1 /* Hellodict -- An example of modules dictionary API
2 *
3 * This module implements a volatile key-value store on top of the
4 * dictionary exported by the Redis modules API.
5 *
6 * -----------------------------------------------------------------------------
7 *
8 * Copyright (c) 2018, Salvatore Sanfilippo <antirez at gmail dot com>
9 * All rights reserved.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions are met:
13 *
14 * * Redistributions of source code must retain the above copyright notice,
15 * this list of conditions and the following disclaimer.
16 * * Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 * * Neither the name of Redis nor the names of its contributors may be used
20 * to endorse or promote products derived from this software without
21 * specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
24 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
27 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
28 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
29 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
30 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
31 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
32 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
33 * POSSIBILITY OF SUCH DAMAGE.
34 */
35
36 #define REDISMODULE_EXPERIMENTAL_API
37 #include "../redismodule.h"
38 #include <stdio.h>
39 #include <stdlib.h>
40 #include <ctype.h>
41 #include <string.h>
42
43 static RedisModuleDict *Keyspace;
44
45 /* HELLODICT.SET <key> <value>
46 *
47 * Set the specified key to the specified value. */
cmd_SET(RedisModuleCtx * ctx,RedisModuleString ** argv,int argc)48 int cmd_SET(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
49 if (argc != 3) return RedisModule_WrongArity(ctx);
50 RedisModule_DictSet(Keyspace,argv[1],argv[2]);
51 /* We need to keep a reference to the value stored at the key, otherwise
52 * it would be freed when this callback returns. */
53 RedisModule_RetainString(NULL,argv[2]);
54 return RedisModule_ReplyWithSimpleString(ctx, "OK");
55 }
56
57 /* HELLODICT.GET <key>
58 *
59 * Return the value of the specified key, or a null reply if the key
60 * is not defined. */
cmd_GET(RedisModuleCtx * ctx,RedisModuleString ** argv,int argc)61 int cmd_GET(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
62 if (argc != 2) return RedisModule_WrongArity(ctx);
63 RedisModuleString *val = RedisModule_DictGet(Keyspace,argv[1],NULL);
64 if (val == NULL) {
65 return RedisModule_ReplyWithNull(ctx);
66 } else {
67 return RedisModule_ReplyWithString(ctx, val);
68 }
69 }
70
71 /* HELLODICT.KEYRANGE <startkey> <endkey> <count>
72 *
73 * Return a list of matching keys, lexicographically between startkey
74 * and endkey. No more than 'count' items are emitted. */
cmd_KEYRANGE(RedisModuleCtx * ctx,RedisModuleString ** argv,int argc)75 int cmd_KEYRANGE(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
76 if (argc != 4) return RedisModule_WrongArity(ctx);
77
78 /* Parse the count argument. */
79 long long count;
80 if (RedisModule_StringToLongLong(argv[3],&count) != REDISMODULE_OK) {
81 return RedisModule_ReplyWithError(ctx,"ERR invalid count");
82 }
83
84 /* Seek the iterator. */
85 RedisModuleDictIter *iter = RedisModule_DictIteratorStart(
86 Keyspace, ">=", argv[1]);
87
88 /* Reply with the matching items. */
89 char *key;
90 size_t keylen;
91 long long replylen = 0; /* Keep track of the amitted array len. */
92 RedisModule_ReplyWithArray(ctx,REDISMODULE_POSTPONED_ARRAY_LEN);
93 while((key = RedisModule_DictNextC(iter,&keylen,NULL)) != NULL) {
94 if (replylen >= count) break;
95 if (RedisModule_DictCompare(iter,"<=",argv[2]) == REDISMODULE_ERR)
96 break;
97 RedisModule_ReplyWithStringBuffer(ctx,key,keylen);
98 replylen++;
99 }
100 RedisModule_ReplySetArrayLength(ctx,replylen);
101
102 /* Cleanup. */
103 RedisModule_DictIteratorStop(iter);
104 return REDISMODULE_OK;
105 }
106
107 /* This function must be present on each Redis module. It is used in order to
108 * register the commands into the Redis server. */
RedisModule_OnLoad(RedisModuleCtx * ctx,RedisModuleString ** argv,int argc)109 int RedisModule_OnLoad(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
110 REDISMODULE_NOT_USED(argv);
111 REDISMODULE_NOT_USED(argc);
112
113 if (RedisModule_Init(ctx,"hellodict",1,REDISMODULE_APIVER_1)
114 == REDISMODULE_ERR) return REDISMODULE_ERR;
115
116 if (RedisModule_CreateCommand(ctx,"hellodict.set",
117 cmd_SET,"write deny-oom",1,1,0) == REDISMODULE_ERR)
118 return REDISMODULE_ERR;
119
120 if (RedisModule_CreateCommand(ctx,"hellodict.get",
121 cmd_GET,"readonly",1,1,0) == REDISMODULE_ERR)
122 return REDISMODULE_ERR;
123
124 if (RedisModule_CreateCommand(ctx,"hellodict.keyrange",
125 cmd_KEYRANGE,"readonly",1,1,0) == REDISMODULE_ERR)
126 return REDISMODULE_ERR;
127
128 /* Create our global dictionray. Here we'll set our keys and values. */
129 Keyspace = RedisModule_CreateDict(NULL);
130
131 return REDISMODULE_OK;
132 }
133