1/*
2 * Copyright (C) 2017 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef SRC_TRACING_CORE_ID_ALLOCATOR_H_
18#define SRC_TRACING_CORE_ID_ALLOCATOR_H_
19
20#include <stdint.h>
21
22#include <type_traits>
23#include <vector>
24
25namespace perfetto {
26
27// Handles assigment of IDs (int types) from a fixed-size pool.
28// Zero is not considered a valid ID.
29// The base class takes always a uint32_t and the derived class casts and checks
30// bounds at compile time. This is to avoid bloating code with different
31// instances of the main class for each size.
32class IdAllocatorGeneric {
33 public:
34  // |max_id| is inclusive.
35  explicit IdAllocatorGeneric(uint32_t max_id);
36  ~IdAllocatorGeneric();
37
38  // Returns an ID in the range [1, max_id] or 0 if no more ids are available.
39  uint32_t AllocateGeneric();
40  void FreeGeneric(uint32_t);
41
42 private:
43  IdAllocatorGeneric(const IdAllocatorGeneric&) = delete;
44  IdAllocatorGeneric& operator=(const IdAllocatorGeneric&) = delete;
45
46  const uint32_t max_id_;
47  uint32_t last_id_ = 0;
48  std::vector<bool> ids_;
49};
50
51template <typename T = uint32_t>
52class IdAllocator : public IdAllocatorGeneric {
53 public:
54  explicit IdAllocator(T end) : IdAllocatorGeneric(end) {
55    static_assert(std::is_integral<T>::value && std::is_unsigned<T>::value,
56                  "T must be an unsigned integer");
57    static_assert(sizeof(T) <= sizeof(uint32_t), "T is too big");
58  }
59
60  T Allocate() { return static_cast<T>(AllocateGeneric()); }
61  void Free(T id) { FreeGeneric(id); }
62};
63
64}  // namespace perfetto
65
66#endif  // SRC_TRACING_CORE_ID_ALLOCATOR_H_
67