->flags & REDIS_MASTER) c->reploff += nread;
} else {
server.current_client = NULL;
return;
}
//客户端请求的字符串长度大于服务器最大的请求长度值
if (sdslen(c->querybuf) > server.client_max_querybuf_len) {
sds ci = getClientInfoString(c), bytes = sdsempty();
bytes = sdscatrepr(bytes,c->querybuf,64);
redisLog(REDIS_WARNING,"Closing client that reached max query buffer length: %s (qbuf initial bytes: %s)", ci, bytes);
sdsfree(ci);
sdsfree(bytes);
freeClient(c);
return;
}
//解析请求
processInputBuffer(c);
server.current_client = NULL;
}
processInputBuffer函数主要用来处理请求的解析工作，redis有两种解析方式；行指令解析与多重指令解析，行指令解析直接忽略，下面详解多重指令解析。
void processInputBuffer(redisClient *c) {
/* Keep processing while there is something in the input buffer */
while(sdslen(c->querybuf)) {
/* Immediately abort if the client is in the middle of something. */
if (c->flags & REDIS_BLOCKED) return;
/* REDIS_CLOSE_AFTER_REPLY closes the connection once the reply is
* written to the client. Make sure to not let the reply grow after
* this flag has been set (i.e. don't process more commands). */
if (c->flags & REDIS_CLOSE_AFTER_REPLY) return;
/* Determine request type when unknown. */
//当请求类型未知时，先确定属于哪种请求
if (!c->reqtype) {
if (c->querybuf[0] == '*') {
c->reqtype = REDIS_REQ_MULTIBULK;//多重指令解析
} else {
c->reqtype = REDIS_REQ_INLINE;//按行解析
}
}
if (c->reqtype == REDIS_REQ_INLINE) {
if (processInlineBuffer(c) != REDIS_OK) break;
} else if (c->reqtype == REDIS_REQ_MULTIBULK) {
if (processMultibulkBuffer(c) != REDIS_OK) break;
} else {
redisPanic("Unknown request type");
}
/* Multibulk processing could see a <= 0 length. */
if (c->argc == 0) {
resetClient(c);
} else {
/* Only reset the client when the command was executed. */
//执行相应指令
if (processCommand(c) == REDIS_OK)
resetClient(c);
}
}
}
多重指令解析的处理函数为processMultibulkBuffer，下面先简单介绍下Redis的通讯协议：
以下是这个协议的一般形式：
*< 参数数量 > CR LF
$< 参数 1 的字节数量 > CR LF
< 参数 1 的数据 > CR LF
...
$< 参数 N 的字节数量 > CR LF
< 参数 N 的数据 > CR LF
举个例子，以下是一个命令协议的打印版本：
*3
$3
SET
$3
foo
$3
bar
这个命令的实际协议值如下：
"*3\r\n$3\r\nSET\r\n$3\r\foo\r\n$3\r\bar\r\n"
/**
例：querybuf = "*3\r\n$3\r\nSET\r\n$3\r\nfoo\r\n$3\r\nbar\r\n"
*/
int processMultibulkBuffer(redisClient *c) {
char *newline = NULL;
int pos = 0, ok;
long long ll;
if (c->multibulklen == 0) {//参数数目为0，表示这是新的请求指令
/* The client should have been reset */
redisAssertWithInfo(c,NULL,c->argc == 0);
/* Multi bulk length cannot be read without a \r\n */
newline = strchr(c->querybuf,'\r');
if (newline == NULL) {
if (sdslen(c->querybuf) > REDIS_INLINE_MAX_SIZE) {
addReplyError(c,"Protocol error: too big mbulk count string");
setProtocolError(c,0);
}
return REDIS_ERR;
}
/* Buffer should also contain \n */
if (newline-(c->querybuf) > ((signed)sdslen(c->querybuf)-2))
return REDIS_ERR;
/* We know for sure there is a whole line since newline != NULL,
* so go ahead and find out the multi bulk length. */
redisAssertWithInfo(c,NULL,c->querybuf[0] == '*');
//将字符串转为long long整数，转换得到的结果存到ll中,ll就是后面参数的个数
ok = string2ll(c->querybuf+1,newline-(c->querybuf+1),&ll);
if (!ok || ll > 1024*1024) {
addReplyError(c,"Protocol error: invalid multibulk length");
setProtocolError(c,pos);
return REDIS_ERR;
}
pos = (newline-c->querybuf)+2;//跳过\r\n
if (ll <= 0) {//参数个数小于0，表示后面的参数数目大于等于绝对值ll
/** s = sdsnew("Hello World");
* sdsrange(s,1,-1); => "ello World"
*/
sdsrange(c->querybuf,pos,-1);//querybuf="$3\r\nSET\r\n$3\r\nfoo\r\n$3