// 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.

#include "exec/operator/data_queue.h"

#include <glog/logging.h>

#include <algorithm>

#include <utility>

#include "common/thread_safety_annotations.h"

#include "core/block/block.h"

#include "exec/pipeline/dependency.h"

#include "fmt/format.h"

namespace doris {

void SubQueue::try_pop(std::unique_ptr<Block>* output_block) {

    LockGuard l(queue_lock);

    if (!blocks.empty()) {

        *output_block = std::move(blocks.front());

        blocks.pop_front();

        bytes_in_queue -= (*output_block)->allocated_bytes();

        blocks_in_queue -= 1;

        if (blocks.empty()) {

            sink_dependency->set_ready();

        }

    }

}

bool SubQueue::try_push(std::unique_ptr<Block> block, std::atomic_uint32_t& total_counter) {

    LockGuard l(queue_lock);

    if (is_finished) {

        return false;

    }

    total_counter++;

    bytes_in_queue += block->allocated_bytes();

    blocks.emplace_back(std::move(block));

    blocks_in_queue += 1;

    if (static_cast<int64_t>(blocks.size()) > max_blocks_in_queue.load()) {

        sink_dependency->block();

    }

    return true;

}

bool SubQueue::mark_finished(std::atomic_uint32_t& unfinished_counter,

                             std::atomic_bool& all_finished) {

    LockGuard l(queue_lock);

    if (is_finished) {

        return false;

    }

    is_finished = true;

    if (unfinished_counter.fetch_sub(1) == 1) {

        all_finished = true;

    }

    return true;

}

void SubQueue::clear_blocks() {

    bool need_set_always_ready = false;

    {

        LockGuard l(queue_lock);

        if (!blocks.empty()) {

            blocks.clear();

            bytes_in_queue = 0;

            blocks_in_queue = 0;

            need_set_always_ready = true;

        }

    }

    // Notify outside of queue_lock to keep lock ordering simple.

    if (need_set_always_ready) {

        sink_dependency->set_always_ready();

    }

}

DataQueue::DataQueue(int child_count) : _sub_queues(child_count), _child_count(child_count) {

    for (auto& sub : _sub_queues) {

        sub = std::make_unique<SubQueue>();

    }

    _un_finished_counter = child_count;

}

bool DataQueue::has_more_data() const {

    return _cur_blocks_total_nums.load() > 0;

}

std::string DataQueue::debug_string() const {

    return fmt::format("(is_all_finish = {}, has_data = {})", is_all_finish(), has_more_data());

}

void DataQueue::set_source_dependency(std::shared_ptr<Dependency> source_dependency)

        NO_THREAD_SAFETY_ANALYSIS {

    _source_dependency = std::move(source_dependency);

}

void DataQueue::set_sink_dependency(Dependency* sink_dependency, int child_idx) {

    _sub_queues[child_idx]->sink_dependency = sink_dependency;

}

void DataQueue::set_max_blocks_in_sub_queue(int64_t max_blocks) {

    for (auto& sub : _sub_queues) {

        sub->max_blocks_in_queue = max_blocks;

    }

}

void DataQueue::set_low_memory_mode() {

    _is_low_memory_mode = true;

    for (auto& sub : _sub_queues) {

        sub->max_blocks_in_queue = 1;

    }

    clear_free_blocks();

}

std::unique_ptr<Block> DataQueue::get_free_block(int child_idx) {

    auto& sub = *_sub_queues[child_idx];

    {

        LockGuard l(sub.free_lock);

        if (!sub.free_blocks.empty()) {

            auto block = std::move(sub.free_blocks.front());

            sub.free_blocks.pop_front();

            return block;

        }

    }

    return Block::create_unique();

}

void DataQueue::push_free_block(DataQueueBlock&& queue_block) {

    if (!queue_block.block) {

        return;

    }

    DCHECK(queue_block.block->rows() == 0);

    if (!_is_low_memory_mode) {

        auto& sub = *_sub_queues[queue_block.child_idx];

        LockGuard l(sub.free_lock);

        sub.free_blocks.emplace_back(std::move(queue_block.block));

    }

}

void DataQueue::clear_free_blocks() {

    for (auto& sub : _sub_queues) {

        LockGuard l(sub->free_lock);

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

        sub->free_blocks.swap(tmp_queue);

    }

}

void DataQueue::terminate() {

    for (int i = 0; i < _child_count; ++i) {

        mark_finish(i);

        _sub_queues[i]->clear_blocks();

    }

    _cur_blocks_total_nums = 0;

    clear_free_blocks();

    set_source_always_ready();

}

Result<DataQueueBlock> DataQueue::get_block_from_queue() {

    DataQueueBlock result;

    const int start_idx = (_flag_queue_idx + 1) % _child_count;

    for (int offset = 0; offset < _child_count; ++offset) {

        const int idx = (start_idx + offset) % _child_count;

        if (_sub_queues[idx]->blocks_in_queue.load() == 0) {

            continue;

        }

        auto& sub = *_sub_queues[idx];

        sub.try_pop(&result.block);

        if (!result.block) {

            continue;

        }

        result.child_idx = idx;

        _flag_queue_idx = idx;

        auto old_total = _cur_blocks_total_nums.fetch_sub(1);

        if (old_total == 1) {

            set_source_block();

        }

        break;

    }

    // A producer enqueues its final block before marking the child finished. Observe completion

    // first, then recheck queued data to avoid reporting EOS while the final block is still queued.

    result.eos = is_all_finish() && !has_more_data();

    return result;

}

Status DataQueue::push_block(std::unique_ptr<Block> block, int child_idx, bool eos) {

    DCHECK(block || eos);

    if (!block && !eos) {

        return Status::OK();

    }

    if (block) {

        auto& sub = *_sub_queues[child_idx];

        // total_counter is incremented inside try_push under queue_lock, only when the

        // block is actually enqueued. This ensures get_block_from_queue() always observes

        // _cur_blocks_total_nums >= 1 when it successfully pops a block, with no risk of

        // underflow or the need for a rollback on failure.

        if (!sub.try_push(std::move(block), _cur_blocks_total_nums)) {

            return Status::EndOfFile("SubQueue already finished");

        }

    }

    if (eos) {

        mark_finish(child_idx);

    }

    set_source_ready();

    return Status::OK();

}

void DataQueue::mark_finish(int child_idx) {

    auto& sub = *_sub_queues[child_idx];

    if (!sub.mark_finished(_un_finished_counter, _is_all_finished)) {

        return;

    }

}

bool DataQueue::is_all_finish() const {

    return _is_all_finished;

}

void DataQueue::set_source_ready() {

    LockGuard lc(_source_lock);

    if (_source_dependency) {

        _source_dependency->set_ready();

    }

}

void DataQueue::set_source_always_ready() {

    LockGuard lc(_source_lock);

    if (_source_dependency) {

        _source_dependency->set_always_ready();

    }

}

void DataQueue::set_source_block() {

    // Re-check under _source_lock to avoid blocking the source when a concurrent push

    // has already added new blocks (or all children have finished) since we observed

    // the counter drop to zero.

    LockGuard lc(_source_lock);

    if (_source_dependency && _cur_blocks_total_nums == 0 && !is_all_finish()) {

        _source_dependency->block();

    }

}

} // namespace doris