Hi all,

This is my virgin question to perlmonks!

I am aiming to write a funtion that impelements a timeout facility.

I have done all the code for the timeout with "eval" "$SIG{ALRM}" "alarm" and I have proven the actual timeout code.

The alarm gets set to a number of seconds, then the next bit of code is where I perform an operation that might hang the script.

What I would like to do is re-use the timeout code by putting it into a timeout funtion, where I pass in the timeout time, address of a funtion and any parameters that need to be passed to that funtion.

In the timeout function, I intend to do the "eval" "$SIG{ALRM}" "alarm" code and then call the funtion that the timeout funtion has been given the address of via the \&<function name> mechanism. This \&<function name> would be a function that might hang.

E.G. 
sub timeout_func{

  # The first parameter is the timeout time
  my $TIMEOUT=sprintf("%s",$_[0]);

  # The second parameter is the address of the function we
  # need to perform a timeout for
  my $ADDRESS=sprintf("%s",$_[1]);

  # The third parameter is the first parameter of the
  # function we need to run
  my $FIRST=sprintf("%s",$_[2]);
  
  eval{
    #set the callback for the alarm signal
    local $SIG{ALRM} = sub { die ("ETIME\n") };

    #specify the alarm timeout
    alarm($TIMEOUT);

    #call the funtion that the calling code has provided
    #the address of via the \&<function name> mechanism

    #if we came back with in the time limit, reset the alarm
    alarm(0);

  };


} # timeout_func


timeout_func(120,\&funtion_that_might_hang,<1st param to
 funtion_that_might_hang>);

[download]


I realise that I stil need to do more work on this code, but the bit I
am hoping that someone can advise me on how to do the following:

#call the funtion that the calling code has provided the
#address of via the \&<function name> mechanism

Please could anybody let me know if they know how I should do this.

I know that the \&<function name> mechanism can be made to work becasue the threads and forks modules use this method.

If I can do this, then I can use this timeout funtion in various places in my scripts without duplicatind the same code.

Thanks in advance.

Richard Thomas

In reply to Passing function to a function using \&<function name> method by rich_d_thomas

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