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diff --git a/docs/tutorials/013/page04.html b/docs/tutorials/013/page04.html deleted file mode 100644 index 4d7b714a025..00000000000 --- a/docs/tutorials/013/page04.html +++ /dev/null @@ -1,131 +0,0 @@ -<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> -/* - 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 simply our object memory management. - */ -class Data_Block : public ACE_Data_Block -{ -public: - typedef ACE_Data_Block inherited; - - // Create a data block with a unit of work to be done - Data_Block( Unit_Of_Work * _data ); - - ~Data_Block(void); - - // Returns the work pointer - Unit_Of_Work * data(void); - -protected: - Unit_Of_Work * data_; - MLD; // Our memory leak detector - - // The ACE_Data_Block allows us to choose a locking strategy - // for making the reference counting thread-safe. The - // ACE_Lock_Adaptor<> template adapts the interface of a - // number of lock objects so that the ACE_Message_Block will - // have an interface it can use. - class Lock : public ACE_Lock_Adapter<ACE_Mutex> - { - public: - typedef ACE_Lock_Adapter<ACE_Mutex> inherited; - - Lock(void); - ~Lock(void); - - // When the Data_Block is destroyed, the Message_Block is - // holding a lock with this object. If we were to destroy - // the Lock with the Data_Block, we would have a - // segfault. Instead, the Data_Block invokes destroy() to - // mark the object as un-needed so that when the - // Message_Block invokes release() to drop the lock, the - // Lock can delete itself. - int destroy(void); - int release(void); - protected: - int destroy_; - MLD; - }; -}; - -/* - This simple derivative of ACE_Message_Block will construct our - Data_Block object to contain a unit of work. - */ -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; -}; -</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> -<HR WIDTH="100%"> -<CENTER>[<A HREF="..">Tutorial Index</A>] [<A HREF="page05.html">Continue -This Tutorial</A>]</CENTER> - -</BODY> -</HTML> |