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* Copyright 2011 Google Inc.
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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* http://www.apache.org/licenses/LICENSE-2.0
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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// Author: jmaessen@google.com (Jan Maessen)
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#ifndef PAGESPEED_KERNEL_THREAD_SCHEDULER_BASED_ABSTRACT_LOCK_H_
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#define PAGESPEED_KERNEL_THREAD_SCHEDULER_BASED_ABSTRACT_LOCK_H_
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#include "pagespeed/kernel/base/basictypes.h"
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#include "pagespeed/kernel/base/named_lock_manager.h"
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namespace net_instaweb {
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// A SchedulerBasedAbstractLock implements a Lock by blocking using the
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// scheduler, using exponential sleep time backoff and polling the lock on
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// wakeup. The total time blocked on a long-held lock will be about 1.5 times
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// the time between the initial call to the lock routine attempt and the time
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// the lock is unlocked (ie we might wait for an extra amount of time equal to
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// half the time we were forced to wait).
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class SchedulerBasedAbstractLock : public NamedLock {
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virtual ~SchedulerBasedAbstractLock();
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virtual bool LockTimedWait(int64 wait_ms);
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virtual void LockTimedWait(int64 wait_ms, Function* callback);
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virtual bool LockTimedWaitStealOld(int64 wait_ms, int64 steal_ms);
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virtual void LockTimedWaitStealOld(
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int64 wait_ms, int64 steal_ms, Function* callback);
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virtual Scheduler* scheduler() const = 0;
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typedef bool (SchedulerBasedAbstractLock::*TryLockMethod)(int64 steal_ms);
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bool TryLockIgnoreSteal(int64 steal_ignored);
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bool BusySpin(TryLockMethod try_lock, int64 steal_ms);
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void PollAndCallback(TryLockMethod try_lock, int64 steal_ms,
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int64 wait_ms, Function* callback);
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} // namespace net_instaweb
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#endif // PAGESPEED_KERNEL_THREAD_SCHEDULER_BASED_ABSTRACT_LOCK_H_