FreeRTOS::RecursiveMutex Class Reference

Class that encapsulates the functionality of a FreeRTOS recursive mutex. More...

#include <FreeRTOS/Mutex.hpp>

Inheritance diagram for FreeRTOS::RecursiveMutex:

Collaboration diagram for FreeRTOS::RecursiveMutex:

Public Member Functions
	RecursiveMutex ()
	Construct a new RecursiveMutex object by calling SemaphoreHandle_t xSemaphoreCreateRecursiveMutex( void )
	RecursiveMutex (const RecursiveMutex &)=delete
RecursiveMutex &	operator= (const RecursiveMutex &)=delete
	RecursiveMutex (RecursiveMutex &&) noexcept=default
RecursiveMutex &	operator= (RecursiveMutex &&) noexcept=default
Public Member Functions inherited from FreeRTOS::RecursiveMutexBase
	RecursiveMutexBase (const RecursiveMutexBase &)=delete
RecursiveMutexBase &	operator= (const RecursiveMutexBase &)=delete
bool	lock (const TickType_t ticksToWait=portMAX_DELAY) const
	Function that calls xSemaphoreTakeRecursive( SemaphoreHandle_t xMutex, TickType_t xTicksToWait )
bool	unlock () const
	Function that calls xSemaphoreGiveRecursive( SemaphoreHandle_t xSemaphore )
Public Member Functions inherited from FreeRTOS::MutexBase
	MutexBase (const MutexBase &)=delete
MutexBase &	operator= (const MutexBase &)=delete
bool	isValid () const
	Function that checks if the underlying semaphore handle is not NULL. This should be used to ensure a semaphore has been created correctly.
bool	lock (const TickType_t ticksToWait=portMAX_DELAY) const
	Function that calls xSemaphoreTake( SemaphoreHandle_t xSemaphore, TickType_t xTicksToWait )
bool	lockFromISR (bool &higherPriorityTaskWoken) const
	Function that calls xSemaphoreTakeFromISR ( SemaphoreHandle_t xSemaphore, signed BaseType_t *pxHigherPriorityTaskWoken )
bool	lockFromISR () const
	Function that calls xSemaphoreTakeFromISR ( SemaphoreHandle_t xSemaphore, signed BaseType_t *pxHigherPriorityTaskWoken )
bool	unlock () const
	Function that calls xSemaphoreGive( SemaphoreHandle_t xSemaphore )

Additional Inherited Members
Static Public Member Functions inherited from FreeRTOS::RecursiveMutexBase
static void *	operator new (size_t, void *)
static void *	operator new[] (size_t, void *)
static void *	operator new (size_t)=delete
static void *	operator new[] (size_t)=delete
Static Public Member Functions inherited from FreeRTOS::MutexBase
static void *	operator new (size_t)=delete
static void *	operator new[] (size_t)=delete
static void *	operator new (size_t, void *ptr)
static void *	operator new[] (size_t, void *ptr)

Detailed Description

Class that encapsulates the functionality of a FreeRTOS recursive mutex.

Each recursive mutex require a small amount of RAM that is used to hold the recursive mutex's state. If a mutex is created using FreeRTOS::RecursiveMutex then the required RAM is automatically allocated from the FreeRTOS heap. If a recursive mutex is created using FreeRTOS::StaticRecursiveMutex then the RAM is provided by the application writer, which requires an additional parameter, but allows the RAM to be statically allocated at compile time. See the Static Vs Dynamic allocation page for more information.

Contrary to non-recursive mutexes, a task can lock a recursive mutex multiple times, and the recursive mutex will only be returned after the holding task has unlocked the mutex the same number of times it locked the mutex.

Like non-recursive mutexes, recursive mutexes implement a priority inheritance algorithm. The priority of a task that locks a mutex will be temporarily raised if another task of higher priority attempts to obtain the same mutex. The task that owns the mutex 'inherits' the priority of the task attempting to lock the same mutex. This means the mutex must always be unlocked otherwise the higher priority task will never be able to obtain the mutex, and the lower priority task will never 'disinherit' the priority.

Constructor & Destructor Documentation

RecursiveMutex()

FreeRTOS::RecursiveMutex::RecursiveMutex ( )

inline

Construct a new RecursiveMutex object by calling SemaphoreHandle_t xSemaphoreCreateRecursiveMutex( void )

Mutex.hpp

See also

https://www.freertos.org/xSemaphoreCreateRecursiveMutex.html

Warning

The user should call isValid() on this object to verify that the recursive mutex was created successfully in case the memory required to create the queue could not be allocated.

Example Usage

#include <FreeRTOS/Mutex.hpp>
#include <FreeRTOS/Task.hpp>
 
class MyTask : public FreeRTOS::Task {
 public:
  void taskFunction() final;
};
 
void MyTask::taskFunction() {
  // Create a recursive mutex.
  FreeRTOS::RecursiveMutex mutex;
 
  if (mutex.isValid()) {
    // The recursive mutex was created successfully and can now be used.
  }
}

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The documentation for this class was generated from the following file:

• /home/runner/work/FreeRTOS-Cpp/FreeRTOS-Cpp/FreeRTOS-Cpp/include/FreeRTOS/Mutex.hpp