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diff --git a/docs/tutorials/013/page04.html b/docs/tutorials/013/page04.html deleted file mode 100644 index af1410396a2..00000000000 --- a/docs/tutorials/013/page04.html +++ /dev/null @@ -1,141 +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 013</TITLE> -</HEAD> -<BODY TEXT="#000000" BGCOLOR="#FFFFFF" LINK="#000FFF" VLINK="#FF0F0F"> - -<CENTER><B><FONT SIZE=+2>ACE Tutorial 013</FONT></B></CENTER> - -<CENTER><B><FONT SIZE=+2>Multiple thread pools</FONT></B></CENTER> - - -<P> -<HR WIDTH="100%"> -<P> -Let's look now at the changes to our ACE_Message_Block derivative and -the new ACE_Data_Block derivative. -<P> -The important thing to remember is that the data block (not the -message block) is reference counted. When you instantiate a new -ACE_Message_Block, it will create one or more ACE_Data_Block objects -to contain the data you need. Optionally, you can provide it with a -pointer to a data block. -<P> -When you finish with a message block, you should use the release() -method to make it go away. Do not ever <em>delete</em> an instance of -a message block! When you invoke release(), the message block will -invoke release() on the data block(s) it contains. If the block's -reference count goes to zero as a result then the block will <em>delete</em> -itself. -<P> -To increment the reference count of a data block, use the -duplicate() method of the message block (or blocks) to get a new -message block referencing the same data block. This is very efficient -since the actual data is not copied. -<P> -<HR WIDTH="100%"> -<PRE> - -<font color=red>// $Id$</font> - -<font color=blue>#ifndef</font> <font color=purple>BLOCK_H</font> -<font color=blue>#define</font> <font color=purple>BLOCK_H</font> - -<font color=blue>#include</font> "<A HREF="../../../ace/Message_Block.h">ace/Message_Block.h</A>" - -<font color=blue>#if !defined</font> (<font color=purple>ACE_LACKS_PRAGMA_ONCE</font>) -<font color=blue># pragma</font> <font color=purple>once</font> -<font color=blue>#endif</font> <font color=red>/* ACE_LACKS_PRAGMA_ONCE */</font> - -<font color=blue>#include</font> "<A HREF="../../../ace/Synch.h">ace/Synch.h</A>" -<font color=blue>#include</font> "<font color=green>mld.h</font>" -<font color=blue>#include</font> "<font color=green>work.h</font>" - -<font color=red>/* - In this Tutorial, we derive from ACE_Data_Block for our special data. With - the possiblilty that our Task object may forward the unit of work on to - another thread pool, we have to make sure that the data object doesn't go - out of scope unexpectedly. An ACE_Message_Block will be deleted as soon as - it's release() method is called but the ACE_Data_Blocks it uses are - reference counted and only delete when the last reference release()es the - block. We use that trait to simplify our object memory management. - */</font> -class Data_Block : public ACE_Data_Block -{ -public: - typedef ACE_Data_Block inherited; - - <font color=red>// Create a data block with a unit of work to be done</font> - Data_Block (Unit_Of_Work * _data); - - ~Data_Block (void); - - <font color=red>// Returns the work pointer</font> - Unit_Of_Work *data (void); - -protected: - Unit_Of_Work * data_; - MLD; <font color=red>// Our memory leak detector</font> - - <font color=red>// The ACE_Data_Block allows us to choose a locking strategy</font> - <font color=red>// for making the reference counting thread-safe. The</font> - <font color=red>// ACE_Lock_Adaptor<> template adapts the interface of a</font> - <font color=red>// number of lock objects so that the ACE_Message_Block will</font> - <font color=red>// have an interface it can use.</font> - class Lock : public ACE_Lock_Adapter < ACE_Mutex > - { - public: - typedef ACE_Lock_Adapter < ACE_Mutex > inherited; - - Lock (void); - ~Lock (void); - - <font color=red>// destroy() will be called to explicitly delete the</font> - <font color=red>// lock when we no longer need it. The method will then</font> - <font color=red>// cleanup to prevent any memory leaks.</font> - int destroy (void); - - protected: - MLD; - }; -}; - -<font color=red>/* - This simple derivative of ACE_Message_Block will construct our Data_Block - object to contain a unit of work. - */</font> -class Message_Block : public ACE_Message_Block -{ -public: - typedef ACE_Message_Block inherited; - - Message_Block (void); - Message_Block (Unit_Of_Work * _data); - - ~Message_Block (void); - -protected: - MLD; -}; - -<font color=blue>#endif</font> -</PRE> -<HR WIDTH="100%"> -<P> -One of the most difficult parts of this to get right was the Lock -object. I didn't even have it in the beginning but I soon realized -that the reference counts were getting weird. A little careful -reading of the comments and the source informed me that some sort of -locking is necessary to keep the counter sane. The simplest thing at -that point was to use the ACE_Lock_Adaptor<> to adapt ACE_Mutex -appropriately. The next trick was to ensure that the lock object was -destroyed at the proper time to prevent both memory leaks and core -dumps. The finaly product may be a little bit intimidating at first -but it's really quite simple once you understand the motivation. -<P> -<P><HR WIDTH="100%"> -<CENTER>[<A HREF="../online-tutorials.html">Tutorial Index</A>] [<A HREF="page05.html">Continue This Tutorial</A>]</CENTER> - |