在netwoking 网络模块，redis服务端响应给客户端
/* -----------------------------------------------------------------------------
* Higher level functions to queue data on the client output buffer.
* The following functions are the ones that commands implementations will call.
* -------------------------------------------------------------------------- */
void addReply(redisClient *c, robj *obj) {
if (prepareClientToWrite(c) != REDIS_OK) return;
/* This is an important place where we can avoid copy-on-write
* when there is a saving child running, avoiding touching the
* refcount field of the object if it's not needed.
*
* If the encoding is RAW and there is room in the static buffer
* we'll be able to send the object to the client without
* messing with its page. */
if (sdsEncodedObject(obj)) {
if (_addReplyToBuffer(c,obj->ptr,sdslen(obj->ptr)) != REDIS_OK)
_addReplyObjectToList(c,obj);
} else if (obj->encoding == REDIS_ENCODING_INT) {
/* Optimization: if there is room in the static buffer for 32 bytes
* (more than the max chars a 64 bit integer can take as string) we
* avoid decoding the object and go for the lower level approach. */
if (listLength(c->reply) == 0 && (sizeof(c->buf) - c->bufpos) >= 32) {
char buf[32];
int len;
len = ll2string(buf,sizeof(buf),(long)obj->ptr);
if (_addReplyToBuffer(c,buf,len) == REDIS_OK)
return;
/* else... continue with the normal code path, but should never
* happen actually since we verified there is room. */
}
obj = getDecodedObject(obj);
if (_addReplyToBuffer(c,obj->ptr,sdslen(obj->ptr)) != REDIS_OK)
_addReplyObjectToList(c,obj);
decrRefCount(obj);
} else {
redisPanic("Wrong obj->encoding in addReply()");
}
}在db.c的文件
/* High level Set operation. This function can be used in order to set
* a key, whatever it was existing or not, to a new object.
*
* 1) The ref count of the value object is incremented.
* 2) clients WATCHing for the destination key notified.
* 3) The expire time of the key is reset (the key is made persistent). */
void setKey(redisDb *db, robj *key, robj *val) {
if (lookupKeyWrite(db,key) == NULL) {
dbAdd(db,key,val);
} else {
dbOverwrite(db,key,val);
}
incrRefCount(val);
removeExpire(db,key);
signalModifiedKey(db,key);
}
/*
* 为执行写入操作而取出键 key 在数据库 db 中的值。
* 和 lookupKeyRead 不同，这个函数不会更新服务器的命中/不命中信息。*
* 找到时返回值对象，没找到返回 NULL 。
*/
robj *lookupKeyWrite(redisDb *db, robj *key) {
expireIfNeeded(db,key); // 删除过期键
return lookupKey(db,key);// 查找并返回 key 的值对象
}
int expireIfNeeded(redisDb *db, robj *key) {
mstime_t when = getExpire(db,key);// 取出键的过期时间
mstime_t now;
// 没有过期时间
if (when < 0) return 0; /* No expire for this key */
// 如果服务器正在进行载入，那么不进行任何过期检查
/* Don't expire anything while loading. It will be done later. */
if (server.loading) return 0;
/* If we are in the context of a Lua script, we claim that time is
* blocked to when the Lua script started. This way a key can expire
* only the first time it is accessed and not in the middle of the
* script execution, making propagation to slaves / AOF consistent.
* See issue #1525 on Github for more information. */
now = server.lua_caller ? server.lua_time_start : mstime();
当服务器运行在 replication 模式时 附属节点并不主动删除 key 它只返回一个逻辑上正确的返回值 真正的删除操作要等待主节点发来删除命令时才执行 从而保证数据的同步
/* If we are running in the context of a slave, return ASAP:
* the slave key expiration is controlled by the master that will
* send us synthesized DEL operations for expired keys.
*
* Still we try to return the right information to the caller,
* that is, 0 if we think the key should be still valid, 1 if
* we think the key is expired at this time. */
if (server.masterhost != NULL) return now > when;
// 运行到这里，表示键带有过期时间，并且服务器为主节点
/* Return when this key has not expired */
if (now <= when) return 0; // 如果未过期，返回 0
/* Delete the key */
server.stat_expiredkeys++; //redis server 结构体 /* Number of expired keys */
propagateExpire(db,key);
notifyKeyspaceEvent(REDIS_NOTIFY_EXPIRED,
"expired",key,db->id);
return dbDelete(db,key);
}