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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-Present, Redis Ltd.
* All rights reserved.
*
* Licensed under your choice of (a) the Redis Source Available License 2.0
* (RSALv2); or (b) the Server Side Public License v1 (SSPLv1); or (c) the
* GNU Affero General Public License v3 (AGPLv3).
*/
#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;
}
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