The Tor Browser: xpcom/threads/nsMemoryPressure.h@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 #ifndef nsMemoryPressure_h__

     8 #define nsMemoryPressure_h__

    10 #include "nscore.h"

    12 enum MemoryPressureState {

    13   /*

    14    * No memory pressure.

    15    */

    16   MemPressure_None = 0,

    18   /*

    19    * New memory pressure deteced.

    20    *

    21    * On a new memory pressure, we stop everything to start cleaning

    22    * aggresively the memory used, in order to free as much memory as

    23    * possible.

    24    */

    25   MemPressure_New,

    27   /*

    28    * Repeated memory pressure.

    29    *

    30    * A repeated memory pressure implies to clean softly recent allocations.

    31    * It is supposed to happen after a new memory pressure which already

    32    * cleaned aggressivley.  So there is no need to damage the reactivity of

    33    * Gecko by stopping the world again.

    34    *

    35    * In case of conflict with an new memory pressue, the new memory pressure

    36    * takes precedence over an ongoing memory pressure.  The reason being

    37    * that if no events are processed between 2 notifications (new followed

    38    * by ongoing, or ongoing followed by a new) we want to be as aggresive as

    39    * possible on the clean-up of the memory.  After all, we are trying to

    40    * keep Gecko alive as long as possible.

    41    */

    42   MemPressure_Ongoing

    43 };

    45 /**

    46  * Return and erase the latest state of the memory pressure event set by any of

    47  * the corresponding dispatch function.

    48  */

    49 MemoryPressureState

    50 NS_GetPendingMemoryPressure();

    52 /**

    53  * This function causes the main thread to fire a memory pressure event

    54  * before processing the next event, but if there are no events pending in

    55  * the main thread's event queue, the memory pressure event would not be

    56  * dispatched until one is enqueued. It is infallible and does not allocate

    57  * any memory.

    58  *

    59  * You may call this function from any thread.

    60  */

    61 void

    62 NS_DispatchEventualMemoryPressure(MemoryPressureState state);

    64 /**

    65  * This function causes the main thread to fire a memory pressure event

    66  * before processing the next event. We wake up the main thread by adding a

    67  * dummy event to its event loop, so, unlike with

    68  * NS_DispatchEventualMemoryPressure, this memory-pressure event is always

    69  * fired relatively quickly, even if the event loop is otherwise empty.

    70  *

    71  * You may call this function from any thread.

    72  */

    73 nsresult

    74 NS_DispatchMemoryPressure(MemoryPressureState state);

    76 #endif // nsMemoryPressure_h__

The Tor Browser / file revision