Redis源码分析2:Redis的事件处理模型

// ae.h
/* State of an event based program */
typedef struct aeEventLoop {
    int maxfd;   /* highest file descriptor currently registered
                注册的最高并发文件描述符*/
    int setsize; /* max number of file descriptors tracked
                最大可跟踪的文件描述符*/
    long long timeEventNextId;
    time_t lastTime;     /* Used to detect system clock skew
                        系统时间存储*/
    aeFileEvent *events; /* Registered events
    注册的事件 这是一个数组，看初始化代码是建立了10128大小的数组*/
    aeFiredEvent *fired; /* Fired events */
    aeTimeEvent *timeEventHead;
    int stop;
    void *apidata; /* This is used for polling API specific data*/
    aeBeforeSleepProc *beforesleep;
    aeBeforeSleepProc *aftersleep;
} aeEventLoop;

    server.el = aeCreateEventLoop(server.maxclients+CONFIG_FDSET_INCR);
    // 这里的参数就制定了上面events这个数组的大小10128.
    if (server.el == NULL) {       
        serverLog(LL_WARNING,      
            "Failed creating the event loop. Error message: '%s'",        
            strerror(errno));      
        exit(1);      
    }  
}

void aeMain(aeEventLoop *eventLoop) {           
    eventLoop->stop = 0;           
    while (!eventLoop->stop) {     // 进入事件循环
        if (eventLoop->beforesleep != NULL)     
            eventLoop->beforesleep(eventLoop);  
        aeProcessEvents(eventLoop, AE_ALL_EVENTS|AE_CALL_AFTER_SLEEP);
        // 这里进行循环处理事件
    }    
}     

    /* Create an event handler for accepting new connections in TCP and Unix           
     * domain sockets. */          
    for (j = 0; j < server.ipfd_count; j++) {   
        if (aeCreateFileEvent(server.el, server.ipfd[j], AE_READABLE,     
            acceptTcpHandler,NULL) == AE_ERR)   
            {         
   serverPanic(       
       "Unrecoverable error creating server.ipfd file event.");           
            }         
    }   

(lldb) bt
* thread #1, queue = 'com.apple.main-thread', stop reason = breakpoint 1.1
  * frame #0: 0x000000010001bdc0 redis-server`acceptTcpHandler(el=0x000000010042f240, fd=7, privdata=0x0000000000000000, mask=1) at networking.c:728
    frame #1: 0x00000001000046bc redis-server`aeProcessEvents(eventLoop=0x000000010042f240, flags=11) at ae.c:443
    frame #2: 0x00000001000049db redis-server`aeMain(eventLoop=0x000000010042f240) at ae.c:501
    frame #3: 0x00000001000105be redis-server`main(argc=1, argv=0x00007ffeefbffb88) at server.c:4197
    frame #4: 0x00007fff5d3e108d libdyld.dylib`start + 1
    frame #5: 0x00007fff5d3e108d libdyld.dylib`start + 1

(lldb) p *el
(aeEventLoop) $1 = {
  maxfd = 7
  setsize = 10128
  timeEventNextId = 1
  lastTime = 1553153284
  events = 0x000000010025c000
  fired = 0x000000010100d600
  timeEventHead = 0x0000000100305cb0
  stop = 0
  apidata = 0x000000010042f290
  beforesleep = 0x0000000100009fc0 (redis-server`beforeSleep at server.c:1358)
  aftersleep = 0x000000010000a100 (redis-server`afterSleep at server.c:1415)
}
(lldb) 

    client *createClient(int fd) {     
    client *c = zmalloc(sizeof(client));        
         
    /* passing -1 as fd it is possible to create a non connected client.  
     * This is useful since all the commands needs to be executed         
     * in the context of a client. When commands are executed in other    
     * contexts (for instance a Lua script) we need a non connected client. */         
    if (fd != -1) {   
        anetNonBlock(NULL,fd);     
        anetEnableTcpNoDelay(NULL,fd);          
        if (server.tcpkeepalive)   
            anetKeepAlive(NULL,fd,server.tcpkeepalive);      
        if (aeCreateFileEvent(server.el,fd,AE_READABLE,      
            readQueryFromClient, c) == AE_ERR)
            // 这里首先是把readQueryFromClient绑定到事件处理对象`aeEventLoop`中
            // readQueryFromClient这里读取客户端请求，进行处理。
        {
            close(fd);
            zfree(c); 
            return NULL;           
        }
    }  
    ......       

(lldb) bt
* thread #1, queue = 'com.apple.main-thread', stop reason = breakpoint 1.1
  * frame #0: 0x0000000100019e91 redis-server`readQueryFromClient(el=0x000000010042ee00, fd=8, privdata=0x0000000100801000, mask=1) at networking.c:1508
    frame #1: 0x00000001000046bc redis-server`aeProcessEvents(eventLoop=0x000000010042ee00, flags=11) at ae.c:443
    frame #2: 0x00000001000049db redis-server`aeMain(eventLoop=0x000000010042ee00) at ae.c:501
    frame #3: 0x00000001000105be redis-server`main(argc=1, argv=0x00007ffeefbffb88) at server.c:4197
    frame #4: 0x00007fff5d3e108d libdyld.dylib`start + 1
    frame #5: 0x00007fff5d3e108d libdyld.dylib`start + 1