// 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/client_cache.h"

#include <memory>

#include <utility>

#include "common/logging.h"

#include "runtime/exec_env.h"

#include "util/dns_cache.h"

#include "util/doris_metrics.h"

#include "util/network_util.h"

namespace doris {

DEFINE_GAUGE_METRIC_PROTOTYPE_3ARG(thrift_used_clients, MetricUnit::NOUNIT,

                                   "Number of clients 'checked-out' from the cache");

DEFINE_GAUGE_METRIC_PROTOTYPE_3ARG(thrift_opened_clients, MetricUnit::NOUNIT,

                                   "Total clients in the cache, including those in use");

ClientCacheHelper::~ClientCacheHelper() {

    for (auto& it : _client_map) {

        delete it.second;

    }

}

void ClientCacheHelper::_get_client_from_cache(const TNetworkAddress& hostport,

                                               const std::string& resolved_ip, void** client_key) {

    *client_key = nullptr;

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

    //VLOG_RPC << "get_client(" << hostport << ")";

    auto cache_entry = _client_cache.find(hostport);

    if (cache_entry == _client_cache.end()) {

        cache_entry =

                _client_cache.insert(std::make_pair(hostport, std::list<CachedClient>())).first;

        DCHECK(cache_entry != _client_cache.end());

    }

    std::list<CachedClient>& info_list = cache_entry->second;

    // Find a cached client with matching resolved IP

    for (auto it = info_list.begin(); it != info_list.end(); ++it) {

        if (it->resolved_ip == resolved_ip) {

            *client_key = it->client_key;

            VLOG_RPC << "get_client(): cached client for " << hostport << " with ip "

                     << resolved_ip;

            info_list.erase(it);

            return;

        }

    }

    // No matching client found. Clear all cached clients with stale IPs for this hostport.

    // These clients were created with old resolved IPs and should be closed.

    for (auto& cached_client : info_list) {

        auto client_map_entry = _client_map.find(cached_client.client_key);

        if (client_map_entry != _client_map.end()) {

            ThriftClientImpl* client_to_close = client_map_entry->second;

            client_to_close->close();

            delete client_to_close;

            _client_map.erase(client_map_entry);

            _client_hostport_map.erase(cached_client.client_key);

            if (_metrics_enabled) {

                thrift_opened_clients->increment(-1);

            }

        }

    }

    info_list.clear();

}

Status ClientCacheHelper::get_client(const TNetworkAddress& hostport, ClientFactory& factory_method,

                                     void** client_key, int timeout_ms) {

    // Resolve hostname to IP address via DNS cache.

    // If the hostname is already an IP address, DNS cache will return it directly.

    std::string resolved_ip;

    Status dns_status = ExecEnv::GetInstance()->dns_cache()->get(hostport.hostname, &resolved_ip);

    if (!dns_status.ok() || resolved_ip.empty()) {

        return Status::InternalError("Failed to resolve hostname {} to IP address: {}",

                                     hostport.hostname, dns_status.to_string());

    }

    // Try to get a cached client with matching resolved IP

    _get_client_from_cache(hostport, resolved_ip, client_key);

    if (*client_key == nullptr) {

        // No cached client with matching IP, create a new one using the resolved IP

        RETURN_IF_ERROR(

                _create_client(hostport, resolved_ip, factory_method, client_key, timeout_ms));

    }

    if (_metrics_enabled) {

        thrift_used_clients->increment(1);

    }

    return Status::OK();

}

Status ClientCacheHelper::reopen_client(ClientFactory& factory_method, void** client_key,

                                        int timeout_ms) {

    DCHECK(*client_key != nullptr) << "Trying to reopen nullptr client";

    ThriftClientImpl* client_to_close = nullptr;

    TNetworkAddress hostport;

    {

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

        auto client_map_entry = _client_map.find(*client_key);

        DCHECK(client_map_entry != _client_map.end());

        client_to_close = client_map_entry->second;

        // Get the original hostport (with hostname) for this client

        auto hostport_entry = _client_hostport_map.find(*client_key);

        DCHECK(hostport_entry != _client_hostport_map.end());

        hostport = hostport_entry->second;

    }

    client_to_close->close();

    // TODO: Thrift TBufferedTransport cannot be re-opened after Close() because it does

    // not clean up internal buffers it reopens. To work around this issue, create a new

    // client instead.

    {

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

        _client_map.erase(*client_key);

        _client_hostport_map.erase(*client_key);

    }

    delete client_to_close;

    *client_key = nullptr;

    if (_metrics_enabled) {

        thrift_opened_clients->increment(-1);

    }

    // Re-resolve hostname to IP address

    std::string resolved_ip;

    Status dns_status = ExecEnv::GetInstance()->dns_cache()->get(hostport.hostname, &resolved_ip);

    if (!dns_status.ok() || resolved_ip.empty()) {

        return Status::InternalError("Failed to resolve hostname {} to IP address: {}",

                                     hostport.hostname, dns_status.to_string());

    }

    RETURN_IF_ERROR(_create_client(hostport, resolved_ip, factory_method, client_key, timeout_ms));

    return Status::OK();

}

Status ClientCacheHelper::_create_client(const TNetworkAddress& hostport,

                                         const std::string& resolved_ip,

                                         ClientFactory& factory_method, void** client_key,

                                         int timeout_ms) {

    // Create a new TNetworkAddress with the resolved IP instead of hostname.

    // This ensures that all client connections are made using IP addresses.

    TNetworkAddress addr_with_ip;

    addr_with_ip.hostname = resolved_ip;

    addr_with_ip.port = hostport.port;

    std::unique_ptr<ThriftClientImpl> client_impl(factory_method(addr_with_ip, client_key));

    //VLOG_CONNECTION << "create_client(): adding new client for "

    //                << client_impl->ipaddress() << ":" << client_impl->port();

    client_impl->set_conn_timeout(config::thrift_connect_timeout_seconds * 1000);

    Status status = client_impl->open_with_retry(config::thrift_client_open_num_tries, 100);

    if (!status.ok()) {

        *client_key = nullptr;

        return status;

    }

    DCHECK(*client_key != nullptr);

    // In thrift, timeout == 0, means wait infinitely, so that it should not happen.

    // See https://github.com/apache/thrift/blob/master/lib/cpp/src/thrift/transport/TSocket.cpp.

    // There is some code like this:      int ret = THRIFT_POLL(fds, 2, (recvTimeout_ == 0) ? -1 : recvTimeout_);

    // If the developer missed to set the timeout, we should use default timeout, not infinitely.

    // See https://linux.die.net/man/2/poll. Specifying a negative value in timeout means an infinite timeout.

    client_impl->set_send_timeout(timeout_ms == 0 ? config::thrift_rpc_timeout_ms : timeout_ms);

    client_impl->set_recv_timeout(timeout_ms == 0 ? config::thrift_rpc_timeout_ms : timeout_ms);

    {

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

        // Because the client starts life 'checked out', we don't add it to the cache map

        DCHECK(_client_map.count(*client_key) == 0);

        _client_map[*client_key] = client_impl.release();

        // Store the original hostport (with hostname) for this client

        _client_hostport_map[*client_key] = hostport;

    }

    if (_metrics_enabled) {

        thrift_opened_clients->increment(1);

    }

    return Status::OK();

}

void ClientCacheHelper::release_client(void** client_key) {

    DCHECK(*client_key != nullptr) << "Trying to release nullptr client";

    ThriftClientImpl* client_to_close = nullptr;

    {

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

        auto client_map_entry = _client_map.find(*client_key);

        DCHECK(client_map_entry != _client_map.end());

        ThriftClientImpl* client = client_map_entry->second;

        // Get the original hostport (with hostname) for this client

        auto hostport_entry = _client_hostport_map.find(*client_key);

        DCHECK(hostport_entry != _client_hostport_map.end());

        const TNetworkAddress& hostport = hostport_entry->second;

        auto cache_list = _client_cache.find(hostport);

        DCHECK(cache_list != _client_cache.end());

        if (_max_cache_size_per_host >= 0 &&

            cache_list->second.size() >= _max_cache_size_per_host) {

            // cache of this host is full, close this client connection and remove from maps

            _client_map.erase(*client_key);

            _client_hostport_map.erase(*client_key);

            client_to_close = client;

        } else {

            // Store the client with its resolved IP address

            CachedClient cached_client;

            cached_client.client_key = *client_key;

            cached_client.resolved_ip = client->ipaddress();

            cache_list->second.push_back(cached_client);

            // There is no need to close client if we put it to cache list.

            client_to_close = nullptr;

        }

    }

    if (client_to_close != nullptr) {

        client_to_close->close();

        delete client_to_close;

        if (_metrics_enabled) {

            thrift_opened_clients->increment(-1);

        }

    }

    if (_metrics_enabled) {

        thrift_used_clients->increment(-1);

    }

    *client_key = nullptr;

}

std::string ClientCacheHelper::debug_string() {

    std::stringstream out;

    out << "ClientCacheHelper(#hosts=" << _client_cache.size() << " [";

    bool isfirst = true;

    for (const auto& [endpoint, client_keys] : _client_cache) {

        if (!isfirst) {

            out << " ";

            isfirst = false;

        }

        out << endpoint << ":" << client_keys.size();

    }

    out << "])";

    return out.str();

}

void ClientCacheHelper::init_metrics(const std::string& name) {

    // Not strictly needed if init_metrics is called before any cache

    // usage, but ensures that _metrics_enabled is published.

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

    _thrift_client_metric_entity = DorisMetrics::instance()->metric_registry()->register_entity(

            std::string("thrift_client.") + name, {{"name", name}});

    INT_GAUGE_METRIC_REGISTER(_thrift_client_metric_entity, thrift_used_clients);

    INT_GAUGE_METRIC_REGISTER(_thrift_client_metric_entity, thrift_opened_clients);

    _metrics_enabled = true;

}

} // namespace doris