Apache w/FPM: workaround for pages hanging and becoming completely unresponsive.

Reported by Thoraxx.

And yeah, it would be better if users would reconfigure their fcgi proxy and
tweak apache conf with flushpackets=on but I think it is "too difficult" for
users. Ideally we would detect the condition and error or warn, but.. yeah...
if anyone has a better idea, or knows of a PHP trick to force flushpackets=on
at runtime, tell me :D

diff --git a/api/common_api.php b/api/common_api.php
index 0b0f924e9e691b8167cd99c5a9040737ae2740dd..ccb1442636ee4423865b82f20bbe67a8015ab7a6 100644 (file)
--- a/api/common_api.php
+++ b/api/common_api.php
@@ -9,6 +9,17 @@ if (!isset($_SESSION['id']))
 // Close the session now, otherwise other pages block
 session_write_close();
 
+// Apache w/FPM is shit because it doesn't have flushpackets=on
+// or not by default anyway, so we will fill up 4k buffers.
+// Yeah, really silly... I know.
+$fpm_workaround_needed = false;
+if (str_contains($_SERVER['SERVER_SOFTWARE'], 'Apache') &&
+    function_exists('fpm_get_status') &&
+    is_array(fpm_get_status()))
+{
+    $fpm_workaround_needed = true;
+}
+
 // Only now make the connection (this can take a short while)
 include "../inc/connection.php";
 
@@ -30,27 +41,37 @@ set_time_limit(0);
 ob_implicit_flush(1);
 
 // Flush and stop output buffering (eg fastcgi w/NGINX)
-while (1)
+function flush_completely()
 {
-       try {
-               $ret = @ob_end_flush();
-               if ($ret === false)
-                       break;
-       } catch(Exception $e)
+       while (1)
        {
-               break;
+               try {
+                       $ret = @ob_end_flush();
+                       if ($ret === false)
+                               break;
+               } catch(Exception $e)
+               {
+                       break;
+               }
        }
-};
+}
+
+flush_completely();
 
 /* Send server-sent events (SSE) message */
 function send_sse($json)
 {
-       echo "data: ".json_encode($json)."\n\n";
+       GLOBAL $fpm_workaround_needed;
+       $str = "data: ".json_encode($json)."\n\n";
+       if ($fpm_workaround_needed)
+               $str .= str_repeat(" ", 4096 - ((strlen($str)+1) % 4096))."\n";
+       echo $str;
 }
 
 function api_log_loop($sources)
 {
        GLOBAL $rpc;
+       GLOBAL $fpm_workaround_needed;
 
        $rpc->log()->subscribe($sources);
        if ($rpc->error)
@@ -68,7 +89,10 @@ function api_log_loop($sources)
                         * otherwise PHP may not
                         * notice when the webclient is gone.
                         */
-                       echo "\n";
+                       if ($fpm_workaround_needed)
+                               echo str_repeat(" ", 4095)."\n";
+                       else
+                               echo "\n";
                        continue;
                }
                send_sse($res);
@@ -114,7 +138,10 @@ function api_timer_loop(int $every_msec, string $method, array|null $params = nu
                         * otherwise PHP may not
                         * notice when the webclient is gone.
                         */
-                       echo "\n";
+                       if ($fpm_workaround_needed)
+                               echo str_repeat(" ", 4095)."\n";
+                       else
+                               echo "\n";
                        continue;
                }
                send_sse($res);