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POMutual exclusion and semaphores
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  1. POMutual exclusion and semaphores
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    copied!<p>I am writing a program (for homework) that simulates a unisex bathroom. Only 4 people are allowed at a time and men and woman cannot enter if the other sex is already using the bathroom. My problem is with allowing a max of 4 people in the bathroom. As you can see from the output, only 1 person is getting into the restroom at a time. Here is my code:</p> <pre><code>const int Delayx = 60; int i; int restroom = 0; int Menwaiting = 0; int Womenwaiting = 0; semaphore max_capacity; semaphore woman; semaphore man; semaphore mutex; semaphore restroomcount; void Delay(void) { int DelayTime; DelayTime = random(Delayx); for (i = 0; i&lt;DelayTime; i++); } void Woman(void) { // for(;;){ Womenwaiting++; //wait(mutex); wait(woman); wait(max_capacity); //wait(woman); wait(mutex); wait(restroomcount); cout &lt;&lt; "A Woman has entered Restroom"&lt;&lt;endl; cout &lt;&lt; "People in the Restroom:" &lt;&lt; restroom++ &lt;&lt;endl &lt;&lt;endl; signal(restroomcount); Womenwaiting--; Delay(); wait(restroomcount); cout &lt;&lt; "A woman has exited Restroom"&lt;&lt;endl; cout &lt;&lt; "People in the Restroom:" &lt;&lt; restroom-- &lt;&lt;endl&lt;&lt;endl; signal(restroomcount); signal(mutex); signal(max_capacity); if(Menwaiting &gt; Womenwaiting){ signal(man); } else{ signal(woman); } //signal(max_capacity); //signal(man); // } } void Man(void) { // for(;;){ Menwaiting++; //wait(mutex); wait(man); wait(max_capacity); //wait(man); wait(mutex); wait(restroomcount); cout &lt;&lt;"A Man has entered the Restroom"&lt;&lt;endl; cout &lt;&lt;"People in the Restroom:" &lt;&lt; restroom++ &lt;&lt;endl&lt;&lt;endl; signal(restroomcount); Menwaiting--; //signal(mutex); Delay(); //wait(mutex); wait(restroomcount); cout &lt;&lt; "A man has exited the Restroom"&lt;&lt;endl; cout &lt;&lt;"People in the Restroom:" &lt;&lt; restroom-- &lt;&lt;endl&lt;&lt;endl; signal(restroomcount); signal(mutex); signal(max_capacity); if(Womenwaiting &gt; Menwaiting){ signal(woman); } else{ signal(man); } //signal(max_capacity); //signal(woman); //} } void main() { initialsem(woman,1); initialsem(man,1); initialsem(max_capacity,4); initialsem(mutex,1); initialsem(restroomcount,1); cobegin { Woman(); Woman(); Woman(); Woman(); Woman(); Man(); Man(); Man(); Man(); Man(); } } </code></pre> <p>This generates the following output:</p> <blockquote> <p>A Man has entered the Restroom <br>People in the Restroom:1</p> <p>A man has exited the Restroom <br>People in the Restroom:0</p> <p>A Man has entered the Restroom <br>People in the Restroom:1</p> <p>A man has exited the Restroom <br>People in the Restroom:0</p> <p>A Woman has entered Restroom <br>People in the Restroom:1</p> <p>A woman has exited Restroom <br>People in the Restroom:0</p> <p>A Woman has entered Restroom <br>People in the Restroom:1</p> <p>A woman has exited Restroom <br>People in the Restroom:0</p> </blockquote> <p>And so on, forever.</p>
 

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