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// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
#pragma once
#include <stdint.h>
#include <atomic>
#include <mutex>
#include "util/autovector.h"
namespace ROCKSDB_NAMESPACE {
class ColumnFamilyData;
// Similar to FlushScheduler, TrimHistoryScheduler is a FIFO queue that keeps
// track of column families whose flushed immutable memtables may need to be
// removed (aka trimmed). The actual trimming may be slightly delayed. Due to
// the use of the mutex and atomic variable, ScheduleWork,
// TakeNextColumnFamily, and, Empty can be called concurrently.
class TrimHistoryScheduler {
public:
TrimHistoryScheduler() : is_empty_(true) {}
// When a column family needs history trimming, add cfd to the FIFO queue
void ScheduleWork(ColumnFamilyData* cfd);
// Remove the column family from the queue, the caller is responsible for
// calling `MemtableList::TrimHistory`
ColumnFamilyData* TakeNextColumnFamily();
bool Empty();
void Clear();
// Not on critical path, use mutex to ensure thread safety
private:
std::atomic<bool> is_empty_;
autovector<ColumnFamilyData*> cfds_;
std::mutex checking_mutex_;
};
} // namespace ROCKSDB_NAMESPACE
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