Hack around race condition in timers.

.vscode/settings.json

@@ -67,6 +67,7 @@
         "unordered_map": "cpp",
         "istream": "cpp",
         "thread": "cpp",
-        "utility": "cpp"
+        "utility": "cpp",
+        "streambuf": "cpp"
     }
 }

src/common/StaggeredLogger.cxx

@@ -43,7 +43,8 @@ StaggeredLogger::StaggeredLogger(const string& message, Logger logger)
     myMaxIntervalFactor(9),
     myCurrentIntervalFactor(1),
     myCooldownTime(1000),
-    myTimer(new TimerManager())
+    myTimer(new TimerManager()),
+    myTimerCallbackId(0)
 {
   if (logger) myLogger = logger;
 }
@@ -148,14 +149,16 @@ void StaggeredLogger::startInterval()
   myLastIntervalStartTimestamp = now;
 
   myTimer->clear(myTimerId);
-  myTimerId = myTimer->setTimeout(std::bind(&StaggeredLogger::onTimerExpired, this), myCurrentIntervalSize);
+  myTimerId = myTimer->setTimeout(std::bind(&StaggeredLogger::onTimerExpired, this, ++myTimerCallbackId), myCurrentIntervalSize);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void StaggeredLogger::onTimerExpired()
+void StaggeredLogger::onTimerExpired(uInt32 timerCallbackId)
 {
   std::lock_guard<std::mutex> lock(myMutex);
 
+  if (timerCallbackId != myTimerCallbackId) return;
+
   logLine();
 
   myIsCurrentlyCollecting = false;

src/common/StaggeredLogger.hxx

@@ -52,7 +52,7 @@ class StaggeredLogger {
 
     void _setLogger(Logger logger);
 
-    void onTimerExpired();
+    void onTimerExpired(uInt32 timerId);
 
     void startInterval();
 
@@ -83,6 +83,11 @@ class StaggeredLogger {
     // our destructor.
     TimerManager *myTimer;
     TimerManager::TimerId myTimerId;
+
+    // It is possible that the timer callback is running even after TimerManager::clear
+    // returns. This id is unique per timer and is used to return from the callback
+    // early in case the time is stale.
+    uInt32 myTimerCallbackId;
 };
 
 #endif // STAGGERED_LOGGER