1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/xpcom/threads/nsMemoryPressure.cpp Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,53 @@
1.4 +/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
1.5 +/* vim:set ts=2 sw=2 sts=2 et cindent: */
1.6 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.7 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.8 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.9 +
1.10 +#include "nsMemoryPressure.h"
1.11 +#include "mozilla/Assertions.h"
1.12 +#include "mozilla/Atomics.h"
1.13 +
1.14 +#include "nsThreadUtils.h"
1.15 +
1.16 +using namespace mozilla;
1.17 +
1.18 +static Atomic<int32_t, Relaxed> sMemoryPressurePending;
1.19 +static_assert(MemPressure_None == 0,
1.20 + "Bad static initialization with the default constructor.");
1.21 +
1.22 +MemoryPressureState
1.23 +NS_GetPendingMemoryPressure()
1.24 +{
1.25 + int32_t value = sMemoryPressurePending.exchange(MemPressure_None);
1.26 + return MemoryPressureState(value);
1.27 +}
1.28 +
1.29 +void
1.30 +NS_DispatchEventualMemoryPressure(MemoryPressureState state)
1.31 +{
1.32 + /*
1.33 + * A new memory pressure event erases an ongoing memory pressure, but an
1.34 + * existing "new" memory pressure event takes precedence over a new "ongoing"
1.35 + * memory pressure event.
1.36 + */
1.37 + switch (state) {
1.38 + case MemPressure_None:
1.39 + sMemoryPressurePending = MemPressure_None;
1.40 + break;
1.41 + case MemPressure_New:
1.42 + sMemoryPressurePending = MemPressure_New;
1.43 + break;
1.44 + case MemPressure_Ongoing:
1.45 + sMemoryPressurePending.compareExchange(MemPressure_None, MemPressure_Ongoing);
1.46 + break;
1.47 + }
1.48 +}
1.49 +
1.50 +nsresult
1.51 +NS_DispatchMemoryPressure(MemoryPressureState state)
1.52 +{
1.53 + NS_DispatchEventualMemoryPressure(state);
1.54 + nsCOMPtr<nsIRunnable> event = new nsRunnable;
1.55 + return NS_DispatchToMainThread(event);
1.56 +}
