漫话Redis源码之一百零一

本文主要是介绍漫话Redis源码之一百零一，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

这里仍是redis module相关的代码，带看redis源码时，建议略看这一看，不重要的东西：

#define REDISMODULE_EXPERIMENTAL_API/* define macros for having usleep */
#define _BSD_SOURCE
#define _DEFAULT_SOURCE#include "redismodule.h"
#include <string.h>
#include <assert.h>
#include <unistd.h>#define UNUSED(V) ((void) V)int child_pid = -1;
int exitted_with_code = -1;void done_handler(int exitcode, int bysignal, void *user_data) {child_pid = -1;exitted_with_code = exitcode;assert(user_data==(void*)0xdeadbeef);UNUSED(bysignal);
}int fork_create(RedisModuleCtx *ctx, RedisModuleString **argv, int argc)
{long long code_to_exit_with;if (argc != 2) {RedisModule_WrongArity(ctx);return REDISMODULE_OK;}if(!RMAPI_FUNC_SUPPORTED(RedisModule_Fork)){RedisModule_ReplyWithError(ctx, "Fork api is not supported in the current redis version");return REDISMODULE_OK;}RedisModule_StringToLongLong(argv[1], &code_to_exit_with);exitted_with_code = -1;child_pid = RedisModule_Fork(done_handler, (void*)0xdeadbeef);if (child_pid < 0) {RedisModule_ReplyWithError(ctx, "Fork failed");return REDISMODULE_OK;} else if (child_pid > 0) {/* parent */RedisModule_ReplyWithLongLong(ctx, child_pid);return REDISMODULE_OK;}/* child */RedisModule_Log(ctx, "notice", "fork child started");usleep(500000);RedisModule_Log(ctx, "notice", "fork child exiting");RedisModule_ExitFromChild(code_to_exit_with);/* unreachable */return 0;
}int fork_exitcode(RedisModuleCtx *ctx, RedisModuleString **argv, int argc)
{UNUSED(argv);UNUSED(argc);RedisModule_ReplyWithLongLong(ctx, exitted_with_code);return REDISMODULE_OK;
}int fork_kill(RedisModuleCtx *ctx, RedisModuleString **argv, int argc)
{UNUSED(argv);UNUSED(argc);if (RedisModule_KillForkChild(child_pid) != REDISMODULE_OK)RedisModule_ReplyWithError(ctx, "KillForkChild failed");elseRedisModule_ReplyWithLongLong(ctx, 1);child_pid = -1;return REDISMODULE_OK;
}int RedisModule_OnLoad(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {UNUSED(argv);UNUSED(argc);if (RedisModule_Init(ctx,"fork",1,REDISMODULE_APIVER_1)== REDISMODULE_ERR)return REDISMODULE_ERR;if (RedisModule_CreateCommand(ctx,"fork.create", fork_create,"",0,0,0) == REDISMODULE_ERR)return REDISMODULE_ERR;if (RedisModule_CreateCommand(ctx,"fork.exitcode", fork_exitcode,"",0,0,0) == REDISMODULE_ERR)return REDISMODULE_ERR;if (RedisModule_CreateCommand(ctx,"fork.kill", fork_kill,"",0,0,0) == REDISMODULE_ERR)return REDISMODULE_ERR;return REDISMODULE_OK;
}

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