// 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 "io/cache/cached_remote_file_reader.h"

#include <brpc/controller.h>

#include <fmt/format.h>

#include <gen_cpp/Types_types.h>

#include <gen_cpp/internal_service.pb.h>

#include <glog/logging.h>

#include <algorithm>

#include <atomic>

#include <condition_variable>

#include <cstring>

#include <functional>

#include <list>

#include <memory>

#include <mutex>

#include <thread>

#include <vector>

#include "cloud/cloud_warm_up_manager.h"

#include "cloud/config.h"

#include "common/compiler_util.h" // IWYU pragma: keep

#include "common/config.h"

#include "cpp/sync_point.h"

#include "cpp/token_bucket_rate_limiter.h"

#include "io/cache/block_file_cache.h"

#include "io/cache/block_file_cache_factory.h"

#include "io/cache/block_file_cache_profile.h"

#include "io/cache/file_block.h"

#include "io/cache/file_cache_common.h"

#include "io/cache/peer_file_cache_reader.h"

#include "io/fs/file_reader.h"

#include "io/fs/local_file_system.h"

#include "io/io_common.h"

#include "runtime/exec_env.h"

#include "runtime/runtime_profile.h"

#include "runtime/thread_context.h"

#include "runtime/workload_management/io_throttle.h"

#include "service/backend_options.h"

#include "util/bit_util.h"

#include "util/brpc_client_cache.h" // BrpcClientCache

#include "util/client_cache.h"

#include "util/concurrency_stats.h"

#include "util/debug_points.h"

namespace doris::io {

bvar::Adder<uint64_t> s3_read_counter("cached_remote_reader_s3_read");

bvar::Adder<uint64_t> peer_read_counter("cached_remote_reader_peer_read");

bvar::LatencyRecorder g_skip_cache_num("cached_remote_reader_skip_cache_num");

bvar::Adder<uint64_t> g_skip_cache_sum("cached_remote_reader_skip_cache_sum");

bvar::Adder<uint64_t> g_skip_local_cache_io_sum_bytes(

        "cached_remote_reader_skip_local_cache_io_sum_bytes");

bvar::Adder<uint64_t> g_read_cache_direct_whole_num("cached_remote_reader_cache_direct_whole_num");

bvar::Adder<uint64_t> g_read_cache_direct_partial_num(

        "cached_remote_reader_cache_direct_partial_num");

bvar::Adder<uint64_t> g_read_cache_indirect_num("cached_remote_reader_cache_indirect_num");

bvar::Adder<uint64_t> g_read_cache_direct_whole_bytes(

        "cached_remote_reader_cache_direct_whole_bytes");

bvar::Adder<uint64_t> g_read_cache_direct_partial_bytes(

        "cached_remote_reader_cache_direct_partial_bytes");

bvar::Adder<uint64_t> g_read_cache_indirect_bytes("cached_remote_reader_cache_indirect_bytes");

bvar::Adder<uint64_t> g_read_cache_indirect_total_bytes(

        "cached_remote_reader_cache_indirect_total_bytes");

bvar::Adder<uint64_t> g_read_cache_self_heal_on_not_found(

        "cached_remote_reader_self_heal_on_not_found");

bvar::Window<bvar::Adder<uint64_t>> g_read_cache_indirect_bytes_1min_window(

        "cached_remote_reader_indirect_bytes_1min_window", &g_read_cache_indirect_bytes, 60);

bvar::Window<bvar::Adder<uint64_t>> g_read_cache_indirect_total_bytes_1min_window(

        "cached_remote_reader_indirect_total_bytes_1min_window", &g_read_cache_indirect_total_bytes,

        60);

bvar::Adder<uint64_t> g_failed_get_peer_addr_counter(

        "cached_remote_reader_failed_get_peer_addr_counter");

CachedRemoteFileReader::CachedRemoteFileReader(FileReaderSPtr remote_file_reader,

                                               const FileReaderOptions& opts)

        : _tablet_id(opts.tablet_id), _remote_file_reader(std::move(remote_file_reader)) {

    DCHECK(!opts.is_doris_table || _tablet_id > 0);

    _is_doris_table = opts.is_doris_table;

    if (_is_doris_table) {

        _cache_hash = BlockFileCache::hash(path().filename().native());

        _cache = FileCacheFactory::instance()->get_by_path(_cache_hash);

        if (config::enable_read_cache_file_directly) {

            // this is designed for and test in doris table, external table need extra tests

            _cache_file_readers = _cache->get_blocks_by_key(_cache_hash);

        }

    } else {

        // Use path and modification time to build cache key

        std::string unique_path = fmt::format("{}:{}", path().native(), opts.mtime);

        _cache_hash = BlockFileCache::hash(unique_path);

        if (opts.cache_base_path.empty()) {

            // if cache path is not specified by session variable, chose randomly.

            _cache = FileCacheFactory::instance()->get_by_path(_cache_hash);

        } else {

            // from query session variable: file_cache_base_path

            _cache = FileCacheFactory::instance()->get_by_path(opts.cache_base_path);

            if (_cache == nullptr) {

                LOG(WARNING) << "Can't get cache from base path: " << opts.cache_base_path

                             << ", using random instead.";

                _cache = FileCacheFactory::instance()->get_by_path(_cache_hash);

            }

        }

    }

}

void CachedRemoteFileReader::_insert_file_reader(FileBlockSPtr file_block) {

    if (_is_doris_table && config::enable_read_cache_file_directly) {

        std::lock_guard lock(_mtx);

        DCHECK(file_block->state() == FileBlock::State::DOWNLOADED);

        file_block->_owned_by_cached_reader = true;

        _cache_file_readers.emplace(file_block->offset(), std::move(file_block));

    }

}

CachedRemoteFileReader::~CachedRemoteFileReader() {

    for (auto& it : _cache_file_readers) {

        it.second->_owned_by_cached_reader = false;

    }

    static_cast<void>(close());

}

Status CachedRemoteFileReader::close() {

    return _remote_file_reader->close();

}

std::pair<size_t, size_t> CachedRemoteFileReader::s_align_size(size_t offset, size_t read_size,

                                                               size_t length) {

    size_t left = offset;

    size_t right = offset + read_size - 1;

    size_t align_left =

            (left / config::file_cache_each_block_size) * config::file_cache_each_block_size;

    size_t align_right =

            (right / config::file_cache_each_block_size + 1) * config::file_cache_each_block_size;

    align_right = align_right < length ? align_right : length;

    size_t align_size = align_right - align_left;

    if (align_size < config::file_cache_each_block_size && align_left != 0) {

        align_size += config::file_cache_each_block_size;

        align_left -= config::file_cache_each_block_size;

    }

    return std::make_pair(align_left, align_size);

}

namespace {

// Execute S3 read

Status execute_s3_read(size_t empty_start, size_t& size, std::unique_ptr<char[]>& buffer,

                       ReadStatistics& stats, const IOContext* io_ctx,

                       FileReaderSPtr remote_file_reader) {

    s3_read_counter << 1;

    SCOPED_RAW_TIMER(&stats.remote_read_timer);

    stats.from_peer_cache = false;

    return remote_file_reader->read_at(empty_start, Slice(buffer.get(), size), &size, io_ctx);

}

// Get peer connection info from tablet_id

std::pair<std::string, int> get_peer_connection_info(int64_t tablet_id,

                                                     const std::string& file_path) {

    std::string host = "";

    int port = 0;

    DCHECK(tablet_id > 0);

    auto& manager = ExecEnv::GetInstance()->storage_engine().to_cloud().cloud_warm_up_manager();

    if (auto tablet_info = manager.get_balanced_tablet_info(tablet_id)) {

        host = tablet_info->first;

        port = tablet_info->second;

    } else {

        LOG_EVERY_N(WARNING, 100) << "get peer connection info not found"

                                  << ", tablet_id=" << tablet_id << ", file_path=" << file_path;

    }

    DBUG_EXECUTE_IF("PeerFileCacheReader::_fetch_from_peer_cache_blocks", {

        host = dp->param<std::string>("host", "127.0.0.1");

        port = dp->param("port", 9060);

        LOG_WARNING("debug point PeerFileCacheReader::_fetch_from_peer_cache_blocks")

                .tag("host", host)

                .tag("port", port);

    });

    return {host, port};

}

// Execute peer read with fallback to S3

// file_size is the size of the file

// used to calculate the rightmost boundary value of the block, due to inaccurate current block meta information.

Status execute_peer_read(const std::vector<FileBlockSPtr>& empty_blocks, size_t empty_start,

                         size_t& size, std::unique_ptr<char[]>& buffer,

                         const std::string& file_path, size_t file_size, bool is_doris_table,

                         int64_t tablet_id, ReadStatistics& stats, const IOContext* io_ctx) {

    auto [host, port] = get_peer_connection_info(tablet_id, file_path);

    VLOG_DEBUG << "PeerFileCacheReader read from peer, host=" << host << ", port=" << port

               << ", file_path=" << file_path;

    if (host.empty() || port == 0) {

        g_failed_get_peer_addr_counter << 1;

        VLOG_DEBUG << "PeerFileCacheReader host or port is empty"

                   << ", host=" << host << ", port=" << port << ", file_path=" << file_path;

        return Status::InternalError<false>("host or port is empty");

    }

    SCOPED_RAW_TIMER(&stats.peer_read_timer);

    peer_read_counter << 1;

    PeerFileCacheReader peer_reader(file_path, is_doris_table, host, port);

    auto st = peer_reader.fetch_blocks(empty_blocks, empty_start, Slice(buffer.get(), size), &size,

                                       file_size, io_ctx);

    if (!st.ok()) {

        VLOG_DEBUG << "PeerFileCacheReader read from peer failed"

                   << ", host=" << host << ", port=" << port << ", error=" << st.msg();

    }

    stats.from_peer_cache = true;

    return st;

}

} // anonymous namespace

Status CachedRemoteFileReader::_execute_remote_read(const std::vector<FileBlockSPtr>& empty_blocks,

                                                    size_t empty_start, size_t& size,

                                                    std::unique_ptr<char[]>& buffer,

                                                    ReadStatistics& stats,

                                                    const IOContext* io_ctx) {

    DBUG_EXECUTE_IF("CachedRemoteFileReader.read_at_impl.change_type", {

        // Determine read type from debug point or default to S3

        std::string read_type = "s3";

        read_type = dp->param<std::string>("type", "s3");

        LOG_WARNING("CachedRemoteFileReader.read_at_impl.change_type")

                .tag("path", path().native())

                .tag("off", empty_start)

                .tag("size", size)

                .tag("type", read_type);

        // Execute appropriate read strategy

        if (read_type == "s3") {

            return execute_s3_read(empty_start, size, buffer, stats, io_ctx, _remote_file_reader);

        } else {

            return execute_peer_read(empty_blocks, empty_start, size, buffer, path().native(),

                                     this->size(), _is_doris_table, _tablet_id, stats, io_ctx);

        }

    });

    if (!doris::config::is_cloud_mode() || !_is_doris_table || io_ctx->is_warmup ||

        !doris::config::enable_cache_read_from_peer) {

        return execute_s3_read(empty_start, size, buffer, stats, io_ctx, _remote_file_reader);

    } else {

        // first try peer read, if peer failed, fallback to S3

        // peer timeout is 5 seconds

        // TODO(dx): here peer and s3 reader need to get data in parallel, and take the one that is correct and returns first

        // ATTN: Save original size before peer read, as it may be modified by fetch_blocks, read peer ref size

        size_t original_size = size;

        auto st = execute_peer_read(empty_blocks, empty_start, size, buffer, path().native(),

                                    this->size(), _is_doris_table, _tablet_id, stats, io_ctx);

        if (!st.ok()) {

            // Restore original size for S3 fallback, as peer read may have modified it

            size = original_size;

            // Fallback to S3

            return execute_s3_read(empty_start, size, buffer, stats, io_ctx, _remote_file_reader);

        }

        return st;

    }

}

Status CachedRemoteFileReader::read_at_impl(size_t offset, Slice result, size_t* bytes_read,

                                            const IOContext* io_ctx) {

    size_t already_read = 0;

    SCOPED_CONCURRENCY_COUNT(ConcurrencyStatsManager::instance().cached_remote_reader_read_at);

    const IOContext default_io_ctx;

    if (io_ctx == nullptr) {

        io_ctx = &default_io_ctx;

    }

    DCHECK(io_ctx);

    const bool is_dryrun = io_ctx->is_dryrun;

    DCHECK(!closed());

    if (offset > size()) {

        return Status::InvalidArgument(

                fmt::format("offset exceeds file size(offset: {}, file size: {}, path: {})", offset,

                            size(), path().native()));

    }

    size_t bytes_req = result.size;

    bytes_req = std::min(bytes_req, size() - offset);

    if (UNLIKELY(bytes_req == 0)) {

        *bytes_read = 0;

        return Status::OK();

    }

    ReadStatistics stats;

    stats.bytes_read += bytes_req;

    bool read_success = false;

    MonotonicStopWatch read_at_sw;

    read_at_sw.start();

    auto defer_func = [&](int*) {

        if (config::print_stack_when_cache_miss) {

            if (io_ctx->file_cache_stats == nullptr && !stats.hit_cache && !io_ctx->is_warmup) {

                LOG_INFO("[verbose] {}", Status::InternalError<true>("not hit cache"));

            }

        }

        if (!stats.hit_cache && config::read_cluster_cache_opt_verbose_log) {

            LOG_INFO(

                    "[verbose] not hit cache, path: {}, offset: {}, size: {}, cost: {} ms, warmup: "

                    "{}",

                    path().native(), offset, bytes_req, read_at_sw.elapsed_time_milliseconds(),

                    io_ctx->is_warmup);

        }

        if (is_dryrun) {

            return;

        }

        if (!read_success) {

            return;

        }

        if (!io_ctx->is_warmup) {

            // update stats increment in this reading procedure for file cache metrics

            FileCacheStatistics fcache_stats_increment;

            _update_stats(stats, &fcache_stats_increment, io_ctx->is_inverted_index);

            io::FileCacheMetrics::instance().update(&fcache_stats_increment);

        }

        if (io_ctx->file_cache_stats) {

            // update stats in io_ctx, for query profile

            _update_stats(stats, io_ctx->file_cache_stats, io_ctx->is_inverted_index);

        }

    };

    std::unique_ptr<int, decltype(defer_func)> defer((int*)0x01, std::move(defer_func));

    if (_is_doris_table && config::enable_read_cache_file_directly) {

        // read directly

        SCOPED_RAW_TIMER(&stats.read_cache_file_directly_timer);

        size_t need_read_size = bytes_req;

        std::shared_lock lock(_mtx);

        if (!_cache_file_readers.empty()) {

            // find the last offset > offset.

            auto iter = _cache_file_readers.upper_bound(offset);

            if (iter != _cache_file_readers.begin()) {

                iter--;

            }

            size_t cur_offset = offset;

            while (need_read_size != 0 && iter != _cache_file_readers.end()) {

                if (iter->second->offset() > cur_offset ||

                    iter->second->range().right < cur_offset) {

                    break;

                }

                size_t file_offset = cur_offset - iter->second->offset();

                size_t reserve_bytes =

                        std::min(need_read_size, iter->second->range().size() - file_offset);

                if (is_dryrun) [[unlikely]] {

                    g_skip_local_cache_io_sum_bytes << reserve_bytes;

                } else {

                    SCOPED_RAW_TIMER(&stats.local_read_timer);

                    if (!iter->second

                                 ->read(Slice(result.data + (cur_offset - offset), reserve_bytes),

                                        file_offset)

                                 .ok()) { //TODO: maybe read failed because block evict, should handle error

                        break;

                    }

                    stats.bytes_read_from_local += reserve_bytes;

                }

                _cache->add_need_update_lru_block(iter->second);

                need_read_size -= reserve_bytes;

                cur_offset += reserve_bytes;

                already_read += reserve_bytes;

                iter++;

            }

            if (need_read_size == 0) {

                *bytes_read = bytes_req;

                stats.hit_cache = true;

                g_read_cache_direct_whole_num << 1;

                g_read_cache_direct_whole_bytes << bytes_req;

                read_success = true;

                return Status::OK();

            } else {

                g_read_cache_direct_partial_num << 1;

                g_read_cache_direct_partial_bytes << already_read;

            }

        }

    }

    // read from cache or remote

    g_read_cache_indirect_num << 1;

    size_t indirect_read_bytes = 0;

    auto [align_left, align_size] =

            s_align_size(offset + already_read, bytes_req - already_read, size());

    CacheContext cache_context(io_ctx);

    cache_context.stats = &stats;

    cache_context.tablet_id = _tablet_id;

    MonotonicStopWatch sw;

    sw.start();

    ConcurrencyStatsManager::instance().cached_remote_reader_get_or_set->increment();

    FileBlocksHolder holder =

            _cache->get_or_set(_cache_hash, align_left, align_size, cache_context);

    ConcurrencyStatsManager::instance().cached_remote_reader_get_or_set->decrement();

    stats.cache_get_or_set_timer += sw.elapsed_time();

    std::vector<FileBlockSPtr> empty_blocks;

    for (auto& block : holder.file_blocks) {

        switch (block->state()) {

        case FileBlock::State::EMPTY:

            VLOG_DEBUG << fmt::format("Block EMPTY path={} hash={}:{}:{} offset={} cache_path={}",

                                      path().native(), _cache_hash.to_string(), _cache_hash.high(),

                                      _cache_hash.low(), block->offset(), block->get_cache_file());

            block->get_or_set_downloader();

            if (block->is_downloader()) {

                empty_blocks.push_back(block);

                TEST_SYNC_POINT_CALLBACK("CachedRemoteFileReader::EMPTY");

            }

            stats.hit_cache = false;

            break;

        case FileBlock::State::SKIP_CACHE:

            VLOG_DEBUG << fmt::format(

                    "Block SKIP_CACHE path={} hash={}:{}:{} offset={} cache_path={}",

                    path().native(), _cache_hash.to_string(), _cache_hash.high(), _cache_hash.low(),

                    block->offset(), block->get_cache_file());

            empty_blocks.push_back(block);

            stats.hit_cache = false;

            stats.skip_cache = true;

            break;

        case FileBlock::State::DOWNLOADING:

            stats.hit_cache = false;

            break;

        case FileBlock::State::DOWNLOADED:

            _insert_file_reader(block);

            break;

        }

    }

    size_t empty_start = 0;

    size_t empty_end = 0;

    if (!empty_blocks.empty()) {

        empty_start = empty_blocks.front()->range().left;

        empty_end = empty_blocks.back()->range().right;

        size_t size = empty_end - empty_start + 1;

        std::unique_ptr<char[]> buffer(new char[size]);

        // Apply rate limiting for warmup download tasks (node level)

        // Rate limiting is applied before remote read to limit both S3 read and local cache write

        if (io_ctx->is_warmup) {

            auto* rate_limiter = ExecEnv::GetInstance()->warmup_download_rate_limiter();

            if (rate_limiter != nullptr) {

                rate_limiter->add(size);

            }

        }

        // Determine read type and execute remote read

        RETURN_IF_ERROR(

                _execute_remote_read(empty_blocks, empty_start, size, buffer, stats, io_ctx));

        bool empty_blocks_from_peer_cache = stats.from_peer_cache;

        {

            SCOPED_CONCURRENCY_COUNT(

                    ConcurrencyStatsManager::instance().cached_remote_reader_write_back);

            for (auto& block : empty_blocks) {

                if (block->state() == FileBlock::State::SKIP_CACHE) {

                    continue;

                }

                SCOPED_RAW_TIMER(&stats.local_write_timer);

                char* cur_ptr = buffer.get() + block->range().left - empty_start;

                size_t block_size = block->range().size();

                Status st = block->append(Slice(cur_ptr, block_size));

                if (st.ok()) {

                    st = block->finalize();

                }

                if (!st.ok()) {

                    LOG_EVERY_N(WARNING, 100)

                            << "Write data to file cache failed. err=" << st.msg();

                } else {

                    _insert_file_reader(block);

                }

                stats.bytes_write_into_file_cache += block_size;

            }

        }

        // copy from memory directly

        size_t right_offset = offset + bytes_req - 1;

        if (empty_start <= right_offset && empty_end >= offset + already_read && !is_dryrun) {

            size_t copy_left_offset = std::max(offset + already_read, empty_start);

            size_t copy_right_offset = std::min(right_offset, empty_end);

            char* dst = result.data + (copy_left_offset - offset);

            char* src = buffer.get() + (copy_left_offset - empty_start);

            size_t copy_size = copy_right_offset - copy_left_offset + 1;

            memcpy(dst, src, copy_size);

            indirect_read_bytes += copy_size;

            if (empty_blocks_from_peer_cache) {

                stats.bytes_read_from_peer += copy_size;

            } else {

                stats.bytes_read_from_remote += copy_size;

            }

        }

    }

    size_t current_offset = offset + already_read;

    size_t end_offset = offset + bytes_req - 1;

    bool need_self_heal = false;

    *bytes_read = already_read;

    for (auto& block : holder.file_blocks) {

        if (current_offset > end_offset) {

            break;

        }

        size_t left = block->range().left;

        size_t right = block->range().right;

        if (right < current_offset) {

            continue;

        }

        size_t read_size =

                end_offset > right ? right - current_offset + 1 : end_offset - current_offset + 1;

        if (empty_start <= left && right <= empty_end) {

            *bytes_read += read_size;

            current_offset = right + 1;

            continue;

        }

        FileBlock::State block_state = block->state();

        int64_t wait_time = 0;

        static int64_t max_wait_time = 10;

        TEST_SYNC_POINT_CALLBACK("CachedRemoteFileReader::max_wait_time", &max_wait_time);

        if (block_state != FileBlock::State::DOWNLOADED) {

            SCOPED_CONCURRENCY_COUNT(

                    ConcurrencyStatsManager::instance().cached_remote_reader_blocking);

            do {

                SCOPED_RAW_TIMER(&stats.remote_wait_timer);

                SCOPED_RAW_TIMER(&stats.remote_read_timer);

                TEST_SYNC_POINT_CALLBACK("CachedRemoteFileReader::DOWNLOADING");

                block_state = block->wait();

                if (block_state != FileBlock::State::DOWNLOADING) {

                    break;

                }

            } while (++wait_time < max_wait_time);

        }

        if (wait_time == max_wait_time) [[unlikely]] {

            LOG_WARNING("Waiting too long for the download to complete");

        }

        {

            Status st;

            /*

             * If block_state == EMPTY, the thread reads the data from remote.

             * If block_state == DOWNLOADED, when the cache file is deleted by the other process,

             * the thread reads the data from remote too.

             */

            if (block_state == FileBlock::State::DOWNLOADED) {

                if (is_dryrun) [[unlikely]] {

                    g_skip_local_cache_io_sum_bytes << read_size;

                } else {

                    size_t file_offset = current_offset - left;

                    SCOPED_RAW_TIMER(&stats.local_read_timer);

                    SCOPED_CONCURRENCY_COUNT(

                            ConcurrencyStatsManager::instance().cached_remote_reader_local_read);

                    st = block->read(Slice(result.data + (current_offset - offset), read_size),

                                     file_offset);

                    if (st.ok()) {

                        indirect_read_bytes += read_size;

                        stats.bytes_read_from_local += read_size;

                    }

                }

            }

            if (!st || block_state != FileBlock::State::DOWNLOADED) {

                if (is_dryrun) [[unlikely]] {

                    // dryrun mode uses a null buffer, skip actual remote IO

                } else {

                    if (block_state == FileBlock::State::DOWNLOADED &&

                        st.is<ErrorCode::NOT_FOUND>()) {

                        need_self_heal = true;

                        g_read_cache_self_heal_on_not_found << 1;

                        LOG_EVERY_N(WARNING, 100)

                                << "Cache block file is missing, will self-heal by clearing cache "

                                   "hash. "

                                << "path=" << path().native()

                                << ", hash=" << _cache_hash.to_string() << ", offset=" << left

                                << ", err=" << st.msg();

                    }

                    LOG(WARNING) << "Read data failed from file cache downloaded by others. err="

                                 << st.msg() << ", block state=" << block_state;

                    size_t nest_bytes_read {0};

                    stats.hit_cache = false;

                    stats.from_peer_cache = false;

                    s3_read_counter << 1;

                    SCOPED_RAW_TIMER(&stats.remote_read_timer);

                    RETURN_IF_ERROR(_remote_file_reader->read_at(

                            current_offset,

                            Slice(result.data + (current_offset - offset), read_size),

                            &nest_bytes_read));

                    indirect_read_bytes += read_size;

                    DCHECK(nest_bytes_read == read_size);

                    stats.bytes_read_from_remote += nest_bytes_read;

                }

            }

        }

        *bytes_read += read_size;

        current_offset = right + 1;

    }

    if (need_self_heal && _cache != nullptr) {

        _cache->remove_if_cached_async(_cache_hash);

    }

    g_read_cache_indirect_bytes << indirect_read_bytes;

    g_read_cache_indirect_total_bytes << *bytes_read;

    DCHECK(*bytes_read == bytes_req);

    if (!is_dryrun) {

        DCHECK_EQ(stats.bytes_read_from_local + stats.bytes_read_from_remote +

                          stats.bytes_read_from_peer,

                  bytes_req);

    }

    read_success = true;

    return Status::OK();

}

void CachedRemoteFileReader::_update_stats(const ReadStatistics& read_stats,

                                           FileCacheStatistics* statis,

                                           bool is_inverted_index) const {

    if (statis == nullptr) {

        return;

    }

    if (read_stats.bytes_read_from_local > 0) {

        statis->num_local_io_total++;

        statis->bytes_read_from_local += read_stats.bytes_read_from_local;

    }

    if (read_stats.bytes_read_from_remote > 0) {

        statis->num_remote_io_total++;

        statis->bytes_read_from_remote += read_stats.bytes_read_from_remote;

        statis->remote_io_timer += read_stats.remote_read_timer;

    }

    if (read_stats.bytes_read_from_peer > 0) {

        statis->num_peer_io_total++;

        statis->bytes_read_from_peer += read_stats.bytes_read_from_peer;

        statis->peer_io_timer += read_stats.peer_read_timer;

    }

    statis->remote_wait_timer += read_stats.remote_wait_timer;

    statis->local_io_timer += read_stats.local_read_timer;

    statis->num_skip_cache_io_total += read_stats.skip_cache;

    statis->bytes_write_into_cache += read_stats.bytes_write_into_file_cache;

    statis->write_cache_io_timer += read_stats.local_write_timer;

    statis->read_cache_file_directly_timer += read_stats.read_cache_file_directly_timer;

    statis->cache_get_or_set_timer += read_stats.cache_get_or_set_timer;

    statis->lock_wait_timer += read_stats.lock_wait_timer;

    statis->get_timer += read_stats.get_timer;

    statis->set_timer += read_stats.set_timer;

    if (is_inverted_index) {

        if (read_stats.bytes_read_from_local > 0) {

            statis->inverted_index_num_local_io_total++;

            statis->inverted_index_bytes_read_from_local += read_stats.bytes_read_from_local;

        }

        if (read_stats.bytes_read_from_remote > 0) {

            statis->inverted_index_num_remote_io_total++;

            statis->inverted_index_bytes_read_from_remote += read_stats.bytes_read_from_remote;

            statis->inverted_index_remote_io_timer += read_stats.remote_read_timer;

        }

        if (read_stats.bytes_read_from_peer > 0) {

            statis->inverted_index_num_peer_io_total++;

            statis->inverted_index_bytes_read_from_peer += read_stats.bytes_read_from_peer;

            statis->inverted_index_peer_io_timer += read_stats.peer_read_timer;

        }

        statis->inverted_index_local_io_timer += read_stats.local_read_timer;

    }

    g_skip_cache_sum << read_stats.skip_cache;

}

void CachedRemoteFileReader::prefetch_range(size_t offset, size_t size, const IOContext* io_ctx) {

    if (offset >= this->size() || size == 0) {

        return;

    }

    size = std::min(size, this->size() - offset);

    ThreadPool* pool = ExecEnv::GetInstance()->segment_prefetch_thread_pool();

    if (pool == nullptr) {

        return;

    }

    IOContext dryrun_ctx;

    if (io_ctx != nullptr) {

        dryrun_ctx = *io_ctx;

    }

    dryrun_ctx.is_dryrun = true;

    dryrun_ctx.query_id = nullptr;

    dryrun_ctx.file_cache_stats = nullptr;

    dryrun_ctx.file_reader_stats = nullptr;

    LOG_IF(INFO, config::enable_segment_prefetch_verbose_log)

            << fmt::format("[verbose] Submitting prefetch task for offset={} size={}, file={}",

                           offset, size, path().filename().native());

    std::weak_ptr<CachedRemoteFileReader> weak_this = shared_from_this();

    auto st = pool->submit_func([weak_this, offset, size, dryrun_ctx]() {

        auto self = weak_this.lock();

        if (self == nullptr) {

            return;

        }

        size_t bytes_read;

        Slice dummy_buffer((char*)nullptr, size);

        (void)self->read_at_impl(offset, dummy_buffer, &bytes_read, &dryrun_ctx);

        LOG_IF(INFO, config::enable_segment_prefetch_verbose_log)

                << fmt::format("[verbose] Prefetch task completed for offset={} size={}, file={}",

                               offset, size, self->path().filename().native());

    });

    if (!st.ok()) {

        VLOG_DEBUG << "Failed to submit prefetch task for offset=" << offset << " size=" << size

                   << " error=" << st.to_string();

    }

}

} // namespace doris::io