commit 4e490f752d7057127c230a64c9376c92d41e0c07
author Maxim Dounin <mdounin@mdounin.ru> Thu Feb 11 21:52:09 2021 +0300
committer Maxim Dounin <mdounin@mdounin.ru> Thu Feb 11 21:52:09 2021 +0300
tree d52fd9885ae461bca64cc3f51452e76d6ad6f77f
parent 6dec7b4df8824756407d5b3f37b11e5694075124

Reuse of connections in lingering close.

This is particularly important in HTTP/2, where keepalive connections
are closed with lingering.  Before the patch, reusing a keepalive HTTP/2
connection resulted in the connection waiting for lingering close to
remain in the reusable connections queue, preventing ngx_drain_connections()
from closing additional connections.

The patch fixes it by marking the connection reusable again, and so
moving it in the reusable connections queue.  Further, it makes actually
possible to reuse such connections if needed.

src/http/ngx_http_request.c

diff --git a/src/http/ngx_http_request.c b/src/http/ngx_http_request.c
index 68d81e9..d129f80 100644
--- a/src/http/ngx_http_request.c
+++ b/src/http/ngx_http_request.c
@@ -3437,6 +3437,9 @@
         return;
     }
 
+    c->close = 0;
+    ngx_reusable_connection(c, 1);
+
     ngx_add_timer(rev, clcf->lingering_timeout);
 
     if (rev->ready) {
@@ -3461,7 +3464,7 @@
     ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0,
                    "http lingering close handler");
 
-    if (rev->timedout) {
+    if (rev->timedout || c->close) {
         ngx_http_close_request(r, 0);
         return;
     }

src/http/v2/ngx_http_v2.c

diff --git a/src/http/v2/ngx_http_v2.c b/src/http/v2/ngx_http_v2.c
index 7c1ba59..2af3ef7 100644
--- a/src/http/v2/ngx_http_v2.c
+++ b/src/http/v2/ngx_http_v2.c
@@ -767,6 +767,9 @@
         return;
     }
 
+    c->close = 0;
+    ngx_reusable_connection(c, 1);
+
     ngx_add_timer(rev, clcf->lingering_timeout);
 
     if (rev->ready) {
@@ -791,7 +794,7 @@
     ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0,
                    "http2 lingering close handler");
 
-    if (rev->timedout) {
+    if (rev->timedout || c->close) {
         ngx_http_close_connection(c);
         return;
     }