Question

6.23 Servers can be designed to limit the number of open connections. For example, a server may wish to have only N socket connections at any point in time. As soon as N connections are made, the server will not accept another incoming connection until an existing connection is released. Illustrate how semaphores can be used by a server to limit the number of concurrent connections.

Answer 1

Answer:

Following are the code to this question:

code:

wait(semaphore *S)  //define method

{

        S-> count++;  //increment value

         if( S -> count = 100)  //define condition that check count is equal to 100

                block; //use block keyword

         else

               add this connection to S -> list;  //add value in list

}

signal(semaphore *S)  //pass the value in method parameter

{

      S -> count--;  //decrement value

      if(S ->count < 100)  //define condition that check value count is less then 100

         removeprocess P from S -> list  //remove from list

     else

         wakeup(P)  //start process

}

Explanation:

In the given Semaphores code, a count variable is used, which counts from 0 to 100, and a connection is used, that adds is value and increments by one.

• In the next line, a connection is used, that uses the code to decrements its value.
• In the last step, a code value that is equal to 100, and other connections did not enable to decrements to 99.