Fibonacci Interface-Pipe-Thread Server

• Creates a named pipe, named "FIBOPIPE" (if the pipe already exists, you can use it, or delete it before creating a new one)
• Sets up a signal handler for SIGXCPU. The handler ignores any further SIGXCPU signals, and sends a SIGUSR1 to the child process. If the SIGXCPU interrupted the system call to read off the pipe, that read should not be restarted.
• Limits its CPU usage to the number of seconds given as the command line parameter.
• Set a global counter of the number running threads 0.
• Creates a child process.
  • The child process runs the user interface program described below, passing the named pipe's name in as the command line parameter.
• Opens the named pipe for reading.
• Repeatedly
  • Reports the CPU time used (not including the user interface time)
  • Reads an integer N off the pipe (the integers are placed there by the user interface program).
  • Starts and detaches a new thread that ...
    • Calculates the Nth Fibonacci number using the recursive O(2ⁿ) algorithm.
    • Prints out the result
    • Decrements the number of running threads
  • Increment number of running threads
  Until the integer is 0.
• Closes the pipe
• Waits for number of running threads to get down to 0
• Reports the CPU time used (not including the user interface time)
• Cleans up the user interface program zombie
• Deletes the named pipe
• Exits

• Sets up a signal handler for SIGUSR1. The handler causes the loop below to end, including sending 0 to the server. If the SIGUSR1 interrupted the system call to read from the user, that read should not be restarted.
• Opens the named pipe given as the command line argument for writing.
• Repeatedly
  • Prompts the user and read an integer from the terminal (you may assume that the user will enter a positive integer).
  • If the signal handler has stopped the loop, change the integer to 0.
  • Write the integer up the pipe (and flush the pipe to make sure the integer gets to the Fibonacci server).
  Until the integer is 0.
• Closes the pipe
• Exits

Sample Runs

This run does not reach the CPU limit. The user inputs were given in rapid succession.

> ThreadFibServer.out 100
S: Setting CPU limit to 100s
I: Which Fibonacci number do you want : 44
I: Which Fibonacci number do you want : S: Server has used 0s 1756us
S: Received 44 from interface
S: Created and detached the thread for 44
43
I: Which Fibonacci number do you want : S: Server has used 0s 515572us
S: Received 43 from interface
S: Created and detached the thread for 43
33
I: Which Fibonacci number do you want : S: Server has used 2s 210572us
S: Received 33 from interface
S: Created and detached the thread for 33
S: Fibonacci 33 is 3524578
42
I: Which Fibonacci number do you want : S: Server has used 3s 795963us
S: Received 42 from interface
S: Created and detached the thread for 42
0
I: Interface is exiting
S: Waiting for 3 threads
S: Waiting for 3 threads
S: Fibonacci 43 is 433494437
S: Fibonacci 42 is 267914296
S: Waiting for 1 threads
S: Fibonacci 44 is 701408733
S: Server has used 11s 654368us
S: Child 3948743 completed with status 0 

This run does reach the CPU limit. The user inputs were given in rapid succession.

> ThreadFibServer.out 4
S: Setting CPU limit to 4s
I: Which Fibonacci number do you want : 44
I: Which Fibonacci number do you want : S: Server has used 0s 1727us
S: Received 44 from interface
S: Created and detached the thread for 44
43
I: Which Fibonacci number do you want : S: Server has used 0s 602763us
S: Received 43 from interface
S: Created and detached the thread for 43
33
I: Which Fibonacci number do you want : S: Server has used 1s 793560us
S: Received 33 from interface
S: Created and detached the thread for 33
S: Fibonacci 33 is 3524578
42
I: Which Fibonacci number do you want : S: Server has used 2s 906340us
S: Received 42 from interface
S: Created and detached the thread for 42
0
S: Received a SIGXCPU, ignoring any more
S: Received a SIGXCPU, sending SIGUSR1 to interface
I: Received a SIGUSR1, stopping loop
I: Reading from user abandoned
I: Interface is exiting
S: Waiting for 3 threads
S: Waiting for 3 threads
S: Waiting for 3 threads
S: Fibonacci 42 is 267914296
S: Fibonacci 43 is 433494437
S: Waiting for 1 threads
S: Fibonacci 44 is 701408733
S: Server has used 12s 845677us
S: Child 3949093 completed with status 0 

This run does reach the CPU limit. The user inputs were given slowly.

> ThreadFibServer.out 4
S: Setting CPU limit to 4s
I: Which Fibonacci number do you want : 44
I: Which Fibonacci number do you want : S: Server has used 0s 1668us
S: Received 44 from interface
S: Created and detached the thread for 44
43
I: Which Fibonacci number do you want : S: Server has used 2s 71053us
S: Received 43 from interface
S: Created and detached the thread for 43
S: Received a SIGXCPU, ignoring any more
S: Received a SIGXCPU, sending SIGUSR1 to interface
I: Received a SIGUSR1, stopping loop
I: Reading from user abandoned
I: Interface is exiting
S: Waiting for 2 threads
33
S: Waiting for 2 threads
S: Waiting for 2 threads
S: Fibonacci 43 is 433494437
S: Waiting for 1 threads
S: Fibonacci 44 is 701408733
S: Server has used 9s 474782us
S: Child 3949066 completed with status 0 

Submission

• Submit your source code in Bb by 11am on 10th May.
• Here is the grading sheet.
• It is worth 15% of the course assessment.

Solution

• ThreadFibServer.c
• ThreadFibInterface.c