hal/fallback/FallbackAlarm.cpp

   1 /* This Source Code Form is subject to the terms of the Mozilla Public
   2  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
   3  * You can obtain one at http://mozilla.org/MPL/2.0/. */
   4
   5 #include "Hal.h"
   6
   7 #include <algorithm>
   8
   9 #include "mozilla/ClearOnShutdown.h"
  10 #include "mozilla/StaticPtr.h"
  11 #include "nsComponentManagerUtils.h"
  12 #include "nsITimer.h"
  13 #include "nsThreadUtils.h"
  14
  15 namespace mozilla {
  16 namespace hal_impl {
  17
  18 static void
  19 TimerCallbackFunc(nsITimer *aTimer, void *aClosure)
  20 {
  21   hal::NotifyAlarmFired();
  22 }
  23
  24 static StaticRefPtr<nsITimer> sTimer;
  25
  26 bool
  27 EnableAlarm()
  28 {
  29   static bool initialized = false;
  30   if (!initialized) {
  31     initialized = true;
  32     ClearOnShutdown(&sTimer);
  33   }
  34
  35   nsCOMPtr<nsITimer> timer = do_CreateInstance("@mozilla.org/timer;1");
  36   sTimer = timer;
  37   MOZ_ASSERT(sTimer);
  38   return true;
  39 }
  40
  41 void
  42 DisableAlarm()
  43 {
  44   /*
  45    * DisableAlarm() may be called after sTimer has been set to null by
  46    * ClearOnShutdown().
  47    */
  48   if (sTimer) {
  49     sTimer->Cancel();
  50   }
  51 }
  52
  53 bool
  54 SetAlarm(int32_t aSeconds, int32_t aNanoseconds)
  55 {
  56   if (!sTimer) {
  57     HAL_LOG(("We should have enabled the alarm"));
  58     MOZ_ASSERT(false);
  59     return false;
  60   }
  61
  62   // Do the math to convert aSeconds and aNanoseconds into milliseconds since
  63   // the epoch.
  64   int64_t milliseconds = static_cast<int64_t>(aSeconds) * 1000 +
  65                          static_cast<int64_t>(aNanoseconds) / 1000000;
  66
  67   // nsITimer expects relative milliseconds.
  68   int64_t relMilliseconds = milliseconds - PR_Now() / 1000;
  69
  70   // If the alarm time is in the past relative to PR_Now(),
  71   // we choose to immediately fire the alarm. Passing 0 means nsITimer will
  72   // queue a timeout event immediately.
  73   sTimer->InitWithFuncCallback(TimerCallbackFunc, nullptr,
  74                                clamped<int64_t>(relMilliseconds, 0, INT32_MAX),
  75                                nsITimer::TYPE_ONE_SHOT);
  76   return true;
  77 }
  78
  79 } // hal_impl
  80 } // namespace mozilla