Method get

src/Interpreters/FileCache/FileCache.cpp:1001–1042

}

FileSegmentsHolderPtr FileCache::get(
    const Key & key,
    size_t offset,
    size_t size,
    size_t file_segments_limit,
    const UserID & user_id)
{
    ProfileEventTimeIncrement<Microseconds> watch(ProfileEvents::FilesystemCacheGetMicroseconds);

    assertInitialized();

    std::unique_ptr<FileSegmentsHolder> holder;
    if (auto locked_key = metadata.lockKeyMetadata(key, CacheMetadata::KeyNotFoundPolicy::RETURN_NULL, OriginInfo(user_id));
        locked_key != nullptr)
    {
        FileSegment::Range range(offset, offset + size - 1);

        /// Get all segments which intersect with the given range.
        auto file_segments = getImpl(*locked_key, range, file_segments_limit);
        if (!file_segments.empty())
        {
            if (file_segments_limit)
            {
                chassert(file_segments.size() <= file_segments_limit);
                if (file_segments.size() == file_segments_limit)
                    range.right = file_segments.back()->range().right;
            }

            fillHolesWithEmptyFileSegments(
                *locked_key, file_segments, range, offset + size - 1, file_segments_limit, /* fill_with_detached */true, CreateFileSegmentSettings{});

            chassert(!file_segments_limit || file_segments.size() <= file_segments_limit);
            holder = std::make_unique<FileSegmentsHolder>(std::move(file_segments));
        }
    }

    if (!holder)
        holder = std::make_unique<FileSegmentsHolder>(FileSegments{std::make_shared<FileSegment>(key, offset, size, FileSegment::State::DETACHED)});

    assertCacheCorrectnessWithProbability();
    return holder;
}

FileSegmentsHolderPtr FileCache::getDownloadedContiguousOrEmpty(
    const Key & key,