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Diffstat (limited to 'src/modules/hellodict.c')
| -rw-r--r-- | src/modules/hellodict.c | 131 |
1 files changed, 131 insertions, 0 deletions
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; +} |