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diff --git a/docs/tutorials/017/page04.html b/docs/tutorials/017/page04.html deleted file mode 100644 index b725c19324a..00000000000 --- a/docs/tutorials/017/page04.html +++ /dev/null @@ -1,187 +0,0 @@ -<!-- $Id$ --> -<HTML> -<HEAD> - <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1"> - <META NAME="Author" CONTENT="James CE Johnson"> - <TITLE>ACE Tutorial 017</TITLE> -</HEAD> -<BODY TEXT="#000000" BGCOLOR="#FFFFFF" LINK="#000FFF" VLINK="#FF0F0F"> - -<CENTER><B><FONT SIZE=+2>ACE Tutorial 017</FONT></B></CENTER> - -<CENTER><B><FONT SIZE=+2>Using the ACE_Barrier synch object</FONT></B></CENTER> - -<P> -<HR WIDTH="100%"> -The Barrier implementation is quite simple. The threads() mutator -took a couple of tries to get right. In particular, be sure you know -when to apply the _wait paramter and when not to! In fact, the -requirement that only the "owning" thread can change the thread count -is rather limiting. A more appropriate solution would allow any -thread to safely change the count but that would require more complex -locking that is just a bit more than what I wanted to present here. -<HR> -<PRE> - -<font color=red>// $Id$</font> - -<font color=blue>#include</font> "<font color=green>Barrier_i.h</font>" - -<font color=red>/* Initialize the threads_ count to zero and the barrier_ pointer to a - safe value. At the same time, we remember the thread that created - us so that we can allow it to change the thread count. -*/</font> -<font color=#008888>Barrier::Barrier</font>(void) - : threads_(0) - ,barrier_(0) - ,new_barrier_(0) -{ - owner_ = <font color=#008888>ACE_OS::thr_self</font>(); -} - -<font color=red>/* Ensure that barrier_ get's deleted so that we don't have a memory leak. - */</font> -<font color=#008888>Barrier::~Barrier</font>(void) -{ - delete barrier_; -} - -void <font color=#008888>Barrier::owner</font>( ACE_thread_t _owner ) -{ - owner_ = _owner; -} - -<font color=red>// Report on the number of threads.</font> -u_int <font color=#008888>Barrier::threads</font>(void) -{ - return threads_.value(); -} - -<font color=red>/* Allow the owning thread to (re)set the number of threads. - make_barrier() is called because it will wait() if we were already - configured. Typical usage would be for the worker threads to - wait() while the primary (eg -- owner) thread adjusts the thread - count. - - For instance: - In the worker threads: - if( myBarrier.threads() != current_thread_count ) - myBarrier.wait(); - - In the primary thread: - if( myBarrier.threads() != current_thread_count ) - myBarrier.threads( current_thread_count, 1 ); - */</font> -int <font color=#008888>Barrier::threads</font>( u_int _threads, int _wait ) -{ - if( ! <font color=#008888>ACE_OS::thr_equal</font>(ACE_OS::thr_self(), owner_) ) - { - return -1; - } - - threads_ = _threads; - - return make_barrier(_wait); -} - -<font color=red>/* Wait for all threads to synch if the thread count is valid. Note - that barrier_ will be 0 if the threads() mutator has not been - invoked. -*/</font> -int <font color=#008888>Barrier::wait</font>(void) -{ - if( ! barrier_ ) - { - return -1; - } - - <font color=red>// If the threads() mutator has been used, new_barrier_ will</font> - <font color=red>// point to a new ACE_Barrier instance. We'll use a</font> - <font color=red>// traditional double-check here to move that new object into</font> - <font color=red>// place and cleanup the old one.</font> - if( new_barrier_ ) - { - <font color=red>// mutex so that only one thread can do this part.</font> - ACE_Guard<ACE_Mutex> mutex(barrier_mutex_); - - <font color=red>// We only want the first thread to plug in the new barrier...</font> - if( new_barrier_ ) - { - <font color=red>// out with the old and in with the new.</font> - delete barrier_; - barrier_ = new_barrier_; - new_barrier_ = 0; - } - } - - return barrier_->wait(); -} - -<font color=red>/* Wait for all threads to synch. As each thread passes wait(), it - will decrement our thread counter. (That is why we had to make - threads_ an atomic op.) When the last thread decrements the - counter it will also delete the ACE_Barrier & free up a little - memory. -*/</font> -int <font color=#008888>Barrier::done</font>(void) -{ - if( this->wait() == -1 ) - { - return -1; - } - - --threads_; - - if( ! threads_.value() ) - { - delete barrier_; - barrier_ = 0; - } - - return 0; -} - -<font color=red>/* This will build the actual barrier. I broke this code out of the - threads() mutator in case it might be useful elsewhere. - If a barrier already exists, we will wait for all threads before - creating a new one. This trait is what allows the threads mutator - to be used as shown above. - */</font> -int <font color=#008888>Barrier::make_barrier</font>( int _wait ) -{ - <font color=red>// Ensure we have a valid thread count.</font> - if( ! threads_.value() ) - { - return -1; - } - - <font color=red>// If a barrier already exists, we'll arrange for it to be</font> - <font color=red>// replaced through the wait() method above.</font> - if( barrier_ ) - { - <font color=red>// Create the new barrier that wait() will install for us.</font> - ACE_NEW_RETURN(new_barrier_,ACE_Barrier(threads_.value()),-1); - - <font color=red>// Wait for our siblings to synch before continuing</font> - if( _wait ) - { - barrier_->wait(); - } - } - else - { - <font color=red>// Create the initial barrier.</font> - ACE_NEW_RETURN(barrier_,ACE_Barrier(threads_.value()),-1); - } - - return 0; -} - -<font color=blue>#if defined</font> (<font color=purple>ACE_HAS_EXPLICIT_TEMPLATE_INSTANTIATION</font>) -template class ACE_Atomic_Op <ACE_Mutex, u_int>; -<font color=blue>#elif defined</font> (<font color=purple>ACE_HAS_TEMPLATE_INSTANTIATION_PRAGMA</font>) -<font color=blue>#pragma</font> <font color=purple>instantiate</font> ACE_Atomic_Op <ACE_Mutex, u_int> -<font color=blue>#endif</font> <font color=red>/* ACE_HAS_EXPLICIT_TEMPLATE_INSTANTIATION */</font> -</PRE> -<P><HR WIDTH="100%"> -<CENTER>[<A HREF="../online-tutorials.html">Tutorial Index</A>] [<A HREF="page05.html">Continue This Tutorial</A>]</CENTER> |