rstatus_t
server_connect(struct context *ctx, struct server *server, struct conn *conn)
{
rstatus_t status;
struct server_pool *sp = server->owner;
ASSERT(!conn->client && !conn->proxy);
if (conn->err) {
ASSERT(conn->done && conn->sd < 0);
errno = conn->err;
return NC_ERROR;
}
if (conn->sd > 0) {
/* already connected on server connection */
return NC_OK;
}
log_debug(LOG_VVERB, "connect to server '%.*s'", server->pname.len,
server->pname.data);
conn->sd = socket(conn->family, SOCK_STREAM, 0);
if (conn->sd < 0) {
log_error("socket for server '%.*s' failed: %s", server->pname.len,
server->pname.data, strerror(errno));
status = NC_ERROR;
goto error;
}
status = nc_set_nonblocking(conn->sd);
if (status != NC_OK) {
log_error("set nonblock on s %d for server '%.*s' failed: %s",
conn->sd, server->pname.len, server->pname.data,
strerror(errno));
goto error;
}
if (server->pname.data[0] != '/') {
status = nc_set_tcpnodelay(conn->sd);
if (status != NC_OK) {
log_warn("set tcpnodelay on s %d for server '%.*s' failed, ignored: %s",
conn->sd, server->pname.len, server->pname.data,
strerror(errno));
}
}
status = event_add_conn(ctx->evb, conn);
if (status != NC_OK) {
log_error("event add conn s %d for server '%.*s' failed: %s",
conn->sd, server->pname.len, server->pname.data,
strerror(errno));
goto error;
}
ASSERT(!conn->connecting && !conn->connected);
status = connect(conn->sd, conn->addr, conn->addrlen);
if (status != NC_OK) {
if (errno == EINPROGRESS) {
conn->connecting = 1;
log_debug(LOG_INFO, "connecting on s %d to server '%.*s'",
conn->sd, server->pname.len, server->pname.data);
if (sp->tcpkeepalive) {
status = nc_set_tcpkeepalive(conn->sd, sp->tcpkeepidle,
sp->tcpkeepintvl, sp->tcpkeepcnt);
if (status != NC_OK) {
log_warn("set tcpkeepalive on s %d from pool %.*s failed, ignored: %s",
conn->sd, sp->name.len, sp->name.data, strerror(errno));
}
}
return NC_OK;
}
log_error("connect on s %d to server '%.*s' failed: %s", conn->sd,
server->pname.len, server->pname.data, strerror(errno));
goto error;
}
ASSERT(!conn->connecting);
conn->connected = 1;
log_debug(LOG_INFO, "connected on s %d to server '%.*s'", conn->sd,
server->pname.len, server->pname.data);
if (sp->tcpkeepalive) {
status = nc_set_tcpkeepalive(conn->sd, sp->tcpkeepidle,
sp->tcpkeepintvl, sp->tcpkeepcnt);
if (status != NC_OK) {
log_warn("set tcpkeepalive on s %d from pool %.*s failed, ignored: %s",
conn->sd, sp->name.len, sp->name.data, strerror(errno));
}
}
return NC_OK;
error:
conn->err = errno;
return status;
}
//接收到客户端连接后，返回新的fd，为该fd创建新的conn来读取数据
static rstatus_t
proxy_accept(struct context *ctx, struct conn *p) //p对应的是proxy conn 也就是用于监听客户端的conn信息
{
rstatus_t status;
struct conn *c;
int sd;
struct server_pool *pool = p->owner;
ASSERT(p->proxy && !p->client);
ASSERT(p->sd > 0);
ASSERT(p->recv_active && p->recv_ready);
for (;;) {
sd = accept(p->sd, NULL, NULL); //获取到新的客户端连接，产生新的fd
if (sd < 0) {
if (errno == EINTR) {
log_debug(LOG_VERB, "accept on p %d not ready - eintr", p->sd);
continue;
}
if (errno == EAGAIN || errno == EWOULDBLOCK || errno == ECONNABORTED) {
log_debug(LOG_VERB, "accept on p %d not ready - eagain", p->sd);
p->recv_ready = 0;
return NC_OK;
}
/*
* Workaround of https://github.com/twitter/twemproxy/issues/97
*
* We should never reach here because the check for conn_ncurr_cconn()
* against ctx->max_ncconn should catch this earlier in the cycle.
* If we reach here ignore EMFILE/ENFILE, return NC_OK will enable
* the server continue to run instead of close the server socket
*
* The right solution however, is on EMFILE/ENFILE to mask out IN
* event on the proxy and mask it back in when some existing
* connections gets closed
*/
if (errno == EMFILE || errno == ENFILE) {
log_debug(LOG_CRIT, "accept on p %d with max fds %"PRIu32" "
"used connections %"PRIu32" max client connections %"PRIu32" "
"curr client connections %"PRIu32" failed: %s",
p->sd, ctx->max_nfd, conn_ncurr_conn(),
ctx->max_ncconn, conn_ncurr_cconn(), strerror(errno));
p->recv_ready = 0;
return NC_OK;
}
log_error("accept on p %d failed: %s", p->sd, strerror(errno));
return NC_ERROR;
}
break;
}
if (conn_ncurr_cconn() >= ctx->max_ncconn) {
log_debug(LOG_CRIT, "client connections %"PRIu32" exceed limit %"PRIu32,
conn_ncurr_cconn(), ctx->max_ncconn);
status = close(sd);
if (status < 0) {
log_error("close c %d failed, ignored: %s", sd, strerror(errno));
}
return NC_OK;
}
c = conn_get(p->owner, true, p->redis);
if (c == NULL) {
log_error("get conn for c %d from p %d failed: %s", sd, p->sd,
strerror(errno));
status = close(sd);
if (status < 0) {
log_error("close c %d failed, ignored: %s", sd, strerror(errno));
}
return NC_ENOMEM;
}
c->sd = sd;
stats_pool_incr(ctx, c->owner, client_connections);
status = nc_set_nonblocking(c->sd);
if (status < 0) {
log_error("set nonblock on c %d from p %d failed: %s", c->sd, p->sd,
strerror(errno));
c->close(ctx, c);
return status;
}
if (pool->tcpkeepalive) {
status = nc_set_tcpkeepalive(c->sd);
if (status < 0) {
log_warn("set tcpkeepalive on c %d from p %d failed, ignored: %s",
c->sd, p->sd, strerror(errno));
}
}
if (p->family == AF_INET || p->family == AF_INET6) {
status = nc_set_tcpnodelay(c->sd);
if (status < 0) {
log_warn("set tcpnodelay on c %d from p %d failed, ignored: %s",
c->sd, p->sd, strerror(errno));
}
}
status = event_add_conn(ctx->evb, c);
if (status < 0) {
log_error("event add conn from p %d failed: %s", p->sd,
strerror(errno));
c->close(ctx, c);
return status;
}
log_debug(LOG_INFO, "accepted c %d on p %d from '%s'", c->sd, p->sd,
nc_unresolve_peer_desc(c->sd));
return NC_OK;
}
