10d14693ac
Summary: ValidateSnapshot checks if another txn has committed a value to about-to-be-locked key since a particular snapshot. It applies an optimization of looking into only the memtable if snapshot seq is larger than the earliest seq in the memtables. With a long-running txn in WritePrepared, the prepared value might be flushed out to the disk and yet it commits after the snapshot, which breaks this optimization. The patch fixes that by disabling this optimization when the min_uncomitted seq at the time the snapshot was taken is lower than earliest seq in the memtables. Pull Request resolved: https://github.com/facebook/rocksdb/pull/4961 Differential Revision: D14009947 Pulled By: maysamyabandeh fbshipit-source-id: 1d11679950326f7c4094b433e6b821b729f08850
85 lines
2.7 KiB
C++
85 lines
2.7 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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#ifndef ROCKSDB_LITE
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#include <string>
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#include <unordered_map>
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#include "db/dbformat.h"
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#include "db/read_callback.h"
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#include "rocksdb/db.h"
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#include "rocksdb/slice.h"
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#include "rocksdb/status.h"
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#include "rocksdb/types.h"
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namespace rocksdb {
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struct TransactionKeyMapInfo {
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// Earliest sequence number that is relevant to this transaction for this key
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SequenceNumber seq;
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uint32_t num_writes;
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uint32_t num_reads;
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bool exclusive;
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explicit TransactionKeyMapInfo(SequenceNumber seq_no)
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: seq(seq_no), num_writes(0), num_reads(0), exclusive(false) {}
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};
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using TransactionKeyMap =
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std::unordered_map<uint32_t,
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std::unordered_map<std::string, TransactionKeyMapInfo>>;
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class DBImpl;
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struct SuperVersion;
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class WriteBatchWithIndex;
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class TransactionUtil {
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public:
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// Verifies there have been no commits to this key in the db since this
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// sequence number.
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//
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// If cache_only is true, then this function will not attempt to read any
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// SST files. This will make it more likely this function will
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// return an error if it is unable to determine if there are any conflicts.
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//
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// Returns OK on success, BUSY if there is a conflicting write, or other error
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// status for any unexpected errors.
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static Status CheckKeyForConflicts(
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DBImpl* db_impl, ColumnFamilyHandle* column_family,
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const std::string& key, SequenceNumber snap_seq, bool cache_only,
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ReadCallback* snap_checker = nullptr,
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SequenceNumber min_uncommitted = kMaxSequenceNumber);
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// For each key,SequenceNumber pair in the TransactionKeyMap, this function
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// will verify there have been no writes to the key in the db since that
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// sequence number.
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//
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// Returns OK on success, BUSY if there is a conflicting write, or other error
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// status for any unexpected errors.
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//
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// REQUIRED: this function should only be called on the write thread or if the
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// mutex is held.
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static Status CheckKeysForConflicts(DBImpl* db_impl,
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const TransactionKeyMap& keys,
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bool cache_only);
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private:
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static Status CheckKey(DBImpl* db_impl, SuperVersion* sv,
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SequenceNumber earliest_seq, SequenceNumber snap_seq,
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const std::string& key, bool cache_only,
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ReadCallback* snap_checker = nullptr,
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SequenceNumber min_uncommitted = kMaxSequenceNumber);
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};
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} // namespace rocksdb
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#endif // ROCKSDB_LITE
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