// Licensed to the Apache Software Foundation (ASF) under one

// or more contributor license agreements.  See the NOTICE file

// 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

//

// Unless required by applicable law or agreed to in writing,

// software distributed under the License is distributed on an

// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY

// KIND, either express or implied.  See the License for the

// specific language governing permissions and limitations

// under the License.

#pragma once

#include <concurrentqueue.h>

#include <condition_variable>

#include <queue> // IWYU pragma: keep

#include "exec/sink/writer/result_writer.h"

#include "exprs/vexpr_fwd.h"

#include "runtime/runtime_profile.h"

namespace doris {

class ObjectPool;

class RowDescriptor;

class RuntimeState;

class TDataSink;

class TExpr;

class Dependency;

class PipelineTask;

class Block;

/*

 *  In the pipeline execution engine, there are usually a large number of io operations on the sink side that

 *  will block the limited execution threads of the pipeline execution engine, resulting in a sharp performance

 *  degradation of the pipeline execution engine when there are import tasks.

 *

 *  So all ResultWriter in Sink should use AsyncResultWriter to do the real IO task in thread pool to keep the

 *  pipeline execution engine performance.

 *

 *  The Sub class of AsyncResultWriter need to impl two virtual function

 *     * Status open() the first time IO work like: create file/ connect network

 *     * Status write() do the real IO work for block 

 */

class AsyncResultWriter : public ResultWriter {

public:

    AsyncResultWriter(const VExprContextSPtrs& output_expr_ctxs, std::shared_ptr<Dependency> dep,

                      std::shared_ptr<Dependency> fin_dep);

    void force_close(Status s);

    Status init(RuntimeState* state) override { return Status::OK(); }

    virtual Status open(RuntimeState* state, RuntimeProfile* operator_profile) = 0;

    // sink the block data to data queue, it is async

    Status sink(Block* block, bool eos);

    // Add the IO thread task process block() to thread pool to dispose the IO

    Status start_writer(RuntimeState* state, RuntimeProfile* operator_profile);

    Status get_writer_status() { return _writer_status.status(); }

    void set_low_memory_mode();

protected:

    Status _projection_block(Block& input_block, Block* output_block);

    const VExprContextSPtrs& _vec_output_expr_ctxs;

    RuntimeProfile* _operator_profile = nullptr; // not owned, set when open

    std::unique_ptr<Block> _get_free_block(Block*, size_t rows);

private:

    void process_block(RuntimeState* state, RuntimeProfile* operator_profile);

    [[nodiscard]] bool _data_queue_is_available() const { return _data_queue.size() < QUEUE_SIZE; }

    [[nodiscard]] bool _is_finished() const { return !_writer_status.ok() || _eos; }

    void _set_ready_to_finish();

    void _return_free_block(std::unique_ptr<Block>);

    std::unique_ptr<Block> _get_block_from_queue();

    static constexpr auto QUEUE_SIZE = 3;

    std::mutex _m;

    std::condition_variable _cv;

    std::deque<std::unique_ptr<Block>> _data_queue;

    // Default value is ok

    AtomicStatus _writer_status;

    bool _eos = false;

    std::atomic_bool _low_memory_mode = false;

    std::shared_ptr<Dependency> _dependency;

    std::shared_ptr<Dependency> _finish_dependency;

    moodycamel::ConcurrentQueue<std::unique_ptr<Block>> _free_blocks;

    RuntimeProfile::Counter* _memory_used_counter = nullptr;

};

} // namespace doris