Redis源码分析（三十）--- pubsub发布订阅模式(三)

/* Turn a string representing notification classes into an integer
 * representing notification classes flags xored.
 *
 * The function returns -1 if the input contains characters not mapping to
 * any class. */
/* 键值字符类型转为对应的Class类型 */
int keyspaceEventsStringToFlags(char *classes) {
    char *p = classes;
    int c, flags = 0;

    while((c = *p++) != '\0') {
        switch(c) {
        case 'A': flags |= REDIS_NOTIFY_ALL; break;
        case 'g': flags |= REDIS_NOTIFY_GENERIC; break;
        case '$': flags |= REDIS_NOTIFY_STRING; break;
        case 'l': flags |= REDIS_NOTIFY_LIST; break;
        case 's': flags |= REDIS_NOTIFY_SET; break;
        case 'h': flags |= REDIS_NOTIFY_HASH; break;
        case 'z': flags |= REDIS_NOTIFY_ZSET; break;
        case 'x': flags |= REDIS_NOTIFY_EXPIRED; break;
        case 'e': flags |= REDIS_NOTIFY_EVICTED; break;
        case 'K': flags |= REDIS_NOTIFY_KEYSPACE; break;
        case 'E': flags |= REDIS_NOTIFY_KEYEVENT; break;
        default: return -1;
        }
    }
    return flags;
}

/* The API provided to the rest of the Redis core is a simple function:
 *
 * notifyKeyspaceEvent(char *event, robj *key, int dbid);
 *
 * 'event' is a C string representing the event name.
 * 'key' is a Redis object representing the key name.
 * 'dbid' is the database ID where the key lives.  */
/* 发布通知方法，分为2类，keySpace的通知，keyEvent的通知 */ 
void notifyKeyspaceEvent(int type, char *event, robj *key, int dbid) {
    sds chan;
    robj *chanobj, *eventobj;
    int len = -1;
    char buf[24];

    /* If notifications for this class of events are off, return ASAP. */
    if (!(server.notify_keyspace_events & type)) return;

    eventobj = createStringObject(event,strlen(event));
    
    //2种的通知形式，略有差别
    /* __keyspace@
  
   __:
    
    
      notifications. */ if (server.notify_keyspace_events & REDIS_NOTIFY_KEYSPACE) { chan = sdsnewlen("__keyspace@",11); len = ll2string(buf,sizeof(buf),dbid); chan = sdscatlen(chan, buf, len); chan = sdscatlen(chan, "__:", 3); chan = sdscatsds(chan, key->ptr); chanobj = createObject(REDIS_STRING, chan); //上述几步操作，
     组件格式字符串，最后发布消息，下面keyEvent的通知同理 pubsubPublishMessage(chanobj, eventobj); decrRefCount(chanobj); } /* __keyevente@
     
      __:
       
       
         notifications. */ if (server.notify_keyspace_events & REDIS_NOTIFY_KEYEVENT) { chan = sdsnewlen("__keyevent@",11); if (len == -1) len = ll2string(buf,sizeof(buf),dbid); chan = sdscatlen(chan, buf, len); chan = sdscatlen(chan, "__:", 3); chan = sdscatsds(chan, eventobj->ptr); chanobj = createObject(REDIS_STRING, chan); pubsubPublishMessage(chanobj, key); decrRefCount(chanobj); } decrRefCount(eventobj); }