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https://github.com/ClickHouse/ClickHouse.git
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1326 lines
44 KiB
C++
1326 lines
44 KiB
C++
#include "FileCache.h"
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#include <Common/randomSeed.h>
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#include <Common/SipHash.h>
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#include <Common/FileCacheSettings.h>
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#include <IO/ReadHelpers.h>
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#include <IO/WriteBufferFromFile.h>
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#include <IO/ReadSettings.h>
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#include <IO/WriteBufferFromString.h>
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#include <IO/Operators.h>
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#include <pcg-random/pcg_random.hpp>
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#include <filesystem>
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#include <Common/LRUFileCachePriority.h>
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namespace fs = std::filesystem;
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namespace DB
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{
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namespace ErrorCodes
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{
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extern const int REMOTE_FS_OBJECT_CACHE_ERROR;
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extern const int LOGICAL_ERROR;
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}
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FileCache::FileCache(
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const String & cache_base_path_,
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const FileCacheSettings & cache_settings_)
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: cache_base_path(cache_base_path_)
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, max_size(cache_settings_.max_size)
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, max_element_size(cache_settings_.max_elements)
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, max_file_segment_size(cache_settings_.max_file_segment_size)
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, enable_filesystem_query_cache_limit(cache_settings_.enable_filesystem_query_cache_limit)
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, main_priority(std::make_unique<LRUFileCachePriority>())
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, stash_priority(std::make_unique<LRUFileCachePriority>())
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, max_stash_element_size(cache_settings_.max_elements)
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, enable_cache_hits_threshold(cache_settings_.enable_cache_hits_threshold)
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, log(&Poco::Logger::get("FileCache"))
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, allow_to_remove_persistent_segments_from_cache_by_default(cache_settings_.allow_to_remove_persistent_segments_from_cache_by_default)
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{
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}
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FileCache::Key FileCache::hash(const String & path)
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{
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return Key(sipHash128(path.data(), path.size()));
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}
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String FileCache::getPathInLocalCache(const Key & key, size_t offset, bool is_persistent) const
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{
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auto key_str = key.toString();
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return fs::path(cache_base_path)
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/ key_str.substr(0, 3)
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/ key_str
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/ (std::to_string(offset) + (is_persistent ? "_persistent" : ""));
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}
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String FileCache::getPathInLocalCache(const Key & key) const
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{
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auto key_str = key.toString();
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return fs::path(cache_base_path) / key_str.substr(0, 3) / key_str;
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}
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static bool isQueryInitialized()
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{
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return CurrentThread::isInitialized()
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&& CurrentThread::get().getQueryContext()
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&& !CurrentThread::getQueryId().empty();
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}
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bool FileCache::isReadOnly()
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{
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return !isQueryInitialized();
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}
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void FileCache::assertInitialized() const
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{
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if (!is_initialized)
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throw Exception(ErrorCodes::REMOTE_FS_OBJECT_CACHE_ERROR, "Cache not initialized");
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}
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FileCache::QueryContextPtr FileCache::getCurrentQueryContext(std::lock_guard<std::mutex> & cache_lock)
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{
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if (!isQueryInitialized())
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return nullptr;
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return getQueryContext(std::string(CurrentThread::getQueryId()), cache_lock);
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}
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FileCache::QueryContextPtr FileCache::getQueryContext(const String & query_id, std::lock_guard<std::mutex> & /* cache_lock */)
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{
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auto query_iter = query_map.find(query_id);
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return (query_iter == query_map.end()) ? nullptr : query_iter->second;
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}
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void FileCache::removeQueryContext(const String & query_id)
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{
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std::lock_guard cache_lock(mutex);
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auto query_iter = query_map.find(query_id);
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if (query_iter == query_map.end())
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{
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throw Exception(
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ErrorCodes::LOGICAL_ERROR,
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"Attempt to release query context that does not exist (query_id: {})",
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query_id);
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}
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query_map.erase(query_iter);
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}
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FileCache::QueryContextPtr FileCache::getOrSetQueryContext(
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const String & query_id, const ReadSettings & settings, std::lock_guard<std::mutex> & cache_lock)
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{
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if (query_id.empty())
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return nullptr;
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auto context = getQueryContext(query_id, cache_lock);
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if (context)
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return context;
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auto query_context = std::make_shared<QueryContext>(settings.max_query_cache_size, settings.skip_download_if_exceeds_query_cache);
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auto query_iter = query_map.emplace(query_id, query_context).first;
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return query_iter->second;
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}
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FileCache::QueryContextHolder FileCache::getQueryContextHolder(const String & query_id, const ReadSettings & settings)
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{
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std::lock_guard cache_lock(mutex);
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if (!enable_filesystem_query_cache_limit || settings.max_query_cache_size == 0)
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return {};
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/// if enable_filesystem_query_cache_limit is true, and max_query_cache_size large than zero,
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/// we create context query for current query.
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auto context = getOrSetQueryContext(query_id, settings, cache_lock);
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return QueryContextHolder(query_id, this, context);
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}
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void FileCache::QueryContext::remove(const Key & key, size_t offset, size_t size, std::lock_guard<std::mutex> & cache_lock)
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{
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if (cache_size < size)
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throw Exception(ErrorCodes::LOGICAL_ERROR, "Deleted cache size exceeds existing cache size");
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if (!skip_download_if_exceeds_query_cache)
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{
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auto record = records.find({key, offset});
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if (record != records.end())
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{
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record->second->removeAndGetNext(cache_lock);
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records.erase({key, offset});
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}
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}
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cache_size -= size;
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}
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void FileCache::QueryContext::reserve(const Key & key, size_t offset, size_t size, std::lock_guard<std::mutex> & cache_lock)
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{
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if (cache_size + size > max_cache_size)
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{
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throw Exception(
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ErrorCodes::LOGICAL_ERROR,
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"Reserved cache size exceeds the remaining cache size (key: {}, offset: {})",
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key.toString(), offset);
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}
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if (!skip_download_if_exceeds_query_cache)
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{
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auto record = records.find({key, offset});
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if (record == records.end())
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{
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auto queue_iter = priority->add(key, offset, 0, cache_lock);
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record = records.insert({{key, offset}, queue_iter}).first;
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}
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record->second->incrementSize(size, cache_lock);
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}
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cache_size += size;
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}
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void FileCache::QueryContext::use(const Key & key, size_t offset, std::lock_guard<std::mutex> & cache_lock)
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{
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if (skip_download_if_exceeds_query_cache)
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return;
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auto record = records.find({key, offset});
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if (record != records.end())
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record->second->use(cache_lock);
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}
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FileCache::QueryContextHolder::QueryContextHolder(
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const String & query_id_,
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FileCache * cache_,
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FileCache::QueryContextPtr context_)
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: query_id(query_id_)
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, cache(cache_)
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, context(context_)
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{
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}
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FileCache::QueryContextHolder::~QueryContextHolder()
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{
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/// If only the query_map and the current holder hold the context_query,
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/// the query has been completed and the query_context is released.
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if (context && context.use_count() == 2)
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cache->removeQueryContext(query_id);
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}
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void FileCache::initialize()
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{
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std::lock_guard cache_lock(mutex);
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if (!is_initialized)
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{
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if (fs::exists(cache_base_path))
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{
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try
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{
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loadCacheInfoIntoMemory(cache_lock);
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}
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catch (...)
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{
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tryLogCurrentException(__PRETTY_FUNCTION__);
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throw;
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}
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}
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else
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fs::create_directories(cache_base_path);
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is_initialized = true;
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}
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}
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void FileCache::useCell(
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const FileSegmentCell & cell, FileSegments & result, std::lock_guard<std::mutex> & cache_lock) const
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{
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auto file_segment = cell.file_segment;
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if (file_segment->isDownloaded()
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&& fs::file_size(getPathInLocalCache(file_segment->key(), file_segment->offset(), file_segment->isPersistent())) == 0)
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throw Exception(ErrorCodes::LOGICAL_ERROR,
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"Cannot have zero size downloaded file segments. Current file segment: {}",
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file_segment->range().toString());
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result.push_back(cell.file_segment);
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/**
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* A cell receives a queue iterator on first successful space reservation attempt
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* (space is reserved incrementally on each read buffer nextImpl() call).
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*/
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if (cell.queue_iterator)
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{
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/// Move to the end of the queue. The iterator remains valid.
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cell.queue_iterator->use(cache_lock);
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}
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}
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FileCache::FileSegmentCell * FileCache::getCell(
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const Key & key, size_t offset, std::lock_guard<std::mutex> & /* cache_lock */)
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{
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auto it = files.find(key);
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if (it == files.end())
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return nullptr;
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auto & offsets = it->second;
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auto cell_it = offsets.find(offset);
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if (cell_it == offsets.end())
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return nullptr;
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return &cell_it->second;
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}
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FileSegments FileCache::getImpl(
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const Key & key, const FileSegment::Range & range, std::lock_guard<std::mutex> & cache_lock)
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{
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/// Given range = [left, right] and non-overlapping ordered set of file segments,
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/// find list [segment1, ..., segmentN] of segments which intersect with given range.
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auto it = files.find(key);
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if (it == files.end())
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return {};
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const auto & file_segments = it->second;
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if (file_segments.empty())
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{
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auto key_path = getPathInLocalCache(key);
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files.erase(key);
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/// Note: it is guaranteed that there is no concurrency with files deletion,
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/// because cache files are deleted only inside FileCache and under cache lock.
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if (fs::exists(key_path))
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fs::remove_all(key_path);
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return {};
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}
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FileSegments result;
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auto segment_it = file_segments.lower_bound(range.left);
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if (segment_it == file_segments.end())
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{
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/// N - last cached segment for given file key, segment{N}.offset < range.left:
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/// segment{N} segment{N}
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/// [________ [_______]
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/// [__________] OR [________]
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/// ^ ^
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/// range.left range.left
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const auto & cell = file_segments.rbegin()->second;
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if (cell.file_segment->range().right < range.left)
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return {};
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useCell(cell, result, cache_lock);
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}
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else /// segment_it <-- segmment{k}
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{
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if (segment_it != file_segments.begin())
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{
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const auto & prev_cell = std::prev(segment_it)->second;
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const auto & prev_cell_range = prev_cell.file_segment->range();
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if (range.left <= prev_cell_range.right)
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{
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/// segment{k-1} segment{k}
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/// [________] [_____
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/// [___________
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/// ^
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/// range.left
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useCell(prev_cell, result, cache_lock);
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}
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}
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/// segment{k} ... segment{k-1} segment{k} segment{k}
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/// [______ [______] [____ [________
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/// [_________ OR [________ OR [______] ^
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/// ^ ^ ^ segment{k}.offset
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/// range.left range.left range.right
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while (segment_it != file_segments.end())
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{
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const auto & cell = segment_it->second;
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if (range.right < cell.file_segment->range().left)
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break;
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useCell(cell, result, cache_lock);
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++segment_it;
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}
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}
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return result;
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}
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FileSegments FileCache::splitRangeIntoCells(
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const Key & key, size_t offset, size_t size, FileSegment::State state, bool is_persistent, std::lock_guard<std::mutex> & cache_lock)
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{
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assert(size > 0);
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auto current_pos = offset;
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auto end_pos_non_included = offset + size;
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size_t current_cell_size;
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size_t remaining_size = size;
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FileSegments file_segments;
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while (current_pos < end_pos_non_included)
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{
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current_cell_size = std::min(remaining_size, max_file_segment_size);
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remaining_size -= current_cell_size;
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auto * cell = addCell(key, current_pos, current_cell_size, state, is_persistent, cache_lock);
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if (cell)
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file_segments.push_back(cell->file_segment);
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assert(cell);
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current_pos += current_cell_size;
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}
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assert(file_segments.empty() || offset + size - 1 == file_segments.back()->range().right);
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return file_segments;
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}
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void FileCache::fillHolesWithEmptyFileSegments(
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FileSegments & file_segments,
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const Key & key,
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const FileSegment::Range & range,
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bool fill_with_detached_file_segments,
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bool is_persistent,
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std::lock_guard<std::mutex> & cache_lock)
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{
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/// There are segments [segment1, ..., segmentN]
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/// (non-overlapping, non-empty, ascending-ordered) which (maybe partially)
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/// intersect with given range.
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/// It can have holes:
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/// [____________________] -- requested range
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/// [____] [_] [_________] -- intersecting cache [segment1, ..., segmentN]
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///
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/// For each such hole create a cell with file segment state EMPTY.
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auto it = file_segments.begin();
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auto segment_range = (*it)->range();
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size_t current_pos;
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if (segment_range.left < range.left)
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{
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/// [_______ -- requested range
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/// [_______
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/// ^
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/// segment1
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current_pos = segment_range.right + 1;
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++it;
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}
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else
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current_pos = range.left;
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while (current_pos <= range.right && it != file_segments.end())
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{
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segment_range = (*it)->range();
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if (current_pos == segment_range.left)
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{
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current_pos = segment_range.right + 1;
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++it;
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continue;
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}
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assert(current_pos < segment_range.left);
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auto hole_size = segment_range.left - current_pos;
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if (fill_with_detached_file_segments)
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{
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auto file_segment = std::make_shared<FileSegment>(current_pos, hole_size, key, this, FileSegment::State::EMPTY);
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{
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std::lock_guard segment_lock(file_segment->mutex);
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file_segment->markAsDetached(segment_lock);
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}
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file_segments.insert(it, file_segment);
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}
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else
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{
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file_segments.splice(it, splitRangeIntoCells(key, current_pos, hole_size, FileSegment::State::EMPTY, is_persistent, cache_lock));
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}
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current_pos = segment_range.right + 1;
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++it;
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}
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if (current_pos <= range.right)
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{
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/// ________] -- requested range
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/// _____]
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/// ^
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/// segmentN
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auto hole_size = range.right - current_pos + 1;
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if (fill_with_detached_file_segments)
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{
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auto file_segment = std::make_shared<FileSegment>(current_pos, hole_size, key, this, FileSegment::State::EMPTY);
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{
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std::lock_guard segment_lock(file_segment->mutex);
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file_segment->markAsDetached(segment_lock);
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}
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file_segments.insert(file_segments.end(), file_segment);
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}
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else
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{
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file_segments.splice(
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file_segments.end(), splitRangeIntoCells(key, current_pos, hole_size, FileSegment::State::EMPTY, is_persistent, cache_lock));
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}
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}
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}
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FileSegmentsHolder FileCache::getOrSet(const Key & key, size_t offset, size_t size, bool is_persistent)
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{
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assertInitialized();
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FileSegment::Range range(offset, offset + size - 1);
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std::lock_guard cache_lock(mutex);
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#ifndef NDEBUG
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assertCacheCorrectness(key, cache_lock);
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#endif
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/// Get all segments which intersect with the given range.
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auto file_segments = getImpl(key, range, cache_lock);
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if (file_segments.empty())
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{
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file_segments = splitRangeIntoCells(key, offset, size, FileSegment::State::EMPTY, is_persistent, cache_lock);
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}
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else
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{
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fillHolesWithEmptyFileSegments(file_segments, key, range, /* fill_with_detached */false, is_persistent, cache_lock);
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}
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assert(!file_segments.empty());
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return FileSegmentsHolder(std::move(file_segments));
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}
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FileSegmentsHolder FileCache::get(const Key & key, size_t offset, size_t size)
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{
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assertInitialized();
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FileSegment::Range range(offset, offset + size - 1);
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std::lock_guard cache_lock(mutex);
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#ifndef NDEBUG
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assertCacheCorrectness(key, cache_lock);
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#endif
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/// Get all segments which intersect with the given range.
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auto file_segments = getImpl(key, range, cache_lock);
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if (file_segments.empty())
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{
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auto file_segment = std::make_shared<FileSegment>(offset, size, key, this, FileSegment::State::EMPTY);
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{
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std::lock_guard segment_lock(file_segment->mutex);
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file_segment->markAsDetached(segment_lock);
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}
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file_segments = { file_segment };
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}
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else
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{
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|
fillHolesWithEmptyFileSegments(file_segments, key, range, /* fill_with_detached */true, /* is_persistent */false, cache_lock);
|
|
}
|
|
|
|
return FileSegmentsHolder(std::move(file_segments));
|
|
}
|
|
|
|
FileCache::FileSegmentCell * FileCache::addCell(
|
|
const Key & key, size_t offset, size_t size,
|
|
FileSegment::State state, bool is_persistent,
|
|
std::lock_guard<std::mutex> & cache_lock)
|
|
{
|
|
/// Create a file segment cell and put it in `files` map by [key][offset].
|
|
|
|
if (!size)
|
|
return nullptr; /// Empty files are not cached.
|
|
|
|
if (files[key].contains(offset))
|
|
throw Exception(
|
|
ErrorCodes::LOGICAL_ERROR,
|
|
"Cache already exists for key: `{}`, offset: {}, size: {}.\nCurrent cache structure: {}",
|
|
key.toString(), offset, size, dumpStructureUnlocked(key, cache_lock));
|
|
|
|
auto skip_or_download = [&]() -> FileSegmentPtr
|
|
{
|
|
FileSegment::State result_state = state;
|
|
if (state == FileSegment::State::EMPTY && enable_cache_hits_threshold)
|
|
{
|
|
auto record = stash_records.find({key, offset});
|
|
|
|
if (record == stash_records.end())
|
|
{
|
|
auto priority_iter = stash_priority->add(key, offset, 0, cache_lock);
|
|
stash_records.insert({{key, offset}, priority_iter});
|
|
|
|
if (stash_priority->getElementsNum(cache_lock) > max_stash_element_size)
|
|
{
|
|
auto remove_priority_iter = stash_priority->getLowestPriorityWriteIterator(cache_lock);
|
|
stash_records.erase({remove_priority_iter->key(), remove_priority_iter->offset()});
|
|
remove_priority_iter->removeAndGetNext(cache_lock);
|
|
}
|
|
/// For segments that do not reach the download threshold, we do not download them, but directly read them
|
|
result_state = FileSegment::State::SKIP_CACHE;
|
|
}
|
|
else
|
|
{
|
|
auto priority_iter = record->second;
|
|
priority_iter->use(cache_lock);
|
|
result_state = priority_iter->hits() >= enable_cache_hits_threshold ? FileSegment::State::EMPTY : FileSegment::State::SKIP_CACHE;
|
|
}
|
|
}
|
|
|
|
return std::make_shared<FileSegment>(offset, size, key, this, result_state, is_persistent);
|
|
};
|
|
|
|
FileSegmentCell cell(skip_or_download(), this, cache_lock);
|
|
auto & offsets = files[key];
|
|
|
|
if (offsets.empty())
|
|
{
|
|
auto key_path = getPathInLocalCache(key);
|
|
if (!fs::exists(key_path))
|
|
fs::create_directories(key_path);
|
|
}
|
|
|
|
auto [it, inserted] = offsets.insert({offset, std::move(cell)});
|
|
if (!inserted)
|
|
throw Exception(
|
|
ErrorCodes::LOGICAL_ERROR,
|
|
"Failed to insert into cache key: `{}`, offset: {}, size: {}",
|
|
key.toString(), offset, size);
|
|
|
|
return &(it->second);
|
|
}
|
|
|
|
FileSegmentsHolder FileCache::setDownloading(
|
|
const Key & key,
|
|
size_t offset,
|
|
size_t size,
|
|
bool is_persistent)
|
|
{
|
|
std::lock_guard cache_lock(mutex);
|
|
|
|
#ifndef NDEBUG
|
|
assertCacheCorrectness(key, cache_lock);
|
|
#endif
|
|
|
|
auto * cell = getCell(key, offset, cache_lock);
|
|
if (cell)
|
|
throw Exception(
|
|
ErrorCodes::REMOTE_FS_OBJECT_CACHE_ERROR,
|
|
"Cache cell already exists for key `{}` and offset {}",
|
|
key.toString(), offset);
|
|
|
|
auto file_segments = splitRangeIntoCells(key, offset, size, FileSegment::State::DOWNLOADING, is_persistent, cache_lock);
|
|
return FileSegmentsHolder(std::move(file_segments));
|
|
}
|
|
|
|
bool FileCache::tryReserve(const Key & key, size_t offset, size_t size, std::lock_guard<std::mutex> & cache_lock)
|
|
{
|
|
auto query_context = enable_filesystem_query_cache_limit ? getCurrentQueryContext(cache_lock) : nullptr;
|
|
if (!query_context)
|
|
return tryReserveForMainList(key, offset, size, nullptr, cache_lock);
|
|
|
|
/// The maximum cache capacity of the request is not reached, thus the
|
|
//// cache block is evicted from the main LRU queue by tryReserveForMainList().
|
|
else if (query_context->getCacheSize() + size <= query_context->getMaxCacheSize())
|
|
return tryReserveForMainList(key, offset, size, query_context, cache_lock);
|
|
|
|
/// When skip_download_if_exceeds_query_cache is true, there is no need
|
|
/// to evict old data, skip the cache and read directly from remote fs.
|
|
else if (query_context->isSkipDownloadIfExceed())
|
|
return false;
|
|
|
|
/// The maximum cache size of the query is reached, the cache will be
|
|
/// evicted from the history cache accessed by the current query.
|
|
else
|
|
{
|
|
size_t removed_size = 0;
|
|
size_t queue_size = main_priority->getElementsNum(cache_lock);
|
|
|
|
auto * cell_for_reserve = getCell(key, offset, cache_lock);
|
|
|
|
struct Segment
|
|
{
|
|
Key key;
|
|
size_t offset;
|
|
size_t size;
|
|
|
|
Segment(Key key_, size_t offset_, size_t size_)
|
|
: key(key_), offset(offset_), size(size_) {}
|
|
};
|
|
|
|
std::vector<Segment> ghost;
|
|
std::vector<FileSegmentCell *> trash;
|
|
std::vector<FileSegmentCell *> to_evict;
|
|
|
|
auto is_overflow = [&]
|
|
{
|
|
return (max_size != 0 && main_priority->getCacheSize(cache_lock) + size - removed_size > max_size)
|
|
|| (max_element_size != 0 && queue_size > max_element_size)
|
|
|| (query_context->getCacheSize() + size - removed_size > query_context->getMaxCacheSize());
|
|
};
|
|
|
|
/// Select the cache from the LRU queue held by query for expulsion.
|
|
for (auto iter = query_context->getPriority()->getLowestPriorityWriteIterator(cache_lock); iter->valid();)
|
|
{
|
|
if (!is_overflow())
|
|
break;
|
|
|
|
auto * cell = getCell(iter->key(), iter->offset(), cache_lock);
|
|
|
|
if (!cell)
|
|
{
|
|
/// The cache corresponding to this record may be swapped out by
|
|
/// other queries, so it has become invalid.
|
|
removed_size += iter->size();
|
|
ghost.push_back(Segment(iter->key(), iter->offset(), iter->size()));
|
|
/// next()
|
|
iter->removeAndGetNext(cache_lock);
|
|
}
|
|
else
|
|
{
|
|
size_t cell_size = cell->size();
|
|
assert(iter->size() == cell_size);
|
|
|
|
if (cell->releasable())
|
|
{
|
|
auto & file_segment = cell->file_segment;
|
|
std::lock_guard segment_lock(file_segment->mutex);
|
|
|
|
switch (file_segment->download_state)
|
|
{
|
|
case FileSegment::State::DOWNLOADED:
|
|
{
|
|
to_evict.push_back(cell);
|
|
break;
|
|
}
|
|
default:
|
|
{
|
|
trash.push_back(cell);
|
|
break;
|
|
}
|
|
}
|
|
removed_size += cell_size;
|
|
--queue_size;
|
|
}
|
|
|
|
iter->next();
|
|
}
|
|
}
|
|
|
|
auto remove_file_segment = [&](FileSegmentPtr file_segment, size_t file_segment_size)
|
|
{
|
|
query_context->remove(file_segment->key(), file_segment->offset(), file_segment_size, cache_lock);
|
|
|
|
std::lock_guard segment_lock(file_segment->mutex);
|
|
remove(file_segment->key(), file_segment->offset(), cache_lock, segment_lock);
|
|
};
|
|
|
|
assert(trash.empty());
|
|
for (auto & cell : trash)
|
|
{
|
|
if (auto file_segment = cell->file_segment)
|
|
remove_file_segment(file_segment, cell->size());
|
|
}
|
|
|
|
for (auto & entry : ghost)
|
|
query_context->remove(entry.key, entry.offset, entry.size, cache_lock);
|
|
|
|
if (is_overflow())
|
|
return false;
|
|
|
|
if (cell_for_reserve)
|
|
{
|
|
auto queue_iterator = cell_for_reserve->queue_iterator;
|
|
if (queue_iterator)
|
|
queue_iterator->incrementSize(size, cache_lock);
|
|
else
|
|
cell_for_reserve->queue_iterator = main_priority->add(key, offset, size, cache_lock);
|
|
}
|
|
|
|
for (auto & cell : to_evict)
|
|
{
|
|
if (auto file_segment = cell->file_segment)
|
|
remove_file_segment(file_segment, cell->size());
|
|
}
|
|
|
|
query_context->reserve(key, offset, size, cache_lock);
|
|
return true;
|
|
}
|
|
}
|
|
|
|
bool FileCache::tryReserveForMainList(
|
|
const Key & key, size_t offset, size_t size, QueryContextPtr query_context, std::lock_guard<std::mutex> & cache_lock)
|
|
{
|
|
auto removed_size = 0;
|
|
size_t queue_size = main_priority->getElementsNum(cache_lock);
|
|
assert(queue_size <= max_element_size);
|
|
|
|
/// Since space reservation is incremental, cache cell already exists if it's state is EMPTY.
|
|
/// And it cache cell does not exist on startup -- as we first check for space and then add a cell.
|
|
auto * cell_for_reserve = getCell(key, offset, cache_lock);
|
|
|
|
/// A cell acquires a LRUQueue iterator on first successful space reservation attempt.
|
|
/// cell_for_reserve can be nullptr here when we call tryReserve() from loadCacheInfoIntoMemory().
|
|
if (!cell_for_reserve || !cell_for_reserve->queue_iterator)
|
|
queue_size += 1;
|
|
|
|
auto is_overflow = [&]
|
|
{
|
|
/// max_size == 0 means unlimited cache size, max_element_size means unlimited number of cache elements.
|
|
return (max_size != 0 && main_priority->getCacheSize(cache_lock) + size - removed_size > max_size)
|
|
|| (max_element_size != 0 && queue_size > max_element_size);
|
|
};
|
|
|
|
std::vector<FileSegmentCell *> to_evict;
|
|
std::vector<FileSegmentCell *> trash;
|
|
|
|
for (auto it = main_priority->getLowestPriorityReadIterator(cache_lock); it->valid(); it->next())
|
|
{
|
|
const auto & entry_key = it->key();
|
|
auto entry_offset = it->offset();
|
|
|
|
if (!is_overflow())
|
|
break;
|
|
|
|
auto * cell = getCell(entry_key, entry_offset, cache_lock);
|
|
if (!cell)
|
|
throw Exception(
|
|
ErrorCodes::REMOTE_FS_OBJECT_CACHE_ERROR,
|
|
"Cache became inconsistent. Key: {}, offset: {}",
|
|
key.toString(), offset);
|
|
|
|
size_t cell_size = cell->size();
|
|
assert(it->size() == cell_size);
|
|
|
|
/// It is guaranteed that cell is not removed from cache as long as
|
|
/// pointer to corresponding file segment is hold by any other thread.
|
|
|
|
if (cell->releasable())
|
|
{
|
|
auto & file_segment = cell->file_segment;
|
|
|
|
std::lock_guard segment_lock(file_segment->mutex);
|
|
|
|
switch (file_segment->download_state)
|
|
{
|
|
case FileSegment::State::DOWNLOADED:
|
|
{
|
|
/// Cell will actually be removed only if
|
|
/// we managed to reserve enough space.
|
|
|
|
to_evict.push_back(cell);
|
|
break;
|
|
}
|
|
default:
|
|
{
|
|
trash.push_back(cell);
|
|
break;
|
|
}
|
|
}
|
|
|
|
removed_size += cell_size;
|
|
--queue_size;
|
|
}
|
|
}
|
|
|
|
auto remove_file_segment = [&](FileSegmentPtr file_segment)
|
|
{
|
|
std::lock_guard segment_lock(file_segment->mutex);
|
|
remove(file_segment->key(), file_segment->offset(), cache_lock, segment_lock);
|
|
};
|
|
|
|
/// This case is very unlikely, can happen in case of exception from
|
|
/// file_segment->complete(), which would be a logical error.
|
|
assert(trash.empty());
|
|
for (auto & cell : trash)
|
|
{
|
|
if (auto file_segment = cell->file_segment)
|
|
remove_file_segment(file_segment);
|
|
}
|
|
|
|
if (is_overflow())
|
|
return false;
|
|
|
|
/// cache cell is nullptr on server startup because we first check for space and then add a cell.
|
|
if (cell_for_reserve)
|
|
{
|
|
/// queue_iteratir is std::nullopt here if no space has been reserved yet, a cache cell
|
|
/// acquires queue iterator on first successful space reservation attempt.
|
|
/// If queue iterator already exists, we need to update the size after each space reservation.
|
|
auto queue_iterator = cell_for_reserve->queue_iterator;
|
|
if (queue_iterator)
|
|
queue_iterator->incrementSize(size, cache_lock);
|
|
else
|
|
cell_for_reserve->queue_iterator = main_priority->add(key, offset, size, cache_lock);
|
|
}
|
|
|
|
for (auto & cell : to_evict)
|
|
{
|
|
if (auto file_segment = cell->file_segment)
|
|
remove_file_segment(file_segment);
|
|
}
|
|
|
|
if (main_priority->getCacheSize(cache_lock) > (1ull << 63))
|
|
throw Exception(ErrorCodes::LOGICAL_ERROR, "Cache became inconsistent. There must be a bug");
|
|
|
|
if (query_context)
|
|
query_context->reserve(key, offset, size, cache_lock);
|
|
|
|
return true;
|
|
}
|
|
|
|
void FileCache::removeIfExists(const Key & key)
|
|
{
|
|
assertInitialized();
|
|
|
|
std::lock_guard cache_lock(mutex);
|
|
|
|
auto it = files.find(key);
|
|
if (it == files.end())
|
|
return;
|
|
|
|
auto & offsets = it->second;
|
|
|
|
std::vector<FileSegmentCell *> to_remove;
|
|
to_remove.reserve(offsets.size());
|
|
|
|
for (auto & [offset, cell] : offsets)
|
|
to_remove.push_back(&cell);
|
|
|
|
bool some_cells_were_skipped = false;
|
|
for (auto & cell : to_remove)
|
|
{
|
|
/// In ordinary case we remove data from cache when it's not used by anyone.
|
|
/// But if we have multiple replicated zero-copy tables on the same server
|
|
/// it became possible to start removing something from cache when it is used
|
|
/// by other "zero-copy" tables. That is why it's not an error.
|
|
if (!cell->releasable())
|
|
{
|
|
some_cells_were_skipped = true;
|
|
continue;
|
|
}
|
|
|
|
auto file_segment = cell->file_segment;
|
|
if (file_segment)
|
|
{
|
|
std::lock_guard<std::mutex> segment_lock(file_segment->mutex);
|
|
file_segment->detach(cache_lock, segment_lock);
|
|
remove(file_segment->key(), file_segment->offset(), cache_lock, segment_lock);
|
|
}
|
|
}
|
|
|
|
auto key_path = getPathInLocalCache(key);
|
|
|
|
if (!some_cells_were_skipped)
|
|
{
|
|
files.erase(key);
|
|
|
|
if (fs::exists(key_path))
|
|
fs::remove_all(key_path);
|
|
}
|
|
}
|
|
|
|
void FileCache::removeIfReleasable(bool remove_persistent_files)
|
|
{
|
|
/// Try remove all cached files by cache_base_path.
|
|
/// Only releasable file segments are evicted.
|
|
/// `remove_persistent_files` defines whether non-evictable by some criteria files
|
|
/// (they do not comply with the cache eviction policy) should also be removed.
|
|
|
|
std::lock_guard cache_lock(mutex);
|
|
|
|
std::vector<FileSegmentPtr> to_remove;
|
|
for (auto it = main_priority->getLowestPriorityReadIterator(cache_lock); it->valid(); it->next())
|
|
{
|
|
const auto & key = it->key();
|
|
auto offset = it->offset();
|
|
|
|
auto * cell = getCell(key, offset, cache_lock);
|
|
if (!cell)
|
|
throw Exception(
|
|
ErrorCodes::LOGICAL_ERROR,
|
|
"Cache is in inconsistent state: LRU queue contains entries with no cache cell");
|
|
|
|
if (cell->releasable())
|
|
{
|
|
auto file_segment = cell->file_segment;
|
|
if (file_segment
|
|
&& (!file_segment->isPersistent()
|
|
|| remove_persistent_files
|
|
|| allow_to_remove_persistent_segments_from_cache_by_default))
|
|
{
|
|
to_remove.emplace_back(file_segment);
|
|
}
|
|
}
|
|
}
|
|
|
|
for (auto & file_segment : to_remove)
|
|
{
|
|
std::lock_guard segment_lock(file_segment->mutex);
|
|
file_segment->detach(cache_lock, segment_lock);
|
|
remove(file_segment->key(), file_segment->offset(), cache_lock, segment_lock);
|
|
}
|
|
|
|
/// Remove all access information.
|
|
stash_records.clear();
|
|
stash_priority->removeAll(cache_lock);
|
|
|
|
#ifndef NDEBUG
|
|
assertCacheCorrectness(cache_lock);
|
|
#endif
|
|
}
|
|
|
|
void FileCache::remove(
|
|
Key key, size_t offset,
|
|
std::lock_guard<std::mutex> & cache_lock, std::lock_guard<std::mutex> & /* segment_lock */)
|
|
{
|
|
LOG_TEST(log, "Remove. Key: {}, offset: {}", key.toString(), offset);
|
|
|
|
auto * cell = getCell(key, offset, cache_lock);
|
|
if (!cell)
|
|
throw Exception(ErrorCodes::LOGICAL_ERROR, "No cache cell for key: {}, offset: {}", key.toString(), offset);
|
|
|
|
bool is_persistent_file_segment = cell->file_segment->isPersistent();
|
|
|
|
if (cell->queue_iterator)
|
|
{
|
|
cell->queue_iterator->removeAndGetNext(cache_lock);
|
|
}
|
|
|
|
auto & offsets = files[key];
|
|
offsets.erase(offset);
|
|
|
|
auto cache_file_path = getPathInLocalCache(key, offset, is_persistent_file_segment);
|
|
if (fs::exists(cache_file_path))
|
|
{
|
|
try
|
|
{
|
|
fs::remove(cache_file_path);
|
|
|
|
if (is_initialized && offsets.empty())
|
|
{
|
|
auto key_path = getPathInLocalCache(key);
|
|
|
|
files.erase(key);
|
|
|
|
if (fs::exists(key_path))
|
|
fs::remove_all(key_path);
|
|
}
|
|
}
|
|
catch (...)
|
|
{
|
|
throw Exception(ErrorCodes::REMOTE_FS_OBJECT_CACHE_ERROR,
|
|
"Removal of cached file failed. Key: {}, offset: {}, path: {}, error: {}",
|
|
key.toString(), offset, cache_file_path, getCurrentExceptionMessage(false));
|
|
}
|
|
}
|
|
}
|
|
|
|
void FileCache::loadCacheInfoIntoMemory(std::lock_guard<std::mutex> & cache_lock)
|
|
{
|
|
Key key;
|
|
UInt64 offset = 0;
|
|
size_t size = 0;
|
|
std::vector<std::pair<IFileCachePriority::WriteIterator, std::weak_ptr<FileSegment>>> queue_entries;
|
|
|
|
/// cache_base_path / key_prefix / key / offset
|
|
if (!files.empty())
|
|
throw Exception(
|
|
ErrorCodes::REMOTE_FS_OBJECT_CACHE_ERROR,
|
|
"Cache initialization is partially made. "
|
|
"This can be a result of a failed first attempt to initialize cache. "
|
|
"Please, check log for error messages");
|
|
|
|
fs::directory_iterator key_prefix_it{cache_base_path};
|
|
for (; key_prefix_it != fs::directory_iterator(); ++key_prefix_it)
|
|
{
|
|
fs::directory_iterator key_it{key_prefix_it->path()};
|
|
for (; key_it != fs::directory_iterator(); ++key_it)
|
|
{
|
|
key = Key(unhexUInt<UInt128>(key_it->path().filename().string().data()));
|
|
|
|
fs::directory_iterator offset_it{key_it->path()};
|
|
for (; offset_it != fs::directory_iterator(); ++offset_it)
|
|
{
|
|
auto offset_with_suffix = offset_it->path().filename().string();
|
|
auto delim_pos = offset_with_suffix.find('_');
|
|
bool parsed;
|
|
bool is_persistent = false;
|
|
|
|
if (delim_pos == std::string::npos)
|
|
parsed = tryParse<UInt64>(offset, offset_with_suffix);
|
|
else
|
|
{
|
|
parsed = tryParse<UInt64>(offset, offset_with_suffix.substr(0, delim_pos));
|
|
is_persistent = offset_with_suffix.substr(delim_pos+1) == "persistent";
|
|
}
|
|
|
|
if (!parsed)
|
|
{
|
|
LOG_WARNING(log, "Unexpected file: ", offset_it->path().string());
|
|
continue; /// Or just remove? Some unexpected file.
|
|
}
|
|
|
|
size = offset_it->file_size();
|
|
if (!size)
|
|
{
|
|
fs::remove(offset_it->path());
|
|
continue;
|
|
}
|
|
|
|
if (tryReserve(key, offset, size, cache_lock))
|
|
{
|
|
auto * cell = addCell(key, offset, size, FileSegment::State::DOWNLOADED, is_persistent, cache_lock);
|
|
if (cell)
|
|
queue_entries.emplace_back(cell->queue_iterator, cell->file_segment);
|
|
}
|
|
else
|
|
{
|
|
LOG_WARNING(log,
|
|
"Cache capacity changed (max size: {}, available: {}), cached file `{}` does not fit in cache anymore (size: {})",
|
|
max_size, getAvailableCacheSizeUnlocked(cache_lock), key_it->path().string(), size);
|
|
fs::remove(offset_it->path());
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Shuffle cells to have random order in LRUQueue as at startup all cells have the same priority.
|
|
pcg64 generator(randomSeed());
|
|
std::shuffle(queue_entries.begin(), queue_entries.end(), generator);
|
|
for (const auto & [it, file_segment] : queue_entries)
|
|
{
|
|
/// Cell cache size changed and, for example, 1st file segment fits into cache
|
|
/// and 2nd file segment will fit only if first was evicted, then first will be removed and
|
|
/// cell is nullptr here.
|
|
if (file_segment.expired())
|
|
continue;
|
|
|
|
it->use(cache_lock);
|
|
}
|
|
#ifndef NDEBUG
|
|
assertCacheCorrectness(cache_lock);
|
|
#endif
|
|
}
|
|
|
|
void FileCache::reduceSizeToDownloaded(
|
|
const Key & key, size_t offset,
|
|
std::lock_guard<std::mutex> & cache_lock, std::lock_guard<std::mutex> & /* segment_lock */)
|
|
{
|
|
/**
|
|
* In case file was partially downloaded and it's download cannot be continued
|
|
* because of no space left in cache, we need to be able to cut cell's size to downloaded_size.
|
|
*/
|
|
|
|
auto * cell = getCell(key, offset, cache_lock);
|
|
|
|
if (!cell)
|
|
{
|
|
throw Exception(
|
|
ErrorCodes::LOGICAL_ERROR,
|
|
"No cell found for key: {}, offset: {}",
|
|
key.toString(), offset);
|
|
}
|
|
|
|
const auto & file_segment = cell->file_segment;
|
|
|
|
size_t downloaded_size = file_segment->downloaded_size;
|
|
if (downloaded_size == file_segment->range().size())
|
|
{
|
|
throw Exception(
|
|
ErrorCodes::LOGICAL_ERROR,
|
|
"Nothing to reduce, file segment fully downloaded, key: {}, offset: {}",
|
|
key.toString(), offset);
|
|
}
|
|
|
|
cell->file_segment = std::make_shared<FileSegment>(offset, downloaded_size, key, this, FileSegment::State::DOWNLOADED);
|
|
}
|
|
|
|
bool FileCache::isLastFileSegmentHolder(
|
|
const Key & key, size_t offset,
|
|
std::lock_guard<std::mutex> & cache_lock, std::lock_guard<std::mutex> & /* segment_lock */)
|
|
{
|
|
auto * cell = getCell(key, offset, cache_lock);
|
|
|
|
if (!cell)
|
|
throw Exception(ErrorCodes::LOGICAL_ERROR, "No cell found for key: {}, offset: {}", key.toString(), offset);
|
|
|
|
/// The caller of this method is last file segment holder if use count is 2 (the second pointer is cache itself)
|
|
return cell->file_segment.use_count() == 2;
|
|
}
|
|
|
|
FileSegments FileCache::getSnapshot() const
|
|
{
|
|
std::lock_guard cache_lock(mutex);
|
|
|
|
FileSegments file_segments;
|
|
|
|
for (const auto & [key, cells_by_offset] : files)
|
|
{
|
|
for (const auto & [offset, cell] : cells_by_offset)
|
|
file_segments.push_back(FileSegment::getSnapshot(cell.file_segment, cache_lock));
|
|
}
|
|
return file_segments;
|
|
}
|
|
|
|
std::vector<String> FileCache::tryGetCachePaths(const Key & key)
|
|
{
|
|
std::lock_guard cache_lock(mutex);
|
|
|
|
std::vector<String> cache_paths;
|
|
|
|
const auto & cells_by_offset = files[key];
|
|
|
|
for (const auto & [offset, cell] : cells_by_offset)
|
|
{
|
|
if (cell.file_segment->state() == FileSegment::State::DOWNLOADED)
|
|
cache_paths.push_back(getPathInLocalCache(key, offset, cell.file_segment->isPersistent()));
|
|
}
|
|
|
|
return cache_paths;
|
|
}
|
|
|
|
size_t FileCache::getUsedCacheSize() const
|
|
{
|
|
std::lock_guard cache_lock(mutex);
|
|
return getUsedCacheSizeUnlocked(cache_lock);
|
|
}
|
|
|
|
size_t FileCache::getUsedCacheSizeUnlocked(std::lock_guard<std::mutex> & cache_lock) const
|
|
{
|
|
return main_priority->getCacheSize(cache_lock);
|
|
}
|
|
|
|
size_t FileCache::getAvailableCacheSize() const
|
|
{
|
|
std::lock_guard cache_lock(mutex);
|
|
return getAvailableCacheSizeUnlocked(cache_lock);
|
|
}
|
|
|
|
size_t FileCache::getAvailableCacheSizeUnlocked(std::lock_guard<std::mutex> & cache_lock) const
|
|
{
|
|
return max_size - getUsedCacheSizeUnlocked(cache_lock);
|
|
}
|
|
|
|
size_t FileCache::getFileSegmentsNum() const
|
|
{
|
|
std::lock_guard cache_lock(mutex);
|
|
return getFileSegmentsNumUnlocked(cache_lock);
|
|
}
|
|
|
|
size_t FileCache::getFileSegmentsNumUnlocked(std::lock_guard<std::mutex> & cache_lock) const
|
|
{
|
|
return main_priority->getElementsNum(cache_lock);
|
|
}
|
|
|
|
FileCache::FileSegmentCell::FileSegmentCell(
|
|
FileSegmentPtr file_segment_,
|
|
FileCache * cache,
|
|
std::lock_guard<std::mutex> & cache_lock)
|
|
: file_segment(file_segment_)
|
|
{
|
|
/**
|
|
* Cell can be created with either DOWNLOADED or EMPTY file segment's state.
|
|
* File segment acquires DOWNLOADING state and creates LRUQueue iterator on first
|
|
* successful getOrSetDownaloder call.
|
|
*/
|
|
|
|
switch (file_segment->download_state)
|
|
{
|
|
case FileSegment::State::DOWNLOADED:
|
|
{
|
|
queue_iterator = cache->main_priority->add(file_segment->key(), file_segment->offset(), file_segment->range().size(), cache_lock);
|
|
break;
|
|
}
|
|
case FileSegment::State::SKIP_CACHE:
|
|
case FileSegment::State::EMPTY:
|
|
case FileSegment::State::DOWNLOADING:
|
|
{
|
|
break;
|
|
}
|
|
default:
|
|
throw Exception(ErrorCodes::REMOTE_FS_OBJECT_CACHE_ERROR,
|
|
"Can create cell with either EMPTY, DOWNLOADED, DOWNLOADING state, got: {}",
|
|
FileSegment::stateToString(file_segment->download_state));
|
|
}
|
|
}
|
|
|
|
String FileCache::dumpStructure(const Key & key)
|
|
{
|
|
std::lock_guard cache_lock(mutex);
|
|
return dumpStructureUnlocked(key, cache_lock);
|
|
}
|
|
|
|
String FileCache::dumpStructureUnlocked(const Key & key, std::lock_guard<std::mutex> &)
|
|
{
|
|
WriteBufferFromOwnString result;
|
|
const auto & cells_by_offset = files[key];
|
|
|
|
for (const auto & [offset, cell] : cells_by_offset)
|
|
result << cell.file_segment->getInfoForLog() << "\n";
|
|
|
|
return result.str();
|
|
}
|
|
|
|
void FileCache::assertCacheCellsCorrectness(
|
|
const FileSegmentsByOffset & cells_by_offset, [[maybe_unused]] std::lock_guard<std::mutex> & cache_lock)
|
|
{
|
|
for (const auto & [_, cell] : cells_by_offset)
|
|
{
|
|
const auto & file_segment = cell.file_segment;
|
|
file_segment->assertCorrectness();
|
|
|
|
if (file_segment->reserved_size != 0)
|
|
{
|
|
assert(cell.queue_iterator);
|
|
assert(main_priority->contains(file_segment->key(), file_segment->offset(), cache_lock));
|
|
}
|
|
}
|
|
}
|
|
|
|
void FileCache::assertCacheCorrectness(const Key & key, std::lock_guard<std::mutex> & cache_lock)
|
|
{
|
|
assertCacheCellsCorrectness(files[key], cache_lock);
|
|
assertPriorityCorrectness(cache_lock);
|
|
}
|
|
|
|
void FileCache::assertCacheCorrectness(std::lock_guard<std::mutex> & cache_lock)
|
|
{
|
|
for (const auto & [key, cells_by_offset] : files)
|
|
assertCacheCellsCorrectness(files[key], cache_lock);
|
|
assertPriorityCorrectness(cache_lock);
|
|
}
|
|
|
|
void FileCache::assertPriorityCorrectness(std::lock_guard<std::mutex> & cache_lock)
|
|
{
|
|
[[maybe_unused]] size_t total_size = 0;
|
|
for (auto it = main_priority->getLowestPriorityReadIterator(cache_lock); it->valid(); it->next())
|
|
{
|
|
const auto & key = it->key();
|
|
auto offset = it->offset();
|
|
auto size = it->size();
|
|
|
|
auto * cell = getCell(key, offset, cache_lock);
|
|
if (!cell)
|
|
{
|
|
throw Exception(
|
|
ErrorCodes::LOGICAL_ERROR,
|
|
"Cache is in inconsistent state: LRU queue contains entries with no cache cell (assertCorrectness())");
|
|
}
|
|
assert(cell->size() == size);
|
|
total_size += size;
|
|
}
|
|
assert(total_size == main_priority->getCacheSize(cache_lock));
|
|
assert(main_priority->getCacheSize(cache_lock) <= max_size);
|
|
assert(main_priority->getElementsNum(cache_lock) <= max_element_size);
|
|
}
|
|
|
|
}
|