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diff --git a/docs/tutorials/016/page02.html b/docs/tutorials/016/page02.html deleted file mode 100644 index fdcfc4e8c1b..00000000000 --- a/docs/tutorials/016/page02.html +++ /dev/null @@ -1,221 +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 016</TITLE> -</HEAD> -<BODY TEXT="#000000" BGCOLOR="#FFFFFF" LINK="#000FFF" VLINK="#FF0F0F"> - -<CENTER><B><FONT SIZE=+2>ACE Tutorial 016</FONT></B></CENTER> - -<CENTER><B><FONT SIZE=+2>Making ACE_Condition easier to use</FONT></B></CENTER> - -<P> -<HR WIDTH="100%"> -We'll look first at the declaration of the wrapper class. -<P> -The way you use ACE_Condition is something like this: -<UL> -<LI>First, the setup... -<UL> -<LI>Create a variable using your choice of data types -<LI>Create a mutex that will provide thread-safe access to that -variable -<LI>Create an ACE_Condition that uses the mutex -</UL> -<P> -<LI>Waiting for the condition... -<UL> -<PRE> -the_mutex.acquire(); -while( the_variable != some_desired_state_or_value ) - the_condition.wait(); -the_mutex.release(); -</PRE> -Note that when <i>the_condition</i> is created, it must be given a -reference to the mutex. That's because the wait() method will release -the mutex before waiting and reacquire it after being signaled. -</UL> -<P> -<LI>Setting the condition... -<UL> -<PRE> -the_mutex.acquire(); -the_variable = some_new_value_or_state; -the_condition.signal() <i>OR</i> the_condition.broadcast() -</pre> -</UL> -</UL> -<P> -The problem I have is remembering to setup everything and co-ordinate -the locking, waiting and signaling. Even if I remember it all -correctly it just makes my application code more complex than it -should be. -<P> -To help out with that, I've created the class below to encapsulate the -three elements necessary for the condition to work. I've then added -methods for manipulation of the condition variable and waiting for the -condition to occur. -<HR><PRE> - -<font color=red>// $Id$</font> - -<font color=blue>#ifndef</font> <font color=purple>CONDITION_H</font> -<font color=blue>#define</font> <font color=purple>CONDITION_H</font> - -<font color=blue>#include</font> "<font color=green>ace/Synch.h</font>" - -<font color=red>/** A wrapper for ACE_Condition<>. - When you're using an ACE_Condition<> you have to have three things: - - Some variable that embodies the condition you're looking for - - A mutex to prevent simultaneous access to that variable from different threads - - An ACE_Condition<> that enables blocking on state changes in the variable - The class I create here will contain those three things. For the - actual condition variable I've chosen an integer. You could - easily turn this clas into a template parameterized on the - condition variable's data type if 'int' isn't what you want. - */</font> -class Condition -{ -public: - <font color=red>// From here on I'll use value_t instead of 'int' to make any</font> - <font color=red>// future upgrades easier.</font> - typedef int value_t; - - <font color=red>// Initialize the condition variable</font> - Condition(value_t _value = 0); - ~Condition(void); - - <font color=red>/* I've created a number of arithmetic operators on the class - that pass their operation on to the variable. If you turn - this into a template then some of these may not be - appropriate... - For the ones that take a parameter, I've stuck with 'int' - instead of 'value_t' to reinforce the fact that you'll need - a close look at these if you choose to change the 'value_t' - typedef. - */</font> - - <font color=red>// Increment & decrement</font> - Condition & operator++(void); - Condition & operator--(void); - - <font color=red>// Increase & decrease</font> - Condition & operator+=(int _inc); - Condition & operator-=(int _inc); - - <font color=red>// Just to be complete</font> - Condition & operator*=(int _inc); - Condition & operator/=(int _inc); - Condition & operator%=(int _inc); - - <font color=red>// Set/Reset the condition variable's value</font> - Condition & operator=( value_t _value ); - - <font color=red>/* These four operators perform the actual waiting. For - instance: - - operator!=(int _value) - - is implemented as: - - Guard guard(mutex_) - while( value_ != _value ) - condition_.wait(); - - This is the "<font color=green>typical</font>" use for condition mutexes. Each of - the operators below behaves this way for their respective - comparisions. - - To use one of these in code, you would simply do: - - Condition mycondition; - ... - <font color=red>// Wait until the condition variable has the value 42</font> - mycondition != 42 - ... - */</font> - - <font color=red>// As long as the condition variable is NOT EQUAL TO _value, we wait</font> - int operator!=( value_t _value ); - <font color=red>// As long as the condition variable is EXACTLY EQUAL TO _value, we wait</font> - int operator==( value_t _value ); - <font color=red>// As long as the condition variable is LESS THAN OR EQUAL TO _value, we wait</font> - int operator<=( value_t _value ); - <font color=red>// As long as the condition variable is GREATER THAN OR EQUAL TO _value, we wait</font> - int operator>=( value_t _value ); - - <font color=red>// Return the value of the condition variable</font> - operator value_t (void); - - <font color=red>/* In addition to the four ways of waiting above, I've also - create a method that will invoke a function object for each - iteration of the while() loop. - Derive yourself an object from <font color=#008888>Condition::Compare</font> and - overload operator()(value_t) to take advantage of this. Have - the function return non-zero when you consider the condition - to be met. - */</font> - class Compare - { - public: - virtual int operator() ( value_t _value ) = 0; - }; - - <font color=red>/* Wait on the condition until _compare(value) returns - non-zero. This is a little odd since we're not really testing - equality. Just be sure that _compare(value_) will return - non-zero when you consider the condition to be met. - */</font> - int operator==( Compare & _compare ); - -private: - <font color=red>// Prevent copy construction and assignment.</font> - Condition( const Condition & _condition ); - Condition & operator= ( const Condition & _condition ); - - <font color=red>/* Typedefs make things easier to change later. - ACE_Condition_Thread_Mutex is used as a shorthand for - ACE_Condition<ACE_Thread_Mutex> and also because it may - provide optimizations we can use. - */</font> - typedef ACE_Thread_Mutex mutex_t; - typedef ACE_Condition_Thread_Mutex condition_t; - typedef ACE_Guard<mutex_t> guard_t; - - <font color=red>// The mutex that keeps the data save</font> - mutex_t mutex_; - - <font color=red>// The condition mutex that makes waiting on the condition</font> - <font color=red>// easier.</font> - condition_t * condition_; - - <font color=red>// The acutal variable that embodies the condition we're</font> - <font color=red>// waiting for.</font> - value_t value_; - - <font color=red>// Accessors for the two mutexes.</font> - mutex_t & mutex(void) - { - return this->mutex_; - } - - condition_t & condition(void) - { - return *(this->condition_); - } - - <font color=red>// This particular accessor will make things much easier if we </font> - <font color=red>// decide that 'int' isn't the correct datatype for value_.</font> - <font color=red>// Note that we keep this private and force clients of the class</font> - <font color=red>// to use the cast operator to get a copy of the value.</font> - value_t & value(void) - { - return this->value_; - } -}; - -<font color=blue>#endif</font> <font color=red>// CONDITION_H</font> -</PRE> -<P><HR WIDTH="100%"> -<CENTER>[<A HREF="../online-tutorials.html">Tutorial Index</A>] [<A HREF="page03.html">Continue This Tutorial</A>]</CENTER> |