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IndexedHandleResource.h
1 /*----------------------------------------------------------------------------*/
2 /* Copyright (c) FIRST 2016-2017. All Rights Reserved. */
3 /* Open Source Software - may be modified and shared by FRC teams. The code */
4 /* must be accompanied by the FIRST BSD license file in the root directory of */
5 /* the project. */
6 /*----------------------------------------------------------------------------*/
7 
8 #pragma once
9 
10 #include <stdint.h>
11 
12 #include <array>
13 #include <memory>
14 
15 #include "HAL/Errors.h"
16 #include "HAL/Types.h"
17 #include "HAL/cpp/make_unique.h"
18 #include "HAL/cpp/priority_mutex.h"
19 #include "HAL/handles/HandlesInternal.h"
20 
21 namespace hal {
22 
35 template <typename THandle, typename TStruct, int16_t size,
36  HAL_HandleEnum enumValue>
38  friend class IndexedHandleResourceTest;
39 
40  public:
41  IndexedHandleResource() = default;
43  IndexedHandleResource& operator=(const IndexedHandleResource&) = delete;
44 
45  THandle Allocate(int16_t index, int32_t* status);
46  std::shared_ptr<TStruct> Get(THandle handle);
47  void Free(THandle handle);
48 
49  private:
50  std::array<std::shared_ptr<TStruct>, size> m_structures;
51  std::array<priority_mutex, size> m_handleMutexes;
52 };
53 
54 template <typename THandle, typename TStruct, int16_t size,
55  HAL_HandleEnum enumValue>
57  int16_t index, int32_t* status) {
58  // don't aquire the lock if we can fail early.
59  if (index < 0 || index >= size) {
60  *status = RESOURCE_OUT_OF_RANGE;
61  return HAL_kInvalidHandle;
62  }
63  std::lock_guard<priority_mutex> sync(m_handleMutexes[index]);
64  // check for allocation, otherwise allocate and return a valid handle
65  if (m_structures[index] != nullptr) {
66  *status = RESOURCE_IS_ALLOCATED;
67  return HAL_kInvalidHandle;
68  }
69  m_structures[index] = std::make_shared<TStruct>();
70  return static_cast<THandle>(hal::createHandle(index, enumValue));
71 }
72 
73 template <typename THandle, typename TStruct, int16_t size,
74  HAL_HandleEnum enumValue>
75 std::shared_ptr<TStruct>
76 IndexedHandleResource<THandle, TStruct, size, enumValue>::Get(THandle handle) {
77  // get handle index, and fail early if index out of range or wrong handle
78  int16_t index = getHandleTypedIndex(handle, enumValue);
79  if (index < 0 || index >= size) {
80  return nullptr;
81  }
82  std::lock_guard<priority_mutex> sync(m_handleMutexes[index]);
83  // return structure. Null will propogate correctly, so no need to manually
84  // check.
85  return m_structures[index];
86 }
87 
88 template <typename THandle, typename TStruct, int16_t size,
89  HAL_HandleEnum enumValue>
90 void IndexedHandleResource<THandle, TStruct, size, enumValue>::Free(
91  THandle handle) {
92  // get handle index, and fail early if index out of range or wrong handle
93  int16_t index = getHandleTypedIndex(handle, enumValue);
94  if (index < 0 || index >= size) return;
95  // lock and deallocated handle
96  std::lock_guard<priority_mutex> sync(m_handleMutexes[index]);
97  m_structures[index].reset();
98 }
99 } // namespace hal
The IndexedHandleResource class is a way to track handles.
Definition: IndexedHandleResource.h:37