core: Disable TCP_NOPUSH optimization on OSX. BZ 66019.

OSX supports TCP_NOPUSH but does not release the data retained (in TCP stack)
when the option is unset. It seems that unsetting it before the last write
does not help either so just disable the optimization for OSX in the core
output filter to avoid uncontrollable transmission delays.

* server/core_filters.c():
  Add the sock_nopush() helper that does nothing on OSX and platforms not
  supporting TCP_NOPUSH or TCP_CORK.

* server/core_filters.c(send_brigade_nonblocking):
  Use sock_nopush() instead of apr_socket_opt_set() for APR_TCP_NOPUSH option.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1900100 13f79535-47bb-0310-9956-ffa450edef68

diff --git a/changes-entries/osx_nopush.txt b/changes-entries/osx_nopush.txt
new file mode 100644 (file)
index 0000000..0e2e767
--- /dev/null
+++ b/changes-entries/osx_nopush.txt
@@ -0,0 +1,2 @@
+  *) core: Disable TCP_NOPUSH optimization on OSX since it might introduce
+     transmission delays.  PR 66019.  [Yann Ylavic]

diff --git a/server/core_filters.c b/server/core_filters.c
index c0275dc0de8aa7de1af33943f452c4ce5f86a335..0f7a093a3ae5ad6b24a152f0a0abfd84eafcc0b9 100644 (file)
--- a/server/core_filters.c
+++ b/server/core_filters.c
@@ -493,6 +493,18 @@ static void delete_meta_bucket(apr_bucket *bucket)
     apr_bucket_delete(bucket);
 }
 
+static APR_INLINE void sock_nopush(apr_socket_t *s, int to)
+{
+    /* Disable TCP_NOPUSH handling on OSX since unsetting it won't push
+     * retained data, which might introduce delays if further data don't
+     * come soon enough or cause the last chunk to be sent only when the
+     * connection is shutdown (e.g. after KeepAliveTimeout).
+     */
+#if APR_TCP_NOPUSH_FLAG && !defined(__APPLE__)
+    (void)apr_socket_opt_set(s, APR_TCP_NOPUSH, to);
+#endif
+}
+
 static apr_status_t send_brigade_nonblocking(apr_socket_t *s,
                                              apr_bucket_brigade *bb,
                                              core_output_ctx_t *ctx,
@@ -514,7 +526,7 @@ static apr_status_t send_brigade_nonblocking(apr_socket_t *s,
 #if APR_HAS_SENDFILE
         if (can_sendfile_bucket(bucket)) {
             if (nvec > 0) {
-                (void)apr_socket_opt_set(s, APR_TCP_NOPUSH, 1);
+                sock_nopush(s, 1);
                 rv = writev_nonblocking(s, bb, ctx, nbytes, nvec, c);
                 if (rv != APR_SUCCESS) {
                     goto cleanup;
@@ -544,7 +556,7 @@ static apr_status_t send_brigade_nonblocking(apr_socket_t *s,
                     nbytes = 0;
                     nvec = 0;
                 }
-                (void)apr_socket_opt_set(s, APR_TCP_NOPUSH, 0);
+                sock_nopush(s, 0);
 
                 rv = apr_bucket_read(bucket, &data, &length, APR_BLOCK_READ);
             }
@@ -572,7 +584,7 @@ static apr_status_t send_brigade_nonblocking(apr_socket_t *s,
         /* Make sure that these new data fit in our iovec. */
         if (nvec == ctx->nvec) {
             if (nvec == NVEC_MAX) {
-                (void)apr_socket_opt_set(s, APR_TCP_NOPUSH, 1);
+                sock_nopush(s, 1);
                 rv = writev_nonblocking(s, bb, ctx, nbytes, nvec, c);
                 if (rv != APR_SUCCESS) {
                     goto cleanup;
@@ -610,7 +622,7 @@ static apr_status_t send_brigade_nonblocking(apr_socket_t *s,
         if (nbytes > sconf->flush_max_threshold
                 && next != APR_BRIGADE_SENTINEL(bb)
                 && next->length && !is_in_memory_bucket(next)) {
-            (void)apr_socket_opt_set(s, APR_TCP_NOPUSH, 1);
+            sock_nopush(s, 1);
             rv = writev_nonblocking(s, bb, ctx, nbytes, nvec, c);
             if (rv != APR_SUCCESS) {
                 goto cleanup;
@@ -624,7 +636,7 @@ static apr_status_t send_brigade_nonblocking(apr_socket_t *s,
     }
 
 cleanup:
-    (void)apr_socket_opt_set(s, APR_TCP_NOPUSH, 0);
+    sock_nopush(s, 0);
     return rv;
 }