d758273ceb
Summary: If user-defined timestamp is enabled, current implementation can expose newer data to queries even if an older sequence number is specified via read_options.snapshot. This PR makes Get() respect sequence-number-based snapshot. Solution is simple. Besides using <ukey, ts, seq> to search the index for the key, we also verify that the candidate result's seq is smaller than or equal to seq. This requires passing a seq via `GetContext`, which results in the majority of code change caused by this PR. Also added a few unit tests to demonstrate standard visibility during point lookup and range scan when timestamp and snapshot are both present. Test plan (devserver): ``` make check $./db_bench --benchmarks=fillseq,readrandom -cache_size=$[64*1024*1024] ``` Result this PR: readrandom : 4.827 micros/op 207180 ops/sec; 22.9 MB/s (1000000 of 1000000 found) master: readrandom : 4.936 micros/op 202610 ops/sec; 22.4 MB/s (1000000 of 1000000 found) Pull Request resolved: https://github.com/facebook/rocksdb/pull/7227 Reviewed By: ltamasi Differential Revision: D23015242 Pulled By: riversand963 fbshipit-source-id: ea7b85a728654553ba357d2e6a207b5e40f7376a
54 lines
1.8 KiB
C++
54 lines
1.8 KiB
C++
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root directory).
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#pragma once
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#include "rocksdb/types.h"
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namespace ROCKSDB_NAMESPACE {
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class ReadCallback {
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public:
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explicit ReadCallback(SequenceNumber last_visible_seq)
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: max_visible_seq_(last_visible_seq) {}
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ReadCallback(SequenceNumber last_visible_seq, SequenceNumber min_uncommitted)
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: max_visible_seq_(last_visible_seq), min_uncommitted_(min_uncommitted) {}
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virtual ~ReadCallback() {}
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// Will be called to see if the seq number visible; if not it moves on to
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// the next seq number.
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virtual bool IsVisibleFullCheck(SequenceNumber seq) = 0;
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inline bool IsVisible(SequenceNumber seq) {
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assert(min_uncommitted_ > 0);
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assert(min_uncommitted_ >= kMinUnCommittedSeq);
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if (seq < min_uncommitted_) { // handles seq == 0 as well
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assert(seq <= max_visible_seq_);
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return true;
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} else if (max_visible_seq_ < seq) {
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assert(seq != 0);
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return false;
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} else {
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assert(seq != 0); // already handled in the first if-then clause
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return IsVisibleFullCheck(seq);
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}
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}
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inline SequenceNumber max_visible_seq() { return max_visible_seq_; }
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// Refresh to a more recent visible seq
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virtual void Refresh(SequenceNumber seq) { max_visible_seq_ = seq; }
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protected:
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// The max visible seq, it is usually the snapshot but could be larger if
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// transaction has its own writes written to db.
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SequenceNumber max_visible_seq_ = kMaxSequenceNumber;
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// Any seq less than min_uncommitted_ is committed.
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const SequenceNumber min_uncommitted_ = kMinUnCommittedSeq;
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};
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} // namespace ROCKSDB_NAMESPACE
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