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d010b02e86
Summary: In follow-up to https://github.com/facebook/rocksdb/issues/11922, fix a race in functions like CreateColumnFamily and SetDBOptions where the DB reports one option setting but a different one is left in effect. To fix, we can add an extra mutex around these rare operations. We don't want to hold the DB mutex during I/O or other slow things because of the many purposes it serves, but a mutex more limited to these cases should be fine. I believe this would fix a write-write race in https://github.com/facebook/rocksdb/issues/10079 but not the read-write race. Intended follow-up to this: * Should be able to remove write thread synchronization from DBImpl::WriteOptionsFile Pull Request resolved: https://github.com/facebook/rocksdb/pull/11929 Test Plan: Added two mini-stress style regression tests that fail with >1% probability before this change: DBOptionsTest::SetStatsDumpPeriodSecRace ColumnFamilyTest::CreateAndDropPeriodicRace I haven't reproduced such an inconsistency between in-memory options and on disk latest options, but this change at least improves safety and adds a test anyway: DBOptionsTest::SetStatsDumpPeriodSecRace Reviewed By: ajkr Differential Revision: D50024506 Pulled By: pdillinger fbshipit-source-id: 1e99a9ed4d96fdcf3ac5061ec6b3cee78aecdda4
51 lines
1.3 KiB
C++
51 lines
1.3 KiB
C++
// Copyright (c) Facebook, Inc. and its affiliates. 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/rocksdb_namespace.h"
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// This file declares a wrapper around the efficient folly DistributedMutex
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// that falls back on a standard mutex when not available. See
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// https://github.com/facebook/folly/blob/main/folly/synchronization/DistributedMutex.h
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// for benefits and limitations.
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// At the moment, only scoped locking is supported using DMutexLock
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// RAII wrapper, because lock/unlock APIs will vary.
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#ifdef USE_FOLLY
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#include <folly/synchronization/DistributedMutex.h>
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namespace ROCKSDB_NAMESPACE {
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class DMutex : public folly::DistributedMutex {
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public:
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static const char* kName() { return "folly::DistributedMutex"; }
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explicit DMutex(bool IGNORED_adaptive = false) { (void)IGNORED_adaptive; }
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// currently no-op
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void AssertHeld() const {}
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};
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using DMutexLock = std::lock_guard<folly::DistributedMutex>;
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} // namespace ROCKSDB_NAMESPACE
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#else
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#include <mutex>
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#include "port/port.h"
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namespace ROCKSDB_NAMESPACE {
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using DMutex = port::Mutex;
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using DMutexLock = std::lock_guard<DMutex>;
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} // namespace ROCKSDB_NAMESPACE
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#endif
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