The Tor Browser: xpcom/threads/nsMemoryPressure.cpp@b8a032363ba2

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

     1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

     2 /* vim:set ts=2 sw=2 sts=2 et cindent: */

     3 /* This Source Code Form is subject to the terms of the Mozilla Public

     4  * License, v. 2.0. If a copy of the MPL was not distributed with this

     5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

     7 #include "nsMemoryPressure.h"

     8 #include "mozilla/Assertions.h"

     9 #include "mozilla/Atomics.h"

    11 #include "nsThreadUtils.h"

    13 using namespace mozilla;

    15 static Atomic<int32_t, Relaxed> sMemoryPressurePending;

    16 static_assert(MemPressure_None == 0,

    17               "Bad static initialization with the default constructor.");

    19 MemoryPressureState

    20 NS_GetPendingMemoryPressure()

    21 {

    22   int32_t value = sMemoryPressurePending.exchange(MemPressure_None);

    23   return MemoryPressureState(value);

    24 }

    26 void

    27 NS_DispatchEventualMemoryPressure(MemoryPressureState state)

    28 {

    29   /*

    30    * A new memory pressure event erases an ongoing memory pressure, but an

    31    * existing "new" memory pressure event takes precedence over a new "ongoing"

    32    * memory pressure event.

    33    */

    34   switch (state) {

    35     case MemPressure_None:

    36       sMemoryPressurePending = MemPressure_None;

    37       break;

    38     case MemPressure_New:

    39       sMemoryPressurePending = MemPressure_New;

    40       break;

    41     case MemPressure_Ongoing:

    42       sMemoryPressurePending.compareExchange(MemPressure_None, MemPressure_Ongoing);

    43       break;

    44   }

    45 }

    47 nsresult

    48 NS_DispatchMemoryPressure(MemoryPressureState state)

    49 {

    50   NS_DispatchEventualMemoryPressure(state);

    51   nsCOMPtr<nsIRunnable> event = new nsRunnable;

    52   return NS_DispatchToMainThread(event);

    53 }

The Tor Browser / file revision