学习Redis的源码

预成大事者，必先劳其筋骨，饿其体肤，空乏其身，行扶乱其所为也。

编程之道，写了不少的代码，但是往更高层次的发展，必需要付出更多的艰辛；

写了多年的Java和JavaScript,Oracle也用了不少，静下心来，看看一个高效的Key-value Store是怎么实现的。

源码获取

通过git从官方网址下载redis-2.6.14.tar.gz,解压缩有4个子目录

deps 依赖资源

src 源代码

tests 测试

utils工具

当然还有一些文件，需要关注

Makefile make文件

redis.conf 配置文件

sentinel.conf 

主要内容分析

一：deps目录

下面包含

hiredis 作为Redis的一个mini C客户端库数据库

jemalloc  通用的内存分配工具 所用版本为3.2.0

linenoise 一个零配置的BSD Licensed的readline replacement,也是Android的一部分

lua  由巴西人写的一个脚本语言引擎 所用版本为5.1，官方最新为5.5版本 http://www.lua.org/

二：src目录

52个c文件

29个h文件

关注makefile,几个主要的编译输出

# redis-server
$(REDIS_SERVER_NAME): $(REDIS_SERVER_OBJ)
$(REDIS_LD) -o $@ $^ ../deps/hiredis/libhiredis.a ../deps/lua/src/liblua.a $(FINAL_LIBS)

# redis-sentinel
$(REDIS_SENTINEL_NAME): $(REDIS_SERVER_NAME)
$(REDIS_INSTALL) $(REDIS_SERVER_NAME) $(REDIS_SENTINEL_NAME)

# redis-cli
$(REDIS_CLI_NAME): $(REDIS_CLI_OBJ)
$(REDIS_LD) -o $@ $^ ../deps/hiredis/libhiredis.a ../deps/linenoise/linenoise.o $(FINAL_LIBS)

# redis-benchmark
$(REDIS_BENCHMARK_NAME): $(REDIS_BENCHMARK_OBJ)
$(REDIS_LD) -o $@ $^ ../deps/hiredis/libhiredis.a $(FINAL_LIBS)

# redis-check-dump
$(REDIS_CHECK_DUMP_NAME): $(REDIS_CHECK_DUMP_OBJ)
$(REDIS_LD) -o $@ $^ $(FINAL_LIBS)

# redis-check-aof
$(REDIS_CHECK_AOF_NAME): $(REDIS_CHECK_AOF_OBJ)
$(REDIS_LD) -o $@ $^ $(FINAL_LIBS)

根据安装文件会包括如下几个部分

redis-server :Redis服务器的daemon启动程序

redis-cli 命令行操作工具

redis-benchmark 性能测试工具

redis-check-aof 数据修改

redis-check-dump 检查和数据导出工具

所以源头分析源码从

redis.c, 总2727行

redis-benchmark.c, 总682行

redis-check-aof.c,总218行

redis-check-dump.c, 总771行

redis-cli.c 总1556行

3.1 redis.c

包含关联头文件

#include "redis.h"
#include "slowlog.h"
#include "bio.h"

以及linux下的time.h,signal.h,sys/wait.h,assert.h,ctype.h,stdarg.h,arpa/inet.h,fcntl.h,sys/time.h,sys/resource.h,sys/uioh,limits.h,float.h,mach.h

sys/resource.h,sys/utsname.h

所以需要读懂redis.c必须要先了解这些头文件的用处

首先拜读一下redis.h吧，1226行

有包含 "fmacros.h" 和"config.h"

同时引用其他头文件stdio.h,stdlib.h,string.h,time.h,limits.h,unistd.h,errno.h,inttypes.h,pthread.h,syslog.h,netinet/in.h,lua.h,signal.h

这些头文件都跟unix或者linux的c编程分不开的

#include "ae.h"      /* Event driven programming library */
#include "sds.h"     /* Dynamic safe strings */
#include "dict.h"    /* Hash tables */
#include "adlist.h"  /* Linked lists */
#include "zmalloc.h" /* total memory usage aware version of malloc/free */
#include "anet.h"    /* Networking the easy way */
#include "ziplist.h" /* Compact list data structure */
#include "intset.h"  /* Compact integer set structure */
#include "version.h" /* Version macro */
#include "util.h"    /* Misc functions useful in many places */

redis.h内部内容包括如下几个部分

常量定义

结构体定义【redisObject,redisDb,redisClient,sharedObjectsStruct,zskiplistNode,zskiplist,zset,redisOp,redisOpArray,

redisServer,pubsubPattern,redisCommand,_redisSortObject,_redisSortOperation,】

方法定义,主要涵盖如下几类

utils

long long ustime(void);
long long mstime(void);
void getRandomHexChars(char *p, unsigned int len);
uint64_t crc64(uint64_t crc, const unsigned char *s, uint64_t l);
void exitFromChild(int retcode);

/* networking.c -- Networking and Client related operations */

/* List data type */

/* MULTI/EXEC/WATCH... */

/* Redis object implementation */

/* Synchronous I/O with timeout */

/* Replication */

/* Generic persistence functions */

/* RDB persistence *

/* AOF persistence */

/* Sorted sets data type */

/* Core functions */

/* Set data type */

/* Hash data type */

/* Pub / Sub */

/* Configuration */

/* db.c -- Keyspace access API */

/* API to get key arguments from commands */

/* Sentinel */

/* Scripting */

/* Git SHA1 */

/* Commands prototypes */

/* Debugging stuff */

接下来看看redis.c中的main方法

int main(int argc, char **argv) {
    struct timeval tv;


    /* We need to initialize our libraries, and the server configuration. */
    zmalloc_enable_thread_safeness();
    zmalloc_set_oom_handler(redisOutOfMemoryHandler);
    srand(time(NULL)^getpid());
    gettimeofday(&tv,NULL);
    dictSetHashFunctionSeed(tv.tv_sec^tv.tv_usec^getpid());
    server.sentinel_mode = checkForSentinelMode(argc,argv);
    initServerConfig();


    /* We need to init sentinel right now as parsing the configuration file
     * in sentinel mode will have the effect of populating the sentinel
     * data structures with master nodes to monitor. */
    if (server.sentinel_mode) {
        initSentinelConfig();
        initSentinel();
    }


    if (argc >= 2) {
        int j = 1; /* First option to parse in argv[] */
        sds options = sdsempty();
        char *configfile = NULL;


        /* Handle special options --help and --version */
        if (strcmp(argv[1], "-v") == 0 ||
            strcmp(argv[1], "--version") == 0) version();
        if (strcmp(argv[1], "--help") == 0 ||
            strcmp(argv[1], "-h") == 0) usage();
        if (strcmp(argv[1], "--test-memory") == 0) {
            if (argc == 3) {
                memtest(atoi(argv[2]),50);
                exit(0);
            } else {
                fprintf(stderr,"Please specify the amount of memory to test in megabytes.\n");
                fprintf(stderr,"Example: ./redis-server --test-memory 4096\n\n");
                exit(1);
            }
        }


        /* First argument is the config file name? */
        if (argv[j][0] != '-' || argv[j][1] != '-')
            configfile = argv[j++];
        /* All the other options are parsed and conceptually appended to the
         * configuration file. For instance --port 6380 will generate the
         * string "port 6380\n" to be parsed after the actual file name
         * is parsed, if any. */
        while(j != argc) {
            if (argv[j][0] == '-' && argv[j][1] == '-') {
                /* Option name */
                if (sdslen(options)) options = sdscat(options,"\n");
                options = sdscat(options,argv[j]+2);
                options = sdscat(options," ");
            } else {
                /* Option argument */
                options = sdscatrepr(options,argv[j],strlen(argv[j]));
                options = sdscat(options," ");
            }
            j++;
        }
        resetServerSaveParams();
        loadServerConfig(configfile,options);
        sdsfree(options);
    } else {
        redisLog(REDIS_WARNING, "Warning: no config file specified, using the default config. In order to specify a config file use %s /path/to/%s.conf", argv[0], server.sentinel_mode ? "sentinel" : "redis");
    }
    if (server.daemonize) daemonize();
    initServer();
    if (server.daemonize) createPidFile();
    redisAsciiArt();


    if (!server.sentinel_mode) {
        /* Things only needed when not running in Sentinel mode. */
        redisLog(REDIS_WARNING,"Server started, Redis version " REDIS_VERSION);
    #ifdef __linux__
        linuxOvercommitMemoryWarning();
    #endif
        loadDataFromDisk();
        if (server.ipfd > 0)
            redisLog(REDIS_NOTICE,"The server is now ready to accept connections on port %d", server.port);
        if (server.sofd > 0)
            redisLog(REDIS_NOTICE,"The server is now ready to accept connections at %s", server.unixsocket);
    }


    /* Warning the user about suspicious maxmemory setting. */
    if (server.maxmemory > 0 && server.maxmemory < 1024*1024) {
        redisLog(REDIS_WARNING,"WARNING: You specified a maxmemory value that is less than 1MB (current value is %llu bytes). Are you sure this is what you really want?", server.maxmemory);
    }


    aeSetBeforeSleepProc(server.el,beforeSleep);
    aeMain(server.el);
    aeDeleteEventLoop(server.el);
    return 0;
}