Restore the log depth counter when an aborted logging cycle returns early (#2072)

The infinite loop guard in Logger::addRecord() incremented the depth
counter and then returned before the try/finally that decrements it.
Every aborted cycle therefore left the counter raised: after the first
one it stayed at 3, the next nested record pushed it to 5, and from then
on the logger silently dropped every record for the rest of the process.

Long-running workers are hit hardest. Legitimate nesting (e.g. a handler
whose synchronous HTTP call runs the shared Guzzle promise queue, which
in turn runs callbacks that log) trips the guard once, and the process
never logs again until it is restarted.

Moving the guard inside the try block makes the early returns run the
same finally as every other exit.

Author: dada-amater

src/Monolog/Logger.php

@@ -353,15 +353,15 @@ public function addRecord(int|Level $level, string $message, array $context = []
             $logDepth = 0;
         }
 
-        if ($logDepth === 3) {
-            $this->warning('A possible infinite logging loop was detected and aborted. It appears some of your handler code is triggering logging, see the previous log record for a hint as to what may be the cause.');
+        try {
+            if ($logDepth === 3) {
+                $this->warning('A possible infinite logging loop was detected and aborted. It appears some of your handler code is triggering logging, see the previous log record for a hint as to what may be the cause.');
 
-            return false;
-        } elseif ($logDepth >= 5) { // log depth 4 is let through, so we can log the warning above
-            return false;
-        }
+                return false;
+            } elseif ($logDepth >= 5) { // log depth 4 is let through, so we can log the warning above
+                return false;
+            }
 
-        try {
             $recordInitialized = \count($this->processors) === 0;
 
             $record = new LogRecord(

tests/Monolog/LoggerTest.php

@@ -1052,6 +1052,20 @@ public function testLogCycleDetectionWithFibersWithCycle()
 
         self::assertCount(3, $testHandler->getRecords());
     }
+
+    public function testLogCycleDetectionRecoversAfterAbortedCycle()
+    {
+        $logger = new Logger(__METHOD__);
+
+        $logger->pushHandler(new LoggingHandler($logger));
+        $logger->pushHandler($testHandler = new TestHandler());
+
+        // an aborted cycle must not leave the depth counter raised, or the logger goes silent for good
+        $logger->info('first');
+        $logger->info('second');
+
+        self::assertCount(6, $testHandler->getRecords());
+    }
 }
 
 class LoggingHandler implements HandlerInterface