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+/* 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;
+}