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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:45:59 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:45:59 +0000 |
commit | 19fcec84d8d7d21e796c7624e521b60d28ee21ed (patch) | |
tree | 42d26aa27d1e3f7c0b8bd3fd14e7d7082f5008dc /src/zstd/contrib/pzstd/SkippableFrame.h | |
parent | Initial commit. (diff) | |
download | ceph-upstream.tar.xz ceph-upstream.zip |
Adding upstream version 16.2.11+ds.upstream/16.2.11+dsupstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | src/zstd/contrib/pzstd/SkippableFrame.h | 64 |
1 files changed, 64 insertions, 0 deletions
diff --git a/src/zstd/contrib/pzstd/SkippableFrame.h b/src/zstd/contrib/pzstd/SkippableFrame.h new file mode 100644 index 000000000..60deed040 --- /dev/null +++ b/src/zstd/contrib/pzstd/SkippableFrame.h @@ -0,0 +1,64 @@ +/* + * Copyright (c) 2016-present, Facebook, Inc. + * All rights reserved. + * + * This source code is licensed under both the BSD-style license (found in the + * LICENSE file in the root directory of this source tree) and the GPLv2 (found + * in the COPYING file in the root directory of this source tree). + */ +#pragma once + +#include "utils/Range.h" + +#include <array> +#include <cstddef> +#include <cstdint> +#include <cstdio> + +namespace pzstd { +/** + * We put a skippable frame before each frame. + * It contains a skippable frame magic number, the size of the skippable frame, + * and the size of the next frame. + * Each skippable frame is exactly 12 bytes in little endian format. + * The first 8 bytes are for compatibility with the ZSTD format. + * If we have N threads, the output will look like + * + * [0x184D2A50|4|size1] [frame1 of size size1] + * [0x184D2A50|4|size2] [frame2 of size size2] + * ... + * [0x184D2A50|4|sizeN] [frameN of size sizeN] + * + * Each sizeX is 4 bytes. + * + * These skippable frames should allow us to skip through the compressed file + * and only load at most N pages. + */ +class SkippableFrame { + public: + static constexpr std::size_t kSize = 12; + + private: + std::uint32_t frameSize_; + std::array<std::uint8_t, kSize> data_; + static constexpr std::uint32_t kSkippableFrameMagicNumber = 0x184D2A50; + // Could be improved if the size fits in less bytes + static constexpr std::uint32_t kFrameContentsSize = kSize - 8; + + public: + // Write the skippable frame to data_ in LE format. + explicit SkippableFrame(std::uint32_t size); + + // Read the skippable frame from bytes in LE format. + static std::size_t tryRead(ByteRange bytes); + + ByteRange data() const { + return {data_.data(), data_.size()}; + } + + // Size of the next frame. + std::size_t frameSize() const { + return frameSize_; + } +}; +} |