Better

src/Common/FileCache.cpp

@@ -57,7 +57,7 @@ String IFileCache::getPathInLocalCache(const Key & key)
     return fs::path(cache_base_path) / key_str.substr(0, 3) / key_str;
 }
 
-bool IFileCache::shouldBypassCache()
+bool IFileCache::isReadOnly()
 {
     return !CurrentThread::isInitialized()
         || !CurrentThread::get().getQueryContext()
@@ -708,7 +708,7 @@ bool LRUFileCache::isLastFileSegmentHolder(
     return cell->file_segment.use_count() == 2;
 }
 
-FileSegmentsHolder LRUFileCache::getAll()
+FileSegments LRUFileCache::getSnapshot() const
 {
     std::lock_guard cache_lock(mutex);
 
@@ -717,10 +717,10 @@ FileSegmentsHolder LRUFileCache::getAll()
     for (const auto & [key, cells_by_offset] : files)
     {
         for (const auto & [offset, cell] : cells_by_offset)
-            file_segments.push_back(cell.file_segment);
+            file_segments.push_back(FileSegment::getSnapshot(cell.file_segment));
     }
 
-    return FileSegmentsHolder(std::move(file_segments));
+    return file_segments;
 }
 
 std::vector<String> LRUFileCache::tryGetCachePaths(const Key & key)

src/Common/FileCache.h

@@ -44,7 +44,7 @@ public:
 
     virtual void tryRemoveAll() = 0;
 
-    static bool shouldBypassCache();
+    static bool isReadOnly();
 
     /// Cache capacity in bytes.
     size_t capacity() const { return max_size; }
@@ -72,10 +72,10 @@ public:
      */
     virtual FileSegmentsHolder getOrSet(const Key & key, size_t offset, size_t size) = 0;
 
-    virtual FileSegmentsHolder getAll() = 0;
-
     virtual FileSegmentsHolder setDownloading(const Key & key, size_t offset, size_t size) = 0;
 
+    virtual FileSegments getSnapshot() const = 0;
+
     /// For debug.
     virtual String dumpStructure(const Key & key) = 0;
 
@@ -124,7 +124,7 @@ public:
 
     FileSegmentsHolder getOrSet(const Key & key, size_t offset, size_t size) override;
 
-    FileSegmentsHolder getAll() override;
+    FileSegments getSnapshot() const override;
 
     FileSegmentsHolder setDownloading(const Key & key, size_t offset, size_t size) override;
 

src/Common/FileCacheSettings.h

@@ -2,7 +2,7 @@
 
 #include <Common/FileCache_fwd.h>
 
-namespace Poco { namespace Util { class AbstractConfiguration; }}
+namespace Poco { namespace Util { class AbstractConfiguration; } }
 
 namespace DB
 {

src/Common/FileSegment.cpp

@@ -73,6 +73,12 @@ size_t FileSegment::getDownloadOffset() const
     return range().left + getDownloadedSize(segment_lock);
 }
 
+size_t FileSegment::getDownloadedSize() const
+{
+    std::lock_guard segment_lock(mutex);
+    return getDownloadedSize(segment_lock);
+}
+
 size_t FileSegment::getDownloadedSize(std::lock_guard<std::mutex> & /* segment_lock */) const
 {
     if (download_state == State::DOWNLOADED)
@@ -84,24 +90,15 @@ size_t FileSegment::getDownloadedSize(std::lock_guard<std::mutex> & /* segment_l
 
 String FileSegment::getCallerId()
 {
-    return getCallerIdImpl(false);
+    return getCallerIdImpl();
 }
 
-String FileSegment::getCallerIdImpl(bool allow_non_strict_checking)
+String FileSegment::getCallerIdImpl()
 {
-    if (IFileCache::shouldBypassCache())
-    {
-        /// getCallerId() can be called from completeImpl(), which can be called from complete().
-        /// complete() is called from destructor of CachedReadBufferFromRemoteFS when there is no query id anymore.
-        /// Allow non strict checking in this case. This works correctly as if getCallerIdImpl() is called from destructor,
-        /// then we know that caller is not a downloader, because downloader is reset each nextImpl() call either
-        /// manually or via SCOPE_EXIT.
-
-        if (allow_non_strict_checking)
-            return "None";
-
-        throw Exception(ErrorCodes::REMOTE_FS_OBJECT_CACHE_ERROR, "Cannot use cache without query id");
-    }
+    if (!CurrentThread::isInitialized()
+        || !CurrentThread::get().getQueryContext()
+        || CurrentThread::getQueryId().size == 0)
+        return "None:" + toString(getThreadId());
 
     return CurrentThread::getQueryId().toString() + ":" + toString(getThreadId());
 }
@@ -244,15 +241,9 @@ void FileSegment::write(const char * from, size_t size, size_t offset_)
     {
         std::lock_guard segment_lock(mutex);
 
-        auto info = getInfoForLogImpl(segment_lock);
-        e.addMessage("while writing into cache, info: " + info);
+        wrapWithCacheInfo(e, "while writing into cache", segment_lock);
 
-        LOG_ERROR(log, "Failed to write to cache. File segment info: {}", info);
-
-        download_state = State::PARTIALLY_DOWNLOADED_NO_CONTINUATION;
-
-        cache_writer->finalize();
-        cache_writer.reset();
+        setDownloadFailed(segment_lock);
 
         cv.notify_all();
 
@@ -265,7 +256,7 @@ void FileSegment::write(const char * from, size_t size, size_t offset_)
 void FileSegment::writeInMemory(const char * from, size_t size)
 {
     if (!size)
-        throw Exception(ErrorCodes::REMOTE_FS_OBJECT_CACHE_ERROR, "Writing zero size is not allowed");
+        throw Exception(ErrorCodes::REMOTE_FS_OBJECT_CACHE_ERROR, "Attempt to write zero size cache file");
 
     if (availableSize() < size)
         throw Exception(
@@ -284,14 +275,13 @@ void FileSegment::writeInMemory(const char * from, size_t size)
     {
         cache_writer->write(from, size);
     }
-    catch (...)
+    catch (Exception & e)
     {
-        LOG_ERROR(log, "Failed to write to cache. File segment info: {}", getInfoForLogImpl(segment_lock));
+        wrapWithCacheInfo(e, "while writing into cache", segment_lock);
 
-        download_state = State::PARTIALLY_DOWNLOADED_NO_CONTINUATION;
+        setDownloadFailed(segment_lock);
 
-        cache_writer->finalize();
-        cache_writer.reset();
+        cv.notify_all();
 
         throw;
     }
@@ -313,23 +303,23 @@ size_t FileSegment::finalizeWrite()
     {
         cache_writer->next();
     }
-    catch (...)
+    catch (Exception & e)
     {
-        download_state = State::PARTIALLY_DOWNLOADED_NO_CONTINUATION;
+        wrapWithCacheInfo(e, "while writing into cache", segment_lock);
 
-        cache_writer->finalize();
-        cache_writer.reset();
+        setDownloadFailed(segment_lock);
+
+        cv.notify_all();
 
         throw;
     }
 
     downloaded_size += size;
-    cache_writer.reset();
-    downloader_id.clear();
-    download_state = State::DOWNLOADED;
 
     if (downloaded_size != range().size())
-        throw Exception(ErrorCodes::LOGICAL_ERROR, "Expected {} == {}", downloaded_size, range().size());
+        throw Exception(ErrorCodes::LOGICAL_ERROR, "Expected downloaded size to equal file segment size ({} == {})", downloaded_size, range().size());
+
+    setDownloaded(segment_lock);
 
     return size;
 }
@@ -398,6 +388,20 @@ void FileSegment::setDownloaded(std::lock_guard<std::mutex> & /* segment_lock */
 {
     download_state = State::DOWNLOADED;
     is_downloaded = true;
+    downloader_id.clear();
+
+    if (cache_writer)
+    {
+        cache_writer->finalize();
+        cache_writer.reset();
+        remote_file_reader.reset();
+    }
+}
+
+void FileSegment::setDownloadFailed(std::lock_guard<std::mutex> & /* segment_lock */)
+{
+    download_state = State::PARTIALLY_DOWNLOADED_NO_CONTINUATION;
+    downloader_id.clear();
 
     if (cache_writer)
     {
@@ -455,7 +459,7 @@ void FileSegment::complete(State state)
     }
     catch (...)
     {
-        if (!downloader_id.empty() && downloader_id == getCallerIdImpl(true))
+        if (!downloader_id.empty() && downloader_id == getCallerIdImpl())
             downloader_id.clear();
 
         cv.notify_all();
@@ -480,7 +484,7 @@ void FileSegment::complete(std::lock_guard<std::mutex> & cache_lock)
         /// Segment state can be changed from DOWNLOADING or EMPTY only if the caller is the
         /// downloader or the only owner of the segment.
 
-        bool can_update_segment_state = downloader_id == getCallerIdImpl(true)
+        bool can_update_segment_state = downloader_id == getCallerIdImpl()
             || cache->isLastFileSegmentHolder(key(), offset(), cache_lock, segment_lock);
 
         if (can_update_segment_state)
@@ -489,11 +493,11 @@ void FileSegment::complete(std::lock_guard<std::mutex> & cache_lock)
 
     try
     {
-        completeImpl(cache_lock, segment_lock, /* allow_non_strict_checking */true);
+        completeImpl(cache_lock, segment_lock);
     }
     catch (...)
     {
-        if (!downloader_id.empty() && downloader_id == getCallerIdImpl(true))
+        if (!downloader_id.empty() && downloader_id == getCallerIdImpl())
             downloader_id.clear();
 
         cv.notify_all();
@@ -503,7 +507,7 @@ void FileSegment::complete(std::lock_guard<std::mutex> & cache_lock)
     cv.notify_all();
 }
 
-void FileSegment::completeImpl(std::lock_guard<std::mutex> & cache_lock, std::lock_guard<std::mutex> & segment_lock, bool allow_non_strict_checking)
+void FileSegment::completeImpl(std::lock_guard<std::mutex> & cache_lock, std::lock_guard<std::mutex> & segment_lock)
 {
     bool is_last_holder = cache->isLastFileSegmentHolder(key(), offset(), cache_lock, segment_lock);
 
@@ -539,7 +543,7 @@ void FileSegment::completeImpl(std::lock_guard<std::mutex> & cache_lock, std::lo
         }
     }
 
-    if (!downloader_id.empty() && (downloader_id == getCallerIdImpl(allow_non_strict_checking) || is_last_holder))
+    if (!downloader_id.empty() && (downloader_id == getCallerIdImpl() || is_last_holder))
     {
         LOG_TEST(log, "Clearing downloader id: {}, current state: {}", downloader_id, stateToString(download_state));
         downloader_id.clear();
@@ -566,6 +570,11 @@ String FileSegment::getInfoForLogImpl(std::lock_guard<std::mutex> & segment_lock
     return info.str();
 }
 
+void FileSegment::wrapWithCacheInfo(Exception & e, const String & message, std::lock_guard<std::mutex> & segment_lock) const
+{
+    e.addMessage(fmt::format("{}, current cache state: {}", message, getInfoForLogImpl(segment_lock)));
+}
+
 String FileSegment::stateToString(FileSegment::State state)
 {
     switch (state)
@@ -599,6 +608,22 @@ void FileSegment::assertCorrectnessImpl(std::lock_guard<std::mutex> & /* segment
     assert(download_state != FileSegment::State::DOWNLOADED || std::filesystem::file_size(cache->getPathInLocalCache(key(), offset())) > 0);
 }
 
+FileSegmentPtr FileSegment::getSnapshot(const FileSegmentPtr & file_segment)
+{
+    auto snapshot = std::make_shared<FileSegment>(
+        file_segment->offset(),
+        file_segment->range().size(),
+        file_segment->key(),
+        nullptr,
+        file_segment->state());
+
+    snapshot->hits_count = file_segment->getHitsCount();
+    snapshot->ref_count = file_segment.use_count();
+    snapshot->downloaded_size = file_segment->getDownloadedSize();
+
+    return snapshot;
+}
+
 FileSegmentsHolder::~FileSegmentsHolder()
 {
     /// In CacheableReadBufferFromRemoteFS file segment's downloader removes file segments from

src/Common/FileSegment.h

@@ -97,6 +97,11 @@ public:
 
     void write(const char * from, size_t size, size_t offset_);
 
+    /**
+     * writeInMemory and finalizeWrite are used together to write a single file with delay.
+     * Both can be called only once, one after another. Used for writing cache via threadpool
+     * on wrote operations. TODO: this solution is temporary, until adding a separate cache layer.
+     */
     void writeInMemory(const char * from, size_t size);
 
     size_t finalizeWrite();
@@ -121,18 +126,24 @@ public:
 
     size_t getDownloadOffset() const;
 
+    size_t getDownloadedSize() const;
+
     void completeBatchAndResetDownloader();
 
     void complete(State state);
 
     String getInfoForLog() const;
 
-    size_t hits() const { return hits_num; }
+    size_t getHitsCount() const { return hits_count; }
 
-    void hit() { ++hits_num; }
+    size_t getRefCount() const { return ref_count; }
+
+    void incrementHitsCount() { ++hits_count; }
 
     void assertCorrectness() const;
 
+    static FileSegmentPtr getSnapshot(const FileSegmentPtr & file_segment);
+
 private:
     size_t availableSize() const { return reserved_size - downloaded_size; }
 
@@ -141,6 +152,9 @@ private:
     void assertCorrectnessImpl(std::lock_guard<std::mutex> & segment_lock) const;
 
     void setDownloaded(std::lock_guard<std::mutex> & segment_lock);
+    void setDownloadFailed(std::lock_guard<std::mutex> & segment_lock);
+
+    void wrapWithCacheInfo(Exception & e, const String & message, std::lock_guard<std::mutex> & segment_lock) const;
 
     bool lastFileSegmentHolder() const;
 
@@ -152,9 +166,9 @@ private:
 
     void completeImpl(
         std::lock_guard<std::mutex> & cache_lock,
-        std::lock_guard<std::mutex> & segment_lock, bool allow_non_strict_checking = false);
+        std::lock_guard<std::mutex> & segment_lock);
 
-    static String getCallerIdImpl(bool allow_non_strict_checking = false);
+    static String getCallerIdImpl();
 
     void resetDownloaderImpl(std::lock_guard<std::mutex> & segment_lock);
 
@@ -188,7 +202,8 @@ private:
     bool detached = false;
 
     std::atomic<bool> is_downloaded{false};
-    std::atomic<size_t> hits_num = 0; /// cache hits.
+    std::atomic<size_t> hits_count = 0; /// cache hits.
+    std::atomic<size_t> ref_count = 0; /// Used for getting snapshot state
 };
 
 struct FileSegmentsHolder : private boost::noncopyable

src/Disks/DiskCacheWrapper.cpp

@@ -206,6 +206,8 @@ DiskCacheWrapper::writeFile(const String & path, size_t buf_size, WriteMode mode
         return DiskDecorator::writeFile(path, buf_size, mode, settings);
 
     WriteSettings current_settings = settings;
+    /// There are two different cache implementations. Disable second one if the first is enabled.
+    /// The firts will soon be removed, this disabling is temporary.
     current_settings.enable_filesystem_cache_on_write_operations = false;
 
     LOG_TEST(log, "Write file {} to cache", backQuote(path));

src/Disks/DiskWebServer.h

@@ -77,7 +77,7 @@ public:
     UInt64 getTotalSpace() const final override { return std::numeric_limits<UInt64>::max(); }
 
     UInt64 getAvailableSpace() const final override { return std::numeric_limits<UInt64>::max(); }
-UInt64 getUnreservedSpace() const final override { return std::numeric_limits<UInt64>::max(); }
+    UInt64 getUnreservedSpace() const final override { return std::numeric_limits<UInt64>::max(); }
 
     /// Read-only part
 

src/Disks/IDiskRemote.cpp

@@ -343,9 +343,9 @@ void IDiskRemote::removeMetadataRecursive(const String & path, RemoteFSPathKeepe
     }
 }
 
-std::vector<String> IDiskRemote::getRemotePaths(const String & path) const
+std::vector<String> IDiskRemote::getRemotePaths(const String & local_path) const
 {
-    auto metadata = readMetadata(path);
+    auto metadata = readMetadata(local_path);
 
     std::vector<String> remote_paths;
     for (const auto & [remote_path, _] : metadata.remote_fs_objects)
@@ -354,16 +354,16 @@ std::vector<String> IDiskRemote::getRemotePaths(const String & path) const
     return remote_paths;
 }
 
-void IDiskRemote::getRemotePathsRecursive(const String & path, std::vector<LocalPathWithRemotePaths> & paths_map)
+void IDiskRemote::getRemotePathsRecursive(const String & local_path, std::vector<LocalPathWithRemotePaths> & paths_map)
 {
-    if (metadata_disk->isFile(path))
+    if (metadata_disk->isFile(local_path))
     {
-        paths_map.emplace_back(path, getRemotePaths(path));
+        paths_map.emplace_back(local_path, getRemotePaths(local_path));
     }
     else
     {
-        for (auto it = iterateDirectory(path); it->isValid(); it->next())
-            IDiskRemote::getRemotePathsRecursive(fs::path(path) / it->name(), paths_map);
+        for (auto it = iterateDirectory(local_path); it->isValid(); it->next())
+            IDiskRemote::getRemotePathsRecursive(fs::path(local_path) / it->name(), paths_map);
     }
 }
 

src/Disks/IDiskRemote.h

@@ -68,9 +68,9 @@ public:
 
     String getCacheBasePath() const final override;
 
-    std::vector<String> getRemotePaths(const String & path) const final override;
+    std::vector<String> getRemotePaths(const String & local_path) const final override;
 
-    void getRemotePathsRecursive(const String & path, std::vector<LocalPathWithRemotePaths> & paths_map) override;
+    void getRemotePathsRecursive(const String & local_path, std::vector<LocalPathWithRemotePaths> & paths_map) override;
 
     /// Methods for working with metadata. For some operations (like hardlink
     /// creation) metadata can be updated concurrently from multiple threads

src/Disks/IO/CachedReadBufferFromRemoteFS.cpp

@@ -389,7 +389,7 @@ bool CachedReadBufferFromRemoteFS::completeFileSegmentAndGetNext()
     implementation_buffer = getImplementationBuffer(*current_file_segment_it);
 
     if (read_type == ReadType::CACHED)
-        (*current_file_segment_it)->hit();
+        (*current_file_segment_it)->incrementHitsCount();
 
     LOG_TEST(log, "New segment: {}", (*current_file_segment_it)->range().toString());
     return true;
@@ -573,8 +573,6 @@ bool CachedReadBufferFromRemoteFS::nextImpl()
 
 bool CachedReadBufferFromRemoteFS::nextImplStep()
 {
-    assertCacheAllowed();
-
     last_caller_id = FileSegment::getCallerId();
 
     if (!initialized)
@@ -623,7 +621,7 @@ bool CachedReadBufferFromRemoteFS::nextImplStep()
         implementation_buffer = getImplementationBuffer(*current_file_segment_it);
 
         if (read_type == ReadType::CACHED)
-            (*current_file_segment_it)->hit();
+            (*current_file_segment_it)->incrementHitsCount();
     }
 
     assert(!internal_buffer.empty());
@@ -820,12 +818,6 @@ std::optional<size_t> CachedReadBufferFromRemoteFS::getLastNonDownloadedOffset()
     return std::nullopt;
 }
 
-void CachedReadBufferFromRemoteFS::assertCacheAllowed() const
-{
-    if (IFileCache::shouldBypassCache() && !settings.read_from_filesystem_cache_if_exists_otherwise_bypass_cache)
-        throw Exception(ErrorCodes::LOGICAL_ERROR, "Cache used when not allowed");
-}
-
 String CachedReadBufferFromRemoteFS::getInfoForLog()
 {
     auto implementation_buffer_read_range_str =

src/Disks/IO/CachedReadBufferFromRemoteFS.h

@@ -50,8 +50,6 @@ private:
 
     bool nextImplStep();
 
-    void assertCacheAllowed() const;
-
     enum class ReadType
     {
         CACHED,

src/Disks/IO/ReadBufferFromRemoteFSGather.cpp

@@ -38,7 +38,7 @@ SeekableReadBufferPtr ReadBufferFromS3Gather::createImplementationBuffer(const S
     current_path = path;
 
     auto cache = settings.remote_fs_cache;
-    bool with_cache = cache && settings.enable_filesystem_cache && !IFileCache::shouldBypassCache();
+    bool with_cache = cache && settings.enable_filesystem_cache;
 
     auto remote_file_reader_creator = [=, this]()
     {

src/Disks/IO/ThreadPoolRemoteFSReader.cpp

@@ -1,6 +1,5 @@
 #include "ThreadPoolRemoteFSReader.h"
 
-#include <Core/UUID.h>
 #include <Common/Exception.h>
 #include <Common/ProfileEvents.h>
 #include <Common/CurrentMetrics.h>
@@ -51,25 +50,6 @@ std::future<IAsynchronousReader::Result> ThreadPoolRemoteFSReader::submit(Reques
     if (CurrentThread::isInitialized())
         query_context = CurrentThread::get().getQueryContext();
 
-    if (!query_context)
-    {
-        if (!shared_query_context)
-        {
-            ContextPtr global_context = CurrentThread::isInitialized() ? CurrentThread::get().getGlobalContext() : nullptr;
-            if (global_context)
-            {
-                shared_query_context = Context::createCopy(global_context);
-                shared_query_context->makeQueryContext();
-            }
-        }
-
-        if (shared_query_context)
-        {
-            shared_query_context->setCurrentQueryId(toString(UUIDHelpers::generateV4()));
-            query_context = shared_query_context;
-        }
-    }
-
     auto task = std::make_shared<std::packaged_task<Result()>>([request, running_group, query_context]
     {
         ThreadStatus thread_status;

src/Disks/IO/ThreadPoolRemoteFSReader.h

@@ -15,7 +15,6 @@ class ThreadPoolRemoteFSReader : public IAsynchronousReader
 
 private:
     ThreadPool pool;
-    ContextMutablePtr shared_query_context;
 
 public:
     ThreadPoolRemoteFSReader(size_t pool_size, size_t queue_size_);

src/Disks/S3/DiskS3.cpp

@@ -230,7 +230,7 @@ std::unique_ptr<ReadBufferFromFileBase> DiskS3::readFile(const String & path, co
     ReadSettings disk_read_settings{read_settings};
     if (cache)
     {
-        if (IFileCache::shouldBypassCache())
+        if (IFileCache::isReadOnly())
             disk_read_settings.read_from_filesystem_cache_if_exists_otherwise_bypass_cache = true;
 
         disk_read_settings.remote_fs_cache = cache;
@@ -272,7 +272,8 @@ std::unique_ptr<WriteBufferFromFileBase> DiskS3::writeFile(const String & path,
     LOG_TRACE(log, "{} to file by path: {}. S3 path: {}",
               mode == WriteMode::Rewrite ? "Write" : "Append", backQuote(metadata_disk->getPath() + path), remote_fs_root_path + blob_name);
 
-    bool cache_on_insert = fs::path(path).extension() != ".tmp"
+    bool cache_on_write = cache
+        && fs::path(path).extension() != ".tmp"
         && write_settings.enable_filesystem_cache_on_write_operations
         && FileCacheFactory::instance().getSettings(getCacheBasePath()).cache_on_write_operations;
 
@@ -285,7 +286,7 @@ std::unique_ptr<WriteBufferFromFileBase> DiskS3::writeFile(const String & path,
         settings->s3_upload_part_size_multiply_parts_count_threshold,
         settings->s3_max_single_part_upload_size,
         std::move(object_metadata),
-        buf_size, threadPoolCallbackRunner(getThreadPoolWriter()), blob_name, cache_on_insert ? cache : nullptr);
+        buf_size, threadPoolCallbackRunner(getThreadPoolWriter()), blob_name, cache_on_write ? cache : nullptr);
 
     auto create_metadata_callback = [this, path, blob_name, mode] (size_t count)
     {

src/IO/ParallelReadBuffer.cpp

@@ -33,7 +33,7 @@ bool ParallelReadBuffer::addReaderToPool(std::unique_lock<std::mutex> & /*buffer
 
     auto worker = read_workers.emplace_back(std::make_shared<ReadWorker>(std::move(reader)));
 
-    schedule([this, worker = std::move(worker)]() mutable { readerThreadFunction(std::move(worker)); }, nullptr);
+    schedule([this, worker = std::move(worker)]() mutable { readerThreadFunction(std::move(worker)); });
 
     return true;
 }

src/IO/WriteBufferFromS3.cpp

@@ -100,28 +100,6 @@ void WriteBufferFromS3::nextImpl()
             ? CurrentThread::get().getThreadGroup()
             : MainThreadStatus::getInstance().getThreadGroup();
 
-    if (CurrentThread::isInitialized())
-        query_context = CurrentThread::get().getQueryContext();
-
-    if (!query_context)
-    {
-        if (!shared_query_context)
-        {
-            ContextPtr global_context = CurrentThread::isInitialized() ? CurrentThread::get().getGlobalContext() : nullptr;
-            if (global_context)
-            {
-                shared_query_context = Context::createCopy(global_context);
-                shared_query_context->makeQueryContext();
-            }
-        }
-
-        if (shared_query_context)
-        {
-            shared_query_context->setCurrentQueryId(toString(UUIDHelpers::generateV4()));
-            query_context = shared_query_context;
-        }
-    }
-
     if (cacheEnabled())
     {
         if (blob_name.empty())
@@ -132,8 +110,10 @@ void WriteBufferFromS3::nextImpl()
         current_download_offset += size;
 
         size_t remaining_size = size;
-        for (const auto & file_segment : file_segments_holder->file_segments)
+        auto & file_segments = file_segments_holder->file_segments;
+        for (auto file_segment_it = file_segments.begin(); file_segment_it != file_segments.end(); ++file_segment_it)
         {
+            auto & file_segment = *file_segment_it;
             size_t current_size = std::min(file_segment->range().size(), remaining_size);
             remaining_size -= current_size;
 
@@ -143,6 +123,7 @@ void WriteBufferFromS3::nextImpl()
             }
             else
             {
+                file_segments.erase(file_segment_it, file_segments.end());
                 break;
             }
         }
@@ -190,7 +171,7 @@ WriteBufferFromS3::~WriteBufferFromS3()
 
 bool WriteBufferFromS3::cacheEnabled() const
 {
-    return cache != nullptr && !IFileCache::shouldBypassCache();
+    return cache != nullptr;
 }
 
 void WriteBufferFromS3::preFinalize()
@@ -317,7 +298,7 @@ void WriteBufferFromS3::writePart()
                 /// Releasing lock and condvar notification.
                 bg_tasks_condvar.notify_one();
             }
-        }, query_context);
+        });
     }
     else
     {
@@ -454,7 +435,7 @@ void WriteBufferFromS3::makeSinglepartUpload()
                 /// Releasing lock and condvar notification.
                 bg_tasks_condvar.notify_one();
             }
-        }, query_context);
+        });
     }
     else
     {

src/IO/WriteBufferFromS3.h

@@ -33,7 +33,7 @@ namespace Aws::S3::Model
 namespace DB
 {
 
-using ScheduleFunc = std::function<void(std::function<void()>, ContextPtr)>;
+using ScheduleFunc = std::function<void(std::function<void()>)>;
 class WriteBufferFromFile;
 
 /**
@@ -128,8 +128,6 @@ private:
     size_t current_download_offset = 0;
     std::optional<FileSegmentsHolder> file_segments_holder;
     static void finalizeCacheIfNeeded(std::optional<FileSegmentsHolder> &);
-    ContextMutablePtr shared_query_context;
-    ContextPtr query_context;
 };
 
 }

src/IO/WriteSettings.h

@@ -3,6 +3,7 @@
 namespace DB
 {
 
+/// Settings to be passed to IDisk::writeFile()
 struct WriteSettings
 {
     bool enable_filesystem_cache_on_write_operations = false;

src/Interpreters/threadPoolCallbackRunner.cpp

@@ -9,19 +9,14 @@ namespace DB
 
 CallbackRunner threadPoolCallbackRunner(ThreadPool & pool)
 {
-    return [pool = &pool, thread_group = CurrentThread::getGroup()](auto callback, ContextPtr query_context) mutable
+    return [pool = &pool, thread_group = CurrentThread::getGroup()](auto callback) mutable
     {
         pool->scheduleOrThrow(
-            [&, callback = std::move(callback), thread_group, query_context]()
+            [&, callback = std::move(callback), thread_group]()
             {
                 if (thread_group)
                     CurrentThread::attachTo(thread_group);
 
-                std::optional<CurrentThread::QueryScope> query_scope;
-
-                if (query_context && !CurrentThread::get().getQueryContext())
-                    query_scope.emplace(query_context);
-
                 SCOPE_EXIT_SAFE({
                     if (thread_group)
                         CurrentThread::detachQueryIfNotDetached();

src/Interpreters/threadPoolCallbackRunner.h

@@ -7,7 +7,7 @@ namespace DB
 {
 
 /// High-order function to run callbacks (functions with 'void()' signature) somewhere asynchronously
-using CallbackRunner = std::function<void(std::function<void()>, ContextPtr)>;
+using CallbackRunner = std::function<void(std::function<void()>)>;
 
 /// Creates CallbackRunner that runs every callback with 'pool->scheduleOrThrow()'
 CallbackRunner threadPoolCallbackRunner(ThreadPool & pool);

src/Storages/MergeTree/MergedColumnOnlyOutputStream.cpp

@@ -27,7 +27,7 @@ MergedColumnOnlyOutputStream::MergedColumnOnlyOutputStream(
 
     MergeTreeWriterSettings writer_settings(
         global_settings,
-        WriteSettings{},
+        data_part->storage.getContext()->getWriteSettings(),
         storage_settings,
         index_granularity_info ? index_granularity_info->is_adaptive : data_part->storage.canUseAdaptiveGranularity(),
         /* rewrite_primary_key = */false);

src/Storages/System/StorageSystemFilesystemCache.cpp

@@ -22,6 +22,7 @@ NamesAndTypesList StorageSystemFilesystemCache::getNamesAndTypes()
         {"state", std::make_shared<DataTypeString>()},
         {"cache_hits", std::make_shared<DataTypeUInt64>()},
         {"references", std::make_shared<DataTypeUInt64>()},
+        {"downloaded_size", std::make_shared<DataTypeUInt64>()},
     };
 }
 
@@ -37,9 +38,9 @@ void StorageSystemFilesystemCache::fillData(MutableColumns & res_columns, Contex
     for (const auto & [cache_base_path, cache_data] : caches)
     {
         const auto & cache = cache_data.cache;
-        auto holder = cache->getAll();
+        auto file_segments = cache->getSnapshot();
 
-        for (const auto & file_segment : holder.file_segments)
+        for (const auto & file_segment : file_segments)
         {
             res_columns[0]->insert(cache_base_path);
             res_columns[1]->insert(cache->getPathInLocalCache(file_segment->key(), file_segment->offset()));
@@ -49,8 +50,9 @@ void StorageSystemFilesystemCache::fillData(MutableColumns & res_columns, Contex
             res_columns[3]->insert(range.right);
             res_columns[4]->insert(range.size());
             res_columns[5]->insert(FileSegment::stateToString(file_segment->state()));
-            res_columns[6]->insert(file_segment->hits());
-            res_columns[7]->insert(file_segment.use_count());
+            res_columns[6]->insert(file_segment->getHitsCount());
+            res_columns[7]->insert(file_segment->getRefCount());
+            res_columns[8]->insert(file_segment->getDownloadedSize());
         }
     }
 }

src/Storages/System/StorageSystemFilesystemCache.h

@@ -7,12 +7,14 @@ namespace DB
 {
 
 /**
+ * Usgae example. How to get mapping from local paths to remote paths:
  * SELECT
  *     cache_path,
  *     cache_hits,
  *     remote_path,
  *     local_path,
- *     file_segment_range,
+ *     file_segment_range_begin,
+ *     file_segment_range_end,
  *     size,
  *     state
  * FROM