src/tracing/core/id_allocator.h

/*
 * Copyright (C) 2017 The Android Open Source Project
 *
 * 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.
 */

#ifndef SRC_TRACING_CORE_ID_ALLOCATOR_H_
#define SRC_TRACING_CORE_ID_ALLOCATOR_H_

#include <stdint.h>

#include <vector>

namespace perfetto {

// Handles assigment of IDs (int types) from a fixed-size pool.
// Zero is not considered a valid ID.
class IdAllocator {
 public:
  using IdType = uint32_t;

  // |end| is exclusive.
  explicit IdAllocator(IdType end);
  ~IdAllocator();

  // Returns an ID in the range [1, end - 1] or 0 if no more ids are available.
  IdType Allocate();
  void Free(IdType);

 private:
  IdAllocator(const IdAllocator&) = delete;
  IdAllocator& operator=(const IdAllocator&) = delete;

  const IdType max_id_;
  IdType last_id_ = 0;
  std::vector<bool> ids_;
};

}  // namespace perfetto

#endif  // SRC_TRACING_CORE_ID_ALLOCATOR_H_