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diff --git a/docs/tutorials/016/page02.html b/docs/tutorials/016/page02.html deleted file mode 100644 index b43c18e5a87..00000000000 --- a/docs/tutorials/016/page02.html +++ /dev/null @@ -1,218 +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 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> "<A HREF="../../../ace/Synch.h">ace/Synch.h</A>" - -<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 class 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</font> - <font color=red>// wait</font> - int operator== (value_t value); - - <font color=red>// As long as the condition variable is LESS THAN OR EQUAL TO</font> - <font color=red>// <value>, we wait</font> - int operator<= (value_t value); - - <font color=red>// As long as the condition variable is GREATER THAN OR EQUAL TO</font> - <font color=red>// <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 easier.</font> - condition_t *condition_; - - <font color=red>// The acutal variable that embodies the condition we're waiting</font> - <font color=red>// 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_. Note</font> - <font color=red>// that we keep this private and force clients of the class to use</font> - <font color=red>// 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> |