Proc/NiceSleep version 0.49
STATUS
This is BETA software; it seems to work, but use it at you own risk :).
The API is subject to change until release 0.75, at which point it
will be considered stable.
Currently tested on linux and freebsd, but it should work on
most machines that run perl. Comments, ideas, bug reports,
patches, and ports are greatly appreciated.
ABSTRACT
Proc::NiceSleep is a Perl module which defines simple functions
to allow a process to yield use of the system in a quasi-intelligent
manner. See SYNOPSIS and DESCRIPTION below for details.
The Proc::NiceSleep module is available on the Comprehensive Perl Archive
Network (CPAN). The latest version should always be available at
http://joshr.com/src/ ,
http://cpan.perl.org/authors/id/J/JO/JOSHR/
and mirrors may lag behind.
INSTALLATION
To install this module type the following:
perl Makefile.PL
make
make test
make install
or, if you use the CPAN shell, from the command line you can try:
echo 'install Proc::NiceSleep' | perl -MCPAN -e shell
DEPENDENCIES
This module requires no other non-standard perl modules,
but will perform with sub-second resolution only if Time::HiRes is
detected and supports it.
NAME
Proc::NiceSleep - Perl module to have a process yield use of the system
in a quasi-intelligent fashion, consistent with a runtime-specified
policy.
SYNOPSIS
use Proc::NiceSleep qw( sleepfactor minruntime maybesleep nice );
nice(5); # lower our priority if our OS supports it
sleepfactor(2); # sleep 2x as long as we run
minruntime(2); # run at least 2 seconds without sleep
while($somecondition) {
dosomething();
$slept = maybesleep(); # sleep some amount of time if appropriate
}
DESCRIPTION
Proc::NiceSleep is a Perl 5 module which defines subroutines to allow a
process to yield use of the system in a method consistent with the
configured policy.
Proc::NiceSleep is intended for use in situations where the operating
system does not support priorities, or where using the operating
system's built-in priorities does not yield the system sufficiently.
A convenient nice() function, which acts much like the shell command and
executable of the same name, is also provided for easy, platform
independent access to your system's priorities (if available).
If Proc::NiceSleep autodetects the presence of the Time::HiRes module
and your operating system supports it then timing and yielding
operations will occur with sub-second granularity. If not, no warning or
error will be issued but Proc::NiceSleep operations will occur with a
granularity of about one second.
By default Proc::NiceSleep expects to yield the process for an amount of
time equal to the amount of time that process runs without sleeping
(wallclock time). This is expressed by the default Sleep Factor of 1.0.
The following functions can be imported from this module. No functions
are exported by default.
nice ()
Sets or gets the priority of the process, as understood by the
operating system. If passed an integer, nice() attempts to set
priority of the process to the value specified, and returns that
value. If no parameter is passed, nice() attempts to query the
operating system for the priority of the process and return it. If
your OS doesn't support priorities then nice() will likely always
return 0.
The exact nice() values returned and recognized, and their meanings
to the system, are system dependent, but usually range from about
-20 (signifying highest priority) to 20 (signifying lowest priority,
'nicest').
maybesleep ()
Checks to see if this process should yield use of the system by
issuing some kind of sleep at this point, and if so, does so for an
appropriate amount of time. Returns 0 if no sleep was performed,
otherwise returns the amount of seconds we think maybesleep()
actually slept for.
sleepfactor ()
Sets or gets the sleep factor depending on whether a number is
passed or not. A sleep factor of 1 means to sleep an equal amount of
time as we run, 2 means to sleep twice as long, and so on. The
default value is 1.
minruntime ()
Sets or gets the minimum run time, in seconds, depending on whether
a number is passed or not. The minumum run time is the least amount
of time that Proc::NiceSleep will allow the process to run between
sleeps. The default value is 1.
Dump ()
Returns a reference to a hash with internal information about
Proc::NiceSleep configuration and statistics. The names and presence
of Dump()'s returned hash names and values are for informational and
debugging purposes only and are subject to change without notice.
Modifying this hash will have no effect on the operation of
Proc::NiceSleep
Proc::NiceSleep is loosely modeled on Lincoln Stein's CGI.pm and on D.
Wegscheid and other's Time::HiRes.pm.
EXPORT
None by default.
AUTHOR
Josh Rabinowitz, <
[email protected]>
REVISION
$Log: NiceSleep.pm,v $ Revision 1.21 2002/02/20 20:36:40 root *** empty
log message ***
Revision 1.20 2002/02/20 19:33:43 test made work with perl 5.004, wrote
DumpText() so example.pl wouldn't want to use Data::Dumper.
Revision 1.19 2002/02/20 18:28:31 root doc touches, pre-emptive version
bump to .48 (.47 is last release)
Revision 1.18 2002/02/19 22:53:28 root release 0.47
CAVEATS
sleepfactor() and minruntime() require numeric parameters if present,
but no check is made that the passed scalar is a number.
Uncoordinated use of sleep() (and possibly of signal() and alarm()) in
your perl program may cause your program to yield the system more or
less than specified via Proc::NiceSleep policies.
SEE ALSO
Time::HiRes
COPYRIGHT
Copyright (c) 2002 Josh Rabinowitz
All rights reserved. This program is free software; you can
redistribute it and/or modify it under the same terms as Perl itself.
ACKNOWLEDGEMENTS
Thanks to D. Wegscheid and others for Time::HiRes.pm. Thanks also to
Michael G Schwern, Terrence Brannon, and David Alban for their valuable
input.
