Fix block checksum for >=4GB, refactor #6978
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Summary: Although RocksDB falls over in various other ways with KVs around 4GB or more, this change fixes how XXH32 and XXH64 were being called by the block checksum code to support >= 4GB in case that should ever happen, or the code copied for other uses. This change is not a schema compatibility issue because the checksum verification code would checksum the first (block_size + 1) mod 2^32 bytes while the checksum construction code would checksum the first block_size mod 2^32 plus the compression type byte, meaning the XXH32/64 checksums for >=4GB block would not match about 255/256 times. While touching this code, I refactored to consolidate redundant implementations, improving diagnostics and performance tracking in some cases. Also used less confusing language in those diagnostics. Makes facebook#6875 obsolete. Test Plan: I was able to write a test for this using an SST file writer and VerifyChecksum in a reader. The test fails before the fix, though I'm leaving the test disabled because I don't think it's worth the expense of running regularly.
gg814
reviewed
Jun 19, 2020
table/block_based/reader_common.cc
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| // the checksummed section. | ||
| size_t len = block_size + 1; | ||
| // And then the stored checksum value (4 bytes). | ||
| uint32_t stored = DecodeFixed32(data + block_size + 1); |
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A minor comment: could use data + len here :)
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All good, and thanks for making the code cleaner :) |
gg814
approved these changes
Jun 19, 2020
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@pdillinger has imported this pull request. If you are a Facebook employee, you can view this diff on Phabricator.
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@pdillinger merged this pull request in 25a0d0c. |
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@pdillinger merged this pull request in 25a0d0c. |
levichen94
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to bytedance/terarkdb
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Jun 18, 2021
Summary: Although RocksDB falls over in various other ways with KVs around 4GB or more, this change fixes how XXH32 and XXH64 were being called by the block checksum code to support >= 4GB in case that should ever happen, or the code copied for other uses. This change is not a schema compatibility issue because the checksum verification code would checksum the first (block_size + 1) mod 2^32 bytes while the checksum construction code would checksum the first block_size mod 2^32 plus the compression type byte, meaning the XXH32/64 checksums for >=4GB block would not match about 255/256 times. While touching this code, I refactored to consolidate redundant implementations, improving diagnostics and performance tracking in some cases. Also used less confusing language in those diagnostics. Makes facebook/rocksdb#6875 obsolete. Pull Request resolved: facebook/rocksdb#6978 Test Plan: I was able to write a test for this using an SST file writer and VerifyChecksum in a reader. The test fails before the fix, though I'm leaving the test disabled because I don't think it's worth the expense of running regularly. Reviewed By: gg814 Differential Revision: D22143260 Pulled By: pdillinger fbshipit-source-id: 982993d16134e8c50bea2269047f901c1783726e Signed-off-by: Changlong Chen <levisonchen@live.cn>
mm304321141
pushed a commit
to bytedance/terarkdb
that referenced
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Jun 23, 2021
Summary: Although RocksDB falls over in various other ways with KVs around 4GB or more, this change fixes how XXH32 and XXH64 were being called by the block checksum code to support >= 4GB in case that should ever happen, or the code copied for other uses. This change is not a schema compatibility issue because the checksum verification code would checksum the first (block_size + 1) mod 2^32 bytes while the checksum construction code would checksum the first block_size mod 2^32 plus the compression type byte, meaning the XXH32/64 checksums for >=4GB block would not match about 255/256 times. While touching this code, I refactored to consolidate redundant implementations, improving diagnostics and performance tracking in some cases. Also used less confusing language in those diagnostics. Makes facebook/rocksdb#6875 obsolete. Pull Request resolved: facebook/rocksdb#6978 Test Plan: I was able to write a test for this using an SST file writer and VerifyChecksum in a reader. The test fails before the fix, though I'm leaving the test disabled because I don't think it's worth the expense of running regularly. Reviewed By: gg814 Differential Revision: D22143260 Pulled By: pdillinger fbshipit-source-id: 982993d16134e8c50bea2269047f901c1783726e Signed-off-by: Changlong Chen <levisonchen@live.cn>
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Summary: Although RocksDB falls over in various other ways with KVs
around 4GB or more, this change fixes how XXH32 and XXH64 were being
called by the block checksum code to support >= 4GB in case that should
ever happen, or the code copied for other uses.
This change is not a schema compatibility issue because the checksum
verification code would checksum the first (block_size + 1) mod 2^32
bytes while the checksum construction code would checksum the first
block_size mod 2^32 plus the compression type byte, meaning the
XXH32/64 checksums for >=4GB block would not match about 255/256 times.
While touching this code, I refactored to consolidate redundant
implementations, improving diagnostics and performance tracking in some
cases. Also used less confusing language in those diagnostics.
Makes #6875 obsolete.
Test Plan: I was able to write a test for this using an SST file writer
and VerifyChecksum in a reader. The test fails before the fix, though
I'm leaving the test disabled because I don't think it's worth the
expense of running regularly.