service.hpp"
+#include <string>
+
+namespace db
+{
+    class ti : public wsrep::thread_service
+    {
+    public:
+        ti();
+        int before_init() override;
+        int after_init() override;
+
+        /* Thread */
+        const wsrep::thread_service::thread_key*
+        create_thread_key(const char* name) WSREP_NOEXCEPT override;
+        int create_thread(const wsrep::thread_service::thread_key* key,
+                          wsrep::thread_service::thread**,
+                          void* (*fn)(void*), void*) WSREP_NOEXCEPT override;
+        int detach(wsrep::thread_service::thread*) WSREP_NOEXCEPT override;
+        int equal(wsrep::thread_service::thread*,
+                  wsrep::thread_service::thread*) WSREP_NOEXCEPT override;
+        int join(wsrep::thread_service::thread*, void**) WSREP_NOEXCEPT override;
+        wsrep::thread_service::thread* self() WSREP_NOEXCEPT override;
+        int setschedparam(wsrep::thread_service::thread*, int,
+                          const struct sched_param*) WSREP_NOEXCEPT override;
+        int getschedparam(wsrep::thread_service::thread*, int*,
+                          struct sched_param*) WSREP_NOEXCEPT override;
+
+        /* Mutex */
+        const wsrep::thread_service::mutex_key*
+        create_mutex_key(const char* name) WSREP_NOEXCEPT override;
+        wsrep::thread_service::mutex*
+        init_mutex(const wsrep::thread_service::mutex_key* key, void* memblock,
+                   size_t memblock_size) WSREP_NOEXCEPT override;
+        int destroy(wsrep::thread_service::mutex* mutex) WSREP_NOEXCEPT override;
+        int lock(wsrep::thread_service::mutex* mutex) WSREP_NOEXCEPT override;
+        int trylock(wsrep::thread_service::mutex* mutex) WSREP_NOEXCEPT override;
+        int unlock(wsrep::thread_service::mutex* mutex) WSREP_NOEXCEPT override;
+        /* Cond */
+        const wsrep::thread_service::cond_key*
+        create_cond_key(const char* name) WSREP_NOEXCEPT override;
+        wsrep::thread_service::cond*
+        init_cond(const wsrep::thread_service::cond_key* key, void* memblock,
+                  size_t memblock_size) WSREP_NOEXCEPT override;
+        int destroy(wsrep::thread_service::cond* cond) WSREP_NOEXCEPT override;
+        int wait(wsrep::thread_service::cond* cond,
+                 wsrep::thread_service::mutex* mutex) WSREP_NOEXCEPT override;
+        int timedwait(wsrep::thread_service::cond* cond,
+                      wsrep::thread_service::mutex* mutex,
+                      const struct timespec* ts) WSREP_NOEXCEPT override;
+        int signal(wsrep::thread_service::cond* cond) WSREP_NOEXCEPT override;
+        int broadcast(wsrep::thread_service::cond* cond) WSREP_NOEXCEPT override;
+
+        static void level(int level);
+        static void cond_checks(bool cond_checks);
+        static std::string stats();
+    };
+
+
+}
+
+#endif // WSREP_DB_THREADS_HPP
diff --git a/wsrep-lib/dbsim/db_tls.cpp b/wsrep-lib/dbsim/db_tls.cpp
new file mode 100644
index 00000000..c242668c
--- /dev/null
+++ b/wsrep-lib/dbsim/db_tls.cpp
@@ -0,0 +1,451 @@
+/*
+ * Copyright (C) 2020 Codership Oy <info@codership.com>
+ *
+ * This file is part of wsrep-lib.
+ *
+ * Wsrep-lib 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, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Wsrep-lib 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 wsrep-lib.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/** @file db_tls.cpp
+ *
+ * This file demonstrates the use of TLS service. It does not implement
+ * real encryption, but may manipulate stream bytes for testing purposes.
+ */
+
+#include "db_tls.hpp"
+
+#include "wsrep/logger.hpp"
+
+#include <unistd.h> // read()
+#include <fcntl.h>
+#include <sys/types.h>
+#include <sys/socket.h> // send()
+#include <cassert>
+#include <cerrno>
+#include <cstring>
+
+#include <mutex>
+#include <string>
+
+namespace
+{
+    class db_stream : public wsrep::tls_stream
+    {
+    public:
+        db_stream(int fd, int mode)
+            : fd_(fd)
+            , state_(s_initialized)
+            , last_error_()
+            , mode_(mode)
+            , stats_()
+            , is_blocking_()
+        {
+            int val(fcntl(fd_, F_GETFL, 0));
+            is_blocking_ = not (val & O_NONBLOCK);
+        }
+        struct stats
+        {
+            size_t bytes_read{0};
+            size_t bytes_written{0};
+        };
+
+        /*
+         *    in            idle --|
+         *     |-> ch -|      ^    | -> want_read  --|
+         *     |-> sh -| ---- |--> | -> want_write --|
+         *                    |----------------------|
+         */
+        enum state
+        {
+            s_initialized,
+            s_client_handshake,
+            s_server_handshake,
+            s_idle,
+            s_want_read,
+            s_want_write
+        };
+
+        int get_error_number() const { return last_error_; }
+        const void* get_error_category() const
+        {
+            return reinterpret_cast<const void*>(1);
+        }
+
+        static char* get_error_message(int value, const void*)
+        {
+            return ::strerror(value);
+        }
+
+        enum wsrep::tls_service::status client_handshake();
+
+        enum wsrep::tls_service::status server_handshake();
+
+        wsrep::tls_service::op_result read(void*, size_t);
+
+        wsrep::tls_service::op_result write(const void*, size_t);
+
+        enum state state() const { return state_; }
+
+        int fd() const { return fd_; }
+        void inc_reads(size_t val) { stats_.bytes_read += val; }
+        void inc_writes(size_t val) { stats_.bytes_written += val; }
+        const stats& get_stats() const { return stats_; }
+    private:
+        enum wsrep::tls_service::status handle_handshake_read(const char* expect);
+        size_t determine_read_count(size_t max_count)
+        {
+            if (is_blocking_ || mode_ < 2) return max_count;
+            else if (::rand() % 100 == 0) return std::min(size_t(42), max_count);
+            else return max_count;
+        }
+        size_t determine_write_count(size_t count)
+        {
+            if (is_blocking_ || mode_ < 2) return count;
+            else if (::rand() % 100 == 0) return std::min(size_t(43), count);
+            else return count;
+        }
+
+        ssize_t do_read(void* buf, size_t max_count)
+        {
+            if (is_blocking_ || mode_ < 3 )
+                return ::read(fd_, buf, max_count);
+            else if (::rand() % 1000 == 0) return EINTR;
+            else return ::read(fd_, buf, max_count);
+        }
+
+        ssize_t do_write(const void* buf, size_t count)
+        {
+            if (is_blocking_ || mode_ < 3)
+                return ::send(fd_, buf, count, MSG_NOSIGNAL);
+            else if (::rand() % 1000 == 0) return EINTR;
+            else return ::send(fd_, buf, count, MSG_NOSIGNAL);
+        }
+
+        wsrep::tls_service::op_result map_success(ssize_t result)
+        {
+            if (is_blocking_ || mode_ < 2)
+            {
+                return wsrep::tls_service::op_result{
+                    wsrep::tls_service::success, size_t(result)};
+            }
+            else if (::rand() % 1000 == 0)
+            {
+                wsrep::log_info() << "Success want extra read";
+                state_ = s_want_read;
+                return wsrep::tls_service::op_result{
+                    wsrep::tls_service::want_read, size_t(result)};
+            }
+            else if (::rand() % 1000 == 0)
+            {
+                wsrep::log_info() << "Success want extra write";
+                state_ = s_want_write;
+                return wsrep::tls_service::op_result{
+                    wsrep::tls_service::want_write, size_t(result)};
+            }
+            else
+            {
+                return wsrep::tls_service::op_result{
+                    wsrep::tls_service::success, size_t(result)};
+            }
+        }
+
+        wsrep::tls_service::op_result map_result(ssize_t result)
+        {
+            if (result > 0)
+            {
+                return map_success(result);
+            }
+            else if (result == 0)
+            {
+                return wsrep::tls_service::op_result{
+                    wsrep::tls_service::eof, 0};
+            }
+            else if (errno == EAGAIN || errno == EWOULDBLOCK)
+            {
+                return wsrep::tls_service::op_result{
+                    wsrep::tls_service::want_read, 0};
+            }
+            else
+            {
+                last_error_ = errno;
+                return wsrep::tls_service::op_result{
+                    wsrep::tls_service::error, 0};
+            }
+        }
+
+        void clear_error() { last_error_ = 0; }
+
+        int fd_;
+        enum state state_;
+        int last_error_;
+        // Operation mode:
+        // 1 - simulate handshake exchange
+        // 2 - simulate errors and short reads
+        int mode_;
+        stats stats_;
+        bool is_blocking_;
+    };
+
+    enum wsrep::tls_service::status db_stream::client_handshake()
+    {
+        clear_error();
+        enum wsrep::tls_service::status ret;
+        assert(state_ == s_initialized ||
+               state_ == s_client_handshake ||
+               state_ == s_want_write);
+        if (state_ == s_initialized)
+        {
+            (void)::send(fd_, "clie", 4, MSG_NOSIGNAL);
+            ret = wsrep::tls_service::want_read;
+            state_ = s_client_handshake;
+            wsrep::log_info() << this << " client handshake sent";
+            stats_.bytes_written += 4;
+            if (not is_blocking_) return ret;
+        }
+
+        if (state_ == s_client_handshake)
+        {
+            if ((ret = handle_handshake_read("serv")) ==
+                wsrep::tls_service::success)
+            {
+                state_ = s_want_write;
+                ret = wsrep::tls_service::want_write;
+            }
+            if (not is_blocking_) return ret;
+        }
+
+        if (state_ == s_want_write)
+        {
+            state_ = s_idle;
+            ret = wsrep::tls_service::success;
+            if (not is_blocking_) return ret;
+        }
+
+        if (not is_blocking_)
+        {
+            last_error_ = EPROTO;
+            ret = wsrep::tls_service::error;
+        }
+        return ret;
+    }
+
+
+
+    enum wsrep::tls_service::status db_stream::server_handshake()
+    {
+        enum wsrep::tls_service::status ret;
+        assert(state_ == s_initialized ||
+               state_ == s_server_handshake ||
+               state_ == s_want_write);
+
+        if (state_ == s_initialized)
+        {
+            ::send(fd_, "serv", 4, MSG_NOSIGNAL);
+            ret = wsrep::tls_service::want_read;
+            state_ = s_server_handshake;
+            stats_.bytes_written += 4;
+            if (not is_blocking_) return ret;
+        }
+
+        if (state_ == s_server_handshake)
+        {
+            if ((ret = handle_handshake_read("clie")) ==
+                wsrep::tls_service::success)
+            {
+                state_ = s_want_write;
+                ret = wsrep::tls_service::want_write;
+            }
+            if (not is_blocking_) return ret;
+        }
+
+        if (state_ == s_want_write)
+        {
+            state_ = s_idle;
+            ret = wsrep::tls_service::success;
+            if (not is_blocking_) return ret;
+        }
+
+        if (not is_blocking_)
+        {
+            last_error_ = EPROTO;
+            ret = wsrep::tls_service::error;
+        }
+        return ret;
+    }
+
+    enum wsrep::tls_service::status db_stream::handle_handshake_read(
+        const char* expect)
+    {
+        assert(::strlen(expect) >= 4);
+        char buf[4] = { };
+        ssize_t read_result(::read(fd_, buf, sizeof(buf)));
+        if (read_result > 0) stats_.bytes_read += size_t(read_result);
+        enum wsrep::tls_service::status ret;
+        if (read_result == -1 &&
+            (errno == EWOULDBLOCK || errno == EAGAIN))
+        {
+            ret = wsrep::tls_service::want_read;
+        }
+        else if (read_result == 0)
+        {
+            ret = wsrep::tls_service::eof;
+        }
+        else if (read_result != 4 || ::memcmp(buf, expect, 4))
+        {
+            last_error_ = EPROTO;
+            ret = wsrep::tls_service::error;
+        }
+        else
+        {
+            wsrep::log_info() << "Handshake success: " << std::string(buf, 4);
+            ret = wsrep::tls_service::success;
+        }
+        return ret;
+    }
+
+    wsrep::tls_service::op_result db_stream::read(void* buf, size_t max_count)
+    {
+        clear_error();
+        if (state_ == s_want_read)
+        {
+            state_ = s_idle;
+            if (max_count == 0)
+                return wsrep::tls_service::op_result{
+                    wsrep::tls_service::success, 0};
+        }
+        max_count = determine_read_count(max_count);
+        ssize_t read_result(do_read(buf, max_count));
+        if (read_result > 0)
+        {
+            inc_reads(size_t(read_result));
+        }
+        return map_result(read_result);
+    }
+
+    wsrep::tls_service::op_result db_stream::write(
+        const void* buf, size_t count)
+    {
+        clear_error();
+        if (state_ == s_want_write)
+        {
+            state_ = s_idle;
+            if (count == 0)
+                return wsrep::tls_service::op_result{
+                    wsrep::tls_service::success, 0};
+        }
+        count = determine_write_count(count);
+        ssize_t write_result(do_write(buf, count));
+        if (write_result > 0)
+        {
+            inc_writes(size_t(write_result));
+        }
+        return map_result(write_result);
+    }
+}
+
+
+static db_stream::stats global_stats;
+std::mutex global_stats_lock;
+static int global_mode;
+
+static void merge_to_global_stats(const db_stream::stats& stats)
+{
+    std::lock_guard<std::mutex> lock(global_stats_lock);
+    global_stats.bytes_read += stats.bytes_read;
+    global_stats.bytes_written += stats.bytes_written;
+}
+
+wsrep::tls_stream* db::tls::create_tls_stream(int fd) WSREP_NOEXCEPT
+{
+    auto ret(new db_stream(fd, global_mode));
+    wsrep::log_debug() << "New DB stream: " << ret;
+    return ret;
+}
+
+void db::tls::destroy(wsrep::tls_stream* stream) WSREP_NOEXCEPT
+{
+    auto dbs(static_cast<db_stream*>(stream));
+    merge_to_global_stats(dbs->get_stats());
+    wsrep::log_debug() << "Stream destroy: " << dbs->get_stats().bytes_read
+                       << " " << dbs->get_stats().bytes_written;
+    wsrep::log_debug() << "Stream destroy" << dbs;
+    delete dbs;
+}
+
+int db::tls::get_error_number(const wsrep::tls_stream* stream)
+    const WSREP_NOEXCEPT
+{
+    return static_cast<const db_stream*>(stream)->get_error_number();
+}
+
+const void* db::tls::get_error_category(const wsrep::tls_stream* stream)
+    const WSREP_NOEXCEPT
+{
+    return static_cast<const db_stream*>(stream)->get_error_category();
+}
+
+const char* db::tls::get_error_message(const wsrep::tls_stream*,
+                                       int value, const void* category)
+    const WSREP_NOEXCEPT
+{
+    return db_stream::get_error_message(value, category);
+}
+
+enum wsrep::tls_service::status
+db::tls::client_handshake(wsrep::tls_stream* stream) WSREP_NOEXCEPT
+{
+    return static_cast<db_stream*>(stream)->client_handshake();
+}
+
+enum wsrep::tls_service::status
+db::tls::server_handshake(wsrep::tls_stream* stream) WSREP_NOEXCEPT
+{
+    return static_cast<db_stream*>(stream)->server_handshake();
+}
+
+wsrep::tls_service::op_result db::tls::read(
+    wsrep::tls_stream* stream,
+    void* buf, size_t max_count) WSREP_NOEXCEPT
+{
+    return static_cast<db_stream*>(stream)->read(buf, max_count);
+}
+
+wsrep::tls_service::op_result db::tls::write(
+    wsrep::tls_stream* stream,
+    const void* buf, size_t count) WSREP_NOEXCEPT
+{
+    return static_cast<db_stream*>(stream)->write(buf, count);
+}
+
+wsrep::tls_service::status
+db::tls::shutdown(wsrep::tls_stream*) WSREP_NOEXCEPT
+{
+    // @todo error simulation
+    return wsrep::tls_service::success;
+}
+
+
+void db::tls::init(int mode)
+{
+    global_mode = mode;
+}
+
+std::string db::tls::stats()
+{
+    std::ostringstream oss;
+    oss << "Transport stats:\n"
+        << "  bytes_read: " << global_stats.bytes_read << "\n"
+        << "  bytes_written: " << global_stats.bytes_written << "\n";
+    return oss.str();
+}
diff --git a/wsrep-lib/dbsim/db_tls.hpp b/wsrep-lib/dbsim/db_tls.hpp
new file mode 100644
index 00000000..02051dce
--- /dev/null
+++ b/wsrep-lib/dbsim/db_tls.hpp
@@ -0,0 +1,62 @@
+/*
+ * Copyright (C) 2020 Codership Oy <info@codership.com>
+ *
+ * This file is part of wsrep-lib.
+ *
+ * Wsrep-lib 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, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Wsrep-lib 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 wsrep-lib.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef WSREP_DB_TLS_HPP
+#define WSREP_DB_TLS_HPP
+
+#include "wsrep/tls_service.hpp"
+
+#include <string>
+
+namespace db
+{
+    class tls : public wsrep::tls_service
+    {
+    public:
+        virtual wsrep::tls_stream* create_tls_stream(int)
+            WSREP_NOEXCEPT override;
+        virtual void destroy(wsrep::tls_stream*) WSREP_NOEXCEPT override;
+        virtual int get_error_number(const wsrep::tls_stream*) const
+            WSREP_NOEXCEPT override;
+        virtual const void* get_error_category(const wsrep::tls_stream*) const
+            WSREP_NOEXCEPT override;
+        virtual const char* get_error_message(const wsrep::tls_stream*,
+                                              int, const void*) const
+            WSREP_NOEXCEPT override;
+        virtual enum wsrep::tls_service::status
+        client_handshake(wsrep::tls_stream*)
+            WSREP_NOEXCEPT override;
+        virtual enum wsrep::tls_service::status
+        server_handshake(wsrep::tls_stream*)
+            WSREP_NOEXCEPT override;
+        virtual wsrep::tls_service::op_result
+        read(wsrep::tls_stream*, void* buf, size_t max_count)
+            WSREP_NOEXCEPT override;
+        virtual wsrep::tls_service::op_result
+        write(wsrep::tls_stream*, const void* buf, size_t count)
+            WSREP_NOEXCEPT override;
+        virtual wsrep::tls_service::status
+        shutdown(wsrep::tls_stream*) WSREP_NOEXCEPT override;
+
+        static void init(int mode);
+        static std::string stats();
+    };
+}
+
+#endif // WSREP_DB_TLS_HPP
diff --git a/wsrep-lib/dbsim/dbsim.cpp b/wsrep-lib/dbsim/dbsim.cpp
new file mode 100644
index 00000000..070f83b4
--- /dev/null
+++ b/wsrep-lib/dbsim/dbsim.cpp
@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) 2018 Codership Oy <info@codership.com>
+ *
+ * This file is part of wsrep-lib.
+ *
+ * Wsrep-lib 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, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Wsrep-lib 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 wsrep-lib.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "db_params.hpp"
+#include "db_simulator.hpp"
+
+int main(int argc, char** argv)
+{
+    try
+    {
+        db::simulator(db::parse_args(argc, argv)).run();
+    }
+    catch (const std::exception& e)
+    {
+        std::cerr << e.what() << std::endl;
+        return 1;
+    }
+    return 0;
+}