YugabyteDB (2.13.0.0-b42, bfc6a6643e7399ac8a0e81d06a3ee6d6571b33ab)

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//    http://www.apache.org/licenses/LICENSE-2.0

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//  under the License.

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// The following only applies to changes made to this file as part of YugaByte development.

//

// Portions Copyright (c) YugaByte, Inc.

//

// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except

// in compliance with the License.  You may obtain a copy of the License at

//

// http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software distributed under the License

// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express

// or implied.  See the License for the specific language governing permissions and limitations

// under the License.

//

//  Copyright (c) 2014, Facebook, Inc.  All rights reserved.

//  This source code is licensed under the BSD-style license found in the

//  LICENSE file in the root directory of this source tree. An additional grant

//  of patent rights can be found in the PATENTS file in the same directory.

#pragma once

#include <string>

#include <unordered_map>

#include <unordered_set>

#include <vector>

#include "yb/util/condition_variable.h"

#include "yb/util/mutex.h"

#ifdef NDEBUG

#define TEST_SYNC_POINT(x)

#else

namespace yb {

// This class provides facility to reproduce race conditions deterministically

// in unit tests.

// Developer could specify sync points in the codebase via TEST_SYNC_POINT.

// Each sync point represents a position in the execution stream of a thread.

// In the unit test, 'Happens After' relationship among sync points could be

// setup via SyncPoint::LoadDependency, to reproduce a desired interleave of

// threads execution.

class SyncPoint {

 public:

  static SyncPoint* GetInstance();

  struct Dependency {

    Dependency(std::string predecessor, std::string successor);

    std::string predecessor_;

    std::string successor_;

  };

  // call once at the beginning of a test to setup the dependency between

  // sync points

  void LoadDependency(const std::vector<Dependency>& dependencies);

  // enable sync point processing (disabled on startup)

  void EnableProcessing();

  // disable sync point processing

  void DisableProcessing();

  // remove the execution trace of all sync points

  void ClearTrace();

  // triggered by TEST_SYNC_POINT, blocking execution until all predecessors

  // are executed.

  void Process(const std::string& point);

  // TODO: it might be useful to provide a function that blocks until all

  // sync points are cleared.

 private:

  SyncPoint();

  bool PredecessorsAllCleared(const std::string& point);

  // successor/predecessor map loaded from LoadDependency

  std::unordered_map<std::string, std::vector<std::string> > successors_;

  std::unordered_map<std::string, std::vector<std::string> > predecessors_;

  Mutex mutex_;

  ConditionVariable cv_;

  // sync points that have been passed through

  std::unordered_set<std::string> cleared_points_;

  bool enabled_;

};

}  // namespace yb

// Use TEST_SYNC_POINT to specify sync points inside code base.

// Sync points can have happens-after depedency on other sync points,

// configured at runtime via SyncPoint::LoadDependency. This could be

// utilized to re-produce race conditions between threads.

// TEST_SYNC_POINT is no op in release build.

#define TEST_SYNC_POINT(x) yb::SyncPoint::GetInstance()->Process(x)

#endif  // NDEBUG