Bug 762620 - Make daily timer callback resilient against Android misfiring. r=roc

widget/xpwidgets/nsIdleService.cpp

@@ -112,6 +112,9 @@ nsIdleServiceDaily::Observe(nsISupports *,
                       nowSec);
 #endif
 
+  // Note the moment we started our timer.
+  mDailyTimerStart  = PR_Now();
+
   // Start timer for the next check in one day.
   (void)mTimer->InitWithFuncCallback(DailyCallback,
                                      this,
@@ -153,6 +156,10 @@ nsIdleServiceDaily::Init()
 #ifdef ANDROID
     __android_log_print(ANDROID_LOG_INFO, "IdleService", "Setting timer a day from now");
 #endif
+
+    // Note the moment we started our timer.
+    mDailyTimerStart  = PR_Now();
+
     // Start timer for the next check in one day.
     (void)mTimer->InitWithFuncCallback(DailyCallback,
                                        this,
@@ -182,11 +189,40 @@ void
 nsIdleServiceDaily::DailyCallback(nsITimer* aTimer, void* aClosure)
 {
 #ifdef ANDROID
-  __android_log_print(ANDROID_LOG_INFO, "IdleService", "DailyCallback running, registering Idle observer");
+  __android_log_print(ANDROID_LOG_INFO, "IdleService", "DailyCallback running");
 #endif
 
   nsIdleServiceDaily* me = static_cast<nsIdleServiceDaily*>(aClosure);
 
+  PRTime now = PR_Now();
+  PRTime launchTime = me->mDailyTimerStart + ((PRTime)SECONDS_PER_DAY * PR_USEC_PER_SEC);
+
+  // Check if it has been a day since we launched this timer.
+  if (now < launchTime) {
+      // Timer returned early, reschedule.
+      PRTime newTime = launchTime;
+
+      // Add 10 ms to ensure we don't undershoot, and never get a "0" timer.
+      newTime += 10 * PR_USEC_PER_MSEC;
+
+#ifdef ANDROID
+      __android_log_print(ANDROID_LOG_INFO, "IdleService",
+                          "DailyCallback resetting timer to %lld msec",
+                          (newTime - now) / PR_USEC_PER_MSEC);
+#endif
+
+      // Refire the timer.
+      (void)me->mTimer->InitWithFuncCallback(DailyCallback,
+                                             me,
+                                             (newTime - now) / PR_USEC_PER_MSEC,
+                                             nsITimer::TYPE_ONE_SHOT);
+      return;
+  }
+
+#ifdef ANDROID
+  __android_log_print(ANDROID_LOG_INFO, "IdleService", "DailyCallback registering Idle observer");
+#endif
+
   // The one thing we do every day is to start waiting for the user to "have
   // a significant idle time".
   (void)me->mIdleService->AddIdleObserver(me,

widget/xpwidgets/nsIdleService.h

@@ -89,6 +89,12 @@ private:
    * Boolean set to true when daily idle notifications should be disabled.
    */
   bool mShutdownInProgress;
+
+  /**
+   * Real time we fired off the one-day timer, in case timers aren't
+   * very reliable.
+   */
+  PRTime mDailyTimerStart;
 };
 
 class nsIdleService : public nsIIdleServiceInternal