From 1dd37ea37debc148020e505b9add3dd5e4b47b89 Mon Sep 17 00:00:00 2001
From: Randell Jesup <rjesup@jesup.org>
Date: Tue, 8 Sep 2015 11:34:09 -0400
Subject: [PATCH] Bug 1197152: Alternative to remove all sleep/wake
 functionality from Timers r=froydnj CLOSED TREE

---
 xpcom/threads/TimerThread.cpp | 25 +++----------------------
 xpcom/threads/TimerThread.h   |  1 -
 2 files changed, 3 insertions(+), 23 deletions(-)

diff --git a/xpcom/threads/TimerThread.cpp b/xpcom/threads/TimerThread.cpp
index 65135a5929a..3225384c280 100644
--- a/xpcom/threads/TimerThread.cpp
+++ b/xpcom/threads/TimerThread.cpp
@@ -31,8 +31,7 @@ TimerThread::TimerThread() :
   mShutdown(false),
   mWaiting(false),
   mNotified(false),
-  mSleeping(false),
-  mLastTimerEventLoopRun(TimeStamp::Now())
+  mSleeping(false)
 {
 }
 
@@ -441,7 +440,6 @@ TimerThread::Run()
     } else {
       waitFor = PR_INTERVAL_NO_TIMEOUT;
       TimeStamp now = TimeStamp::Now();
-      mLastTimerEventLoopRun = now;
       nsTimerImpl* timer = nullptr;
 
       if (!mTimers.IsEmpty()) {
@@ -747,7 +745,6 @@ TimerThread::DoBeforeSleep()
 {
   // Mainthread
   MonitorAutoLock lock(mMonitor);
-  mLastTimerEventLoopRun = TimeStamp::Now();
   mSleeping = true;
 }
 
@@ -756,27 +753,11 @@ void
 TimerThread::DoAfterSleep()
 {
   // Mainthread
-  TimeStamp now = TimeStamp::Now();
-
   MonitorAutoLock lock(mMonitor);
-
-  // an over-estimate of time slept, usually small
-  TimeDuration slept = now - mLastTimerEventLoopRun;
-
-  // Adjust all old timers to expire roughly similar times in the future
-  // compared to when we went to sleep, by adding the time we slept to the
-  // target time. It's slightly possible a few will end up slightly in the
-  // past and fire immediately, but ordering should be preserved.  All
-  // timers retain the exact same order (and relative times) as before
-  // going to sleep.
-  for (uint32_t i = 0; i < mTimers.Length(); i ++) {
-    nsTimerImpl* timer = mTimers[i];
-    timer->mTimeout += slept;
-  }
   mSleeping = false;
-  mLastTimerEventLoopRun = now;
 
-  // Wake up the timer thread to process the updated array
+  // Wake up the timer thread to re-process the array to ensure the sleep delay is correct,
+  // and fire any expired timers (perhaps quite a few)
   mNotified = true;
   mMonitor.Notify();
 }
diff --git a/xpcom/threads/TimerThread.h b/xpcom/threads/TimerThread.h
index 63caeaca2d9..7d18a4c6ee1 100644
--- a/xpcom/threads/TimerThread.h
+++ b/xpcom/threads/TimerThread.h
@@ -77,7 +77,6 @@ private:
   bool mWaiting;
   bool mNotified;
   bool mSleeping;
-  TimeStamp mLastTimerEventLoopRun;
 
   nsTArray<nsTimerImpl*> mTimers;
 };