Adding upstream version 5:7.0.15.upstream/5%7.0.15upstream

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

10 files changed, 1878 insertions, 0 deletions

diff --git a/src/modules/.gitignore b/src/modules/.gitignore
new file mode 100644
index 0000000..4de1735
--- /dev/null
+++ b/src/modules/.gitignore
@@ -0,0 +1,2 @@
+*.so
+*.xo
diff --git a/src/modules/Makefile b/src/modules/Makefile
new file mode 100644
index 0000000..b9ef578
--- /dev/null
+++ b/src/modules/Makefile
@@ -0,0 +1,69 @@
+
+# find the OS
+uname_S := $(shell sh -c 'uname -s 2>/dev/null || echo not')
+
+# Compile flags for linux / osx
+ifeq ($(uname_S),Linux)
+	SHOBJ_CFLAGS ?= -W -Wall -fno-common -g -ggdb -std=c99 -O2
+	SHOBJ_LDFLAGS ?= -shared
+else
+	SHOBJ_CFLAGS ?= -W -Wall -dynamic -fno-common -g -ggdb -std=c99 -O2
+	SHOBJ_LDFLAGS ?= -bundle -undefined dynamic_lookup
+endif
+
+# OS X 11.x doesn't have /usr/lib/libSystem.dylib and needs an explicit setting.
+ifeq ($(uname_S),Darwin)
+ifeq ("$(wildcard /usr/lib/libSystem.dylib)","")
+LIBS = -L /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/lib -lsystem
+endif
+endif
+
+.SUFFIXES: .c .so .xo .o
+
+all: helloworld.so hellotype.so helloblock.so hellocluster.so hellotimer.so hellodict.so hellohook.so helloacl.so
+
+.c.xo:
+	$(CC) -I. $(CFLAGS) $(SHOBJ_CFLAGS) -fPIC -c $< -o $@
+
+helloworld.xo: ../redismodule.h
+
+helloworld.so: helloworld.xo
+	$(LD) -o $@ $^ $(SHOBJ_LDFLAGS) $(LIBS) -lc
+
+hellotype.xo: ../redismodule.h
+
+hellotype.so: hellotype.xo
+	$(LD) -o $@ $^ $(SHOBJ_LDFLAGS) $(LIBS) -lc
+
+helloblock.xo: ../redismodule.h
+
+helloblock.so: helloblock.xo
+	$(LD) -o $@ $^ $(SHOBJ_LDFLAGS) $(LIBS) -lpthread -lc
+
+hellocluster.xo: ../redismodule.h
+
+hellocluster.so: hellocluster.xo
+	$(LD) -o $@ $^ $(SHOBJ_LDFLAGS) $(LIBS) -lc
+
+hellotimer.xo: ../redismodule.h
+
+hellotimer.so: hellotimer.xo
+	$(LD) -o $@ $^ $(SHOBJ_LDFLAGS) $(LIBS) -lc
+
+hellodict.xo: ../redismodule.h
+
+hellodict.so: hellodict.xo
+	$(LD) -o $@ $^ $(SHOBJ_LDFLAGS) $(LIBS) -lc
+
+hellohook.xo: ../redismodule.h
+
+hellohook.so: hellohook.xo
+	$(LD) -o $@ $^ $(SHOBJ_LDFLAGS) $(LIBS) -lc
+
+helloacl.xo: ../redismodule.h
+
+helloacl.so: helloacl.xo
+	$(LD) -o $@ $^ $(SHOBJ_LDFLAGS) $(LIBS) -lc
+
+clean:
+	rm -rf *.xo *.so
diff --git a/src/modules/helloacl.c b/src/modules/helloacl.c
new file mode 100644
index 0000000..53f3a44
--- /dev/null
+++ b/src/modules/helloacl.c
@@ -0,0 +1,190 @@
+/* ACL API example - An example for performing custom synchronous and
+ * asynchronous password authentication.
+ *
+ * -----------------------------------------------------------------------------
+ *
+ * Copyright 2019 Amazon.com, Inc. or its affiliates.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *   * Redistributions of source code must retain the above copyright notice,
+ *     this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ *   * Neither the name of Redis nor the names of its contributors may be used
+ *     to endorse or promote products derived from this software without
+ *     specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "../redismodule.h"
+#include <pthread.h>
+#include <unistd.h>
+
+// A simple global user
+static RedisModuleUser *global;
+static uint64_t global_auth_client_id = 0;
+
+/* HELLOACL.REVOKE 
+ * Synchronously revoke access from a user. */
+int RevokeCommand_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    REDISMODULE_NOT_USED(argv);
+    REDISMODULE_NOT_USED(argc);
+
+    if (global_auth_client_id) {
+        RedisModule_DeauthenticateAndCloseClient(ctx, global_auth_client_id);
+        return RedisModule_ReplyWithSimpleString(ctx, "OK");
+    } else {
+        return RedisModule_ReplyWithError(ctx, "Global user currently not used");    
+    }
+}
+
+/* HELLOACL.RESET 
+ * Synchronously delete and re-create a module user. */
+int ResetCommand_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    REDISMODULE_NOT_USED(argv);
+    REDISMODULE_NOT_USED(argc);
+
+    RedisModule_FreeModuleUser(global);
+    global = RedisModule_CreateModuleUser("global");
+    RedisModule_SetModuleUserACL(global, "allcommands");
+    RedisModule_SetModuleUserACL(global, "allkeys");
+    RedisModule_SetModuleUserACL(global, "on");
+
+    return RedisModule_ReplyWithSimpleString(ctx, "OK");
+}
+
+/* Callback handler for user changes, use this to notify a module of 
+ * changes to users authenticated by the module */
+void HelloACL_UserChanged(uint64_t client_id, void *privdata) {
+    REDISMODULE_NOT_USED(privdata);
+    REDISMODULE_NOT_USED(client_id);
+    global_auth_client_id = 0;
+}
+
+/* HELLOACL.AUTHGLOBAL 
+ * Synchronously assigns a module user to the current context. */
+int AuthGlobalCommand_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    REDISMODULE_NOT_USED(argv);
+    REDISMODULE_NOT_USED(argc);
+
+    if (global_auth_client_id) {
+        return RedisModule_ReplyWithError(ctx, "Global user currently used");    
+    }
+
+    RedisModule_AuthenticateClientWithUser(ctx, global, HelloACL_UserChanged, NULL, &global_auth_client_id);
+
+    return RedisModule_ReplyWithSimpleString(ctx, "OK");
+}
+
+#define TIMEOUT_TIME 1000
+
+/* Reply callback for auth command HELLOACL.AUTHASYNC */
+int HelloACL_Reply(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    REDISMODULE_NOT_USED(argv);
+    REDISMODULE_NOT_USED(argc);
+    size_t length;
+
+    RedisModuleString *user_string = RedisModule_GetBlockedClientPrivateData(ctx);
+    const char *name = RedisModule_StringPtrLen(user_string, &length);
+
+    if (RedisModule_AuthenticateClientWithACLUser(ctx, name, length, NULL, NULL, NULL) == 
+            REDISMODULE_ERR) {
+        return RedisModule_ReplyWithError(ctx, "Invalid Username or password");    
+    }
+    return RedisModule_ReplyWithSimpleString(ctx, "OK");
+}
+
+/* Timeout callback for auth command HELLOACL.AUTHASYNC */
+int HelloACL_Timeout(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    REDISMODULE_NOT_USED(argv);
+    REDISMODULE_NOT_USED(argc);
+    return RedisModule_ReplyWithSimpleString(ctx, "Request timedout");
+}
+
+/* Private data frees data for HELLOACL.AUTHASYNC command. */
+void HelloACL_FreeData(RedisModuleCtx *ctx, void *privdata) {
+    REDISMODULE_NOT_USED(ctx);
+    RedisModule_FreeString(NULL, privdata);
+}
+
+/* Background authentication can happen here. */
+void *HelloACL_ThreadMain(void *args) {
+    void **targs = args;
+    RedisModuleBlockedClient *bc = targs[0];
+    RedisModuleString *user = targs[1];
+    RedisModule_Free(targs);
+
+    RedisModule_UnblockClient(bc,user);
+    return NULL;
+}
+
+/* HELLOACL.AUTHASYNC 
+ * Asynchronously assigns an ACL user to the current context. */
+int AuthAsyncCommand_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    if (argc != 2) return RedisModule_WrongArity(ctx);
+
+    pthread_t tid;
+    RedisModuleBlockedClient *bc = RedisModule_BlockClient(ctx, HelloACL_Reply, HelloACL_Timeout, HelloACL_FreeData, TIMEOUT_TIME);
+    
+
+    void **targs = RedisModule_Alloc(sizeof(void*)*2);
+    targs[0] = bc;
+    targs[1] = RedisModule_CreateStringFromString(NULL, argv[1]);
+
+    if (pthread_create(&tid, NULL, HelloACL_ThreadMain, targs) != 0) {
+        RedisModule_AbortBlock(bc);
+        return RedisModule_ReplyWithError(ctx, "-ERR Can't start thread");
+    }
+
+    return REDISMODULE_OK;
+}
+
+/* This function must be present on each Redis module. It is used in order to
+ * register the commands into the Redis server. */
+int RedisModule_OnLoad(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    REDISMODULE_NOT_USED(argv);
+    REDISMODULE_NOT_USED(argc);
+
+    if (RedisModule_Init(ctx,"helloacl",1,REDISMODULE_APIVER_1)
+        == REDISMODULE_ERR) return REDISMODULE_ERR;
+
+    if (RedisModule_CreateCommand(ctx,"helloacl.reset",
+        ResetCommand_RedisCommand,"",0,0,0) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
+
+    if (RedisModule_CreateCommand(ctx,"helloacl.revoke",
+        RevokeCommand_RedisCommand,"",0,0,0) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
+
+    if (RedisModule_CreateCommand(ctx,"helloacl.authglobal",
+        AuthGlobalCommand_RedisCommand,"no-auth",0,0,0) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
+
+    if (RedisModule_CreateCommand(ctx,"helloacl.authasync",
+        AuthAsyncCommand_RedisCommand,"no-auth",0,0,0) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
+
+    global = RedisModule_CreateModuleUser("global");
+    RedisModule_SetModuleUserACL(global, "allcommands");
+    RedisModule_SetModuleUserACL(global, "allkeys");
+    RedisModule_SetModuleUserACL(global, "on");
+
+    global_auth_client_id = 0;
+
+    return REDISMODULE_OK;
+}
diff --git a/src/modules/helloblock.c b/src/modules/helloblock.c
new file mode 100644
index 0000000..dc3d749
--- /dev/null
+++ b/src/modules/helloblock.c
@@ -0,0 +1,218 @@
+/* Helloblock module -- An example of blocking command implementation
+ * with threads.
+ *
+ * -----------------------------------------------------------------------------
+ *
+ * Copyright (c) 2016, Salvatore Sanfilippo <antirez at gmail dot com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *   * Redistributions of source code must retain the above copyright notice,
+ *     this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ *   * Neither the name of Redis nor the names of its contributors may be used
+ *     to endorse or promote products derived from this software without
+ *     specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "../redismodule.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <pthread.h>
+#include <unistd.h>
+
+/* Reply callback for blocking command HELLO.BLOCK */
+int HelloBlock_Reply(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    REDISMODULE_NOT_USED(argv);
+    REDISMODULE_NOT_USED(argc);
+    int *myint = RedisModule_GetBlockedClientPrivateData(ctx);
+    return RedisModule_ReplyWithLongLong(ctx,*myint);
+}
+
+/* Timeout callback for blocking command HELLO.BLOCK */
+int HelloBlock_Timeout(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    REDISMODULE_NOT_USED(argv);
+    REDISMODULE_NOT_USED(argc);
+    return RedisModule_ReplyWithSimpleString(ctx,"Request timedout");
+}
+
+/* Private data freeing callback for HELLO.BLOCK command. */
+void HelloBlock_FreeData(RedisModuleCtx *ctx, void *privdata) {
+    REDISMODULE_NOT_USED(ctx);
+    RedisModule_Free(privdata);
+}
+
+/* The thread entry point that actually executes the blocking part
+ * of the command HELLO.BLOCK. */
+void *HelloBlock_ThreadMain(void *arg) {
+    void **targ = arg;
+    RedisModuleBlockedClient *bc = targ[0];
+    long long delay = (unsigned long)targ[1];
+    RedisModule_Free(targ);
+
+    sleep(delay);
+    int *r = RedisModule_Alloc(sizeof(int));
+    *r = rand();
+    RedisModule_UnblockClient(bc,r);
+    return NULL;
+}
+
+/* An example blocked client disconnection callback.
+ *
+ * Note that in the case of the HELLO.BLOCK command, the blocked client is now
+ * owned by the thread calling sleep(). In this specific case, there is not
+ * much we can do, however normally we could instead implement a way to
+ * signal the thread that the client disconnected, and sleep the specified
+ * amount of seconds with a while loop calling sleep(1), so that once we
+ * detect the client disconnection, we can terminate the thread ASAP. */
+void HelloBlock_Disconnected(RedisModuleCtx *ctx, RedisModuleBlockedClient *bc) {
+    RedisModule_Log(ctx,"warning","Blocked client %p disconnected!",
+        (void*)bc);
+
+    /* Here you should cleanup your state / threads, and if possible
+     * call RedisModule_UnblockClient(), or notify the thread that will
+     * call the function ASAP. */
+}
+
+/* HELLO.BLOCK <delay> <timeout> -- Block for <count> seconds, then reply with
+ * a random number. Timeout is the command timeout, so that you can test
+ * what happens when the delay is greater than the timeout. */
+int HelloBlock_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    if (argc != 3) return RedisModule_WrongArity(ctx);
+    long long delay;
+    long long timeout;
+
+    if (RedisModule_StringToLongLong(argv[1],&delay) != REDISMODULE_OK) {
+        return RedisModule_ReplyWithError(ctx,"ERR invalid count");
+    }
+
+    if (RedisModule_StringToLongLong(argv[2],&timeout) != REDISMODULE_OK) {
+        return RedisModule_ReplyWithError(ctx,"ERR invalid count");
+    }
+
+    pthread_t tid;
+    RedisModuleBlockedClient *bc = RedisModule_BlockClient(ctx,HelloBlock_Reply,HelloBlock_Timeout,HelloBlock_FreeData,timeout);
+
+    /* Here we set a disconnection handler, however since this module will
+     * block in sleep() in a thread, there is not much we can do in the
+     * callback, so this is just to show you the API. */
+    RedisModule_SetDisconnectCallback(bc,HelloBlock_Disconnected);
+
+    /* Now that we setup a blocking client, we need to pass the control
+     * to the thread. However we need to pass arguments to the thread:
+     * the delay and a reference to the blocked client handle. */
+    void **targ = RedisModule_Alloc(sizeof(void*)*2);
+    targ[0] = bc;
+    targ[1] = (void*)(unsigned long) delay;
+
+    if (pthread_create(&tid,NULL,HelloBlock_ThreadMain,targ) != 0) {
+        RedisModule_AbortBlock(bc);
+        return RedisModule_ReplyWithError(ctx,"-ERR Can't start thread");
+    }
+    return REDISMODULE_OK;
+}
+
+/* The thread entry point that actually executes the blocking part
+ * of the command HELLO.KEYS.
+ *
+ * Note: this implementation is very simple on purpose, so no duplicated
+ * keys (returned by SCAN) are filtered. However adding such a functionality
+ * would be trivial just using any data structure implementing a dictionary
+ * in order to filter the duplicated items. */
+void *HelloKeys_ThreadMain(void *arg) {
+    RedisModuleBlockedClient *bc = arg;
+    RedisModuleCtx *ctx = RedisModule_GetThreadSafeContext(bc);
+    long long cursor = 0;
+    size_t replylen = 0;
+
+    RedisModule_ReplyWithArray(ctx,REDISMODULE_POSTPONED_LEN);
+    do {
+        RedisModule_ThreadSafeContextLock(ctx);
+        RedisModuleCallReply *reply = RedisModule_Call(ctx,
+            "SCAN","l",(long long)cursor);
+        RedisModule_ThreadSafeContextUnlock(ctx);
+
+        RedisModuleCallReply *cr_cursor =
+            RedisModule_CallReplyArrayElement(reply,0);
+        RedisModuleCallReply *cr_keys =
+            RedisModule_CallReplyArrayElement(reply,1);
+
+        RedisModuleString *s = RedisModule_CreateStringFromCallReply(cr_cursor);
+        RedisModule_StringToLongLong(s,&cursor);
+        RedisModule_FreeString(ctx,s);
+
+        size_t items = RedisModule_CallReplyLength(cr_keys);
+        for (size_t j = 0; j < items; j++) {
+            RedisModuleCallReply *ele =
+                RedisModule_CallReplyArrayElement(cr_keys,j);
+            RedisModule_ReplyWithCallReply(ctx,ele);
+            replylen++;
+        }
+        RedisModule_FreeCallReply(reply);
+    } while (cursor != 0);
+    RedisModule_ReplySetArrayLength(ctx,replylen);
+
+    RedisModule_FreeThreadSafeContext(ctx);
+    RedisModule_UnblockClient(bc,NULL);
+    return NULL;
+}
+
+/* HELLO.KEYS -- Return all the keys in the current database without blocking
+ * the server. The keys do not represent a point-in-time state so only the keys
+ * that were in the database from the start to the end are guaranteed to be
+ * there. */
+int HelloKeys_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    REDISMODULE_NOT_USED(argv);
+    if (argc != 1) return RedisModule_WrongArity(ctx);
+
+    pthread_t tid;
+
+    /* Note that when blocking the client we do not set any callback: no
+     * timeout is possible since we passed '0', nor we need a reply callback
+     * because we'll use the thread safe context to accumulate a reply. */
+    RedisModuleBlockedClient *bc = RedisModule_BlockClient(ctx,NULL,NULL,NULL,0);
+
+    /* Now that we setup a blocking client, we need to pass the control
+     * to the thread. However we need to pass arguments to the thread:
+     * the reference to the blocked client handle. */
+    if (pthread_create(&tid,NULL,HelloKeys_ThreadMain,bc) != 0) {
+        RedisModule_AbortBlock(bc);
+        return RedisModule_ReplyWithError(ctx,"-ERR Can't start thread");
+    }
+    return REDISMODULE_OK;
+}
+
+/* This function must be present on each Redis module. It is used in order to
+ * register the commands into the Redis server. */
+int RedisModule_OnLoad(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    REDISMODULE_NOT_USED(argv);
+    REDISMODULE_NOT_USED(argc);
+
+    if (RedisModule_Init(ctx,"helloblock",1,REDISMODULE_APIVER_1)
+        == REDISMODULE_ERR) return REDISMODULE_ERR;
+
+    if (RedisModule_CreateCommand(ctx,"hello.block",
+        HelloBlock_RedisCommand,"",0,0,0) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
+    if (RedisModule_CreateCommand(ctx,"hello.keys",
+        HelloKeys_RedisCommand,"",0,0,0) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
+
+    return REDISMODULE_OK;
+}
diff --git a/src/modules/hellocluster.c b/src/modules/hellocluster.c
new file mode 100644
index 0000000..bc145c2
--- /dev/null
+++ b/src/modules/hellocluster.c
@@ -0,0 +1,118 @@
+/* Helloworld cluster -- A ping/pong cluster API example.
+ *
+ * -----------------------------------------------------------------------------
+ *
+ * Copyright (c) 2018, Salvatore Sanfilippo <antirez at gmail dot com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *   * Redistributions of source code must retain the above copyright notice,
+ *     this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ *   * Neither the name of Redis nor the names of its contributors may be used
+ *     to endorse or promote products derived from this software without
+ *     specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "../redismodule.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <ctype.h>
+#include <string.h>
+
+#define MSGTYPE_PING 1
+#define MSGTYPE_PONG 2
+
+/* HELLOCLUSTER.PINGALL */
+int PingallCommand_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    REDISMODULE_NOT_USED(argv);
+    REDISMODULE_NOT_USED(argc);
+
+    RedisModule_SendClusterMessage(ctx,NULL,MSGTYPE_PING,"Hey",3);
+    return RedisModule_ReplyWithSimpleString(ctx, "OK");
+}
+
+/* HELLOCLUSTER.LIST */
+int ListCommand_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    REDISMODULE_NOT_USED(argv);
+    REDISMODULE_NOT_USED(argc);
+
+    size_t numnodes;
+    char **ids = RedisModule_GetClusterNodesList(ctx,&numnodes);
+    if (ids == NULL) {
+        return RedisModule_ReplyWithError(ctx,"Cluster not enabled");
+    }
+
+    RedisModule_ReplyWithArray(ctx,numnodes);
+    for (size_t j = 0; j < numnodes; j++) {
+        int port;
+        RedisModule_GetClusterNodeInfo(ctx,ids[j],NULL,NULL,&port,NULL);
+        RedisModule_ReplyWithArray(ctx,2);
+        RedisModule_ReplyWithStringBuffer(ctx,ids[j],REDISMODULE_NODE_ID_LEN);
+        RedisModule_ReplyWithLongLong(ctx,port);
+    }
+    RedisModule_FreeClusterNodesList(ids);
+    return REDISMODULE_OK;
+}
+
+/* Callback for message MSGTYPE_PING */
+void PingReceiver(RedisModuleCtx *ctx, const char *sender_id, uint8_t type, const unsigned char *payload, uint32_t len) {
+    RedisModule_Log(ctx,"notice","PING (type %d) RECEIVED from %.*s: '%.*s'",
+        type,REDISMODULE_NODE_ID_LEN,sender_id,(int)len, payload);
+    RedisModule_SendClusterMessage(ctx,NULL,MSGTYPE_PONG,"Ohi!",4);
+    RedisModuleCallReply *reply = RedisModule_Call(ctx, "INCR", "c", "pings_received");
+    RedisModule_FreeCallReply(reply);
+}
+
+/* Callback for message MSGTYPE_PONG. */
+void PongReceiver(RedisModuleCtx *ctx, const char *sender_id, uint8_t type, const unsigned char *payload, uint32_t len) {
+    RedisModule_Log(ctx,"notice","PONG (type %d) RECEIVED from %.*s: '%.*s'",
+        type,REDISMODULE_NODE_ID_LEN,sender_id,(int)len, payload);
+}
+
+/* This function must be present on each Redis module. It is used in order to
+ * register the commands into the Redis server. */
+int RedisModule_OnLoad(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    REDISMODULE_NOT_USED(argv);
+    REDISMODULE_NOT_USED(argc);
+
+    if (RedisModule_Init(ctx,"hellocluster",1,REDISMODULE_APIVER_1)
+        == REDISMODULE_ERR) return REDISMODULE_ERR;
+
+    if (RedisModule_CreateCommand(ctx,"hellocluster.pingall",
+        PingallCommand_RedisCommand,"readonly",0,0,0) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
+
+    if (RedisModule_CreateCommand(ctx,"hellocluster.list",
+        ListCommand_RedisCommand,"readonly",0,0,0) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
+
+    /* Disable Redis Cluster sharding and redirections. This way every node
+     * will be able to access every possible key, regardless of the hash slot.
+     * This way the PING message handler will be able to increment a specific
+     * variable. Normally you do that in order for the distributed system
+     * you create as a module to have total freedom in the keyspace
+     * manipulation. */
+    RedisModule_SetClusterFlags(ctx,REDISMODULE_CLUSTER_FLAG_NO_REDIRECTION);
+
+    /* Register our handlers for different message types. */
+    RedisModule_RegisterClusterMessageReceiver(ctx,MSGTYPE_PING,PingReceiver);
+    RedisModule_RegisterClusterMessageReceiver(ctx,MSGTYPE_PONG,PongReceiver);
+    return REDISMODULE_OK;
+}
diff --git a/src/modules/hellodict.c b/src/modules/hellodict.c
new file mode 100644
index 0000000..12b6e91
--- /dev/null
+++ b/src/modules/hellodict.c
@@ -0,0 +1,131 @@
+/* Hellodict -- An example of modules dictionary API
+ *
+ * This module implements a volatile key-value store on top of the
+ * dictionary exported by the Redis modules API.
+ *
+ * -----------------------------------------------------------------------------
+ *
+ * Copyright (c) 2018, Salvatore Sanfilippo <antirez at gmail dot com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *   * Redistributions of source code must retain the above copyright notice,
+ *     this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ *   * Neither the name of Redis nor the names of its contributors may be used
+ *     to endorse or promote products derived from this software without
+ *     specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "../redismodule.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <ctype.h>
+#include <string.h>
+
+static RedisModuleDict *Keyspace;
+
+/* HELLODICT.SET <key> <value>
+ *
+ * Set the specified key to the specified value. */
+int cmd_SET(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    if (argc != 3) return RedisModule_WrongArity(ctx);
+    RedisModule_DictSet(Keyspace,argv[1],argv[2]);
+    /* We need to keep a reference to the value stored at the key, otherwise
+     * it would be freed when this callback returns. */
+    RedisModule_RetainString(NULL,argv[2]);
+    return RedisModule_ReplyWithSimpleString(ctx, "OK");
+}
+
+/* HELLODICT.GET <key>
+ *
+ * Return the value of the specified key, or a null reply if the key
+ * is not defined. */
+int cmd_GET(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    if (argc != 2) return RedisModule_WrongArity(ctx);
+    RedisModuleString *val = RedisModule_DictGet(Keyspace,argv[1],NULL);
+    if (val == NULL) {
+        return RedisModule_ReplyWithNull(ctx);
+    } else {
+        return RedisModule_ReplyWithString(ctx, val);
+    }
+}
+
+/* HELLODICT.KEYRANGE <startkey> <endkey> <count>
+ *
+ * Return a list of matching keys, lexicographically between startkey
+ * and endkey. No more than 'count' items are emitted. */
+int cmd_KEYRANGE(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    if (argc != 4) return RedisModule_WrongArity(ctx);
+
+    /* Parse the count argument. */
+    long long count;
+    if (RedisModule_StringToLongLong(argv[3],&count) != REDISMODULE_OK) {
+        return RedisModule_ReplyWithError(ctx,"ERR invalid count");
+    }
+
+    /* Seek the iterator. */
+    RedisModuleDictIter *iter = RedisModule_DictIteratorStart(
+        Keyspace, ">=", argv[1]);
+
+    /* Reply with the matching items. */
+    char *key;
+    size_t keylen;
+    long long replylen = 0; /* Keep track of the emitted array len. */
+    RedisModule_ReplyWithArray(ctx,REDISMODULE_POSTPONED_LEN);
+    while((key = RedisModule_DictNextC(iter,&keylen,NULL)) != NULL) {
+        if (replylen >= count) break;
+        if (RedisModule_DictCompare(iter,"<=",argv[2]) == REDISMODULE_ERR)
+            break;
+        RedisModule_ReplyWithStringBuffer(ctx,key,keylen);
+        replylen++;
+    }
+    RedisModule_ReplySetArrayLength(ctx,replylen);
+
+    /* Cleanup. */
+    RedisModule_DictIteratorStop(iter);
+    return REDISMODULE_OK;
+}
+
+/* This function must be present on each Redis module. It is used in order to
+ * register the commands into the Redis server. */
+int RedisModule_OnLoad(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    REDISMODULE_NOT_USED(argv);
+    REDISMODULE_NOT_USED(argc);
+
+    if (RedisModule_Init(ctx,"hellodict",1,REDISMODULE_APIVER_1)
+        == REDISMODULE_ERR) return REDISMODULE_ERR;
+
+    if (RedisModule_CreateCommand(ctx,"hellodict.set",
+        cmd_SET,"write deny-oom",1,1,0) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
+
+    if (RedisModule_CreateCommand(ctx,"hellodict.get",
+        cmd_GET,"readonly",1,1,0) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
+
+    if (RedisModule_CreateCommand(ctx,"hellodict.keyrange",
+        cmd_KEYRANGE,"readonly",1,1,0) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
+
+    /* Create our global dictionary. Here we'll set our keys and values. */
+    Keyspace = RedisModule_CreateDict(NULL);
+
+    return REDISMODULE_OK;
+}
diff --git a/src/modules/hellohook.c b/src/modules/hellohook.c
new file mode 100644
index 0000000..2859a8b
--- /dev/null
+++ b/src/modules/hellohook.c
@@ -0,0 +1,92 @@
+/* Server hooks API example
+ *
+ * -----------------------------------------------------------------------------
+ *
+ * Copyright (c) 2019, Salvatore Sanfilippo <antirez at gmail dot com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *   * Redistributions of source code must retain the above copyright notice,
+ *     this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ *   * Neither the name of Redis nor the names of its contributors may be used
+ *     to endorse or promote products derived from this software without
+ *     specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "../redismodule.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <ctype.h>
+#include <string.h>
+
+/* Client state change callback. */
+void clientChangeCallback(RedisModuleCtx *ctx, RedisModuleEvent e, uint64_t sub, void *data)
+{
+    REDISMODULE_NOT_USED(ctx);
+    REDISMODULE_NOT_USED(e);
+
+    RedisModuleClientInfo *ci = data;
+    printf("Client %s event for client #%llu %s:%d\n",
+        (sub == REDISMODULE_SUBEVENT_CLIENT_CHANGE_CONNECTED) ?
+            "connection" : "disconnection",
+        (unsigned long long)ci->id,ci->addr,ci->port);
+}
+
+void flushdbCallback(RedisModuleCtx *ctx, RedisModuleEvent e, uint64_t sub, void *data)
+{
+    REDISMODULE_NOT_USED(ctx);
+    REDISMODULE_NOT_USED(e);
+
+    RedisModuleFlushInfo *fi = data;
+    if (sub == REDISMODULE_SUBEVENT_FLUSHDB_START) {
+        if (fi->dbnum != -1) {
+            RedisModuleCallReply *reply;
+            reply = RedisModule_Call(ctx,"DBSIZE","");
+            long long numkeys = RedisModule_CallReplyInteger(reply);
+            printf("FLUSHDB event of database %d started (%lld keys in DB)\n",
+                fi->dbnum, numkeys);
+            RedisModule_FreeCallReply(reply);
+        } else {
+            printf("FLUSHALL event started\n");
+        }
+    } else {
+        if (fi->dbnum != -1) {
+            printf("FLUSHDB event of database %d ended\n",fi->dbnum);
+        } else {
+            printf("FLUSHALL event ended\n");
+        }
+    }
+}
+
+/* This function must be present on each Redis module. It is used in order to
+ * register the commands into the Redis server. */
+int RedisModule_OnLoad(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    REDISMODULE_NOT_USED(argv);
+    REDISMODULE_NOT_USED(argc);
+
+    if (RedisModule_Init(ctx,"hellohook",1,REDISMODULE_APIVER_1)
+        == REDISMODULE_ERR) return REDISMODULE_ERR;
+
+    RedisModule_SubscribeToServerEvent(ctx,
+        RedisModuleEvent_ClientChange, clientChangeCallback);
+    RedisModule_SubscribeToServerEvent(ctx,
+        RedisModuleEvent_FlushDB, flushdbCallback);
+    return REDISMODULE_OK;
+}
diff --git a/src/modules/hellotimer.c b/src/modules/hellotimer.c
new file mode 100644
index 0000000..67e1e67
--- /dev/null
+++ b/src/modules/hellotimer.c
@@ -0,0 +1,75 @@
+/* Timer API example -- Register and handle timer events
+ *
+ * -----------------------------------------------------------------------------
+ *
+ * Copyright (c) 2018, Salvatore Sanfilippo <antirez at gmail dot com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *   * Redistributions of source code must retain the above copyright notice,
+ *     this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ *   * Neither the name of Redis nor the names of its contributors may be used
+ *     to endorse or promote products derived from this software without
+ *     specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "../redismodule.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <ctype.h>
+#include <string.h>
+
+/* Timer callback. */
+void timerHandler(RedisModuleCtx *ctx, void *data) {
+    REDISMODULE_NOT_USED(ctx);
+    printf("Fired %s!\n", (char *)data);
+    RedisModule_Free(data);
+}
+
+/* HELLOTIMER.TIMER*/
+int TimerCommand_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    REDISMODULE_NOT_USED(argv);
+    REDISMODULE_NOT_USED(argc);
+
+    for (int j = 0; j < 10; j++) {
+        int delay = rand() % 5000;
+        char *buf = RedisModule_Alloc(256);
+        snprintf(buf,256,"After %d", delay);
+        RedisModuleTimerID tid = RedisModule_CreateTimer(ctx,delay,timerHandler,buf);
+        REDISMODULE_NOT_USED(tid);
+    }
+    return RedisModule_ReplyWithSimpleString(ctx, "OK");
+}
+
+/* This function must be present on each Redis module. It is used in order to
+ * register the commands into the Redis server. */
+int RedisModule_OnLoad(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    REDISMODULE_NOT_USED(argv);
+    REDISMODULE_NOT_USED(argc);
+
+    if (RedisModule_Init(ctx,"hellotimer",1,REDISMODULE_APIVER_1)
+        == REDISMODULE_ERR) return REDISMODULE_ERR;
+
+    if (RedisModule_CreateCommand(ctx,"hellotimer.timer",
+        TimerCommand_RedisCommand,"readonly",0,0,0) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
+
+    return REDISMODULE_OK;
+}
diff --git a/src/modules/hellotype.c b/src/modules/hellotype.c
new file mode 100644
index 0000000..1dc53d2
--- /dev/null
+++ b/src/modules/hellotype.c
@@ -0,0 +1,362 @@
+/* This file implements a new module native data type called "HELLOTYPE".
+ * The data structure implemented is a very simple ordered linked list of
+ * 64 bit integers, in order to have something that is real world enough, but
+ * at the same time, extremely simple to understand, to show how the API
+ * works, how a new data type is created, and how to write basic methods
+ * for RDB loading, saving and AOF rewriting.
+ *
+ * -----------------------------------------------------------------------------
+ *
+ * Copyright (c) 2016, Salvatore Sanfilippo <antirez at gmail dot com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *   * Redistributions of source code must retain the above copyright notice,
+ *     this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ *   * Neither the name of Redis nor the names of its contributors may be used
+ *     to endorse or promote products derived from this software without
+ *     specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "../redismodule.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <ctype.h>
+#include <string.h>
+#include <stdint.h>
+
+static RedisModuleType *HelloType;
+
+/* ========================== Internal data structure  =======================
+ * This is just a linked list of 64 bit integers where elements are inserted
+ * in-place, so it's ordered. There is no pop/push operation but just insert
+ * because it is enough to show the implementation of new data types without
+ * making things complex. */
+
+struct HelloTypeNode {
+    int64_t value;
+    struct HelloTypeNode *next;
+};
+
+struct HelloTypeObject {
+    struct HelloTypeNode *head;
+    size_t len; /* Number of elements added. */
+};
+
+struct HelloTypeObject *createHelloTypeObject(void) {
+    struct HelloTypeObject *o;
+    o = RedisModule_Alloc(sizeof(*o));
+    o->head = NULL;
+    o->len = 0;
+    return o;
+}
+
+void HelloTypeInsert(struct HelloTypeObject *o, int64_t ele) {
+    struct HelloTypeNode *next = o->head, *newnode, *prev = NULL;
+
+    while(next && next->value < ele) {
+        prev = next;
+        next = next->next;
+    }
+    newnode = RedisModule_Alloc(sizeof(*newnode));
+    newnode->value = ele;
+    newnode->next = next;
+    if (prev) {
+        prev->next = newnode;
+    } else {
+        o->head = newnode;
+    }
+    o->len++;
+}
+
+void HelloTypeReleaseObject(struct HelloTypeObject *o) {
+    struct HelloTypeNode *cur, *next;
+    cur = o->head;
+    while(cur) {
+        next = cur->next;
+        RedisModule_Free(cur);
+        cur = next;
+    }
+    RedisModule_Free(o);
+}
+
+/* ========================= "hellotype" type commands ======================= */
+
+/* HELLOTYPE.INSERT key value */
+int HelloTypeInsert_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    RedisModule_AutoMemory(ctx); /* Use automatic memory management. */
+
+    if (argc != 3) return RedisModule_WrongArity(ctx);
+    RedisModuleKey *key = RedisModule_OpenKey(ctx,argv[1],
+        REDISMODULE_READ|REDISMODULE_WRITE);
+    int type = RedisModule_KeyType(key);
+    if (type != REDISMODULE_KEYTYPE_EMPTY &&
+        RedisModule_ModuleTypeGetType(key) != HelloType)
+    {
+        return RedisModule_ReplyWithError(ctx,REDISMODULE_ERRORMSG_WRONGTYPE);
+    }
+
+    long long value;
+    if ((RedisModule_StringToLongLong(argv[2],&value) != REDISMODULE_OK)) {
+        return RedisModule_ReplyWithError(ctx,"ERR invalid value: must be a signed 64 bit integer");
+    }
+
+    /* Create an empty value object if the key is currently empty. */
+    struct HelloTypeObject *hto;
+    if (type == REDISMODULE_KEYTYPE_EMPTY) {
+        hto = createHelloTypeObject();
+        RedisModule_ModuleTypeSetValue(key,HelloType,hto);
+    } else {
+        hto = RedisModule_ModuleTypeGetValue(key);
+    }
+
+    /* Insert the new element. */
+    HelloTypeInsert(hto,value);
+    RedisModule_SignalKeyAsReady(ctx,argv[1]);
+
+    RedisModule_ReplyWithLongLong(ctx,hto->len);
+    RedisModule_ReplicateVerbatim(ctx);
+    return REDISMODULE_OK;
+}
+
+/* HELLOTYPE.RANGE key first count */
+int HelloTypeRange_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    RedisModule_AutoMemory(ctx); /* Use automatic memory management. */
+
+    if (argc != 4) return RedisModule_WrongArity(ctx);
+    RedisModuleKey *key = RedisModule_OpenKey(ctx,argv[1],
+        REDISMODULE_READ|REDISMODULE_WRITE);
+    int type = RedisModule_KeyType(key);
+    if (type != REDISMODULE_KEYTYPE_EMPTY &&
+        RedisModule_ModuleTypeGetType(key) != HelloType)
+    {
+        return RedisModule_ReplyWithError(ctx,REDISMODULE_ERRORMSG_WRONGTYPE);
+    }
+
+    long long first, count;
+    if (RedisModule_StringToLongLong(argv[2],&first) != REDISMODULE_OK ||
+        RedisModule_StringToLongLong(argv[3],&count) != REDISMODULE_OK ||
+        first < 0 || count < 0)
+    {
+        return RedisModule_ReplyWithError(ctx,
+            "ERR invalid first or count parameters");
+    }
+
+    struct HelloTypeObject *hto = RedisModule_ModuleTypeGetValue(key);
+    struct HelloTypeNode *node = hto ? hto->head : NULL;
+    RedisModule_ReplyWithArray(ctx,REDISMODULE_POSTPONED_LEN);
+    long long arraylen = 0;
+    while(node && count--) {
+        RedisModule_ReplyWithLongLong(ctx,node->value);
+        arraylen++;
+        node = node->next;
+    }
+    RedisModule_ReplySetArrayLength(ctx,arraylen);
+    return REDISMODULE_OK;
+}
+
+/* HELLOTYPE.LEN key */
+int HelloTypeLen_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    RedisModule_AutoMemory(ctx); /* Use automatic memory management. */
+
+    if (argc != 2) return RedisModule_WrongArity(ctx);
+    RedisModuleKey *key = RedisModule_OpenKey(ctx,argv[1],
+        REDISMODULE_READ|REDISMODULE_WRITE);
+    int type = RedisModule_KeyType(key);
+    if (type != REDISMODULE_KEYTYPE_EMPTY &&
+        RedisModule_ModuleTypeGetType(key) != HelloType)
+    {
+        return RedisModule_ReplyWithError(ctx,REDISMODULE_ERRORMSG_WRONGTYPE);
+    }
+
+    struct HelloTypeObject *hto = RedisModule_ModuleTypeGetValue(key);
+    RedisModule_ReplyWithLongLong(ctx,hto ? hto->len : 0);
+    return REDISMODULE_OK;
+}
+
+/* ====================== Example of a blocking command ==================== */
+
+/* Reply callback for blocking command HELLOTYPE.BRANGE, this will get
+ * called when the key we blocked for is ready: we need to check if we
+ * can really serve the client, and reply OK or ERR accordingly. */
+int HelloBlock_Reply(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    REDISMODULE_NOT_USED(argv);
+    REDISMODULE_NOT_USED(argc);
+
+    RedisModuleString *keyname = RedisModule_GetBlockedClientReadyKey(ctx);
+    RedisModuleKey *key = RedisModule_OpenKey(ctx,keyname,REDISMODULE_READ);
+    int type = RedisModule_KeyType(key);
+    if (type != REDISMODULE_KEYTYPE_MODULE ||
+        RedisModule_ModuleTypeGetType(key) != HelloType)
+    {
+        RedisModule_CloseKey(key);
+        return REDISMODULE_ERR;
+    }
+
+    /* In case the key is able to serve our blocked client, let's directly
+     * use our original command implementation to make this example simpler. */
+    RedisModule_CloseKey(key);
+    return HelloTypeRange_RedisCommand(ctx,argv,argc-1);
+}
+
+/* Timeout callback for blocking command HELLOTYPE.BRANGE */
+int HelloBlock_Timeout(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    REDISMODULE_NOT_USED(argv);
+    REDISMODULE_NOT_USED(argc);
+    return RedisModule_ReplyWithSimpleString(ctx,"Request timedout");
+}
+
+/* Private data freeing callback for HELLOTYPE.BRANGE command. */
+void HelloBlock_FreeData(RedisModuleCtx *ctx, void *privdata) {
+    REDISMODULE_NOT_USED(ctx);
+    RedisModule_Free(privdata);
+}
+
+/* HELLOTYPE.BRANGE key first count timeout -- This is a blocking version of
+ * the RANGE operation, in order to show how to use the API
+ * RedisModule_BlockClientOnKeys(). */
+int HelloTypeBRange_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    if (argc != 5) return RedisModule_WrongArity(ctx);
+    RedisModule_AutoMemory(ctx); /* Use automatic memory management. */
+    RedisModuleKey *key = RedisModule_OpenKey(ctx,argv[1],
+        REDISMODULE_READ|REDISMODULE_WRITE);
+    int type = RedisModule_KeyType(key);
+    if (type != REDISMODULE_KEYTYPE_EMPTY &&
+        RedisModule_ModuleTypeGetType(key) != HelloType)
+    {
+        return RedisModule_ReplyWithError(ctx,REDISMODULE_ERRORMSG_WRONGTYPE);
+    }
+
+    /* Parse the timeout before even trying to serve the client synchronously,
+     * so that we always fail ASAP on syntax errors. */
+    long long timeout;
+    if (RedisModule_StringToLongLong(argv[4],&timeout) != REDISMODULE_OK) {
+        return RedisModule_ReplyWithError(ctx,
+            "ERR invalid timeout parameter");
+    }
+
+    /* Can we serve the reply synchronously? */
+    if (type != REDISMODULE_KEYTYPE_EMPTY) {
+        return HelloTypeRange_RedisCommand(ctx,argv,argc-1);
+    }
+
+    /* Otherwise let's block on the key. */
+    void *privdata = RedisModule_Alloc(100);
+    RedisModule_BlockClientOnKeys(ctx,HelloBlock_Reply,HelloBlock_Timeout,HelloBlock_FreeData,timeout,argv+1,1,privdata);
+    return REDISMODULE_OK;
+}
+
+/* ========================== "hellotype" type methods ======================= */
+
+void *HelloTypeRdbLoad(RedisModuleIO *rdb, int encver) {
+    if (encver != 0) {
+        /* RedisModule_Log("warning","Can't load data with version %d", encver);*/
+        return NULL;
+    }
+    uint64_t elements = RedisModule_LoadUnsigned(rdb);
+    struct HelloTypeObject *hto = createHelloTypeObject();
+    while(elements--) {
+        int64_t ele = RedisModule_LoadSigned(rdb);
+        HelloTypeInsert(hto,ele);
+    }
+    return hto;
+}
+
+void HelloTypeRdbSave(RedisModuleIO *rdb, void *value) {
+    struct HelloTypeObject *hto = value;
+    struct HelloTypeNode *node = hto->head;
+    RedisModule_SaveUnsigned(rdb,hto->len);
+    while(node) {
+        RedisModule_SaveSigned(rdb,node->value);
+        node = node->next;
+    }
+}
+
+void HelloTypeAofRewrite(RedisModuleIO *aof, RedisModuleString *key, void *value) {
+    struct HelloTypeObject *hto = value;
+    struct HelloTypeNode *node = hto->head;
+    while(node) {
+        RedisModule_EmitAOF(aof,"HELLOTYPE.INSERT","sl",key,node->value);
+        node = node->next;
+    }
+}
+
+/* The goal of this function is to return the amount of memory used by
+ * the HelloType value. */
+size_t HelloTypeMemUsage(const void *value) {
+    const struct HelloTypeObject *hto = value;
+    struct HelloTypeNode *node = hto->head;
+    return sizeof(*hto) + sizeof(*node)*hto->len;
+}
+
+void HelloTypeFree(void *value) {
+    HelloTypeReleaseObject(value);
+}
+
+void HelloTypeDigest(RedisModuleDigest *md, void *value) {
+    struct HelloTypeObject *hto = value;
+    struct HelloTypeNode *node = hto->head;
+    while(node) {
+        RedisModule_DigestAddLongLong(md,node->value);
+        node = node->next;
+    }
+    RedisModule_DigestEndSequence(md);
+}
+
+/* This function must be present on each Redis module. It is used in order to
+ * register the commands into the Redis server. */
+int RedisModule_OnLoad(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    REDISMODULE_NOT_USED(argv);
+    REDISMODULE_NOT_USED(argc);
+
+    if (RedisModule_Init(ctx,"hellotype",1,REDISMODULE_APIVER_1)
+        == REDISMODULE_ERR) return REDISMODULE_ERR;
+
+    RedisModuleTypeMethods tm = {
+        .version = REDISMODULE_TYPE_METHOD_VERSION,
+        .rdb_load = HelloTypeRdbLoad,
+        .rdb_save = HelloTypeRdbSave,
+        .aof_rewrite = HelloTypeAofRewrite,
+        .mem_usage = HelloTypeMemUsage,
+        .free = HelloTypeFree,
+        .digest = HelloTypeDigest
+    };
+
+    HelloType = RedisModule_CreateDataType(ctx,"hellotype",0,&tm);
+    if (HelloType == NULL) return REDISMODULE_ERR;
+
+    if (RedisModule_CreateCommand(ctx,"hellotype.insert",
+        HelloTypeInsert_RedisCommand,"write deny-oom",1,1,1) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
+
+    if (RedisModule_CreateCommand(ctx,"hellotype.range",
+        HelloTypeRange_RedisCommand,"readonly",1,1,1) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
+
+    if (RedisModule_CreateCommand(ctx,"hellotype.len",
+        HelloTypeLen_RedisCommand,"readonly",1,1,1) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
+
+    if (RedisModule_CreateCommand(ctx,"hellotype.brange",
+        HelloTypeBRange_RedisCommand,"readonly",1,1,1) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
+
+    return REDISMODULE_OK;
+}
diff --git a/src/modules/helloworld.c b/src/modules/helloworld.c
new file mode 100644
index 0000000..e517963
--- /dev/null
+++ b/src/modules/helloworld.c
@@ -0,0 +1,621 @@
+/* Helloworld module -- A few examples of the Redis Modules API in the form
+ * of commands showing how to accomplish common tasks.
+ *
+ * This module does not do anything useful, if not for a few commands. The
+ * examples are designed in order to show the API.
+ *
+ * -----------------------------------------------------------------------------
+ *
+ * Copyright (c) 2016, Salvatore Sanfilippo <antirez at gmail dot com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *   * Redistributions of source code must retain the above copyright notice,
+ *     this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ *   * Neither the name of Redis nor the names of its contributors may be used
+ *     to endorse or promote products derived from this software without
+ *     specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "../redismodule.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <ctype.h>
+#include <string.h>
+
+/* HELLO.SIMPLE is among the simplest commands you can implement.
+ * It just returns the currently selected DB id, a functionality which is
+ * missing in Redis. The command uses two important API calls: one to
+ * fetch the currently selected DB, the other in order to send the client
+ * an integer reply as response. */
+int HelloSimple_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    REDISMODULE_NOT_USED(argv);
+    REDISMODULE_NOT_USED(argc);
+    RedisModule_ReplyWithLongLong(ctx,RedisModule_GetSelectedDb(ctx));
+    return REDISMODULE_OK;
+}
+
+/* HELLO.PUSH.NATIVE re-implements RPUSH, and shows the low level modules API
+ * where you can "open" keys, make low level operations, create new keys by
+ * pushing elements into non-existing keys, and so forth.
+ *
+ * You'll find this command to be roughly as fast as the actual RPUSH
+ * command. */
+int HelloPushNative_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc)
+{
+    if (argc != 3) return RedisModule_WrongArity(ctx);
+
+    RedisModuleKey *key = RedisModule_OpenKey(ctx,argv[1],
+        REDISMODULE_READ|REDISMODULE_WRITE);
+
+    RedisModule_ListPush(key,REDISMODULE_LIST_TAIL,argv[2]);
+    size_t newlen = RedisModule_ValueLength(key);
+    RedisModule_CloseKey(key);
+    RedisModule_ReplyWithLongLong(ctx,newlen);
+    return REDISMODULE_OK;
+}
+
+/* HELLO.PUSH.CALL implements RPUSH using an higher level approach, calling
+ * a Redis command instead of working with the key in a low level way. This
+ * approach is useful when you need to call Redis commands that are not
+ * available as low level APIs, or when you don't need the maximum speed
+ * possible but instead prefer implementation simplicity. */
+int HelloPushCall_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc)
+{
+    if (argc != 3) return RedisModule_WrongArity(ctx);
+
+    RedisModuleCallReply *reply;
+
+    reply = RedisModule_Call(ctx,"RPUSH","ss",argv[1],argv[2]);
+    long long len = RedisModule_CallReplyInteger(reply);
+    RedisModule_FreeCallReply(reply);
+    RedisModule_ReplyWithLongLong(ctx,len);
+    return REDISMODULE_OK;
+}
+
+/* HELLO.PUSH.CALL2
+ * This is exactly as HELLO.PUSH.CALL, but shows how we can reply to the
+ * client using directly a reply object that Call() returned. */
+int HelloPushCall2_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc)
+{
+    if (argc != 3) return RedisModule_WrongArity(ctx);
+
+    RedisModuleCallReply *reply;
+
+    reply = RedisModule_Call(ctx,"RPUSH","ss",argv[1],argv[2]);
+    RedisModule_ReplyWithCallReply(ctx,reply);
+    RedisModule_FreeCallReply(reply);
+    return REDISMODULE_OK;
+}
+
+/* HELLO.LIST.SUM.LEN returns the total length of all the items inside
+ * a Redis list, by using the high level Call() API.
+ * This command is an example of the array reply access. */
+int HelloListSumLen_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc)
+{
+    if (argc != 2) return RedisModule_WrongArity(ctx);
+
+    RedisModuleCallReply *reply;
+
+    reply = RedisModule_Call(ctx,"LRANGE","sll",argv[1],(long long)0,(long long)-1);
+    size_t strlen = 0;
+    size_t items = RedisModule_CallReplyLength(reply);
+    size_t j;
+    for (j = 0; j < items; j++) {
+        RedisModuleCallReply *ele = RedisModule_CallReplyArrayElement(reply,j);
+        strlen += RedisModule_CallReplyLength(ele);
+    }
+    RedisModule_FreeCallReply(reply);
+    RedisModule_ReplyWithLongLong(ctx,strlen);
+    return REDISMODULE_OK;
+}
+
+/* HELLO.LIST.SPLICE srclist dstlist count
+ * Moves 'count' elements from the tail of 'srclist' to the head of
+ * 'dstlist'. If less than count elements are available, it moves as much
+ * elements as possible. */
+int HelloListSplice_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    if (argc != 4) return RedisModule_WrongArity(ctx);
+
+    RedisModuleKey *srckey = RedisModule_OpenKey(ctx,argv[1],
+        REDISMODULE_READ|REDISMODULE_WRITE);
+    RedisModuleKey *dstkey = RedisModule_OpenKey(ctx,argv[2],
+        REDISMODULE_READ|REDISMODULE_WRITE);
+
+    /* Src and dst key must be empty or lists. */
+    if ((RedisModule_KeyType(srckey) != REDISMODULE_KEYTYPE_LIST &&
+         RedisModule_KeyType(srckey) != REDISMODULE_KEYTYPE_EMPTY) ||
+        (RedisModule_KeyType(dstkey) != REDISMODULE_KEYTYPE_LIST &&
+         RedisModule_KeyType(dstkey) != REDISMODULE_KEYTYPE_EMPTY))
+    {
+        RedisModule_CloseKey(srckey);
+        RedisModule_CloseKey(dstkey);
+        return RedisModule_ReplyWithError(ctx,REDISMODULE_ERRORMSG_WRONGTYPE);
+    }
+
+    long long count;
+    if ((RedisModule_StringToLongLong(argv[3],&count) != REDISMODULE_OK) ||
+        (count < 0)) {
+        RedisModule_CloseKey(srckey);
+        RedisModule_CloseKey(dstkey);
+        return RedisModule_ReplyWithError(ctx,"ERR invalid count");
+    }
+
+    while(count-- > 0) {
+        RedisModuleString *ele;
+
+        ele = RedisModule_ListPop(srckey,REDISMODULE_LIST_TAIL);
+        if (ele == NULL) break;
+        RedisModule_ListPush(dstkey,REDISMODULE_LIST_HEAD,ele);
+        RedisModule_FreeString(ctx,ele);
+    }
+
+    size_t len = RedisModule_ValueLength(srckey);
+    RedisModule_CloseKey(srckey);
+    RedisModule_CloseKey(dstkey);
+    RedisModule_ReplyWithLongLong(ctx,len);
+    return REDISMODULE_OK;
+}
+
+/* Like the HELLO.LIST.SPLICE above, but uses automatic memory management
+ * in order to avoid freeing stuff. */
+int HelloListSpliceAuto_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    if (argc != 4) return RedisModule_WrongArity(ctx);
+
+    RedisModule_AutoMemory(ctx);
+
+    RedisModuleKey *srckey = RedisModule_OpenKey(ctx,argv[1],
+        REDISMODULE_READ|REDISMODULE_WRITE);
+    RedisModuleKey *dstkey = RedisModule_OpenKey(ctx,argv[2],
+        REDISMODULE_READ|REDISMODULE_WRITE);
+
+    /* Src and dst key must be empty or lists. */
+    if ((RedisModule_KeyType(srckey) != REDISMODULE_KEYTYPE_LIST &&
+         RedisModule_KeyType(srckey) != REDISMODULE_KEYTYPE_EMPTY) ||
+        (RedisModule_KeyType(dstkey) != REDISMODULE_KEYTYPE_LIST &&
+         RedisModule_KeyType(dstkey) != REDISMODULE_KEYTYPE_EMPTY))
+    {
+        return RedisModule_ReplyWithError(ctx,REDISMODULE_ERRORMSG_WRONGTYPE);
+    }
+
+    long long count;
+    if ((RedisModule_StringToLongLong(argv[3],&count) != REDISMODULE_OK) ||
+        (count < 0))
+    {
+        return RedisModule_ReplyWithError(ctx,"ERR invalid count");
+    }
+
+    while(count-- > 0) {
+        RedisModuleString *ele;
+
+        ele = RedisModule_ListPop(srckey,REDISMODULE_LIST_TAIL);
+        if (ele == NULL) break;
+        RedisModule_ListPush(dstkey,REDISMODULE_LIST_HEAD,ele);
+    }
+
+    size_t len = RedisModule_ValueLength(srckey);
+    RedisModule_ReplyWithLongLong(ctx,len);
+    return REDISMODULE_OK;
+}
+
+/* HELLO.RAND.ARRAY <count>
+ * Shows how to generate arrays as commands replies.
+ * It just outputs <count> random numbers. */
+int HelloRandArray_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    if (argc != 2) return RedisModule_WrongArity(ctx);
+    long long count;
+    if (RedisModule_StringToLongLong(argv[1],&count) != REDISMODULE_OK ||
+        count < 0)
+        return RedisModule_ReplyWithError(ctx,"ERR invalid count");
+
+    /* To reply with an array, we call RedisModule_ReplyWithArray() followed
+     * by other "count" calls to other reply functions in order to generate
+     * the elements of the array. */
+    RedisModule_ReplyWithArray(ctx,count);
+    while(count--) RedisModule_ReplyWithLongLong(ctx,rand());
+    return REDISMODULE_OK;
+}
+
+/* This is a simple command to test replication. Because of the "!" modified
+ * in the RedisModule_Call() call, the two INCRs get replicated.
+ * Also note how the ECHO is replicated in an unexpected position (check
+ * comments the function implementation). */
+int HelloRepl1_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc)
+{
+    REDISMODULE_NOT_USED(argv);
+    REDISMODULE_NOT_USED(argc);
+    RedisModule_AutoMemory(ctx);
+
+    /* This will be replicated *after* the two INCR statements, since
+     * the Call() replication has precedence, so the actual replication
+     * stream will be:
+     *
+     * MULTI
+     * INCR foo
+     * INCR bar
+     * ECHO c foo
+     * EXEC
+     */
+    RedisModule_Replicate(ctx,"ECHO","c","foo");
+
+    /* Using the "!" modifier we replicate the command if it
+     * modified the dataset in some way. */
+    RedisModule_Call(ctx,"INCR","c!","foo");
+    RedisModule_Call(ctx,"INCR","c!","bar");
+
+    RedisModule_ReplyWithLongLong(ctx,0);
+
+    return REDISMODULE_OK;
+}
+
+/* Another command to show replication. In this case, we call
+ * RedisModule_ReplicateVerbatim() to mean we want just the command to be
+ * propagated to slaves / AOF exactly as it was called by the user.
+ *
+ * This command also shows how to work with string objects.
+ * It takes a list, and increments all the elements (that must have
+ * a numerical value) by 1, returning the sum of all the elements
+ * as reply.
+ *
+ * Usage: HELLO.REPL2 <list-key> */
+int HelloRepl2_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    if (argc != 2) return RedisModule_WrongArity(ctx);
+
+    RedisModule_AutoMemory(ctx); /* Use automatic memory management. */
+    RedisModuleKey *key = RedisModule_OpenKey(ctx,argv[1],
+        REDISMODULE_READ|REDISMODULE_WRITE);
+
+    if (RedisModule_KeyType(key) != REDISMODULE_KEYTYPE_LIST)
+        return RedisModule_ReplyWithError(ctx,REDISMODULE_ERRORMSG_WRONGTYPE);
+
+    size_t listlen = RedisModule_ValueLength(key);
+    long long sum = 0;
+
+    /* Rotate and increment. */
+    while(listlen--) {
+        RedisModuleString *ele = RedisModule_ListPop(key,REDISMODULE_LIST_TAIL);
+        long long val;
+        if (RedisModule_StringToLongLong(ele,&val) != REDISMODULE_OK) val = 0;
+        val++;
+        sum += val;
+        RedisModuleString *newele = RedisModule_CreateStringFromLongLong(ctx,val);
+        RedisModule_ListPush(key,REDISMODULE_LIST_HEAD,newele);
+    }
+    RedisModule_ReplyWithLongLong(ctx,sum);
+    RedisModule_ReplicateVerbatim(ctx);
+    return REDISMODULE_OK;
+}
+
+/* This is an example of strings DMA access. Given a key containing a string
+ * it toggles the case of each character from lower to upper case or the
+ * other way around.
+ *
+ * No automatic memory management is used in this example (for the sake
+ * of variety).
+ *
+ * HELLO.TOGGLE.CASE key */
+int HelloToggleCase_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    if (argc != 2) return RedisModule_WrongArity(ctx);
+
+    RedisModuleKey *key = RedisModule_OpenKey(ctx,argv[1],
+        REDISMODULE_READ|REDISMODULE_WRITE);
+
+    int keytype = RedisModule_KeyType(key);
+    if (keytype != REDISMODULE_KEYTYPE_STRING &&
+        keytype != REDISMODULE_KEYTYPE_EMPTY)
+    {
+        RedisModule_CloseKey(key);
+        return RedisModule_ReplyWithError(ctx,REDISMODULE_ERRORMSG_WRONGTYPE);
+    }
+
+    if (keytype == REDISMODULE_KEYTYPE_STRING) {
+        size_t len, j;
+        char *s = RedisModule_StringDMA(key,&len,REDISMODULE_WRITE);
+        for (j = 0; j < len; j++) {
+            if (isupper(s[j])) {
+                s[j] = tolower(s[j]);
+            } else {
+                s[j] = toupper(s[j]);
+            }
+        }
+    }
+
+    RedisModule_CloseKey(key);
+    RedisModule_ReplyWithSimpleString(ctx,"OK");
+    RedisModule_ReplicateVerbatim(ctx);
+    return REDISMODULE_OK;
+}
+
+/* HELLO.MORE.EXPIRE key milliseconds.
+ *
+ * If the key has already an associated TTL, extends it by "milliseconds"
+ * milliseconds. Otherwise no operation is performed. */
+int HelloMoreExpire_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    RedisModule_AutoMemory(ctx); /* Use automatic memory management. */
+    if (argc != 3) return RedisModule_WrongArity(ctx);
+
+    mstime_t addms, expire;
+
+    if (RedisModule_StringToLongLong(argv[2],&addms) != REDISMODULE_OK)
+        return RedisModule_ReplyWithError(ctx,"ERR invalid expire time");
+
+    RedisModuleKey *key = RedisModule_OpenKey(ctx,argv[1],
+        REDISMODULE_READ|REDISMODULE_WRITE);
+    expire = RedisModule_GetExpire(key);
+    if (expire != REDISMODULE_NO_EXPIRE) {
+        expire += addms;
+        RedisModule_SetExpire(key,expire);
+    }
+    return RedisModule_ReplyWithSimpleString(ctx,"OK");
+}
+
+/* HELLO.ZSUMRANGE key startscore endscore
+ * Return the sum of all the scores elements between startscore and endscore.
+ *
+ * The computation is performed two times, one time from start to end and
+ * another time backward. The two scores, returned as a two element array,
+ * should match.*/
+int HelloZsumRange_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    double score_start, score_end;
+    if (argc != 4) return RedisModule_WrongArity(ctx);
+
+    if (RedisModule_StringToDouble(argv[2],&score_start) != REDISMODULE_OK ||
+        RedisModule_StringToDouble(argv[3],&score_end) != REDISMODULE_OK)
+    {
+        return RedisModule_ReplyWithError(ctx,"ERR invalid range");
+    }
+
+    RedisModuleKey *key = RedisModule_OpenKey(ctx,argv[1],
+        REDISMODULE_READ|REDISMODULE_WRITE);
+    if (RedisModule_KeyType(key) != REDISMODULE_KEYTYPE_ZSET) {
+        return RedisModule_ReplyWithError(ctx,REDISMODULE_ERRORMSG_WRONGTYPE);
+    }
+
+    double scoresum_a = 0;
+    double scoresum_b = 0;
+
+    RedisModule_ZsetFirstInScoreRange(key,score_start,score_end,0,0);
+    while(!RedisModule_ZsetRangeEndReached(key)) {
+        double score;
+        RedisModuleString *ele = RedisModule_ZsetRangeCurrentElement(key,&score);
+        RedisModule_FreeString(ctx,ele);
+        scoresum_a += score;
+        RedisModule_ZsetRangeNext(key);
+    }
+    RedisModule_ZsetRangeStop(key);
+
+    RedisModule_ZsetLastInScoreRange(key,score_start,score_end,0,0);
+    while(!RedisModule_ZsetRangeEndReached(key)) {
+        double score;
+        RedisModuleString *ele = RedisModule_ZsetRangeCurrentElement(key,&score);
+        RedisModule_FreeString(ctx,ele);
+        scoresum_b += score;
+        RedisModule_ZsetRangePrev(key);
+    }
+
+    RedisModule_ZsetRangeStop(key);
+
+    RedisModule_CloseKey(key);
+
+    RedisModule_ReplyWithArray(ctx,2);
+    RedisModule_ReplyWithDouble(ctx,scoresum_a);
+    RedisModule_ReplyWithDouble(ctx,scoresum_b);
+    return REDISMODULE_OK;
+}
+
+/* HELLO.LEXRANGE key min_lex max_lex min_age max_age
+ * This command expects a sorted set stored at key in the following form:
+ * - All the elements have score 0.
+ * - Elements are pairs of "<name>:<age>", for example "Anna:52".
+ * The command will return all the sorted set items that are lexicographically
+ * between the specified range (using the same format as ZRANGEBYLEX)
+ * and having an age between min_age and max_age. */
+int HelloLexRange_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    RedisModule_AutoMemory(ctx); /* Use automatic memory management. */
+
+    if (argc != 6) return RedisModule_WrongArity(ctx);
+
+    RedisModuleKey *key = RedisModule_OpenKey(ctx,argv[1],
+        REDISMODULE_READ|REDISMODULE_WRITE);
+    if (RedisModule_KeyType(key) != REDISMODULE_KEYTYPE_ZSET) {
+        return RedisModule_ReplyWithError(ctx,REDISMODULE_ERRORMSG_WRONGTYPE);
+    }
+
+    if (RedisModule_ZsetFirstInLexRange(key,argv[2],argv[3]) != REDISMODULE_OK) {
+        return RedisModule_ReplyWithError(ctx,"invalid range");
+    }
+
+    int arraylen = 0;
+    RedisModule_ReplyWithArray(ctx,REDISMODULE_POSTPONED_LEN);
+    while(!RedisModule_ZsetRangeEndReached(key)) {
+        double score;
+        RedisModuleString *ele = RedisModule_ZsetRangeCurrentElement(key,&score);
+        RedisModule_ReplyWithString(ctx,ele);
+        RedisModule_FreeString(ctx,ele);
+        RedisModule_ZsetRangeNext(key);
+        arraylen++;
+    }
+    RedisModule_ZsetRangeStop(key);
+    RedisModule_ReplySetArrayLength(ctx,arraylen);
+    RedisModule_CloseKey(key);
+    return REDISMODULE_OK;
+}
+
+/* HELLO.HCOPY key srcfield dstfield
+ * This is just an example command that sets the hash field dstfield to the
+ * same value of srcfield. If srcfield does not exist no operation is
+ * performed.
+ *
+ * The command returns 1 if the copy is performed (srcfield exists) otherwise
+ * 0 is returned. */
+int HelloHCopy_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    RedisModule_AutoMemory(ctx); /* Use automatic memory management. */
+
+    if (argc != 4) return RedisModule_WrongArity(ctx);
+    RedisModuleKey *key = RedisModule_OpenKey(ctx,argv[1],
+        REDISMODULE_READ|REDISMODULE_WRITE);
+    int type = RedisModule_KeyType(key);
+    if (type != REDISMODULE_KEYTYPE_HASH &&
+        type != REDISMODULE_KEYTYPE_EMPTY)
+    {
+        return RedisModule_ReplyWithError(ctx,REDISMODULE_ERRORMSG_WRONGTYPE);
+    }
+
+    /* Get the old field value. */
+    RedisModuleString *oldval;
+    RedisModule_HashGet(key,REDISMODULE_HASH_NONE,argv[2],&oldval,NULL);
+    if (oldval) {
+        RedisModule_HashSet(key,REDISMODULE_HASH_NONE,argv[3],oldval,NULL);
+    }
+    RedisModule_ReplyWithLongLong(ctx,oldval != NULL);
+    return REDISMODULE_OK;
+}
+
+/* HELLO.LEFTPAD str len ch
+ * This is an implementation of the infamous LEFTPAD function, that
+ * was at the center of an issue with the npm modules system in March 2016.
+ *
+ * LEFTPAD is a good example of using a Redis Modules API called
+ * "pool allocator", that was a famous way to allocate memory in yet another
+ * open source project, the Apache web server.
+ *
+ * The concept is very simple: there is memory that is useful to allocate
+ * only in the context of serving a request, and must be freed anyway when
+ * the callback implementing the command returns. So in that case the module
+ * does not need to retain a reference to these allocations, it is just
+ * required to free the memory before returning. When this is the case the
+ * module can call RedisModule_PoolAlloc() instead, that works like malloc()
+ * but will automatically free the memory when the module callback returns.
+ *
+ * Note that PoolAlloc() does not necessarily require AutoMemory to be
+ * active. */
+int HelloLeftPad_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    RedisModule_AutoMemory(ctx); /* Use automatic memory management. */
+    long long padlen;
+
+    if (argc != 4) return RedisModule_WrongArity(ctx);
+
+    if ((RedisModule_StringToLongLong(argv[2],&padlen) != REDISMODULE_OK) ||
+        (padlen< 0)) {
+        return RedisModule_ReplyWithError(ctx,"ERR invalid padding length");
+    }
+    size_t strlen, chlen;
+    const char *str = RedisModule_StringPtrLen(argv[1], &strlen);
+    const char *ch = RedisModule_StringPtrLen(argv[3], &chlen);
+
+    /* If the string is already larger than the target len, just return
+     * the string itself. */
+    if (strlen >= (size_t)padlen)
+        return RedisModule_ReplyWithString(ctx,argv[1]);
+
+    /* Padding must be a single character in this simple implementation. */
+    if (chlen != 1)
+        return RedisModule_ReplyWithError(ctx,
+            "ERR padding must be a single char");
+
+    /* Here we use our pool allocator, for our throw-away allocation. */
+    padlen -= strlen;
+    char *buf = RedisModule_PoolAlloc(ctx,padlen+strlen);
+    for (long long j = 0; j < padlen; j++) buf[j] = *ch;
+    memcpy(buf+padlen,str,strlen);
+
+    RedisModule_ReplyWithStringBuffer(ctx,buf,padlen+strlen);
+    return REDISMODULE_OK;
+}
+
+/* This function must be present on each Redis module. It is used in order to
+ * register the commands into the Redis server. */
+int RedisModule_OnLoad(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    if (RedisModule_Init(ctx,"helloworld",1,REDISMODULE_APIVER_1)
+        == REDISMODULE_ERR) return REDISMODULE_ERR;
+
+    /* Log the list of parameters passing loading the module. */
+    for (int j = 0; j < argc; j++) {
+        const char *s = RedisModule_StringPtrLen(argv[j],NULL);
+        printf("Module loaded with ARGV[%d] = %s\n", j, s);
+    }
+
+    if (RedisModule_CreateCommand(ctx,"hello.simple",
+        HelloSimple_RedisCommand,"readonly",0,0,0) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
+
+    if (RedisModule_CreateCommand(ctx,"hello.push.native",
+        HelloPushNative_RedisCommand,"write deny-oom",1,1,1) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
+
+    if (RedisModule_CreateCommand(ctx,"hello.push.call",
+        HelloPushCall_RedisCommand,"write deny-oom",1,1,1) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
+
+    if (RedisModule_CreateCommand(ctx,"hello.push.call2",
+        HelloPushCall2_RedisCommand,"write deny-oom",1,1,1) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
+
+    if (RedisModule_CreateCommand(ctx,"hello.list.sum.len",
+        HelloListSumLen_RedisCommand,"readonly",1,1,1) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
+
+    if (RedisModule_CreateCommand(ctx,"hello.list.splice",
+        HelloListSplice_RedisCommand,"write deny-oom",1,2,1) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
+
+    if (RedisModule_CreateCommand(ctx,"hello.list.splice.auto",
+        HelloListSpliceAuto_RedisCommand,
+        "write deny-oom",1,2,1) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
+
+    if (RedisModule_CreateCommand(ctx,"hello.rand.array",
+        HelloRandArray_RedisCommand,"readonly",0,0,0) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
+
+    if (RedisModule_CreateCommand(ctx,"hello.repl1",
+        HelloRepl1_RedisCommand,"write",0,0,0) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
+
+    if (RedisModule_CreateCommand(ctx,"hello.repl2",
+        HelloRepl2_RedisCommand,"write",1,1,1) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
+
+    if (RedisModule_CreateCommand(ctx,"hello.toggle.case",
+        HelloToggleCase_RedisCommand,"write",1,1,1) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
+
+    if (RedisModule_CreateCommand(ctx,"hello.more.expire",
+        HelloMoreExpire_RedisCommand,"write",1,1,1) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
+
+    if (RedisModule_CreateCommand(ctx,"hello.zsumrange",
+        HelloZsumRange_RedisCommand,"readonly",1,1,1) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
+
+    if (RedisModule_CreateCommand(ctx,"hello.lexrange",
+        HelloLexRange_RedisCommand,"readonly",1,1,1) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
+
+    if (RedisModule_CreateCommand(ctx,"hello.hcopy",
+        HelloHCopy_RedisCommand,"write deny-oom",1,1,1) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
+
+    if (RedisModule_CreateCommand(ctx,"hello.leftpad",
+        HelloLeftPad_RedisCommand,"",1,1,1) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
+
+    return REDISMODULE_OK;
+}