diff options
Diffstat (limited to 'src/modules/helloworld.c')
| -rw-r--r-- | src/modules/helloworld.c | 101 |
1 files changed, 100 insertions, 1 deletions
diff --git a/src/modules/helloworld.c b/src/modules/helloworld.c index 3734503bb..8d657a52b 100644 --- a/src/modules/helloworld.c +++ b/src/modules/helloworld.c @@ -1,7 +1,44 @@ +/* Helloworld module -- A few examples of the Redis Modules API in the form + * of commands showing how to accomplish common tasks. + * + * This module does not do anything useful, if not for a few commands. The + * examples are designed in order to show the API. + * + * ------------------------------------------------------------------------------ + * + * Copyright (c) 2016, 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> /* HELLO.SIMPLE is among the simplest commands you can implement. * It just returns the currently selected DB id, a functionality which is @@ -448,12 +485,70 @@ int HelloHCopy_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int a return REDISMODULE_OK; } +/* HELLO.LEFTPAD str len ch + * This is an implementation of the infamous LEFTPAD function, that + * was at the center of an issue with the npm modules system in March 2016. + * + * LEFTPAD is a good example of using a Redis Modules API called + * "pool allocator", that was a famous way to allocate memory in yet another + * open source project, the Apache web server. + * + * The concept is very simple: there is memory that is useful to allocate + * only in the context of serving a request, and must be freed anyway when + * the callback implementing the command returns. So in that case the module + * does not need to retain a reference to these allocations, it is just + * required to free the memory before returning. When this is the case the + * module can call RedisModule_PoolAlloc() instead, that works like malloc() + * but will automatically free the memory when the module callback returns. + * + * Note that PoolAlloc() does not necessarily require AutoMemory to be + * active. */ +int HelloLeftPad_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) { + RedisModule_AutoMemory(ctx); /* Use automatic memory management. */ + long long padlen; + + if (argc != 4) return RedisModule_WrongArity(ctx); + + if ((RedisModule_StringToLongLong(argv[2],&padlen) != REDISMODULE_OK) || + (padlen< 0)) { + return RedisModule_ReplyWithError(ctx,"ERR invalid padding length"); + } + size_t strlen, chlen; + const char *str = RedisModule_StringPtrLen(argv[1], &strlen); + const char *ch = RedisModule_StringPtrLen(argv[3], &chlen); + + /* If the string is already larger than the target len, just return + * the string itself. */ + if (strlen >= padlen) + return RedisModule_ReplyWithString(ctx,argv[1]); + + /* Padding must be a single character in this simple implementation. */ + if (chlen != 1) + return RedisModule_ReplyWithError(ctx, + "ERR padding must be a single char"); + + /* Here we use our pool allocator, for our throw-away allocation. */ + padlen -= strlen; + char *buf = RedisModule_PoolAlloc(ctx,padlen+strlen); + for (size_t j = 0; j < padlen; j++) buf[j] = *ch; + memcpy(buf+padlen,str,strlen); + + RedisModule_ReplyWithStringBuffer(ctx,buf,padlen+strlen); + 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) { +int RedisModule_OnLoad(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) { if (RedisModule_Init(ctx,"helloworld",1,REDISMODULE_APIVER_1) == REDISMODULE_ERR) return REDISMODULE_ERR; + /* Log the list of parameters passing loading the module. */ + for (int j = 0; j < argc; j++) { + const char *s = RedisModule_StringPtrLen(argv[j],NULL); + printf("Module loaded with ARGV[%d] = %s\n", j, s); + } + if (RedisModule_CreateCommand(ctx,"hello.simple", HelloSimple_RedisCommand,"readonly",0,0,0) == REDISMODULE_ERR) return REDISMODULE_ERR; @@ -515,5 +610,9 @@ int RedisModule_OnLoad(RedisModuleCtx *ctx) { HelloHCopy_RedisCommand,"write deny-oom",1,1,1) == REDISMODULE_ERR) return REDISMODULE_ERR; + if (RedisModule_CreateCommand(ctx,"hello.leftpad", + HelloLeftPad_RedisCommand,"",1,1,1) == REDISMODULE_ERR) + return REDISMODULE_ERR; + return REDISMODULE_OK; } |