命令行使用管道（命令以换行符分隔）：
(printf "PING\r\nPING\r\nPING\r\n"; sleep 1) | nc localhost 6379
redis server 接收客户端的输入，调用栈如下：
ae.c/aeProcessEvents
networking.c/processInputBuffer
redis 中客户端的结构体：
typedef struct client {
// 输入缓冲区保存客户端发送的命令
sds querybuf;
// 字符串数组，要执行的命令，例如 PING
robj **argv;
// 记录 argv 长度
int argc;
} client;
分析管道命令的执行过程：按换行符 split 命令，分三次执行 PING 命令。
void processInputBuffer(client *c) {
server.current_client = c;
/* Keep processing while there is something in the input buffer */
// querybuf 的初始值是 "PING\r\nPING\r\nPING\r\n"
// 每经过一次 processInlineBuffer(c)，减少一个 PING
// "PING\r\nPING\r\nPING\r\n" -> "PING\r\nPING\r\n" -> "PING\r\n" -> ""
while(sdslen(c->querybuf)) {
/* Return if clients are paused. */
if (!(c->flags & CLIENT_SLAVE) && clientsArePaused()) break;
/* Immediately abort if the client is in the middle of something. */
if (c->flags & CLIENT_BLOCKED) break;
/* CLIENT_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).
*
* The same applies for clients we want to terminate ASAP. */
if (c->flags & (CLIENT_CLOSE_AFTER_REPLY|CLIENT_CLOSE_ASAP)) break;
/* Determine request type when unknown. */
// 普通命令以 * 开头，请求类型为 PROTO_REQ_MULTIBULK，管道命令类型为 PROTO_REQ_INLINE
if (!c->reqtype) {
if (c->querybuf[] == '*') {
c->reqtype = PROTO_REQ_MULTIBULK;
} else {
c->reqtype = PROTO_REQ_INLINE;
}
}
if (c->reqtype == PROTO_REQ_INLINE) {
if (processInlineBuffer(c) != C_OK) break;
} else if (c->reqtype == PROTO_REQ_MULTIBULK) {
if (processMultibulkBuffer(c) != C_OK) break;
} else {
serverPanic("Unknown request type");
}
/* Multibulk processing could see a <= 0 length. */
if (c->argc == ) {
resetClient(c);
} else {
/* Only reset the client when the command was executed. */
if (processCommand(c) == C_OK)
resetClient(c);
/* freeMemoryIfNeeded may flush slave output buffers. This may result
* into a slave, that may be the active client, to be freed. */
if (server.current_client == NULL) break;
}
}
server.current_client = NULL;
}
执行具体命令：
sever.c/processCommand
sever.c/call