Files
allwpilib/hal/lib/athena/handles/DigitalHandleResource.h
2016-07-09 00:24:26 -07:00

108 lines
4.0 KiB
C++

/*----------------------------------------------------------------------------*/
/* Copyright (c) FIRST 2016. All Rights Reserved. */
/* Open Source Software - may be modified and shared by FRC teams. The code */
/* must be accompanied by the FIRST BSD license file in the root directory of */
/* the project. */
/*----------------------------------------------------------------------------*/
#pragma once
#include <stdint.h>
#include <memory>
#include <vector>
#include "HAL/Errors.h"
#include "HAL/Handles.h"
#include "HAL/cpp/priority_mutex.h"
#include "HandlesInternal.h"
namespace hal {
/**
* The DigitalHandleResource class is a way to track handles. This version
* allows a limited number of handles that are allocated by index.
* The enum value is seperate, as 2 enum values are allowed per handle
* Because they are allocated by index, each individual index holds its own
* mutex, which reduces contention heavily.]
*
* @tparam THandle The Handle Type (Must be typedefed from HAL_Handle)
* @tparam TStruct The struct type held by this resource
* @tparam size The number of resources allowed to be allocated
*
*/
template <typename THandle, typename TStruct, int16_t size>
class DigitalHandleResource {
friend class DigitalHandleResourceTest;
public:
DigitalHandleResource(const DigitalHandleResource&) = delete;
DigitalHandleResource operator=(const DigitalHandleResource&) = delete;
DigitalHandleResource();
~DigitalHandleResource();
THandle Allocate(int16_t index, HAL_HandleEnum enumValue, int32_t* status);
std::shared_ptr<TStruct> Get(THandle handle, HAL_HandleEnum enumValue);
void Free(THandle handle, HAL_HandleEnum enumValue);
private:
// Dynamic array to shrink HAL file size.
std::shared_ptr<TStruct>* m_structures;
priority_mutex* m_handleMutexes;
};
template <typename THandle, typename TStruct, int16_t size>
DigitalHandleResource<THandle, TStruct, size>::DigitalHandleResource() {
m_structures = new std::shared_ptr<TStruct>[size];
m_handleMutexes = new priority_mutex[size];
}
template <typename THandle, typename TStruct, int16_t size>
DigitalHandleResource<THandle, TStruct, size>::~DigitalHandleResource() {
delete[] m_structures;
delete[] m_handleMutexes;
}
template <typename THandle, typename TStruct, int16_t size>
THandle DigitalHandleResource<THandle, TStruct, size>::Allocate(
int16_t index, HAL_HandleEnum enumValue, int32_t* status) {
// don't aquire the lock if we can fail early.
if (index < 0 || index >= size) {
*status = PARAMETER_OUT_OF_RANGE;
return HAL_kInvalidHandle;
}
std::lock_guard<priority_mutex> sync(m_handleMutexes[index]);
// check for allocation, otherwise allocate and return a valid handle
if (m_structures[index] != nullptr) {
*status = RESOURCE_IS_ALLOCATED;
return HAL_kInvalidHandle;
}
m_structures[index] = std::make_shared<TStruct>();
return (THandle)hal::createHandle(index, enumValue);
}
template <typename THandle, typename TStruct, int16_t size>
std::shared_ptr<TStruct> DigitalHandleResource<THandle, TStruct, size>::Get(
THandle handle, HAL_HandleEnum enumValue) {
// get handle index, and fail early if index out of range or wrong handle
int16_t index = getHandleTypedIndex(handle, enumValue);
if (index < 0 || index >= size) {
return nullptr;
}
std::lock_guard<priority_mutex> sync(m_handleMutexes[index]);
// return structure. Null will propogate correctly, so no need to manually
// check.
return m_structures[index];
}
template <typename THandle, typename TStruct, int16_t size>
void DigitalHandleResource<THandle, TStruct, size>::Free(
THandle handle, HAL_HandleEnum enumValue) {
// get handle index, and fail early if index out of range or wrong handle
int16_t index = getHandleTypedIndex(handle, enumValue);
if (index < 0 || index >= size) return;
// lock and deallocated handle
std::lock_guard<priority_mutex> sync(m_handleMutexes[index]);
m_structures[index].reset();
}
}