// 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/snapshot_loader.h"

// IWYU pragma: no_include <bthread/errno.h>

#include <errno.h> // IWYU pragma: keep

#include <fmt/format.h>

#include <gen_cpp/FrontendService.h>

#include <gen_cpp/FrontendService_types.h>

#include <gen_cpp/HeartbeatService_types.h>

#include <gen_cpp/PlanNodes_types.h>

#include <gen_cpp/Status_types.h>

#include <gen_cpp/Types_types.h>

#include <algorithm>

#include <cstring>

#include <filesystem>

#include <istream>

#include <unordered_map>

#include <utility>

#include "common/logging.h"

#include "gutil/strings/split.h"

#include "http/http_client.h"

#include "io/fs/broker_file_system.h"

#include "io/fs/file_system.h"

#include "io/fs/hdfs_file_system.h"

#include "io/fs/local_file_system.h"

#include "io/fs/path.h"

#include "io/fs/remote_file_system.h"

#include "io/fs/s3_file_system.h"

#include "io/hdfs_builder.h"

#include "olap/data_dir.h"

#include "olap/snapshot_manager.h"

#include "olap/storage_engine.h"

#include "olap/tablet.h"

#include "olap/tablet_manager.h"

#include "runtime/client_cache.h"

#include "runtime/exec_env.h"

#include "util/s3_uri.h"

#include "util/s3_util.h"

#include "util/thrift_rpc_helper.h"

namespace doris {

namespace {

Status upload_with_checksum(io::RemoteFileSystem& fs, std::string_view local_path,

                            std::string_view remote_path, std::string_view checksum) {

    auto full_remote_path = fmt::format("{}.{}", remote_path, checksum);

    switch (fs.type()) {

    case io::FileSystemType::HDFS:

    case io::FileSystemType::BROKER: {

        std::string temp = fmt::format("{}.part", remote_path);

        RETURN_IF_ERROR(fs.upload(local_path, temp));

        RETURN_IF_ERROR(fs.rename(temp, full_remote_path));

        break;

    }

    case io::FileSystemType::S3:

        RETURN_IF_ERROR(fs.upload(local_path, full_remote_path));

        break;

    default:

        LOG(FATAL) << "unknown fs type: " << static_cast<int>(fs.type());

    }

    return Status::OK();

}

bool _end_with(std::string_view str, std::string_view match) {

    return str.size() >= match.size() &&

           str.compare(str.size() - match.size(), match.size(), match) == 0;

}

} // namespace

SnapshotLoader::SnapshotLoader(StorageEngine& engine, ExecEnv* env, int64_t job_id, int64_t task_id,

                               const TNetworkAddress& broker_addr,

                               const std::map<std::string, std::string>& prop)

        : _engine(engine),

          _env(env),

          _job_id(job_id),

          _task_id(task_id),

          _broker_addr(broker_addr),

          _prop(prop) {}

Status SnapshotLoader::init(TStorageBackendType::type type, const std::string& location) {

    if (TStorageBackendType::type::S3 == type) {

        S3Conf s3_conf;

        S3URI s3_uri(location);

        RETURN_IF_ERROR(s3_uri.parse());

        RETURN_IF_ERROR(S3ClientFactory::convert_properties_to_s3_conf(_prop, s3_uri, &s3_conf));

        _remote_fs =

                DORIS_TRY(io::S3FileSystem::create(std::move(s3_conf), io::FileSystem::TMP_FS_ID));

    } else if (TStorageBackendType::type::HDFS == type) {

        THdfsParams hdfs_params = parse_properties(_prop);

        _remote_fs = DORIS_TRY(io::HdfsFileSystem::create(hdfs_params, hdfs_params.fs_name,

                                                          io::FileSystem::TMP_FS_ID, nullptr));

    } else if (TStorageBackendType::type::BROKER == type) {

        std::shared_ptr<io::BrokerFileSystem> fs;

        _remote_fs = DORIS_TRY(

                io::BrokerFileSystem::create(_broker_addr, _prop, io::FileSystem::TMP_FS_ID));

    } else {

        return Status::InternalError("Unknown storage type: {}", type);

    }

    return Status::OK();

}

SnapshotLoader::~SnapshotLoader() = default;

Status SnapshotLoader::upload(const std::map<std::string, std::string>& src_to_dest_path,

                              std::map<int64_t, std::vector<std::string>>* tablet_files) {

    if (!_remote_fs) {

        return Status::InternalError("Storage backend not initialized.");

    }

    LOG(INFO) << "begin to upload snapshot files. num: " << src_to_dest_path.size()

              << ", broker addr: " << _broker_addr << ", job: " << _job_id << ", task" << _task_id;

    // check if job has already been cancelled

    int tmp_counter = 1;

    RETURN_IF_ERROR(_report_every(0, &tmp_counter, 0, 0, TTaskType::type::UPLOAD));

    Status status = Status::OK();

    // 1. validate local tablet snapshot paths

    RETURN_IF_ERROR(_check_local_snapshot_paths(src_to_dest_path, true));

    // 2. for each src path, upload it to remote storage

    // we report to frontend for every 10 files, and we will cancel the job if

    // the job has already been cancelled in frontend.

    int report_counter = 0;

    int total_num = src_to_dest_path.size();

    int finished_num = 0;

    for (const auto& iter : src_to_dest_path) {

        const std::string& src_path = iter.first;

        const std::string& dest_path = iter.second;

        int64_t tablet_id = 0;

        int32_t schema_hash = 0;

        RETURN_IF_ERROR(

                _get_tablet_id_and_schema_hash_from_file_path(src_path, &tablet_id, &schema_hash));

        // 2.1 get existing files from remote path

        std::map<std::string, FileStat> remote_files;

        RETURN_IF_ERROR(_list_with_checksum(dest_path, &remote_files));

        for (auto& tmp : remote_files) {

            VLOG_CRITICAL << "get remote file: " << tmp.first << ", checksum: " << tmp.second.md5;

        }

        // 2.2 list local files

        std::vector<std::string> local_files;

        std::vector<std::string> local_files_with_checksum;

        RETURN_IF_ERROR(_get_existing_files_from_local(src_path, &local_files));

        // 2.3 iterate local files

        for (auto& local_file : local_files) {

            RETURN_IF_ERROR(_report_every(10, &report_counter, finished_num, total_num,

                                          TTaskType::type::UPLOAD));

            // calc md5sum of localfile

            std::string md5sum;

            RETURN_IF_ERROR(

                    io::global_local_filesystem()->md5sum(src_path + "/" + local_file, &md5sum));

            VLOG_CRITICAL << "get file checksum: " << local_file << ": " << md5sum;

            local_files_with_checksum.push_back(local_file + "." + md5sum);

            // check if this local file need upload

            bool need_upload = false;

            auto find = remote_files.find(local_file);

            if (find != remote_files.end()) {

                if (md5sum != find->second.md5) {

                    // remote storage file exist, but with different checksum

                    LOG(WARNING) << "remote file checksum is invalid. remote: " << find->first

                                 << ", local: " << md5sum;

                    // TODO(cmy): save these files and delete them later

                    need_upload = true;

                }

            } else {

                need_upload = true;

            }

            if (!need_upload) {

                VLOG_CRITICAL << "file exist in remote path, no need to upload: " << local_file;

                continue;

            }

            // upload

            std::string remote_path = dest_path + '/' + local_file;

            std::string local_path = src_path + '/' + local_file;

            RETURN_IF_ERROR(upload_with_checksum(*_remote_fs, local_path, remote_path, md5sum));

        } // end for each tablet's local files

        tablet_files->emplace(tablet_id, local_files_with_checksum);

        finished_num++;

        LOG(INFO) << "finished to write tablet to remote. local path: " << src_path

                  << ", remote path: " << dest_path;

    } // end for each tablet path

    LOG(INFO) << "finished to upload snapshots. job: " << _job_id << ", task id: " << _task_id;

    return status;

}

/*

 * Download snapshot files from remote.

 * After downloaded, the local dir should contains all files existing in remote,

 * may also contains several useless files.

 */

Status SnapshotLoader::download(const std::map<std::string, std::string>& src_to_dest_path,

                                std::vector<int64_t>* downloaded_tablet_ids) {

    if (!_remote_fs) {

        return Status::InternalError("Storage backend not initialized.");

    }

    LOG(INFO) << "begin to download snapshot files. num: " << src_to_dest_path.size()

              << ", broker addr: " << _broker_addr << ", job: " << _job_id

              << ", task id: " << _task_id;

    // check if job has already been cancelled

    int tmp_counter = 1;

    RETURN_IF_ERROR(_report_every(0, &tmp_counter, 0, 0, TTaskType::type::DOWNLOAD));

    Status status = Status::OK();

    // 1. validate local tablet snapshot paths

    RETURN_IF_ERROR(_check_local_snapshot_paths(src_to_dest_path, false));

    // 2. for each src path, download it to local storage

    int report_counter = 0;

    int total_num = src_to_dest_path.size();

    int finished_num = 0;

    for (const auto& iter : src_to_dest_path) {

        const std::string& remote_path = iter.first;

        const std::string& local_path = iter.second;

        int64_t local_tablet_id = 0;

        int32_t schema_hash = 0;

        RETURN_IF_ERROR(_get_tablet_id_and_schema_hash_from_file_path(local_path, &local_tablet_id,

                                                                      &schema_hash));

        downloaded_tablet_ids->push_back(local_tablet_id);

        int64_t remote_tablet_id;

        RETURN_IF_ERROR(_get_tablet_id_from_remote_path(remote_path, &remote_tablet_id));

        VLOG_CRITICAL << "get local tablet id: " << local_tablet_id

                      << ", schema hash: " << schema_hash

                      << ", remote tablet id: " << remote_tablet_id;

        // 2.1. get local files

        std::vector<std::string> local_files;

        RETURN_IF_ERROR(_get_existing_files_from_local(local_path, &local_files));

        // 2.2. get remote files

        std::map<std::string, FileStat> remote_files;

        RETURN_IF_ERROR(_list_with_checksum(remote_path, &remote_files));

        if (remote_files.empty()) {

            std::stringstream ss;

            ss << "get nothing from remote path: " << remote_path;

            LOG(WARNING) << ss.str();

            return Status::InternalError(ss.str());

        }

        TabletSharedPtr tablet = _engine.tablet_manager()->get_tablet(local_tablet_id);

        if (tablet == nullptr) {

            std::stringstream ss;

            ss << "failed to get local tablet: " << local_tablet_id;

            LOG(WARNING) << ss.str();

            return Status::InternalError(ss.str());

        }

        DataDir* data_dir = tablet->data_dir();

        for (auto& iter : remote_files) {

            RETURN_IF_ERROR(_report_every(10, &report_counter, finished_num, total_num,

                                          TTaskType::type::DOWNLOAD));

            bool need_download = false;

            const std::string& remote_file = iter.first;

            const FileStat& file_stat = iter.second;

            auto find = std::find(local_files.begin(), local_files.end(), remote_file);

            if (find == local_files.end()) {

                // remote file does not exist in local, download it

                need_download = true;

            } else {

                if (_end_with(remote_file, ".hdr")) {

                    // this is a header file, download it.

                    need_download = true;

                } else {

                    // check checksum

                    std::string local_md5sum;

                    Status st = io::global_local_filesystem()->md5sum(

                            local_path + "/" + remote_file, &local_md5sum);

                    if (!st.ok()) {

                        LOG(WARNING) << "failed to get md5sum of local file: " << remote_file

                                     << ". msg: " << st << ". download it";

                        need_download = true;

                    } else {

                        VLOG_CRITICAL << "get local file checksum: " << remote_file << ": "

                                      << local_md5sum;

                        if (file_stat.md5 != local_md5sum) {

                            // file's checksum does not equal, download it.

                            need_download = true;

                        }

                    }

                }

            }

            if (!need_download) {

                LOG(INFO) << "remote file already exist in local, no need to download."

                          << ", file: " << remote_file;

                continue;

            }

            // begin to download

            std::string full_remote_file = remote_path + "/" + remote_file + "." + file_stat.md5;

            std::string local_file_name;

            // we need to replace the tablet_id in remote file name with local tablet id

            RETURN_IF_ERROR(_replace_tablet_id(remote_file, local_tablet_id, &local_file_name));

            std::string full_local_file = local_path + "/" + local_file_name;

            LOG(INFO) << "begin to download from " << full_remote_file << " to " << full_local_file;

            size_t file_len = file_stat.size;

            // check disk capacity

            if (data_dir->reach_capacity_limit(file_len)) {

                return Status::Error<ErrorCode::EXCEEDED_LIMIT>(

                        "reach the capacity limit of path {}, file_size={}", data_dir->path(),

                        file_len);

            }

            // remove file which will be downloaded now.

            // this file will be added to local_files if it be downloaded successfully.

            if (find != local_files.end()) {

                local_files.erase(find);

            }

            RETURN_IF_ERROR(_remote_fs->download(full_remote_file, full_local_file));

            // 3. check md5 of the downloaded file

            std::string downloaded_md5sum;

            RETURN_IF_ERROR(

                    io::global_local_filesystem()->md5sum(full_local_file, &downloaded_md5sum));

            VLOG_CRITICAL << "get downloaded file checksum: " << full_local_file << ": "

                          << downloaded_md5sum;

            if (downloaded_md5sum != file_stat.md5) {

                std::stringstream ss;

                ss << "invalid md5 of downloaded file: " << full_local_file

                   << ", expected: " << file_stat.md5 << ", get: " << downloaded_md5sum;

                LOG(WARNING) << ss.str();

                return Status::InternalError(ss.str());

            }

            // local_files always keep the updated local files

            local_files.push_back(local_file_name);

            LOG(INFO) << "finished to download file via broker. file: " << full_local_file

                      << ", length: " << file_len;

        } // end for all remote files

        // finally, delete local files which are not in remote

        for (const auto& local_file : local_files) {

            // replace the tablet id in local file name with the remote tablet id,

            // in order to compare the file name.

            std::string new_name;

            Status st = _replace_tablet_id(local_file, remote_tablet_id, &new_name);

            if (!st.ok()) {

                LOG(WARNING) << "failed to replace tablet id. unknown local file: " << st

                             << ". ignore it";

                continue;

            }

            VLOG_CRITICAL << "new file name after replace tablet id: " << new_name;

            const auto& find = remote_files.find(new_name);

            if (find != remote_files.end()) {

                continue;

            }

            // delete

            std::string full_local_file = local_path + "/" + local_file;

            VLOG_CRITICAL << "begin to delete local snapshot file: " << full_local_file

                          << ", it does not exist in remote";

            if (remove(full_local_file.c_str()) != 0) {

                LOG(WARNING) << "failed to delete unknown local file: " << full_local_file

                             << ", ignore it";

            }

        }

        finished_num++;

    } // end for src_to_dest_path

    LOG(INFO) << "finished to download snapshots. job: " << _job_id << ", task id: " << _task_id;

    return status;

}

Status SnapshotLoader::remote_http_download(

        const std::vector<TRemoteTabletSnapshot>& remote_tablet_snapshots,

        std::vector<int64_t>* downloaded_tablet_ids) {

    LOG(INFO) << fmt::format("begin to download snapshots via http. job: {}, task id: {}", _job_id,

                             _task_id);

    constexpr uint32_t kListRemoteFileTimeout = 15;

    constexpr uint32_t kDownloadFileMaxRetry = 3;

    constexpr uint32_t kGetLengthTimeout = 10;

    // check if job has already been cancelled

    int tmp_counter = 1;

    RETURN_IF_ERROR(_report_every(0, &tmp_counter, 0, 0, TTaskType::type::DOWNLOAD));

    Status status = Status::OK();

    // Step before, validate all remote

    // Step 1: Validate local tablet snapshot paths

    for (const auto& remote_tablet_snapshot : remote_tablet_snapshots) {

        const auto& path = remote_tablet_snapshot.local_snapshot_path;

        bool res = true;

        RETURN_IF_ERROR(io::global_local_filesystem()->is_directory(path, &res));

        if (!res) {

            std::stringstream ss;

            auto err_msg =

                    fmt::format("snapshot path is not directory or does not exist: {}", path);

            LOG(WARNING) << err_msg;

            return Status::RuntimeError(err_msg);

        }

    }

    // Step 2: get all local files

    struct LocalFileStat {

        uint64_t size;

        std::string md5;

    };

    std::unordered_map<std::string, std::unordered_map<std::string, LocalFileStat>> local_files_map;

    for (const auto& remote_tablet_snapshot : remote_tablet_snapshots) {

        const auto& local_path = remote_tablet_snapshot.local_snapshot_path;

        std::vector<std::string> local_files;

        RETURN_IF_ERROR(_get_existing_files_from_local(local_path, &local_files));

        auto& local_filestat = local_files_map[local_path];

        for (auto& local_file : local_files) {

            // add file size

            std::string local_file_path = local_path + "/" + local_file;

            std::error_code ec;

            uint64_t local_file_size = std::filesystem::file_size(local_file_path, ec);

            if (ec) {

                LOG(WARNING) << "download file error" << ec.message();

                return Status::IOError("can't retrive file_size of {}, due to {}", local_file_path,

                                       ec.message());

            }

            std::string md5;

            auto status = io::global_local_filesystem()->md5sum(local_file_path, &md5);

            if (!status.ok()) {

                LOG(WARNING) << "download file error, local file " << local_file_path

                             << " md5sum: " << status.to_string();

                return status;

            }

            local_filestat[local_file] = {local_file_size, md5};

        }

    }

    // Step 3: Validate remote tablet snapshot paths && remote files map

    // key is remote snapshot paths, value is filelist

    // get all these use http download action

    // http://172.16.0.14:6781/api/_tablet/_download?token=e804dd27-86da-4072-af58-70724075d2a4&file=/home/ubuntu/doris_master/output/be/storage/snapshot/20230410102306.9.180//2774718/217609978/2774718.hdr

    int report_counter = 0;

    int total_num = remote_tablet_snapshots.size();

    int finished_num = 0;

    struct RemoteFileStat {

        std::string url;

        std::string md5;

        uint64_t size;

    };

    std::unordered_map<std::string, std::unordered_map<std::string, RemoteFileStat>>

            remote_files_map;

    for (const auto& remote_tablet_snapshot : remote_tablet_snapshots) {

        const auto& remote_path = remote_tablet_snapshot.remote_snapshot_path;

        auto& remote_files = remote_files_map[remote_path];

        const auto& token = remote_tablet_snapshot.remote_token;

        const auto& remote_be_addr = remote_tablet_snapshot.remote_be_addr;

        // HEAD http://172.16.0.14:6781/api/_tablet/_download?token=e804dd27-86da-4072-af58-70724075d2a4&file=/home/ubuntu/doris_master/output/be/storage/snapshot/20230410102306.9.180/

        std::string base_url = fmt::format("http://{}:{}/api/_tablet/_download?token={}",

                                           remote_be_addr.hostname, remote_be_addr.port, token);

        std::string remote_url_prefix = fmt::format("{}&file={}", base_url, remote_path);

        LOG(INFO) << "list remote files: " << remote_url_prefix << ", job: " << _job_id

                  << ", task id: " << _task_id << ", remote be: " << remote_be_addr;

        string file_list_str;

        auto list_files_cb = [&remote_url_prefix, &file_list_str](HttpClient* client) {

            RETURN_IF_ERROR(client->init(remote_url_prefix));

            client->set_timeout_ms(kListRemoteFileTimeout * 1000);

            return client->execute(&file_list_str);

        };

        RETURN_IF_ERROR(HttpClient::execute_with_retry(kDownloadFileMaxRetry, 1, list_files_cb));

        std::vector<string> filename_list =

                strings::Split(file_list_str, "\n", strings::SkipWhitespace());

        for (const auto& filename : filename_list) {

            std::string remote_file_url =

                    fmt::format("{}&file={}/{}&channel=ingest_binlog", base_url,

                                remote_tablet_snapshot.remote_snapshot_path, filename);

            // get file length

            uint64_t file_size = 0;

            std::string file_md5;

            auto get_file_stat_cb = [&remote_file_url, &file_size, &file_md5](HttpClient* client) {

                std::string url = fmt::format("{}&acquire_md5=true", remote_file_url);

                RETURN_IF_ERROR(client->init(url));

                client->set_timeout_ms(kGetLengthTimeout * 1000);

                RETURN_IF_ERROR(client->head());

                RETURN_IF_ERROR(client->get_content_length(&file_size));

                RETURN_IF_ERROR(client->get_content_md5(&file_md5));

                return Status::OK();

            };

            RETURN_IF_ERROR(

                    HttpClient::execute_with_retry(kDownloadFileMaxRetry, 1, get_file_stat_cb));

            remote_files[filename] = RemoteFileStat {remote_file_url, file_md5, file_size};

        }

    }

    // Step 4: Compare local and remote files && get all need download files

    for (const auto& remote_tablet_snapshot : remote_tablet_snapshots) {

        RETURN_IF_ERROR(_report_every(10, &report_counter, finished_num, total_num,

                                      TTaskType::type::DOWNLOAD));

        const auto& remote_path = remote_tablet_snapshot.remote_snapshot_path;

        const auto& local_path = remote_tablet_snapshot.local_snapshot_path;

        auto& remote_files = remote_files_map[remote_path];

        auto& local_files = local_files_map[local_path];

        auto remote_tablet_id = remote_tablet_snapshot.remote_tablet_id;

        // get all need download files

        std::vector<std::string> need_download_files;

        for (const auto& [remote_file, remote_filestat] : remote_files) {

            LOG(INFO) << "remote file: " << remote_file << ", size: " << remote_filestat.size

                      << ", md5: " << remote_filestat.md5;

            auto it = local_files.find(remote_file);

            if (it == local_files.end()) {

                need_download_files.emplace_back(remote_file);

                continue;

            }

            if (_end_with(remote_file, ".hdr")) {

                need_download_files.emplace_back(remote_file);

                continue;

            }

            if (auto& local_filestat = it->second; local_filestat.size != remote_filestat.size) {

                need_download_files.emplace_back(remote_file);

                continue;

            }

            if (auto& local_filestat = it->second; local_filestat.md5 != remote_filestat.md5) {

                need_download_files.emplace_back(remote_file);

                continue;

            }

            LOG(INFO) << fmt::format("file {} already exists, skip download", remote_file);

        }

        auto local_tablet_id = remote_tablet_snapshot.local_tablet_id;

        TabletSharedPtr tablet = _engine.tablet_manager()->get_tablet(local_tablet_id);

        if (tablet == nullptr) {

            std::stringstream ss;

            ss << "failed to get local tablet: " << local_tablet_id;

            LOG(WARNING) << ss.str();

            return Status::InternalError(ss.str());

        }

        DataDir* data_dir = tablet->data_dir();

        // download all need download files

        uint64_t total_file_size = 0;

        MonotonicStopWatch watch;

        watch.start();

        for (auto& filename : need_download_files) {

            auto& remote_filestat = remote_files[filename];

            auto file_size = remote_filestat.size;

            auto& remote_file_url = remote_filestat.url;

            auto& remote_file_md5 = remote_filestat.md5;

            // check disk capacity

            if (data_dir->reach_capacity_limit(file_size)) {

                return Status::Error<ErrorCode::EXCEEDED_LIMIT>(

                        "reach the capacity limit of path {}, file_size={}", data_dir->path(),

                        file_size);

            }

            total_file_size += file_size;

            uint64_t estimate_timeout = file_size / config::download_low_speed_limit_kbps / 1024;

            if (estimate_timeout < config::download_low_speed_time) {

                estimate_timeout = config::download_low_speed_time;

            }

            std::string local_filename;

            RETURN_IF_ERROR(_replace_tablet_id(filename, local_tablet_id, &local_filename));

            std::string local_file_path = local_path + "/" + local_filename;

            LOG(INFO) << "clone begin to download file from: " << remote_file_url

                      << " to: " << local_file_path << ". size(B): " << file_size

                      << ", timeout(s): " << estimate_timeout;

            auto download_cb = [&remote_file_url, &remote_file_md5, estimate_timeout,

                                &local_file_path, file_size](HttpClient* client) {

                RETURN_IF_ERROR(client->init(remote_file_url));

                client->set_timeout_ms(estimate_timeout * 1000);

                RETURN_IF_ERROR(client->download(local_file_path));

                std::error_code ec;

                // Check file length

                uint64_t local_file_size = std::filesystem::file_size(local_file_path, ec);

                if (ec) {

                    LOG(WARNING) << "download file error" << ec.message();

                    return Status::IOError("can't retrive file_size of {}, due to {}",

                                           local_file_path, ec.message());

                }

                if (local_file_size != file_size) {

                    LOG(WARNING) << "download file length error"

                                 << ", remote_path=" << remote_file_url

                                 << ", file_size=" << file_size

                                 << ", local_file_size=" << local_file_size;

                    return Status::InternalError("downloaded file size is not equal");

                }

                if (!remote_file_md5.empty()) { // keep compatibility

                    std::string local_file_md5;

                    RETURN_IF_ERROR(io::global_local_filesystem()->md5sum(local_file_path,

                                                                          &local_file_md5));

                    if (local_file_md5 != remote_file_md5) {

                        LOG(WARNING) << "download file md5 error"

                                     << ", remote_file_url=" << remote_file_url

                                     << ", local_file_path=" << local_file_path

                                     << ", remote_file_md5=" << remote_file_md5

                                     << ", local_file_md5=" << local_file_md5;

                        return Status::RuntimeError(

                                "download file {} md5 is not equal, local={}, remote={}",

                                remote_file_url, local_file_md5, remote_file_md5);

                    }

                }

                return io::global_local_filesystem()->permission(

                        local_file_path, io::LocalFileSystem::PERMS_OWNER_RW);

            };

            auto status = HttpClient::execute_with_retry(kDownloadFileMaxRetry, 1, download_cb);

            if (!status.ok()) {

                LOG(WARNING) << "failed to download file from " << remote_file_url

                             << ", status: " << status.to_string();

                return status;

            }

            // local_files always keep the updated local files

            local_files[filename] = LocalFileStat {file_size, remote_file_md5};

        }

        uint64_t total_time_ms = watch.elapsed_time() / 1000 / 1000;

        total_time_ms = total_time_ms > 0 ? total_time_ms : 0;

        double copy_rate = 0.0;

        if (total_time_ms > 0) {

            copy_rate = total_file_size / ((double)total_time_ms) / 1000;

        }

        LOG(INFO) << fmt::format(

                "succeed to copy remote tablet {} to local tablet {}, total file size: {} B, cost: "

                "{} ms, rate: {} MB/s",

                remote_tablet_id, local_tablet_id, total_file_size, total_time_ms, copy_rate);

        // local_files: contain all remote files and local files

        // finally, delete local files which are not in remote

        for (const auto& [local_file, local_filestat] : local_files) {

            // replace the tablet id in local file name with the remote tablet id,

            // in order to compare the file name.

            std::string new_name;

            Status st = _replace_tablet_id(local_file, remote_tablet_id, &new_name);

            if (!st.ok()) {

                LOG(WARNING) << "failed to replace tablet id. unknown local file: " << st

                             << ". ignore it";

                continue;

            }

            VLOG_CRITICAL << "new file name after replace tablet id: " << new_name;

            const auto& find = remote_files.find(new_name);

            if (find != remote_files.end()) {

                continue;

            }

            // delete

            std::string full_local_file = local_path + "/" + local_file;

            LOG(INFO) << "begin to delete local snapshot file: " << full_local_file

                      << ", it does not exist in remote";

            if (remove(full_local_file.c_str()) != 0) {

                LOG(WARNING) << "failed to delete unknown local file: " << full_local_file

                             << ", error: " << strerror(errno)

                             << ", file size: " << local_filestat.size << ", ignore it";

            }

        }

        ++finished_num;

    }

    LOG(INFO) << "finished to download snapshots. job: " << _job_id << ", task id: " << _task_id;

    return status;

}

// move the snapshot files in snapshot_path

// to tablet_path

// If overwrite, just replace the tablet_path with snapshot_path,

// else: (TODO)

//

// MUST hold tablet's header lock, push lock, cumulative lock and base compaction lock

Status SnapshotLoader::move(const std::string& snapshot_path, TabletSharedPtr tablet,

                            bool overwrite) {

    auto tablet_path = tablet->tablet_path();

    auto store_path = tablet->data_dir()->path();

    LOG(INFO) << "begin to move snapshot files. from: " << snapshot_path << ", to: " << tablet_path

              << ", store: " << store_path << ", job: " << _job_id << ", task id: " << _task_id;

    Status status = Status::OK();

    // validate snapshot_path and tablet_path

    int64_t snapshot_tablet_id = 0;

    int32_t snapshot_schema_hash = 0;

    RETURN_IF_ERROR(_get_tablet_id_and_schema_hash_from_file_path(

            snapshot_path, &snapshot_tablet_id, &snapshot_schema_hash));

    int64_t tablet_id = 0;

    int32_t schema_hash = 0;

    RETURN_IF_ERROR(

            _get_tablet_id_and_schema_hash_from_file_path(tablet_path, &tablet_id, &schema_hash));

    if (tablet_id != snapshot_tablet_id || schema_hash != snapshot_schema_hash) {

        std::stringstream ss;

        ss << "path does not match. snapshot: " << snapshot_path

           << ", tablet path: " << tablet_path;

        LOG(WARNING) << ss.str();

        return Status::InternalError(ss.str());

    }

    DataDir* store = _engine.get_store(store_path);

    if (store == nullptr) {

        std::stringstream ss;

        ss << "failed to get store by path: " << store_path;

        LOG(WARNING) << ss.str();

        return Status::InternalError(ss.str());

    }

    if (!std::filesystem::exists(tablet_path)) {

        std::stringstream ss;

        ss << "tablet path does not exist: " << tablet_path;

        LOG(WARNING) << ss.str();

        return Status::InternalError(ss.str());

    }

    if (!std::filesystem::exists(snapshot_path)) {

        std::stringstream ss;

        ss << "snapshot path does not exist: " << snapshot_path;

        LOG(WARNING) << ss.str();

        return Status::InternalError(ss.str());

    }

    // rename the rowset ids and tabletid info in rowset meta

    auto res = _engine.snapshot_mgr()->convert_rowset_ids(snapshot_path, tablet_id,

                                                          tablet->replica_id(), tablet->table_id(),

                                                          tablet->partition_id(), schema_hash);

    if (!res.has_value()) [[unlikely]] {

        auto err_msg =

                fmt::format("failed to convert rowsetids in snapshot: {}, tablet path: {}, err: {}",

                            snapshot_path, tablet_path, res.error());

        LOG(WARNING) << err_msg;

        return Status::InternalError(err_msg);

    }

    if (overwrite) {

        std::vector<std::string> snapshot_files;

        RETURN_IF_ERROR(_get_existing_files_from_local(snapshot_path, &snapshot_files));

        // 1. simply delete the old dir and replace it with the snapshot dir

        try {

            // This remove seems soft enough, because we already get

            // tablet id and schema hash from this path, which

            // means this path is a valid path.

            std::filesystem::remove_all(tablet_path);

            VLOG_CRITICAL << "remove dir: " << tablet_path;

            std::filesystem::create_directory(tablet_path);

            VLOG_CRITICAL << "re-create dir: " << tablet_path;

        } catch (const std::filesystem::filesystem_error& e) {

            std::stringstream ss;

            ss << "failed to move tablet path: " << tablet_path << ". err: " << e.what();

            LOG(WARNING) << ss.str();

            return Status::InternalError(ss.str());

        }

        // link files one by one

        // files in snapshot dir will be moved in snapshot clean process

        std::vector<std::string> linked_files;

        for (auto& file : snapshot_files) {

            auto full_src_path = fmt::format("{}/{}", snapshot_path, file);

            auto full_dest_path = fmt::format("{}/{}", tablet_path, file);

            if (link(full_src_path.c_str(), full_dest_path.c_str()) != 0) {

                LOG(WARNING) << "failed to link file from " << full_src_path << " to "

                             << full_dest_path << ", err: " << std::strerror(errno);

                // clean the already linked files

                for (auto& linked_file : linked_files) {

                    remove(linked_file.c_str());

                }

                return Status::InternalError("move tablet failed");

            }

            linked_files.push_back(full_dest_path);

            VLOG_CRITICAL << "link file from " << full_src_path << " to " << full_dest_path;

        }

    } else {

        LOG(FATAL) << "only support overwrite now";

        __builtin_unreachable();

    }

    // snapshot loader not need to change tablet uid

    // fixme: there is no header now and can not call load_one_tablet here

    // reload header

    Status ost = _engine.tablet_manager()->load_tablet_from_dir(store, tablet_id, schema_hash,

                                                                tablet_path, true);

    if (!ost.ok()) {

        std::stringstream ss;

        ss << "failed to reload header of tablet: " << tablet_id;

        LOG(WARNING) << ss.str();

        return Status::InternalError(ss.str());

    }

    LOG(INFO) << "finished to reload header of tablet: " << tablet_id;

    return status;

}

Status SnapshotLoader::_get_tablet_id_and_schema_hash_from_file_path(const std::string& src_path,

                                                                     int64_t* tablet_id,

                                                                     int32_t* schema_hash) {

    // path should be like: /path/.../tablet_id/schema_hash

    // we try to extract tablet_id from path

    size_t pos = src_path.find_last_of("/");

    if (pos == std::string::npos || pos == src_path.length() - 1) {

        return Status::InternalError("failed to get tablet id from path: {}", src_path);

    }

    std::string schema_hash_str = src_path.substr(pos + 1);

    std::stringstream ss1;

    ss1 << schema_hash_str;

    ss1 >> *schema_hash;

    // skip schema hash part

    size_t pos2 = src_path.find_last_of("/", pos - 1);

    if (pos2 == std::string::npos) {

        return Status::InternalError("failed to get tablet id from path: {}", src_path);

    }

    std::string tablet_str = src_path.substr(pos2 + 1, pos - pos2);

    std::stringstream ss2;

    ss2 << tablet_str;

    ss2 >> *tablet_id;

    VLOG_CRITICAL << "get tablet id " << *tablet_id << ", schema hash: " << *schema_hash

                  << " from path: " << src_path;

    return Status::OK();

}

Status SnapshotLoader::_check_local_snapshot_paths(

        const std::map<std::string, std::string>& src_to_dest_path, bool check_src) {

    bool res = true;

    for (const auto& pair : src_to_dest_path) {

        std::string path;

        if (check_src) {

            path = pair.first;

        } else {

            path = pair.second;

        }

        RETURN_IF_ERROR(io::global_local_filesystem()->is_directory(path, &res));

        if (!res) {

            std::stringstream ss;

            ss << "snapshot path is not directory or does not exist: " << path;

            LOG(WARNING) << ss.str();

            return Status::RuntimeError(ss.str());

        }

    }

    LOG(INFO) << "all local snapshot paths are existing. num: " << src_to_dest_path.size();

    return Status::OK();

}

Status SnapshotLoader::_get_existing_files_from_local(const std::string& local_path,

                                                      std::vector<std::string>* local_files) {

    bool exists = true;

    std::vector<io::FileInfo> files;

    RETURN_IF_ERROR(io::global_local_filesystem()->list(local_path, true, &files, &exists));

    for (auto& file : files) {

        local_files->push_back(file.file_name);

    }

    LOG(INFO) << "finished to list files in local path: " << local_path

              << ", file num: " << local_files->size();

    return Status::OK();

}

Status SnapshotLoader::_replace_tablet_id(const std::string& file_name, int64_t tablet_id,

                                          std::string* new_file_name) {

    // eg:

    // 10007.hdr

    // 10007_2_2_0_0.idx

    // 10007_2_2_0_0.dat

    if (_end_with(file_name, ".hdr")) {

        std::stringstream ss;

        ss << tablet_id << ".hdr";

        *new_file_name = ss.str();

        return Status::OK();

    } else if (_end_with(file_name, ".idx") || _end_with(file_name, ".dat")) {

        *new_file_name = file_name;

        return Status::OK();