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ACE_Barrier Class Reference

Implements "barrier synchronization". More...

#include <Barrier.h>

Inheritance diagram for ACE_Barrier:
Inheritance graph
Collaboration diagram for ACE_Barrier:
Collaboration graph

Public Member Functions

 ACE_Barrier (unsigned int count, const ACE_TCHAR *name=0, void *arg=0)
 Initialize the barrier to synchronize count threads. More...
 ~ACE_Barrier (void)
 Default destructor. More...
int wait (void)
int shutdown (void)
void dump (void) const
 Dump the state of an object. More...

Public Attributes

 Declare the dynamic allocation hooks. More...

Protected Attributes

ACE_Thread_Mutex lock_
 Serialize access to the barrier state. More...
int current_generation_
int count_
 Total number of threads that can be waiting at any one time. More...
ACE_Sub_Barrier sub_barrier_1_
ACE_Sub_Barrier sub_barrier_2_
ACE_Sub_Barriersub_barrier_ [2]

Private Member Functions

void operator= (const ACE_Barrier &)
 ACE_Barrier (const ACE_Barrier &)

Detailed Description

Implements "barrier synchronization".

This class allows <count> number of threads to synchronize their completion of (one round of) a task, which is known as "barrier synchronization". After all the threads call <wait()> on the barrier they are all atomically released and can begin a new round.

This implementation uses a "sub-barrier generation numbering" scheme to avoid overhead and to ensure that all threads wait to leave the barrier correct. This code is based on an article from SunOpsis Vol. 4, No. 1 by Richard Marejka (

Constructor & Destructor Documentation

ACE_Barrier::ACE_Barrier ( unsigned int  count,
const ACE_TCHAR name = 0,
void *  arg = 0 

Initialize the barrier to synchronize count threads.

ACE_Barrier::~ACE_Barrier ( void  )

Default destructor.

ACE_Barrier::ACE_Barrier ( const ACE_Barrier )

Member Function Documentation

void ACE_Barrier::dump ( void  ) const

Dump the state of an object.

void ACE_Barrier::operator= ( const ACE_Barrier )
int ACE_Barrier::shutdown ( void  )

Shut the barrier down, aborting the wait of all waiting threads. Any threads waiting on the barrier when it is shut down will return with value -1, errno ESHUTDOWN.

Return values
0for success, -1 if already shut down.
ACE beta 5.4.9.
int ACE_Barrier::wait ( void  )

Block the caller until all count threads have called wait and then allow all the caller threads to continue in parallel.

Return values
0after successfully waiting for all threads to wait.
-1if an error occurs or the barrier is shut down (
See Also
shutdown ()).

Member Data Documentation


Declare the dynamic allocation hooks.

int ACE_Barrier::count_

Total number of threads that can be waiting at any one time.

int ACE_Barrier::current_generation_

Either 0 or 1, depending on whether we are the first generation of waiters or the next generation of waiters.

ACE_Thread_Mutex ACE_Barrier::lock_

Serialize access to the barrier state.

ACE_Sub_Barrier* ACE_Barrier::sub_barrier_[2]
ACE_Sub_Barrier ACE_Barrier::sub_barrier_1_

We keep two sub_barriers, one for the first "generation" of waiters, and one for the next "generation" of waiters. This efficiently solves the problem of what to do if all the first generation waiters don't leave the barrier before one of the threads calls wait() again (i.e., starts up the next generation barrier).

ACE_Sub_Barrier ACE_Barrier::sub_barrier_2_

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