From: Willy Tarreau <w@1wt.eu>
Date: Tue, 16 Mar 2010 19:32:04 +0000 (+0100)
Subject: [OPTIM] checks: try to detect the end of response without polling again
X-Git-Tag: v1.4.2~8
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2c7ace07ad1ced87daefb82744b3d417dd606e85;p=thirdparty%2Fhaproxy.git

[OPTIM] checks: try to detect the end of response without polling again

Since the recv() call returns every time it succeeds, we always need
to calls with one intermediate poll before detecting the end of response :

  20:20:03.958207 recv(7, "HTTP/1.1 200\r\nConnection: close\r\n"..., 8030, 0) = 145
  20:20:03.958365 epoll_wait(3, {{EPOLLIN, {u32=7, u64=7}}}, 8, 1000) = 1
  20:20:03.958543 gettimeofday({1268767203, 958626}, NULL) = 0
  20:20:03.958694 recv(7, ""..., 7885, 0) = 0
  20:20:03.958833 shutdown(7, 2 /* send and receive */) = 0

Let's read as long as we can, that way we can detect end of connections
in the same call, which is much more efficient especially for LBs with
hundreds of servers :

  20:29:58.797019 recv(7, "HTTP/1.1 200\r\nConnection: close\r\n"..., 8030, 0) = 145
  20:29:58.797182 recv(7, ""..., 7885, 0) = 0
  20:29:58.797356 shutdown(7, 2 /* send and receive */) = 0
---

diff --git a/src/checks.c b/src/checks.c
index d885c7d882..eeed75af40 100644
--- a/src/checks.c
+++ b/src/checks.c
@@ -865,10 +865,6 @@ static int event_srv_chk_r(int fd)
 	struct task *t = fdtab[fd].owner;
 	struct server *s = t->context;
 	char *desc;
-	char *buffer;
-	int buffer_remaining;
-
-	len = -1;
 
 	if (unlikely((s->result & SRV_CHK_ERROR) ||
 		     (fdtab[fd].state == FD_STERROR) ||
@@ -889,13 +885,12 @@ static int event_srv_chk_r(int fd)
 	 * that there is free space remaining. If the buffer is full, proceed
 	 * with running the checks without attempting another socket read.
 	 */
-	buffer = s->check_data + s->check_data_len;
-	buffer_remaining = BUFSIZE - s->check_data_len;
 
-	if (buffer_remaining > 0)
-		len = recv(fd, buffer, buffer_remaining, 0);
-	else
-		len = 0;
+	for (len = 0; s->check_data_len < BUFSIZE; s->check_data_len += len) {
+		len = recv(fd, s->check_data + s->check_data_len, BUFSIZE - s->check_data_len, 0);
+		if (len <= 0)
+			break;
+	}
 
 	if (len < 0) {			/* recv returned an error */
 		if (errno == EAGAIN) {
@@ -908,19 +903,13 @@ static int event_srv_chk_r(int fd)
 			set_server_check_status(s, HCHK_STATUS_SOCKERR, NULL);
 		goto out_wakeup;
 	}
-	else if (len != 0)		/* recv hasn't seen end of connection */
-	{
-		s->check_data_len += len;
-		fdtab[fd].ev &= ~FD_POLL_IN;
-		return 0;
-	}
 
 	/* Full response received.
 	 * Terminate string in check_data buffer... */
 	if (s->check_data_len < BUFSIZE)
-		*buffer = '\0';
+		s->check_data[s->check_data_len] = '\0';
 	else
-		*(buffer - 1) = '\0';
+		s->check_data[s->check_data_len - 1] = '\0';
 
 	/* Close the connection... */
 	int shut = shutdown(fd, SHUT_RDWR);