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/*
* Copyright (C) 2011, 2012 Apple Inc. All Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#import "config.h"
#import "MemoryPressureHandler.h"
#import <WebCore/CSSValuePool.h>
#import <WebCore/GCController.h>
#import <WebCore/FontCache.h>
#import <WebCore/MemoryCache.h>
#import <WebCore/PageCache.h>
#import <WebCore/LayerPool.h>
#import <WebCore/ScrollingThread.h>
#import <WebCore/StorageThread.h>
#import <WebCore/WorkerThread.h>
#import <wtf/CurrentTime.h>
#import <wtf/FastMalloc.h>
#import <wtf/Functional.h>
#if !PLATFORM(IOS) && __MAC_OS_X_VERSION_MIN_REQUIRED >= 1070
#import "WebCoreSystemInterface.h"
#import <notify.h>
#endif
using std::max;
namespace WebCore {
#if PLATFORM(IOS) || __MAC_OS_X_VERSION_MIN_REQUIRED >= 1070
#if !PLATFORM(IOS)
static dispatch_source_t _cache_event_source = 0;
static dispatch_source_t _timer_event_source = 0;
static int _notifyToken;
// Disable memory event reception for a minimum of s_minimumHoldOffTime
// seconds after receiving an event. Don't let events fire any sooner than
// s_holdOffMultiplier times the last cleanup processing time. Effectively
// this is 1 / s_holdOffMultiplier percent of the time.
// These value seems reasonable and testing verifies that it throttles frequent
// low memory events, greatly reducing CPU usage.
static const unsigned s_minimumHoldOffTime = 5;
static const unsigned s_holdOffMultiplier = 20;
void MemoryPressureHandler::install()
{
if (m_installed || _timer_event_source)
return;
dispatch_async(dispatch_get_main_queue(), ^{
#if MAC_OS_X_VERSION_MIN_REQUIRED >= 1090
_cache_event_source = wkCreateMemoryStatusPressureCriticalDispatchOnMainQueue();
#else
_cache_event_source = wkCreateVMPressureDispatchOnMainQueue();
#endif
if (_cache_event_source) {
dispatch_set_context(_cache_event_source, this);
dispatch_source_set_event_handler(_cache_event_source, ^{ memoryPressureHandler().respondToMemoryPressure();});
dispatch_resume(_cache_event_source);
}
});
notify_register_dispatch("org.WebKit.lowMemory", &_notifyToken,
dispatch_get_main_queue(), ^(int) { memoryPressureHandler().respondToMemoryPressure();});
m_installed = true;
}
void MemoryPressureHandler::uninstall()
{
if (!m_installed)
return;
dispatch_async(dispatch_get_main_queue(), ^{
if (_cache_event_source) {
dispatch_source_cancel(_cache_event_source);
dispatch_release(_cache_event_source);
_cache_event_source = 0;
}
if (_timer_event_source) {
dispatch_source_cancel(_timer_event_source);
dispatch_release(_timer_event_source);
_timer_event_source = 0;
}
});
m_installed = false;
notify_cancel(_notifyToken);
}
void MemoryPressureHandler::holdOff(unsigned seconds)
{
dispatch_async(dispatch_get_main_queue(), ^{
_timer_event_source = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, dispatch_get_main_queue());
if (_timer_event_source) {
dispatch_set_context(_timer_event_source, this);
dispatch_source_set_timer(_timer_event_source, dispatch_time(DISPATCH_TIME_NOW, seconds * NSEC_PER_SEC), DISPATCH_TIME_FOREVER, 1 * s_minimumHoldOffTime);
dispatch_source_set_event_handler(_timer_event_source, ^{
if (_timer_event_source) {
dispatch_source_cancel(_timer_event_source);
dispatch_release(_timer_event_source);
_timer_event_source = 0;
}
memoryPressureHandler().install();
});
dispatch_resume(_timer_event_source);
}
});
}
void MemoryPressureHandler::respondToMemoryPressure()
{
uninstall();
double startTime = monotonicallyIncreasingTime();
m_lowMemoryHandler(false);
unsigned holdOffTime = (monotonicallyIncreasingTime() - startTime) * s_holdOffMultiplier;
holdOff(max(holdOffTime, s_minimumHoldOffTime));
}
#endif // !PLATFORM(IOS)
void MemoryPressureHandler::releaseMemory(bool)
{
int savedPageCacheCapacity = pageCache()->capacity();
pageCache()->setCapacity(0);
pageCache()->setCapacity(savedPageCacheCapacity);
NSURLCache *nsurlCache = [NSURLCache sharedURLCache];
NSUInteger savedNsurlCacheMemoryCapacity = [nsurlCache memoryCapacity];
[nsurlCache setMemoryCapacity:0];
[nsurlCache setMemoryCapacity:savedNsurlCacheMemoryCapacity];
fontCache()->purgeInactiveFontData();
memoryCache()->pruneToPercentage(0);
LayerPool::sharedPool()->drain();
cssValuePool().drain();
gcController().discardAllCompiledCode();
// FastMalloc has lock-free thread specific caches that can only be cleared from the thread itself.
StorageThread::releaseFastMallocFreeMemoryInAllThreads();
#if ENABLE(WORKERS)
WorkerThread::releaseFastMallocFreeMemoryInAllThreads();
#endif
#if ENABLE(THREADED_SCROLLING)
ScrollingThread::dispatch(bind(WTF::releaseFastMallocFreeMemory));
#endif
WTF::releaseFastMallocFreeMemory();
}
#endif
} // namespace WebCore
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