redis源码笔记－ae.h

ae框架是redis作者开发的事件处理框架，其目的和libevent项目类似。redis本着最小依赖原则，自己实现了一套，而且速度更快。ae只有不到500行代码，但据说libevent有3万加的代码，实现这一个功能所付出的代码量已经超过了redis所有的代码量。

ae.h

 1 #ifndef __AE_H__
 2 #define __AE_H__
 3 
   //同时支持的连接数，其实这个还是可以设的更大一些
 4 #define AE_SETSIZE (1024*10)    /* Max number of fd supported */
 5 
 6 #define AE_OK 0
 7 #define AE_ERR -1
 8 
 9 #define AE_NONE 0
10 #define AE_READABLE 1
11 #define AE_WRITABLE 2
12 
   //ae框架处理两类事件，file event和time event
13 #define AE_FILE_EVENTS 1
14 #define AE_TIME_EVENTS 2
15 #define AE_ALL_EVENTS (AE_FILE_EVENTS|AE_TIME_EVENTS)
16 #define AE_DONT_WAIT 4
17 
18 #define AE_NOMORE -1
19 
20 /* Macros */
21 #define AE_NOTUSED(V) ((void) V)
22 
23 struct aeEventLoop;
24 
   //为方便使用定义的函数指针别名
25 /* Types and data structures */
26 typedef void aeFileProc(struct aeEventLoop *eventLoop, int fd, void *clientData, int mask);
27 typedef int aeTimeProc(struct aeEventLoop *eventLoop, long long id, void *clientData);
   //这个函数类似于析构函数，在event删除前调用
28 typedef void aeEventFinalizerProc(struct aeEventLoop *eventLoop, void *clientData);
29 typedef void aeBeforeSleepProc(struct aeEventLoop *eventLoop);
30 
   //文件事件结构，是一个数组
31 /* File event structure */
32 typedef struct aeFileEvent {
33     int mask; /* one of AE_(READABLE|WRITABLE) */
34     aeFileProc *rfileProc;
35     aeFileProc *wfileProc;
36     void *clientData;
37 } aeFileEvent;
38 
   //时间事件结构，是一个链表
39 /* Time event structure */
40 typedef struct aeTimeEvent {
41     long long id; /* time event identifier. */
42     long when_sec; /* seconds */
43     long when_ms; /* milliseconds */
44     aeTimeProc *timeProc;
45     aeEventFinalizerProc *finalizerProc;
46     void *clientData;
47     struct aeTimeEvent *next;
48 } aeTimeEvent;
49 
   //表示即将执行的事件
50 /* A fired event */
51 typedef struct aeFiredEvent {
52     int fd;
53     int mask;
54 } aeFiredEvent;
55 
56 /* State of an event based program */
57 typedef struct aeEventLoop {
58     int maxfd;
59     long long timeEventNextId;
60     aeFileEvent events[AE_SETSIZE]; /* Registered events */
61     aeFiredEvent fired[AE_SETSIZE]; /* Fired events */
62     aeTimeEvent *timeEventHead;
63     int stop;
64     void *apidata; /* This is used for polling API specific data */
65     aeBeforeSleepProc *beforesleep;
66 } aeEventLoop;
67 
68 /* Prototypes */
69 aeEventLoop *aeCreateEventLoop(void);
70 void aeDeleteEventLoop(aeEventLoop *eventLoop);
71 void aeStop(aeEventLoop *eventLoop);
72 int aeCreateFileEvent(aeEventLoop *eventLoop, int fd, int mask,
73         aeFileProc *proc, void *clientData);
74 void aeDeleteFileEvent(aeEventLoop *eventLoop, int fd, int mask);
75 int aeGetFileEvents(aeEventLoop *eventLoop, int fd);
76 long long aeCreateTimeEvent(aeEventLoop *eventLoop, long long milliseconds,
77         aeTimeProc *proc, void *clientData,
78         aeEventFinalizerProc *finalizerProc);
79 int aeDeleteTimeEvent(aeEventLoop *eventLoop, long long id);
80 int aeProcessEvents(aeEventLoop *eventLoop, int flags);
81 int aeWait(int fd, int mask, long long milliseconds);
82 void aeMain(aeEventLoop *eventLoop);
83 char *aeGetApiName(void);
84 void aeSetBeforeSleepProc(aeEventLoop *eventLoop, aeBeforeSleepProc *beforesleep);
85 
86 #endif