diff options
Diffstat (limited to 'docs/tutorials/018/page04.html')
| -rw-r--r-- | docs/tutorials/018/page04.html | 229 |
1 files changed, 0 insertions, 229 deletions
diff --git a/docs/tutorials/018/page04.html b/docs/tutorials/018/page04.html deleted file mode 100644 index 809d05e06fd..00000000000 --- a/docs/tutorials/018/page04.html +++ /dev/null @@ -1,229 +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 018</TITLE> -</HEAD> -<BODY TEXT="#000000" BGCOLOR="#FFFFFF" LINK="#000FFF" VLINK="#FF0F0F"> - -<CENTER><B><FONT SIZE=+2>ACE Tutorial 018</FONT></B></CENTER> - -<CENTER><B><FONT SIZE=+2>The FIFO Nature of ACE_Token</FONT></B></CENTER> - -<P> -<HR WIDTH="100%"> -Our Test implementation looks much like the other ACE_Task derivatives -we've used in the past. The most obvious change is the addition of -the run() method. run() will activate the threads and put a few -messages into the queue. We could have done that in main() but it -just makes more sense here. -<P> -Notice how svc() grabs the guard after getting a message from the -queue. Since we constructed our Task baseclass with ACE_MT_SYNCH, we -know that the queue is already thread-safe. Our purpose in grabbing -the additional lock is to show how ACE_Token and ACE_Mutex behave -differently. In a real app, you'd be doing this to protect shared -resources that the threads might clobber. -<HR> -<PRE> -<font color=red>// $Id$</font> - -<font color=red>/* This is something new... Since we're included by the header, we - have to provide a sentry to protect against recursive inclusion. - */</font> -<font color=blue>#ifndef</font> <font color=purple>TEST_T_C</font> -<font color=blue>#define</font> <font color=purple>TEST_T_C</font> - -<font color=red>// Get our definition</font> -<font color=blue>#include</font> "<font color=green>Test_T.h</font>" - -<font color=red>// We'll hard-code the thread count. Mucking around with that isn't</font> -<font color=red>// really the point of the exercise today...</font> -<font color=blue>#define</font> <font color=purple>TEST_THREAD_COUNT</font> 5 - -<font color=red>/* Construction time... - Initialize the baseclass, the name and the barrier. Since the - client will probably invoke run() next, we go ahead an announce our - creation to make the output more readable. - */</font> -template <class MUTEX> -Test_T<MUTEX>::Test_T (const char *name) - : ACE_Task<ACE_MT_SYNCH>(), - name_ (name), - barrier_ (TEST_THREAD_COUNT) -{ - ACE_DEBUG ((LM_INFO, - "<font color=green>(%P|%t|%T)\tTest_T (%s) created\n</font>", - name)); -} - -<font color=red>/* Activate the threads and create some test data... - */</font> -template <class MUTEX> int -Test_T<MUTEX>::run (void) -{ - <font color=red>// Try to activate the set of threads that will test the mutex</font> - if (this->open () == -1) - return -1; - - <font color=red>// Create a set of messages. I chose twice the thread count so that</font> - <font color=red>// we can see how they get distributed.</font> - for (int i = 0; i < TEST_THREAD_COUNT*2; ++i) - { - <font color=red>// A message block big enough for a simple message.</font> - ACE_Message_Block *message; - - ACE_NEW_RETURN (message, - ACE_Message_Block (64), - -1); - - <font color=red>// Put some text into the message block so that we can know</font> - <font color=red>// what's going on when we get to svc()</font> - sprintf (message->wr_ptr (), - "<font color=green>Message Number %d</font>", - i); - message->wr_ptr (<font color=#008888>ACE_OS::strlen</font> (message->rd_ptr ()) + 1); - - <font color=red>// Send the message to the thread pool</font> - if (this->send (message) == -1) - break; - } - - <font color=red>// Send a hangup to the thread pool so that we can exit.</font> - if (this->send () == -1) - return -1; - - <font color=red>// Wait for all of the threads to exit and then return to the client.</font> - return this->wait (); -} - -<font color=red>/* Send a message to the thread pool - */</font> -template <class MUTEX> int -Test_T<MUTEX>::send (ACE_Message_Block *message) -{ - <font color=red>// If no message was provided, create a hangup message.</font> - if (message == 0) - { - <font color=#008888>ACE_Message_Block::ACE_Message_Type</font> mb_hangup = - <font color=#008888>ACE_Message_Block::MB_HANGUP</font> ; - - ACE_NEW_RETURN (message, - ACE_Message_Block (0, mb_hangup), - -1); - } - - <font color=red>// Use the duplicate() method when sending the message. For this</font> - <font color=red>// simple application, that may be overkill but it's a good habit.</font> - <font color=red>// duplicate() will increment the reference count so that each user</font> - <font color=red>// of the message can release() it when done. The last user to call</font> - <font color=red>// release() will cause the data to be deleted.</font> - if (this->putq (message->duplicate ()) == -1) - { - <font color=red>// Error? release() the message block and return failure.</font> - message->release (); - return -1; - } - - <font color=red>// release() the data to prevent memory leaks.</font> - message->release(); - - return 0; -} - -<font color=red>/* A farily typical open(). Just activate the set of threads and return. - */</font> -template <class MUTEX> int -Test_T<MUTEX>::open (void *arg) -{ - ACE_UNUSED_ARG(arg); - return this->activate (THR_NEW_LWP, - TEST_THREAD_COUNT); -} - -<font color=red>/* svc() is also fairly typical. The new part is the use of the guard - to simulate protection of shared resources. - */</font> -template <class MUTEX> int -Test_T<MUTEX>::svc (void) -{ - <font color=red>// Keep a simple thread identifier. We could always use the</font> - <font color=red>// thread id but this is a nice, simple number.</font> - int my_number = ++thread_num_; - - ACE_DEBUG ((LM_INFO, - "<font color=green>%d (%P|%t|%T)\<font color=#008888>tTest_T::svc</font>() Entry\n</font>", - my_number)); - - <font color=red>// Wait for all of threads to get started so that they all have a</font> - <font color=red>// fair shot at the message queue. Comment this out and see how the</font> - <font color=red>// behaviour changes. Does it surprise you?</font> - barrier_.wait (); - - ACE_Message_Block *message; - int mcount = 0; - - <font color=red>// This would usually be an almost-infinite loop. Instead, I've</font> - <font color=red>// governed it so that no single thread can get more than "thread</font> - <font color=red>// count" number of messages. You'll see that with ACE_Mutex, this</font> - <font color=red>// is just about the only way to keep the first thread from getting</font> - <font color=red>// all the action. Ths is obviously just for sake of the test since</font> - <font color=red>// you don't want your real-world app to exit after a fixed number</font> - <font color=red>// of messages!</font> - while (mcount < TEST_THREAD_COUNT) - { - <font color=red>// Get a message. Since the message queue is already</font> - <font color=red>// thread-safe we don't have to guard it. In fact, moving the</font> - <font color=red>// guard up above getq() will decrease your parallelization.</font> - if (getq (message) == -1) - break; - - <font color=red>// Now we pretend that there are shared resources required to</font> - <font color=red>// process the data. We grab the mutex through the guard and</font> - <font color=red>// "<font color=green>do work</font>". In a real application, you'll want to keep these</font> - <font color=red>// critical sections as small as possible since they will reduce</font> - <font color=red>// the usefulness of multi-threading.</font> - guard_t guard (mutex_); - - <font color=red>// Increase our message count for the debug output and the</font> - <font color=red>// governor.</font> - ++mcount; - - <font color=red>// Check for a hangup request... Notice the use of release()</font> - <font color=red>// again to prevent leaks</font> - if (message->msg_type () == <font color=#008888>ACE_Message_Block::MB_HANGUP</font>) - { - message->release (); - break; - } - - <font color=red>// Display the message so that we can see if things are working</font> - <font color=red>// the way we want.</font> - ACE_DEBUG ((LM_INFO, - "<font color=green>%d (%P|%t|%T)\<font color=#008888>tTest_T::svc</font>() received message #%d (%s)\n</font>", - my_number, - mcount, - message->rd_ptr ())); - - <font color=red>// Pretend that the work takes some time to complete. Remember,</font> - <font color=red>// we're holding that lock during this time!</font> - <font color=#008888>ACE_OS::sleep</font> (1); - - <font color=red>// No leaks...</font> - message->release (); - } - - <font color=red>// Send a hangup to the other threads in the pool. If we don't do</font> - <font color=red>// this then wait() will never exit since all of the other threads</font> - <font color=red>// are still blocked on getq().</font> - this->send (); - - return 0; -}; - -<font color=blue>#endif</font> <font color=red>/* TEST_T_C */</font> -</PRE> -<P><HR WIDTH="100%"> -<CENTER>[<A HREF="../online-tutorials.html">Tutorial Index</A>] [<A HREF="page05.html">Continue This Tutorial</A>]</CENTER> - |