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// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef FLUTTER_FML_SHARED_THREAD_MERGER_H_
#define FLUTTER_FML_SHARED_THREAD_MERGER_H_
#include <condition_variable>
#include <mutex>
#include "flutter/fml/macros.h"
#include "flutter/fml/memory/ref_counted.h"
#include "flutter/fml/message_loop_task_queues.h"
namespace fml {
class RasterThreadMerger;
typedef void* RasterThreadMergerId;
/// Instance of this class is shared between multiple |RasterThreadMerger|
/// instances, Most of the callings from |RasterThreadMerger| will be redirected
/// to this class with one more caller parameter.
class SharedThreadMerger
: public fml::RefCountedThreadSafe<SharedThreadMerger> {
public:
SharedThreadMerger(TaskQueueId owner, TaskQueueId subsumed);
// It's called by |RasterThreadMerger::MergeWithLease|.
// See the doc of |RasterThreadMerger::MergeWithLease|.
bool MergeWithLease(RasterThreadMergerId caller, size_t lease_term);
// It's called by |RasterThreadMerger::UnMergeNowIfLastOne|.
// See the doc of |RasterThreadMerger::UnMergeNowIfLastOne|.
bool UnMergeNowIfLastOne(RasterThreadMergerId caller);
// It's called by |RasterThreadMerger::ExtendLeaseTo|.
// See the doc of |RasterThreadMerger::ExtendLeaseTo|.
void ExtendLeaseTo(RasterThreadMergerId caller, size_t lease_term);
// It's called by |RasterThreadMerger::IsMergedUnSafe|.
// See the doc of |RasterThreadMerger::IsMergedUnSafe|.
bool IsMergedUnSafe() const;
// It's called by |RasterThreadMerger::IsEnabledUnSafe|.
// See the doc of |RasterThreadMerger::IsEnabledUnSafe|.
bool IsEnabledUnSafe() const;
// It's called by |RasterThreadMerger::Enable| or
// |RasterThreadMerger::Disable|.
void SetEnabledUnSafe(bool enabled);
// It's called by |RasterThreadMerger::DecrementLease|.
// See the doc of |RasterThreadMerger::DecrementLease|.
bool DecrementLease(RasterThreadMergerId caller);
private:
fml::TaskQueueId owner_;
fml::TaskQueueId subsumed_;
fml::MessageLoopTaskQueues* task_queues_;
std::mutex mutex_;
bool enabled_ = false;
/// The |MergeWithLease| or |ExtendLeaseTo| method will record the caller
/// into this lease_term_by_caller_ map, |UnMergeNowIfLastOne|
/// method will remove the caller from this lease_term_by_caller_.
std::map<RasterThreadMergerId, std::atomic_size_t> lease_term_by_caller_;
bool IsAllLeaseTermsZeroUnSafe() const;
bool UnMergeNowUnSafe();
FML_DISALLOW_COPY_AND_ASSIGN(SharedThreadMerger);
};
} // namespace fml
#endif // FLUTTER_FML_SHARED_THREAD_MERGER_H_