db03739340
Summary: When having fixed max_bytes_for_level_base, the ratio of size of largest level and the second one can range from 0 to the multiplier. This makes LSM tree frequently irregular and unpredictable. It can also cause poor space amplification in some cases. In this improvement (proposed by Igor Kabiljo), we introduce a parameter option.level_compaction_use_dynamic_max_bytes. When turning it on, RocksDB is free to pick a level base in the range of (options.max_bytes_for_level_base/options.max_bytes_for_level_multiplier, options.max_bytes_for_level_base] so that real level ratios are close to options.max_bytes_for_level_multiplier. Test Plan: New unit tests and pass tests suites including valgrind. Reviewers: MarkCallaghan, rven, yhchiang, igor, ikabiljo Reviewed By: ikabiljo Subscribers: yoshinorim, ikabiljo, dhruba, leveldb Differential Revision: https://reviews.facebook.net/D31437
88 lines
3.0 KiB
C++
88 lines
3.0 KiB
C++
// Copyright (c) 2014, Facebook, Inc. All rights reserved.
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// This source code is licensed under the BSD-style license found in the
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// LICENSE file in the root directory of this source tree. An additional grant
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// of patent rights can be found in the PATENTS file in the same directory.
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#pragma once
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#include <condition_variable>
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#include <mutex>
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#include <string>
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#include <unordered_set>
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#include <unordered_map>
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#include <vector>
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#ifdef NDEBUG
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#define TEST_SYNC_POINT(x)
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#else
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namespace rocksdb {
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// This class provides facility to reproduce race conditions deterministically
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// in unit tests.
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// Developer could specify sync points in the codebase via TEST_SYNC_POINT.
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// Each sync point represents a position in the execution stream of a thread.
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// In the unit test, 'Happens After' relationship among sync points could be
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// setup via SyncPoint::LoadDependency, to reproduce a desired interleave of
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// threads execution.
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// Refer to (DBTest,TransactionLogIteratorRace), for an exmaple use case.
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class SyncPoint {
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public:
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static SyncPoint* GetInstance();
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struct Dependency {
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std::string predecessor;
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std::string successor;
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};
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// call once at the beginning of a test to setup the dependency between
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// sync points
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void LoadDependency(const std::vector<Dependency>& dependencies);
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// Set up a call back function in sync point.
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void SetCallBack(const std::string point, std::function<void()> callback);
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// Clear all call back functions.
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void ClearAllCallBacks();
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// enable sync point processing (disabled on startup)
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void EnableProcessing();
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// disable sync point processing
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void DisableProcessing();
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// remove the execution trace of all sync points
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void ClearTrace();
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// triggered by TEST_SYNC_POINT, blocking execution until all predecessors
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// are executed.
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void Process(const std::string& point);
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// TODO: it might be useful to provide a function that blocks until all
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// sync points are cleared.
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private:
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bool PredecessorsAllCleared(const std::string& point);
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// successor/predecessor map loaded from LoadDependency
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std::unordered_map<std::string, std::vector<std::string>> successors_;
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std::unordered_map<std::string, std::vector<std::string>> predecessors_;
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std::unordered_map<std::string, std::function<void()> > callbacks_;
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std::mutex mutex_;
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std::condition_variable cv_;
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// sync points that have been passed through
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std::unordered_set<std::string> cleared_points_;
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bool enabled_ = false;
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int num_callbacks_running_ = 0;
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};
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} // namespace rocksdb
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// Use TEST_SYNC_POINT to specify sync points inside code base.
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// Sync points can have happens-after depedency on other sync points,
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// configured at runtime via SyncPoint::LoadDependency. This could be
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// utilized to re-produce race conditions between threads.
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// See TransactionLogIteratorRace in db_test.cc for an example use case.
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// TEST_SYNC_POINT is no op in release build.
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#define TEST_SYNC_POINT(x) rocksdb::SyncPoint::GetInstance()->Process(x)
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#endif // NDEBUG
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