redis源代码分析22–协议

static void addReply(redisClient *c, robj *obj) {
 if (listLength(c->reply) == 0 &&
 (c->replstate == REDIS_REPL_NONE ||
 c->replstate == REDIS_REPL_ONLINE) &&
 aeCreateFileEvent(server.el, c->fd, AE_WRITABLE,
 sendReplyToClient, c) == AE_ERR) return;
 if (server.vm_enabled && obj->storage != REDIS_VM_MEMORY) {
 obj = dupStringObject(obj);
 obj->refcount = 0; /* getDecodedObject() will increment the refcount */
 }
 listAddNodeTail(c->reply,getDecodedObject(obj));
}
static void sendReplyToClient(aeEventLoop *el, int fd, void *privdata, int mask) {
 redisClient *c = privdata;
 int nwritten = 0, totwritten = 0, objlen;
 robj *o;
 REDIS_NOTUSED(el);
 REDIS_NOTUSED(mask);
 /* Use writev() if we have enough buffers to send */
 if (!server.glueoutputbuf &&
 listLength(c->reply) > REDIS_WRITEV_THRESHOLD &&
 !(c->flags & REDIS_MASTER))
 {
 sendReplyToClientWritev(el, fd, privdata, mask);
 return;
 }
 while(listLength(c->reply)) {
 if (server.glueoutputbuf && listLength(c->reply) > 1)
 glueReplyBuffersIfNeeded(c);
 o = listNodeValue(listFirst(c->reply));
 objlen = sdslen(o->ptr);
 if (objlen == 0) {
 listDelNode(c->reply,listFirst(c->reply));
 continue;
 }
 if (c->flags & REDIS_MASTER) {
 /* Don't reply to a master */
 nwritten = objlen - c->sentlen;
 } else {
 nwritten = write(fd, ((char*)o->ptr)+c->sentlen, objlen - c->sentlen);
 if (nwritten <= 0) break;
 }
 c->sentlen += nwritten;
 totwritten += nwritten;
 /* If we fully sent the object on head go to the next one */
 if (c->sentlen == objlen) {
 listDelNode(c->reply,listFirst(c->reply));
 c->sentlen = 0;
 }
 /* Note that we avoid to send more thank REDIS_MAX_WRITE_PER_EVENT
 * bytes, in a single threaded server it's a good idea to serve
 * other clients as well, even if a very large request comes from
 * super fast link that is always able to accept data (in real world
 * scenario think about 'KEYS *' against the loopback interfae) */
 if (totwritten > REDIS_MAX_WRITE_PER_EVENT) break;
 }
 if (nwritten == -1) {
 if (errno == EAGAIN) {
 nwritten = 0;
 } else {
 redisLog(REDIS_VERBOSE,
 "Error writing to client: %s", strerror(errno));
 freeClient(c);
 return;
 }
 }
 if (totwritten > 0) c->lastinteraction = time(NULL);
 if (listLength(c->reply) == 0) {
 c->sentlen = 0;
 aeDeleteFileEvent(server.el,c->fd,AE_WRITABLE);
 }
}