Cgu::Thread::Mutex::Lock Class Reference

A scoped locking class for exception safe Mutex locking. More...

#include <c++-gtk-utils/mutex.h>

Public Member Functions
int	lock ()
int	trylock ()
int	unlock ()
	Lock (Mutex &mutex_)
	Lock (Mutex &mutex_, Locked tag)
	~Lock ()

Friends
class	Cond

Detailed Description

A scoped locking class for exception safe Mutex locking.

See also

Thread::Mutex Thread::Mutex::TrackLock Thread::Thread Thread::Cond

Constructor & Destructor Documentation

Lock() [1/2]

Cgu::Thread::Mutex::Lock::Lock ( Mutex &  mutex_ )

inline

This constructor locks the mutex passed to it. It is not a cancellation point. It does not throw.

Parameters

mutex_

The mutex to be locked.

Lock() [2/2]

Cgu::Thread::Mutex::Lock::Lock ( Mutex &  mutex_, Locked  tag  )

inline

This constructor takes an already locked mutex (say as a result of Mutex::trylock()), and takes ownership of it. It is not a cancellation point. It does not throw.

Parameters

mutex_	The mutex to be managed by this object.
tag	Pass the Cgu::Thread::locked enum tag to this parameter.

~Lock()

Cgu::Thread::Mutex::Lock::~Lock ( )

inline

The destructor unlocks the owned mutex. It is not a cancellation point. It does not throw.

Member Function Documentation

lock()

int Cgu::Thread::Mutex::Lock::lock ( )

inline

Calls Mutex::lock(), and so locks the mutex and reacquires ownership. It blocks if the mutex is already locked until the mutex becomes free. This method should normally only be called if a previous call has been made to Mutex::Lock::unlock() (that is, where the thread owning the Mutex::Lock object has temporarily allowed another thread to take the mutex concerned). It is not a cancellation point. It does not throw.

Returns

0 if successful, otherwise the pthread mutex error number.

Note

With this library implementation, the only pthread error number which could be returned by this method is EDEADLK, which it would do if the default pthread mutex behaviour happens to return that error rather than deadlock in the case of recursive locking. Most default implementations do not do this and hence the return value is usually not worth checking for except during debugging.

See also

Mutex::TrackLock.

trylock()

int Cgu::Thread::Mutex::Lock::trylock ( )

inline

Calls Mutex::trylock(), and so tries to lock the mutex and reacquire ownership, but returns immediately if it is already locked with value EBUSY. This method should normally only be called if a previous call has been made to Mutex::Lock::unlock() (that is, where the thread owning the Mutex::Lock object has temporarily allowed another thread to take the mutex concerned). It is not a cancellation point. It does not throw.

Returns

0 if successful, otherwise EBUSY.

Note

With this library implementation, the only pthread error number which could be returned by this method is EBUSY.

See also

Mutex::TrackLock.

unlock()

int Cgu::Thread::Mutex::Lock::unlock ( )

inline

Calls Mutex::unlock(), and so unlocks a locked mutex owned by the calling thread and relinquishes ownership (so temporarily allowing another thread to take the mutex). This method should normally only be called if it is to be followed by a call to Mutex::Lock::lock() or a successful call to Mutex::Lock::trylock() before the Mutex::Lock object concerned goes out of scope (otherwise Mutex::Lock's destructor will attempt to unlock an already unlocked mutex or a mutex of which another thread has by then taken ownership - Mutex::Lock objects do not maintain state). See Mutex::TrackLock::unlock() for a safe version of this method. It is not a cancellation point. It does not throw.

Returns

0 if successful, otherwise the pthread mutex error number.

Note

With this library implementation, the only pthread error number which could be returned by this method is EPERM because the calling thread does not own the mutex (however POSIX does not require that return value in that case and hence the return value is usually not worth checking for except during debugging).

See also

Mutex::TrackLock.

Friends And Related Function Documentation

Cond

friend class Cond

friend

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

• mutex.h