/* 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 the Redis Source Available License 2.0 * (RSALv2) or the Server Side Public License v1 (SSPLv1). */ #include "../redismodule.h" #include #include #include #include static RedisModuleDict *Keyspace; /* HELLODICT.SET * * 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 * * 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 * * 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; }