mirror of
https://github.com/Amulet-Team/leveldb-mcpe.git
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36a5f8ed7f
- Replace raw slice comparison with a call to user comparator.
Added test for custom comparators.
- Fix end of namespace comments.
- Fixed bug in picking inputs for a level-0 compaction.
When finding overlapping files, the covered range may expand
as files are added to the input set. We now correctly expand
the range when this happens instead of continuing to use the
old range. For example, suppose L0 contains files with the
following ranges:
F1: a .. d
F2: c .. g
F3: f .. j
and the initial compaction target is F3. We used to search
for range f..j which yielded {F2,F3}. However we now expand
the range as soon as another file is added. In this case,
when F2 is added, we expand the range to c..j and restart the
search. That picks up file F1 as well.
This change fixes a bug related to deleted keys showing up
incorrectly after a compaction as described in Issue 44.
(Sync with upstream @25072954)
46 lines
1.4 KiB
C++
46 lines
1.4 KiB
C++
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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#ifndef STORAGE_LEVELDB_UTIL_CRC32C_H_
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#define STORAGE_LEVELDB_UTIL_CRC32C_H_
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#include <stddef.h>
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#include <stdint.h>
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namespace leveldb {
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namespace crc32c {
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// Return the crc32c of concat(A, data[0,n-1]) where init_crc is the
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// crc32c of some string A. Extend() is often used to maintain the
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// crc32c of a stream of data.
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extern uint32_t Extend(uint32_t init_crc, const char* data, size_t n);
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// Return the crc32c of data[0,n-1]
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inline uint32_t Value(const char* data, size_t n) {
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return Extend(0, data, n);
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}
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static const uint32_t kMaskDelta = 0xa282ead8ul;
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// Return a masked representation of crc.
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//
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// Motivation: it is problematic to compute the CRC of a string that
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// contains embedded CRCs. Therefore we recommend that CRCs stored
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// somewhere (e.g., in files) should be masked before being stored.
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inline uint32_t Mask(uint32_t crc) {
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// Rotate right by 15 bits and add a constant.
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return ((crc >> 15) | (crc << 17)) + kMaskDelta;
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}
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// Return the crc whose masked representation is masked_crc.
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inline uint32_t Unmask(uint32_t masked_crc) {
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uint32_t rot = masked_crc - kMaskDelta;
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return ((rot >> 17) | (rot << 15));
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}
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} // namespace crc32c
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} // namespace leveldb
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#endif // STORAGE_LEVELDB_UTIL_CRC32C_H_
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