// 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 "gutil/strings/substitute.h"
#include "olap/lru_cache.h"
#include "runtime/load_channel.h"
#include "runtime/mem_tracker.h"
#include "service/backend_options.h"
#include "util/doris_metrics.h"
#include "util/stopwatch.hpp"

namespace doris {

DEFINE_GAUGE_METRIC_PROTOTYPE_2ARG(load_channel_count, MetricUnit::NOUNIT);

// 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;
    int64_t max_load_memory_bytes = process_mem_limit * max_load_memory_percent / 100;
    return std::min<int64_t>(max_load_memory_bytes, config::load_process_max_memory_limit_bytes);
}

// Calculate the memory limit for a single load job.
static int64_t calc_job_max_load_memory(int64_t mem_limit_in_req, int64_t total_mem_limit) {
    // default mem limit is used to be compatible with old request.
    // new request should be set load_mem_limit.
    const int64_t default_load_mem_limit = 2 * 1024 * 1024 * 1024L; // 2GB
    int64_t load_mem_limit = default_load_mem_limit;
    if (mem_limit_in_req != -1) {
        // mem-limit of a certain load should between config::write_buffer_size
        // and total-memory-limit
        load_mem_limit = std::max<int64_t>(mem_limit_in_req, config::write_buffer_size);
        load_mem_limit = std::min<int64_t>(load_mem_limit, total_mem_limit);
    }
    return load_mem_limit;
}

static int64_t calc_job_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();
    });
    _last_success_channel = new_lru_cache("LastestSuccessChannelCache", 1024);
}

LoadChannelMgr::~LoadChannelMgr() {
    DEREGISTER_HOOK_METRIC(load_channel_count);
    _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) {
    int64_t load_mem_limit = calc_process_max_load_memory(process_mem_limit);
    _mem_tracker = MemTracker::CreateTracker(load_mem_limit, "load channel mgr");
    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 mem_limit_in_req = params.has_load_mem_limit() ? params.load_mem_limit() : -1;
            int64_t job_max_memory =
                    calc_job_max_load_memory(mem_limit_in_req, _mem_tracker->limit());

            int64_t timeout_in_req_s =
                    params.has_load_channel_timeout_s() ? params.load_channel_timeout_s() : -1;
            int64_t job_timeout_s = calc_job_timeout_s(timeout_in_req_s);

            channel.reset(new LoadChannel(load_id, job_max_memory, job_timeout_s, _mem_tracker));
            _load_channels.insert({load_id, channel});
        }
    }

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

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

Status LoadChannelMgr::add_batch(const PTabletWriterAddBatchRequest& request,
                                 google::protobuf::RepeatedPtrField<PTabletInfo>* tablet_vec,
                                 int64_t* wait_lock_time_ns) {
    UniqueId load_id(request.id());
    // 1. get load channel
    std::shared_ptr<LoadChannel> channel;
    {
        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()) {
                    return Status::OK();
                }
            }
            return Status::InternalError(strings::Substitute(
                    "fail to add batch in load channel. unknown load_id=$0", load_id.to_string()));
        }
        channel = it->second;
    }

    // 2. check if mem consumption exceed limit
    _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.
    RETURN_IF_ERROR(channel->add_batch(request, tablet_vec));

    // 4. handle finish
    if (channel->is_finished()) {
        LOG(INFO) << "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(1) << "removed load channel " << load_id;
    }
    return Status::OK();
}

void LoadChannelMgr::_handle_mem_exceed_limit() {
    // lock so that only one thread can check mem limit
    std::lock_guard<std::mutex> l(_lock);
    if (!_mem_tracker->limit_exceeded()) {
        return;
    }

    int64_t max_consume = 0;
    std::shared_ptr<LoadChannel> channel;
    for (auto& kv : _load_channels) {
        if (kv.second->mem_consumption() > max_consume) {
            max_consume = kv.second->mem_consumption();
            channel = kv.second;
        }
    }
    if (max_consume == 0) {
        // should not happen, add log to observe
        LOG(WARNING) << "failed to find suitable load channel when total load mem limit exceed";
        return;
    }
    DCHECK(channel.get() != nullptr);

    // force reduce mem limit of the selected channel
    LOG(INFO) << "reducing memory of " << *channel << " because total load mem consumption "
              << _mem_tracker->consumption() << " has exceeded limit " << _mem_tracker->limit();
    channel->handle_mem_exceed_limit(true);
}

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.get() != 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]() {
#ifdef GOOGLE_PROFILER
                ProfilerRegisterThread();
#endif
#ifndef BE_TEST
                uint32_t interval = 60;
#else
                uint32_t interval = 1;
#endif
                while (!_stop_background_threads_latch.wait_for(MonoDelta::FromSeconds(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);
        VLOG(1) << "there are " << _load_channels.size() << " running load channels";
        int i = 0;
        for (auto& kv : _load_channels) {
            VLOG(1) << "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: " << _mem_tracker->limit()
              << ", current: " << _mem_tracker->consumption()
              << ", peak: " << _mem_tracker->peak_consumption();

    return Status::OK();
}

} // namespace doris