Richard Thompson
Mutex Locker utility class to lock/unlock mbed RTOS mutexes. Create and pass a mutex, it locks the mutex then unlocks it when destroyed.
Dependents: SmartLight HelloThreadsYo
Mutex Locker
This utility class is most useful when you have an activity that needs to be protected by a mutex that has multiple return points.
You would normally do this:
Using standard mutex access
Mutex myMutex;
void do_some_stuff()
{
myMutex.lock();
/* Do Stuff */
if (condition) {
myMutex.unlock();
return 0;
}
/* Call other method */
int temp = other_method(); // Temp so can unlock after function returns
myMutex.unlock();
return temp;
}
However, it's very easy to miss one of the unlock points which would later freeze the application.
Debugging this kind of error can be very hard.
The same example using MutexLocker:
Using a MutexLocker
Mutex myMutex;
int do_some_stuff()
{
MutexLocker locker(myMutex);
/* Do Stuff */
if (condition) {
return 0;
}
/* Call other method */
return other_method();
/* Mutex unlocks itself here */
}
No matter where or how your method returns, the mutex will always be unlocked as the MutexLocker goes out of scope.
Diff: mutexlocker.h
- Revision:
- 1:1a8b1de53954
- Parent:
- 0:0714ae633eab
- Child:
- 2:8bf85ca6ccee
--- a/mutexlocker.h Thu Apr 10 21:59:11 2014 +0000
+++ b/mutexlocker.h Thu Apr 10 22:06:40 2014 +0000
@@ -2,16 +2,21 @@
#include "rtos.h"
+
+//! Lock/Unlokc Mutex using variable scope.
+//! Ensures always unlocked regardless of method exit
class MutexLocker
{
public:
+ //! Lock the mutex
MutexLocker(Mutex &mutex) :
- m_mutex(&mutex) {
- m_mutex->lock();
+ m_mutex(mutex) {
+ m_mutex.lock();
}
+ //! Unlocks on destruction
~MutexLocker() {
- m_mutex->unlock();
+ m_mutex.unlock();
}
private:
- Mutex *m_mutex;
+ Mutex &m_mutex;
};