fawkes::ScopedRWLock Class Reference

Scoped read/write lock. More...

#include <>>

List of all members.

Public Types
enum	LockType { LOCK_WRITE, LOCK_READ }
	What to lock for. More...

Public Member Functions
	ScopedRWLock (RefPtr< ReadWriteLock > rwlock, LockType lock_type=LOCK_WRITE, bool initially_lock=true)
	Constructor.
	ScopedRWLock (ReadWriteLock *rwlock, LockType lock_type=LOCK_WRITE, bool initially_lock=true)
	Constructor.
	~ScopedRWLock ()
	Destructor.
void	relock ()
	Lock this rwlock, again.
void	unlock ()
	Unlock the rwlock.

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Detailed Description

Scoped read/write lock.

This class is a convenience class which can help you prevent quite a few headaches. Consider the following code.

   void my_function()
   {
     rwlock->lock_for_write();
     for (int i = 0; i < LIMIT; ++i) {
       if ( failure ) {
         rwlock->unlock();
       }
     }
  
     switch ( someval ) {
       VALA:
         rwlock->unlock();
         return;
       VALB:
         do_something();
     }
  
     try {
       do_function_that_throws_exceptions();
     } catch (Exception &e) {
       rwlock->unlock();
       throw;
     }
     rwlock->unlock();
   }

This is not a complete list of examples but as you see if you have many exit points in a function it becomes more and more work to have correct locking behavior.

This is a lot simpler with the ScopedRWLock. The ScopedRWLock locks the given ReadWriteLock on creation, and unlocks it in the destructor. If you now have a read/write locker on the stack as integral type the destructor is called automagically on function exit and thus the lock is appropriately unlocked. The code would look like this:

   void my_function()
   {
     ScopedRWLock lock(rwlock);
     // do anything, no need to call rwlock->lock_*()/unlock() if only has to be
     // called on entering and exiting the function.
   }

Author:

Tim Niemueller

Definition at line 33 of file scoped_rwlock.h.

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Member Enumeration Documentation

enum fawkes::ScopedRWLock::LockType

What to lock for.

Enumerator:

LOCK_WRITE	Lock for writing.
LOCK_READ	Lock for reading.

Definition at line 37 of file scoped_rwlock.h.

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Constructor & Destructor Documentation

fawkes::ScopedRWLock::ScopedRWLock	(	RefPtr< ReadWriteLock >	rwlock,
		ScopedRWLock::LockType	lock_type = LOCK_WRITE,
		bool	initially_lock = true
	)

Constructor.

Parameters:

rwlock	ReadWriteLock to lock/unlock appropriately.
initially_lock	true to lock the rwlock in the constructor, false to not lock
lock_type	locking type, lock either for writing or for reading

Definition at line 95 of file scoped_rwlock.cpp.

References fawkes::ReadWriteLock::lock_for_write().

fawkes::ScopedRWLock::ScopedRWLock	(	ReadWriteLock *	rwlock,
		ScopedRWLock::LockType	lock_type = LOCK_WRITE,
		bool	initially_lock = true
	)

Constructor.

Parameters:

rwlock	ReadWriteLock to lock/unlock appropriately.
initially_lock	true to lock the rwlock in the constructor, false to not lock
lock_type	locking type, lock either for writing or for reading

Definition at line 118 of file scoped_rwlock.cpp.

References fawkes::ReadWriteLock::lock_for_write().

fawkes::ScopedRWLock::~ScopedRWLock

(

)

Destructor.

Definition at line 135 of file scoped_rwlock.cpp.

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Member Function Documentation

void fawkes::ScopedRWLock::relock

(

)

Lock this rwlock, again.

Use this if you unlocked the rwlock from the outside.

Definition at line 151 of file scoped_rwlock.cpp.

void fawkes::ScopedRWLock::unlock

(

)

Unlock the rwlock.

Definition at line 172 of file scoped_rwlock.cpp.

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

• src/libs/core/threading/scoped_rwlock.h
• src/libs/core/threading/scoped_rwlock.cpp