From: Christopher Faulet <cfaulet@haproxy.com>
Date: Tue, 8 Jul 2025 05:46:26 +0000 (+0200)
Subject: BUG/MEDIUM: http-client: Don't wake http-client applet if nothing was xferred
X-Git-Tag: v3.0.12~87
X-Git-Url: http://git.haproxy.org/?a=commitdiff_plain;h=c85b1408d222682d04fa7432904f248b4a66232f;p=haproxy-3.0.git

BUG/MEDIUM: http-client: Don't wake http-client applet if nothing was xferred

When data are transferred to or from the htt-pclient, the applet is
systematically woken up, even when no data are transferred. This could lead
to needlessly wakeups. When called from a lua script, if data are blocked
for a while, this leads to a wakeup ping-pong loop where the http-client
applet is woken up by the lua script which wakes back the script.

To fix the issue, in httpclient_req_xfer() and httpclient_res_xfer()
functions, we now take care to not wake the http-client applet up when no
data are transferred.

This patch must be backported as far as 2.6.

(cherry picked from commit fffdac42df4848420028f89b14c2a90c12dbf9ab)
Signed-off-by: Amaury Denoyelle <adenoyelle@haproxy.com>
(cherry picked from commit b35b0aaf82d625c8f78f734fb5b4c0deebd1697a)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 9dab53c6b7ba9928b61d68e5243930b1f72431f3)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
---

diff --git a/src/http_client.c b/src/http_client.c
index 04782a1..0591404 100644
--- a/src/http_client.c
+++ b/src/http_client.c
@@ -377,10 +377,11 @@ int httpclient_res_xfer(struct httpclient *hc, struct buffer *dst)
 	int ret;
 
 	ret = b_force_xfer(dst, &hc->res.buf, MIN(room, b_data(&hc->res.buf)));
+
 	/* call the client once we consumed all data */
 	if (!b_data(&hc->res.buf)) {
 		b_free(&hc->res.buf);
-		if (hc->appctx)
+		if (ret && hc->appctx)
 			appctx_wakeup(hc->appctx);
 	}
 	return ret;
@@ -409,11 +410,10 @@ int httpclient_req_xfer(struct httpclient *hc, struct ist src, int end)
 	if (!htx)
 		goto error;
 
-	if (hc->appctx)
-		appctx_wakeup(hc->appctx);
-
 	ret += htx_add_data(htx, src);
 
+	if (ret && hc->appctx)
+		appctx_wakeup(hc->appctx);
 
 	/* if we copied all the data and the end flag is set */
 	if ((istlen(src) == ret) && end) {