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/*
* Copyright (C) 2025 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. AND ITS CONTRIBUTORS ``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 ITS 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.
*/
#include "config.h"
#include "ResourceMonitorThrottler.h"
#include "Logging.h"
#include "ResourceMonitorPersistence.h"
#include <wtf/MainThread.h>
#include <wtf/Seconds.h>
#include <wtf/StdLibExtras.h>
#if ENABLE(CONTENT_EXTENSIONS)
#define RESOURCEMONITOR_RELEASE_LOG(fmt, ...) RELEASE_LOG(ResourceMonitoring, "ResourceMonitorThrottler::" fmt, ##__VA_ARGS__)
namespace WebCore {
ResourceMonitorThrottler::ResourceMonitorThrottler(String&& path, size_t count, Seconds duration, size_t maxHosts)
: m_config { count, duration, maxHosts }
{
ASSERT(!isMainThread());
ASSERT(maxHosts >= 1);
RESOURCEMONITOR_RELEASE_LOG("Throttler is launching, count=%zu, duration=%f, maxHosts=%zu", count, duration.value(), maxHosts);
RESOURCEMONITOR_RELEASE_LOG("Opening persistence for throttler.");
auto persistence = makeUnique<ResourceMonitorPersistence>();
if (!persistence->openDatabase(WTFMove(path))) {
RESOURCEMONITOR_RELEASE_LOG("Failed to setup persistence for throttler.");
return;
}
m_persistence = WTFMove(persistence);
RESOURCEMONITOR_RELEASE_LOG("Success to setup persistence for throttler.");
auto now = ContinuousApproximateTime::now();
m_persistence->deleteExpiredRecords(now, m_config.duration);
bool changed = false;
for (const auto& record : m_persistence->importRecords()) {
auto& throttler = throttlerForHost(record.host);
changed |= throttler.tryAccessAndUpdateHistory(record.time, m_config);
}
if (changed)
maintainHosts(now);
}
ResourceMonitorThrottler::~ResourceMonitorThrottler()
{
ASSERT(!isMainThread());
if (m_persistence) {
RESOURCEMONITOR_RELEASE_LOG("Closing persistence for throttler.");
m_persistence->deleteExpiredRecords(ContinuousApproximateTime::now(), m_config.duration);
m_persistence = nullptr;
}
}
auto ResourceMonitorThrottler::throttlerForHost(const String& host) -> AccessThrottler&
{
ASSERT(!isMainThread());
return m_throttlersByHost.ensure(host, [] {
return AccessThrottler { };
}).iterator->value;
}
void ResourceMonitorThrottler::removeOldestThrottler()
{
ASSERT(!isMainThread());
auto oldest = ContinuousApproximateTime::infinity();
String oldestKey;
for (auto it : m_throttlersByHost) {
auto time = it.value.newestAccessTime();
if (time < oldest) {
oldest = time;
oldestKey = it.key;
}
}
ASSERT(!oldestKey.isNull());
m_throttlersByHost.remove(oldestKey);
}
bool ResourceMonitorThrottler::tryAccess(const String& host, ContinuousApproximateTime time)
{
ASSERT(!isMainThread());
ASSERT(!host.isEmpty());
auto& throttler = throttlerForHost(host);
bool wasGranted = throttler.tryAccessAndUpdateHistory(time, m_config);
if (wasGranted) {
RESOURCEMONITOR_RELEASE_LOG("Throttler granted for unloading the resource for %" PUBLIC_LOG_STRING ".", host.utf8().data());
maintainHosts(time);
if (m_persistence)
m_persistence->recordAccess(host, time);
} else
RESOURCEMONITOR_RELEASE_LOG("Throttler denied for unloading the resource for %" PUBLIC_LOG_STRING ".", host.utf8().data());
return wasGranted;
}
void ResourceMonitorThrottler::clearAllData()
{
ASSERT(!isMainThread());
if (m_persistence)
m_persistence->deleteAllRecords();
}
void ResourceMonitorThrottler::maintainHosts(ContinuousApproximateTime time)
{
ASSERT(!isMainThread());
if (m_throttlersByHost.size() <= m_config.maxHosts)
return;
// Update and remove all expired access times. If no entry in throttler, remove it.
m_throttlersByHost.removeIf([&](auto& it) -> bool {
return it.value.tryExpire(time, m_config);
});
// If there are still too many hosts, then remove oldest one.
while (m_throttlersByHost.size() > m_config.maxHosts)
removeOldestThrottler();
ASSERT(m_throttlersByHost.size() <= m_config.maxHosts);
}
void ResourceMonitorThrottler::setCountPerDuration(size_t count, Seconds duration)
{
ASSERT(!isMainThread());
m_config.count = count;
m_config.duration = duration;
}
bool ResourceMonitorThrottler::AccessThrottler::tryAccessAndUpdateHistory(ContinuousApproximateTime time, const Config& config)
{
ASSERT(!isMainThread());
tryExpire(time, config);
if (m_accessTimes.size() >= config.count)
return false;
m_accessTimes.enqueue(time);
if (m_newestAccessTime < time)
m_newestAccessTime = time;
return true;
}
ContinuousApproximateTime ResourceMonitorThrottler::AccessThrottler::oldestAccessTime() const
{
ASSERT(!isMainThread());
return m_accessTimes.peek();
}
bool ResourceMonitorThrottler::AccessThrottler::tryExpire(ContinuousApproximateTime time, const Config& config)
{
ASSERT(!isMainThread());
auto expirationTime = time - config.duration;
while (!m_accessTimes.isEmpty()) {
if (oldestAccessTime() > expirationTime)
return false;
m_accessTimes.dequeue();
}
// Tell caller that the queue is empty.
return true;
}
} // namespace WebCore
#undef RESOURCEMONITOR_RELEASE_LOG
#endif
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