// 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 "runtime/load_channel_mgr.h"

#include <fmt/format.h>
#include <gen_cpp/internal_service.pb.h>

#include <algorithm>
// IWYU pragma: no_include <bits/chrono.h>
#include <chrono> // IWYU pragma: keep
#include <ctime>
#include <functional>
#include <map>
#include <memory>
#include <ostream>
#include <queue>
#include <string>
#include <tuple>
#include <vector>

#include "common/config.h"
#include "common/logging.h"
#include "runtime/exec_env.h"
#include "runtime/load_channel.h"
#include "runtime/memory/mem_tracker.h"
#include "util/doris_metrics.h"
#include "util/mem_info.h"
#include "util/metrics.h"
#include "util/perf_counters.h"
#include "util/pretty_printer.h"
#include "util/thread.h"

namespace doris {

#ifndef BE_TEST
constexpr uint32_t START_BG_INTERVAL = 60;
#else
constexpr uint32_t START_BG_INTERVAL = 1;
#endif

DEFINE_GAUGE_METRIC_PROTOTYPE_2ARG(load_channel_count, MetricUnit::NOUNIT);
DEFINE_GAUGE_METRIC_PROTOTYPE_5ARG(load_channel_mem_consumption, MetricUnit::BYTES, "",
                                   mem_consumption, Labels({{"type", "load"}}));

// Calculate the total memory limit of all load tasks on this BE
static int64_t calc_process_max_load_memory(int64_t process_mem_limit) {
    if (process_mem_limit == -1) {
        // no limit
        return -1;
    }
    int32_t max_load_memory_percent = config::load_process_max_memory_limit_percent;
    return process_mem_limit * max_load_memory_percent / 100;
}

static int64_t calc_channel_timeout_s(int64_t timeout_in_req_s) {
    int64_t load_channel_timeout_s = config::streaming_load_rpc_max_alive_time_sec;
    if (timeout_in_req_s > 0) {
        load_channel_timeout_s = std::max<int64_t>(load_channel_timeout_s, timeout_in_req_s);
    }
    return load_channel_timeout_s;
}

LoadChannelMgr::LoadChannelMgr() : _stop_background_threads_latch(1) {
    REGISTER_HOOK_METRIC(load_channel_count, [this]() {
        // std::lock_guard<std::mutex> l(_lock);
        return _load_channels.size();
    });
}

LoadChannelMgr::~LoadChannelMgr() {
    DEREGISTER_HOOK_METRIC(load_channel_count);
    DEREGISTER_HOOK_METRIC(load_channel_mem_consumption);
    _stop_background_threads_latch.count_down();
    if (_load_channels_clean_thread) {
        _load_channels_clean_thread->join();
    }
    delete _last_success_channel;
}

Status LoadChannelMgr::init(int64_t process_mem_limit) {
    _load_hard_mem_limit = calc_process_max_load_memory(process_mem_limit);
    _load_soft_mem_limit = _load_hard_mem_limit * config::load_process_soft_mem_limit_percent / 100;
    _mem_tracker =
            std::make_unique<MemTrackerLimiter>(MemTrackerLimiter::Type::LOAD, "LoadChannelMgr");
    REGISTER_HOOK_METRIC(load_channel_mem_consumption,
                         [this]() { return _mem_tracker->consumption(); });
    _last_success_channel = new_lru_cache("LastestSuccessChannelCache", 1024);
    RETURN_IF_ERROR(_start_bg_worker());
    return Status::OK();
}

Status LoadChannelMgr::open(const PTabletWriterOpenRequest& params) {
    UniqueId load_id(params.id());
    std::shared_ptr<LoadChannel> channel;
    {
        std::lock_guard<std::mutex> l(_lock);
        auto it = _load_channels.find(load_id);
        if (it != _load_channels.end()) {
            channel = it->second;
        } else {
            // create a new load channel
            int64_t timeout_in_req_s =
                    params.has_load_channel_timeout_s() ? params.load_channel_timeout_s() : -1;
            int64_t channel_timeout_s = calc_channel_timeout_s(timeout_in_req_s);
            bool is_high_priority = (params.has_is_high_priority() && params.is_high_priority());

            // Use the same mem limit as LoadChannelMgr for a single load channel
#ifndef BE_TEST
            auto channel_mem_tracker = std::make_unique<MemTracker>(
                    fmt::format("LoadChannel#senderIp={}#loadID={}", params.sender_ip(),
                                load_id.to_string()),
                    ExecEnv::GetInstance()->load_channel_mgr()->mem_tracker());
#else
            auto channel_mem_tracker = std::make_unique<MemTracker>(fmt::format(
                    "LoadChannel#senderIp={}#loadID={}", params.sender_ip(), load_id.to_string()));
#endif
            channel.reset(new LoadChannel(load_id, std::move(channel_mem_tracker),
                                          channel_timeout_s, is_high_priority, params.sender_ip(),
                                          params.backend_id(), params.enable_profile()));
            _load_channels.insert({load_id, channel});
        }
    }

    RETURN_IF_ERROR(channel->open(params));
    return Status::OK();
}

Status LoadChannelMgr::open_partition(const OpenPartitionRequest& params) {
    UniqueId load_id(params.id());
    std::shared_ptr<LoadChannel> channel;
    {
        std::lock_guard<std::mutex> l(_lock);
        auto it = _load_channels.find(load_id);
        if (it != _load_channels.end()) {
            channel = it->second;
        } else {
            return Status::InternalError("unknown load id, load id=" + load_id.to_string());
        }
    }
    RETURN_IF_ERROR(channel->open_partition(params));
    return Status::OK();
}

static void dummy_deleter(const CacheKey& key, void* value) {}

Status LoadChannelMgr::_get_load_channel(std::shared_ptr<LoadChannel>& channel, bool& is_eof,
                                         const UniqueId& load_id,
                                         const PTabletWriterAddBlockRequest& request) {
    is_eof = false;
    std::lock_guard<std::mutex> l(_lock);
    auto it = _load_channels.find(load_id);
    if (it == _load_channels.end()) {
        auto handle = _last_success_channel->lookup(load_id.to_string());
        // success only when eos be true
        if (handle != nullptr) {
            _last_success_channel->release(handle);
            if (request.has_eos() && request.eos()) {
                is_eof = true;
                return Status::OK();
            }
        }
        return Status::InternalError("fail to add batch in load channel. unknown load_id={}",
                                     load_id.to_string());
    }
    channel = it->second;
    return Status::OK();
}

Status LoadChannelMgr::add_batch(const PTabletWriterAddBlockRequest& request,
                                 PTabletWriterAddBlockResult* response) {
    UniqueId load_id(request.id());
    // 1. get load channel
    std::shared_ptr<LoadChannel> channel;
    bool is_eof;
    auto status = _get_load_channel(channel, is_eof, load_id, request);
    if (!status.ok() || is_eof) {
        return status;
    }
    SCOPED_TIMER(channel->get_mgr_add_batch_timer());

    if (!channel->is_high_priority()) {
        // 2. check if mem consumption exceed limit
        // If this is a high priority load task, do not handle this.
        // because this may block for a while, which may lead to rpc timeout.
        SCOPED_TIMER(channel->get_handle_mem_limit_timer());
        _handle_mem_exceed_limit();
    }

    // 3. add batch to load channel
    // batch may not exist in request(eg: eos request without batch),
    // this case will be handled in load channel's add batch method.
    Status st = channel->add_batch(request, response);
    if (UNLIKELY(!st.ok())) {
        channel->cancel();
        return st;
    }

    // 4. handle finish
    if (channel->is_finished()) {
        _finish_load_channel(load_id);
    }
    return Status::OK();
}

void LoadChannelMgr::_finish_load_channel(const UniqueId load_id) {
    VLOG_NOTICE << "removing load channel " << load_id << " because it's finished";
    {
        std::lock_guard<std::mutex> l(_lock);
        _load_channels.erase(load_id);
        auto handle = _last_success_channel->insert(load_id.to_string(), nullptr, 1, dummy_deleter);
        _last_success_channel->release(handle);
    }
    VLOG_CRITICAL << "removed load channel " << load_id;
}

Status LoadChannelMgr::cancel(const PTabletWriterCancelRequest& params) {
    UniqueId load_id(params.id());
    std::shared_ptr<LoadChannel> cancelled_channel;
    {
        std::lock_guard<std::mutex> l(_lock);
        if (_load_channels.find(load_id) != _load_channels.end()) {
            cancelled_channel = _load_channels[load_id];
            _load_channels.erase(load_id);
        }
    }

    if (cancelled_channel != nullptr) {
        cancelled_channel->cancel();
        LOG(INFO) << "load channel has been cancelled: " << load_id;
    }

    return Status::OK();
}

Status LoadChannelMgr::_start_bg_worker() {
    RETURN_IF_ERROR(Thread::create(
            "LoadChannelMgr", "cancel_timeout_load_channels",
            [this]() {
                while (!_stop_background_threads_latch.wait_for(
                        std::chrono::seconds(START_BG_INTERVAL))) {
                    _start_load_channels_clean();
                }
            },
            &_load_channels_clean_thread));

    return Status::OK();
}

Status LoadChannelMgr::_start_load_channels_clean() {
    std::vector<std::shared_ptr<LoadChannel>> need_delete_channels;
    LOG(INFO) << "cleaning timed out load channels";
    time_t now = time(nullptr);
    {
        std::vector<UniqueId> need_delete_channel_ids;
        std::lock_guard<std::mutex> l(_lock);
        int i = 0;
        for (auto& kv : _load_channels) {
            VLOG_CRITICAL << "load channel[" << i++ << "]: " << *(kv.second);
            time_t last_updated_time = kv.second->last_updated_time();
            if (difftime(now, last_updated_time) >= kv.second->timeout()) {
                need_delete_channel_ids.emplace_back(kv.first);
                need_delete_channels.emplace_back(kv.second);
            }
        }

        for (auto& key : need_delete_channel_ids) {
            _load_channels.erase(key);
            LOG(INFO) << "erase timeout load channel: " << key;
        }
    }

    // we must cancel these load channels before destroying them.
    // otherwise some object may be invalid before trying to visit it.
    // eg: MemTracker in load channel
    for (auto& channel : need_delete_channels) {
        channel->cancel();
        LOG(INFO) << "load channel has been safely deleted: " << channel->load_id()
                  << ", timeout(s): " << channel->timeout();
    }

    // this log print every 1 min, so that we could observe the mem consumption of load process
    // on this Backend
    LOG(INFO) << "load mem consumption(bytes). limit: " << _load_hard_mem_limit
              << ", current: " << _mem_tracker->consumption()
              << ", peak: " << _mem_tracker->peak_consumption()
              << ", total running load channels: " << _load_channels.size();

    return Status::OK();
}

void LoadChannelMgr::_handle_mem_exceed_limit() {
    // Check the soft limit.
    DCHECK(_load_soft_mem_limit > 0);
    // Record current memory status.
    int64_t process_soft_mem_limit = MemInfo::soft_mem_limit();
    int64_t proc_mem_no_allocator_cache = MemInfo::proc_mem_no_allocator_cache();
    // If process memory is almost full but data load don't consume more than 5% (50% * 10%) of
    // total memory, we don't need to reduce memory of load jobs.
    bool reduce_on_process_soft_mem_limit =
            proc_mem_no_allocator_cache >= process_soft_mem_limit &&
            _mem_tracker->consumption() >= _load_hard_mem_limit / 10;
    if (_mem_tracker->consumption() < _load_soft_mem_limit && !reduce_on_process_soft_mem_limit) {
        return;
    }
    // Indicate whether current thread is reducing mem on hard limit.
    bool reducing_mem_on_hard_limit = false;
    // tuple<LoadChannel, index_id, tablet_id, mem_size>
    std::vector<std::tuple<std::shared_ptr<LoadChannel>, int64_t, int64_t, int64_t>>
            writers_to_reduce_mem;
    {
        MonotonicStopWatch timer;
        timer.start();
        std::unique_lock<std::mutex> l(_lock);
        while (_should_wait_flush) {
            _wait_flush_cond.wait(l);
        }
        LOG(INFO) << "Reached the load hard limit " << _load_hard_mem_limit
                  << ", waited for flush, time_ns:" << timer.elapsed_time();

        bool hard_limit_reached = _mem_tracker->consumption() >= _load_hard_mem_limit ||
                                  proc_mem_no_allocator_cache >= process_soft_mem_limit;
        // Some other thread is flushing data, and not reached hard limit now,
        // we don't need to handle mem limit in current thread.
        if (_soft_reduce_mem_in_progress && !hard_limit_reached) {
            return;
        }

        // tuple<LoadChannel, index_id, multimap<mem size, tablet_id>>
        using WritersMem = std::tuple<std::shared_ptr<LoadChannel>, int64_t,
                                      std::multimap<int64_t, int64_t, std::greater<int64_t>>>;
        std::vector<WritersMem> all_writers_mem;

        // tuple<current iterator in multimap, end iterator in multimap, pos in all_writers_mem>
        using WriterMemItem =
                std::tuple<std::multimap<int64_t, int64_t, std::greater<int64_t>>::iterator,
                           std::multimap<int64_t, int64_t, std::greater<int64_t>>::iterator,
                           size_t>;
        auto cmp = [](WriterMemItem& lhs, WriterMemItem& rhs) {
            return std::get<0>(lhs)->first < std::get<0>(rhs)->first;
        };
        std::priority_queue<WriterMemItem, std::vector<WriterMemItem>, decltype(cmp)>
                tablets_mem_heap(cmp);

        for (auto& kv : _load_channels) {
            if (kv.second->is_high_priority()) {
                // do not select high priority channel to reduce memory
                // to avoid blocking the.
                continue;
            }
            std::vector<std::pair<int64_t, std::multimap<int64_t, int64_t, std::greater<int64_t>>>>
                    writers_mem_snap;
            kv.second->get_active_memtable_mem_consumption(&writers_mem_snap);
            for (auto item : writers_mem_snap) {
                // multimap is empty
                if (item.second.empty()) {
                    continue;
                }
                all_writers_mem.emplace_back(kv.second, item.first, std::move(item.second));
                size_t pos = all_writers_mem.size() - 1;
                tablets_mem_heap.emplace(std::get<2>(all_writers_mem[pos]).begin(),
                                         std::get<2>(all_writers_mem[pos]).end(), pos);
            }
        }

        // reduce 1/10 memory every time
        int64_t mem_to_flushed = _mem_tracker->consumption() / 10;
        int64_t mem_consumption_in_picked_writer = 0;
        while (!tablets_mem_heap.empty()) {
            WriterMemItem tablet_mem_item = tablets_mem_heap.top();
            size_t pos = std::get<2>(tablet_mem_item);
            auto load_channel = std::get<0>(all_writers_mem[pos]);
            int64_t index_id = std::get<1>(all_writers_mem[pos]);
            int64_t tablet_id = std::get<0>(tablet_mem_item)->second;
            int64_t mem_size = std::get<0>(tablet_mem_item)->first;
            writers_to_reduce_mem.emplace_back(load_channel, index_id, tablet_id, mem_size);
            load_channel->flush_memtable_async(index_id, tablet_id);
            mem_consumption_in_picked_writer += std::get<0>(tablet_mem_item)->first;
            if (mem_consumption_in_picked_writer > mem_to_flushed) {
                break;
            }
            tablets_mem_heap.pop();
            if (++std::get<0>(tablet_mem_item) != std::get<1>(tablet_mem_item)) {
                tablets_mem_heap.push(tablet_mem_item);
            }
        }

        if (writers_to_reduce_mem.empty()) {
            // should not happen, add log to observe
            LOG(WARNING) << "failed to find suitable writers to reduce memory"
                         << " when total load mem limit exceed";
            return;
        }

        std::ostringstream oss;
        oss << "reducing memory of " << writers_to_reduce_mem.size()
            << " delta writers (total mem: "
            << PrettyPrinter::print_bytes(mem_consumption_in_picked_writer) << ", max mem: "
            << PrettyPrinter::print_bytes(std::get<3>(writers_to_reduce_mem.front()))
            << ", tablet_id: " << std::get<2>(writers_to_reduce_mem.front())
            << ", min mem:" << PrettyPrinter::print_bytes(std::get<3>(writers_to_reduce_mem.back()))
            << ", tablet_id: " << std::get<2>(writers_to_reduce_mem.back()) << "), ";
        if (proc_mem_no_allocator_cache < process_soft_mem_limit) {
            oss << "because total load mem consumption "
                << PrettyPrinter::print_bytes(_mem_tracker->consumption()) << " has exceeded";
            if (_mem_tracker->consumption() > _load_hard_mem_limit) {
                _should_wait_flush = true;
                reducing_mem_on_hard_limit = true;
                oss << " hard limit: " << PrettyPrinter::print_bytes(_load_hard_mem_limit);
            } else {
                _soft_reduce_mem_in_progress = true;
                oss << " soft limit: " << PrettyPrinter::print_bytes(_load_soft_mem_limit);
            }
        } else {
            _should_wait_flush = true;
            reducing_mem_on_hard_limit = true;
            oss << "because proc_mem_no_allocator_cache consumption "
                << PrettyPrinter::print_bytes(proc_mem_no_allocator_cache)
                << ", has exceeded process soft limit "
                << PrettyPrinter::print_bytes(process_soft_mem_limit)
                << ", total load mem consumption: "
                << PrettyPrinter::print_bytes(_mem_tracker->consumption())
                << ", vm_rss: " << PerfCounters::get_vm_rss_str();
        }
        LOG(INFO) << oss.str();
    }

    // wait all writers flush without lock
    for (auto item : writers_to_reduce_mem) {
        VLOG_NOTICE << "reducing memory, wait flush load_id: " << std::get<0>(item)->load_id()
                    << ", index_id: " << std::get<1>(item) << ", tablet_id: " << std::get<2>(item)
                    << ", mem_size: " << PrettyPrinter::print_bytes(std::get<3>(item));
        std::get<0>(item)->wait_flush(std::get<1>(item), std::get<2>(item));
    }

    {
        std::lock_guard<std::mutex> l(_lock);
        // If a thread have finished the memtable flush for soft limit, and now
        // the hard limit is already reached, it should not update these variables.
        if (reducing_mem_on_hard_limit && _should_wait_flush) {
            _should_wait_flush = false;
            _wait_flush_cond.notify_all();
        }
        if (_soft_reduce_mem_in_progress) {
            _soft_reduce_mem_in_progress = false;
        }
        // refresh mem tacker to avoid duplicate reduce
        _refresh_mem_tracker_without_lock();
    }
}

} // namespace doris