be/src/olap/compaction_permit_limiter.h

// Licensed to the Apache Software Foundation (ASF) under one
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// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
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// software distributed under the License is distributed on an
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// under the License.

#pragma once

#include <stdint.h>

#include <atomic>
#include <condition_variable>
#include <mutex>

namespace doris {

/*
    This class is used to control compaction permission. To some extent, it can be used to control memory consumption.
    "permits" should be applied before a compaction task can execute. When the sum of "permites" held by executing
    compaction tasks reaches a threshold, subsequent compaction task will be no longer allowed, until some "permits"
    are released by some finished compaction tasks. "compaction score" for tablet is used as "permits" here.
*/
class CompactionPermitLimiter {
public:
    CompactionPermitLimiter();
    virtual ~CompactionPermitLimiter() {}

    void request(int64_t permits);

    void release(int64_t permits);

    int64_t usage() const { return _used_permits.load(std::memory_order_relaxed); }

private:
    // sum of "permits" held by executing compaction tasks currently
    std::atomic<int64_t> _used_permits;
    std::mutex _permits_mutex;
    std::condition_variable _permits_cv;
};
} // namespace doris