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5234fc1b70
Summary: In prepare phase of 2PC, the db promises to remember the prepared data, for possible future commits. To fulfill the promise the prepared data must be persisted in the WAL so that they could be recovered after a crash. The log that contains a prepare batch that is not committed yet, is marked so that it is not garbage collected before the transaction commits/rollbacks. The bug was that the write to the log file and the mark of the file was not atomic, and WAL gc could have happened before the WAL log is actually marked. This patch moves the marking logic to PreReleaseCallback so that the WAL gc logic that joins both write threads would see the WAL write and WAL mark atomically. Pull Request resolved: https://github.com/facebook/rocksdb/pull/5121 Differential Revision: D14665210 Pulled By: maysamyabandeh fbshipit-source-id: 1d66aeb1c66a296cb4899a5a20c4d40c59e4b534
35 lines
1.3 KiB
C++
35 lines
1.3 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/status.h"
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namespace rocksdb {
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class DB;
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class PreReleaseCallback {
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public:
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virtual ~PreReleaseCallback() {}
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// Will be called while on the write thread after the write to the WAL and
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// before the write to memtable. This is useful if any operation needs to be
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// done before the write gets visible to the readers, or if we want to reduce
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// the overhead of locking by updating something sequentially while we are on
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// the write thread. If the callback fails, this function returns a non-OK
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// status, the sequence number will not be released, and same status will be
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// propagated to all the writers in the write group.
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// seq is the sequence number that is used for this write and will be
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// released.
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// is_mem_disabled is currently used for debugging purposes to assert that
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// the callback is done from the right write queue.
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// If non-zero, log_number indicates the WAL log to which we wrote.
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virtual Status Callback(SequenceNumber seq, bool is_mem_disabled,
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uint64_t log_number) = 0;
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};
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} // namespace rocksdb
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