// 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 "load/memtable/memtable_flush_executor.h"

#include <gen_cpp/olap_file.pb.h>

#include <algorithm>

#include <cstddef>

#include <ostream>

#include "common/config.h"

#include "common/logging.h"

#include "common/metrics/doris_metrics.h"

#include "common/metrics/metrics.h"

#include "common/metrics/system_metrics.h"

#include "common/signal_handler.h"

#include "load/memtable/memtable.h"

#include "runtime/thread_context.h"

#include "storage/rowset/rowset_writer.h"

#include "storage/storage_engine.h"

#include "util/debug_points.h"

#include "util/pretty_printer.h"

#include "util/stopwatch.hpp"

#include "util/time.h"

namespace doris {

using namespace ErrorCode;

bvar::Adder<int64_t> g_flush_task_num("memtable_flush_task_num");

class MemtableFlushTask final : public Runnable {

    ENABLE_FACTORY_CREATOR(MemtableFlushTask);

public:

    MemtableFlushTask(std::shared_ptr<FlushToken> flush_token, std::shared_ptr<MemTable> memtable,

                      int32_t segment_id, int64_t submit_task_time)

            : _flush_token(flush_token),

              _memtable(memtable),

              _segment_id(segment_id),

              _submit_task_time(submit_task_time) {

        g_flush_task_num << 1;

    }

    ~MemtableFlushTask() override { g_flush_task_num << -1; }

    void run() override {

        auto token = _flush_token.lock();

        if (token) {

            token->_flush_memtable(_memtable, _segment_id, _submit_task_time);

        } else {

            LOG(WARNING) << "flush token is deconstructed, ignore the flush task";

        }

    }

private:

    std::weak_ptr<FlushToken> _flush_token;

    std::shared_ptr<MemTable> _memtable;

    int32_t _segment_id;

    int64_t _submit_task_time;

};

std::ostream& operator<<(std::ostream& os, const FlushStatistic& stat) {

    os << "(flush time(ms)=" << stat.flush_time_ns / NANOS_PER_MILLIS

       << ", flush wait time(ms)=" << stat.flush_wait_time_ns / NANOS_PER_MILLIS

       << ", flush submit count=" << stat.flush_submit_count

       << ", running flush count=" << stat.flush_running_count

       << ", finish flush count=" << stat.flush_finish_count

       << ", flush bytes: " << stat.flush_size_bytes

       << ", flush disk bytes: " << stat.flush_disk_size_bytes << ")";

    return os;

}

Status FlushToken::submit(std::shared_ptr<MemTable> mem_table) {

    {

        std::shared_lock rdlk(_flush_status_lock);

        DBUG_EXECUTE_IF("FlushToken.submit_flush_error", {

            _flush_status = Status::IOError<false>("dbug_be_memtable_submit_flush_error");

        });

        if (!_flush_status.ok()) {

            return _flush_status;

        }

    }

    if (mem_table == nullptr || mem_table->empty()) {

        return Status::OK();

    }

    int64_t submit_task_time = MonotonicNanos();

    auto task = MemtableFlushTask::create_shared(

            shared_from_this(), mem_table, _rowset_writer->allocate_segment_id(), submit_task_time);

    // NOTE: we should guarantee WorkloadGroup is not deconstructed when submit memtable flush task.

    // because currently WorkloadGroup's can only be destroyed when all queries in the group is finished,

    // but not consider whether load channel is finish.

    std::shared_ptr<WorkloadGroup> wg_sptr = _wg_wptr.lock();

    ThreadPool* wg_thread_pool = nullptr;

    if (wg_sptr) {

        wg_thread_pool = wg_sptr->get_memtable_flush_pool();

    }

    Status ret = wg_thread_pool ? wg_thread_pool->submit(std::move(task))

                                : _thread_pool->submit(std::move(task));

    if (ret.ok()) {

        // _wait_running_task_finish was executed after this function, so no need to notify _cond here

        _stats.flush_submit_count++;

    }

    return ret;

}

// NOTE: FlushToken's submit/cancel/wait run in one thread,

// so we don't need to make them mutually exclusive, std::atomic is enough.

void FlushToken::_wait_submit_task_finish() {

    std::unique_lock<std::mutex> lock(_mutex);

    _submit_task_finish_cond.wait(lock, [&]() { return _stats.flush_submit_count.load() == 0; });

}

void FlushToken::_wait_running_task_finish() {

    std::unique_lock<std::mutex> lock(_mutex);

    _running_task_finish_cond.wait(lock, [&]() { return _stats.flush_running_count.load() == 0; });

}

void FlushToken::cancel() {

    _shutdown_flush_token();

    _wait_running_task_finish();

}

Status FlushToken::wait() {

    _wait_submit_task_finish();

    {

        std::shared_lock rdlk(_flush_status_lock);

        if (!_flush_status.ok()) {

            return _flush_status;

        }

    }

    return Status::OK();

}

Status FlushToken::_try_reserve_memory(const std::shared_ptr<ResourceContext>& resource_context,

                                       int64_t size) {

    auto* thread_context = doris::thread_context();

    auto* memtable_flush_executor =

            ExecEnv::GetInstance()->storage_engine().memtable_flush_executor();

    Status st;

    int32_t max_waiting_time = config::memtable_wait_for_memory_sleep_time_s;

    do {

        // only try to reserve process memory

        st = thread_context->thread_mem_tracker_mgr->try_reserve(

                size, ThreadMemTrackerMgr::TryReserveChecker::CHECK_PROCESS);

        if (st.ok()) {

            memtable_flush_executor->inc_flushing_task();

            break;

        }

        if (_is_shutdown() || resource_context->task_controller()->is_cancelled()) {

            st = Status::Cancelled("flush memtable already cancelled");

            break;

        }

        // Make sure at least one memtable is flushing even reserve memory failed.

        if (memtable_flush_executor->check_and_inc_has_any_flushing_task()) {

            // If there are already any flushing task, Wait for some time and retry.

            LOG_EVERY_T(INFO, 60) << fmt::format(

                    "Failed to reserve memory {} for flush memtable, retry after 100ms",

                    PrettyPrinter::print_bytes(size));

            std::this_thread::sleep_for(std::chrono::seconds(1));

            max_waiting_time -= 1;

        } else {

            st = Status::OK();

            break;

        }

    } while (max_waiting_time > 0);

    return st;

}

Status FlushToken::_do_flush_memtable(MemTable* memtable, int32_t segment_id, int64_t* flush_size) {

    VLOG_CRITICAL << "begin to flush memtable for tablet: " << memtable->tablet_id()

                  << ", memsize: " << PrettyPrinter::print_bytes(memtable->memory_usage())

                  << ", rows: " << memtable->stat().raw_rows;

    memtable->update_mem_type(MemType::FLUSH);

    int64_t duration_ns = 0;

    {

        SCOPED_RAW_TIMER(&duration_ns);

        SCOPED_ATTACH_TASK(memtable->resource_ctx());

        SCOPED_SWITCH_THREAD_MEM_TRACKER_LIMITER(

                memtable->resource_ctx()->memory_context()->mem_tracker()->write_tracker());

        SCOPED_CONSUME_MEM_TRACKER(memtable->mem_tracker());

        // DEFER_RELEASE_RESERVED();

        // auto reserve_size = memtable->get_flush_reserve_memory_size();

        // if (memtable->resource_ctx()->task_controller()->is_enable_reserve_memory() &&

        //     reserve_size > 0) {

        //     RETURN_IF_ERROR(_try_reserve_memory(memtable->resource_ctx(), reserve_size));

        // }

        // Defer defer {[&]() {

        //     ExecEnv::GetInstance()->storage_engine().memtable_flush_executor()->dec_flushing_task();

        // }};

        std::unique_ptr<Block> block;

        RETURN_IF_ERROR(memtable->to_block(&block));

        RETURN_IF_ERROR(_rowset_writer->flush_memtable(block.get(), segment_id, flush_size));

        memtable->set_flush_success();

    }

    _memtable_stat += memtable->stat();

    DorisMetrics::instance()->memtable_flush_total->increment(1);

    DorisMetrics::instance()->memtable_flush_duration_us->increment(duration_ns / 1000);

    VLOG_CRITICAL << "after flush memtable for tablet: " << memtable->tablet_id()

                  << ", flushsize: " << PrettyPrinter::print_bytes(*flush_size);

    return Status::OK();

}

void FlushToken::_flush_memtable(std::shared_ptr<MemTable> memtable_ptr, int32_t segment_id,

                                 int64_t submit_task_time) {

    signal::set_signal_task_id(_rowset_writer->load_id());

    signal::tablet_id = memtable_ptr->tablet_id();

    // Count the task as running before registering the deferred cleanup so

    // cancel/shutdown paths keep flush_running_count symmetric on every exit.

    _stats.flush_running_count++;

    Defer defer {[&]() {

        std::lock_guard<std::mutex> lock(_mutex);

        _stats.flush_submit_count--;

        if (_stats.flush_submit_count == 0) {

            _submit_task_finish_cond.notify_one();

        }

        _stats.flush_running_count--;

        if (_stats.flush_running_count == 0) {

            _running_task_finish_cond.notify_one();

        }

    }};

    DBUG_EXECUTE_IF("FlushToken.flush_memtable.wait_before_first_shutdown",

                    { std::this_thread::sleep_for(std::chrono::milliseconds(10 * 1000)); });

    if (_is_shutdown()) {

        return;

    }

    DBUG_EXECUTE_IF("FlushToken.flush_memtable.wait_after_first_shutdown",

                    { std::this_thread::sleep_for(std::chrono::milliseconds(10 * 1000)); });

    // double check if shutdown to avoid wait running task finish count not accurate

    if (_is_shutdown()) {

        return;

    }

    DBUG_EXECUTE_IF("FlushToken.flush_memtable.wait_after_second_shutdown",

                    { std::this_thread::sleep_for(std::chrono::milliseconds(10 * 1000)); });

    uint64_t flush_wait_time_ns = MonotonicNanos() - submit_task_time;

    _stats.flush_wait_time_ns += flush_wait_time_ns;

    // If previous flush has failed, return directly

    {

        std::shared_lock rdlk(_flush_status_lock);

        if (!_flush_status.ok()) {

            return;

        }

    }

    MonotonicStopWatch timer;

    timer.start();

    size_t memory_usage = memtable_ptr->memory_usage();

    int64_t flush_size;

    Status s = _do_flush_memtable(memtable_ptr.get(), segment_id, &flush_size);

    {

        std::shared_lock rdlk(_flush_status_lock);

        if (!_flush_status.ok()) {

            return;

        }

    }

    if (!s.ok()) {

        std::lock_guard wrlk(_flush_status_lock);

        LOG(WARNING) << "Flush memtable failed with res = " << s

                     << ", load_id: " << print_id(_rowset_writer->load_id());

        _flush_status = s;

        return;

    }

    VLOG_CRITICAL << "flush memtable wait time: "

                  << PrettyPrinter::print(flush_wait_time_ns, TUnit::TIME_NS)

                  << ", flush memtable cost: "

                  << PrettyPrinter::print(timer.elapsed_time(), TUnit::TIME_NS)

                  << ", submit count: " << _stats.flush_submit_count

                  << ", running count: " << _stats.flush_running_count

                  << ", finish count: " << _stats.flush_finish_count

                  << ", mem size: " << PrettyPrinter::print_bytes(memory_usage)

                  << ", disk size: " << PrettyPrinter::print_bytes(flush_size);

    _stats.flush_time_ns += timer.elapsed_time();

    _stats.flush_finish_count++;

    _stats.flush_size_bytes += memtable_ptr->memory_usage();

    _stats.flush_disk_size_bytes += flush_size;

}

std::pair<int, int> MemTableFlushExecutor::calc_flush_thread_count(int num_cpus, int num_disk,

                                                                   int thread_num_per_store) {

    if (config::enable_adaptive_flush_threads && num_cpus > 0) {

        int min = std::max(1, (int)(num_cpus * config::min_flush_thread_num_per_cpu));

        int max = std::max(min, num_cpus * config::max_flush_thread_num_per_cpu);

        return {min, max};

    }

    int min = std::max(1, thread_num_per_store);

    int max = num_cpus == 0

                      ? num_disk * min

                      : std::min(num_disk * min, num_cpus * config::max_flush_thread_num_per_cpu);

    return {min, max};

}

void MemTableFlushExecutor::init(int num_disk) {

    _num_disk = std::max(1, num_disk);

    int num_cpus = std::thread::hardware_concurrency();

    auto [min_threads, max_threads] =

            calc_flush_thread_count(num_cpus, _num_disk, config::flush_thread_num_per_store);

    static_cast<void>(ThreadPoolBuilder("MemTableFlushThreadPool")

                              .set_min_threads(min_threads)

                              .set_max_threads(max_threads)

                              .build(&_flush_pool));

    auto [hi_min, hi_max] = calc_flush_thread_count(

            num_cpus, _num_disk, config::high_priority_flush_thread_num_per_store);

    static_cast<void>(ThreadPoolBuilder("MemTableHighPriorityFlushThreadPool")

                              .set_min_threads(hi_min)

                              .set_max_threads(hi_max)

                              .build(&_high_prio_flush_pool));

}

void MemTableFlushExecutor::update_memtable_flush_threads() {

    int num_cpus = std::thread::hardware_concurrency();

    auto [min_threads, max_threads] =

            calc_flush_thread_count(num_cpus, _num_disk, config::flush_thread_num_per_store);

    // Update max_threads first to avoid constraint violation when increasing min_threads

    static_cast<void>(_flush_pool->set_max_threads(max_threads));

    static_cast<void>(_flush_pool->set_min_threads(min_threads));

    auto [hi_min, hi_max] = calc_flush_thread_count(

            num_cpus, _num_disk, config::high_priority_flush_thread_num_per_store);

    // Update max_threads first to avoid constraint violation when increasing min_threads

    static_cast<void>(_high_prio_flush_pool->set_max_threads(hi_max));

    static_cast<void>(_high_prio_flush_pool->set_min_threads(hi_min));

}

// NOTE: we use SERIAL mode here to ensure all mem-tables from one tablet are flushed in order.

Status MemTableFlushExecutor::create_flush_token(std::shared_ptr<FlushToken>& flush_token,

                                                 std::shared_ptr<RowsetWriter> rowset_writer,

                                                 bool is_high_priority,

                                                 std::shared_ptr<WorkloadGroup> wg_sptr) {

    switch (rowset_writer->type()) {

    case ALPHA_ROWSET:

        // alpha rowset do not support flush in CONCURRENT.  and not support alpha rowset now.

        return Status::InternalError<false>("not support alpha rowset load now.");

    case BETA_ROWSET: {

        // beta rowset can be flush in CONCURRENT, because each memtable using a new segment writer.

        ThreadPool* pool = is_high_priority ? _high_prio_flush_pool.get() : _flush_pool.get();

        flush_token = FlushToken::create_shared(pool, wg_sptr);

        flush_token->set_rowset_writer(rowset_writer);

        return Status::OK();

    }

    default:

        return Status::InternalError<false>("unknown rowset type.");

    }

}

} // namespace doris