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https://git.savannah.gnu.org/git/parallel.git
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592 lines
22 KiB
Perl
592 lines
22 KiB
Perl
package Time::HiRes;
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use strict;
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use vars qw($VERSION $XS_VERSION @ISA @EXPORT @EXPORT_OK $AUTOLOAD);
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require Exporter;
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require DynaLoader;
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@ISA = qw(Exporter DynaLoader);
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@EXPORT = qw( );
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@EXPORT_OK = qw (usleep sleep ualarm alarm gettimeofday time tv_interval
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getitimer setitimer nanosleep clock_gettime clock_getres
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clock clock_nanosleep
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CLOCK_HIGHRES CLOCK_MONOTONIC CLOCK_PROCESS_CPUTIME_ID
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CLOCK_REALTIME CLOCK_SOFTTIME CLOCK_THREAD_CPUTIME_ID
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CLOCK_TIMEOFDAY CLOCKS_PER_SEC
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ITIMER_REAL ITIMER_VIRTUAL ITIMER_PROF ITIMER_REALPROF
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TIMER_ABSTIME
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d_usleep d_ualarm d_gettimeofday d_getitimer d_setitimer
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d_nanosleep d_clock_gettime d_clock_getres
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d_clock d_clock_nanosleep
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stat
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);
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$VERSION = '1.9721_01';
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$XS_VERSION = $VERSION;
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$VERSION = eval $VERSION;
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sub AUTOLOAD {
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my $constname;
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($constname = $AUTOLOAD) =~ s/.*:://;
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# print "AUTOLOAD: constname = $constname ($AUTOLOAD)\n";
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die "&Time::HiRes::constant not defined" if $constname eq 'constant';
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my ($error, $val) = constant($constname);
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# print "AUTOLOAD: error = $error, val = $val\n";
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if ($error) {
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my (undef,$file,$line) = caller;
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die "$error at $file line $line.\n";
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}
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{
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no strict 'refs';
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*$AUTOLOAD = sub { $val };
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}
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goto &$AUTOLOAD;
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}
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sub import {
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my $this = shift;
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for my $i (@_) {
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if (($i eq 'clock_getres' && !&d_clock_getres) ||
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($i eq 'clock_gettime' && !&d_clock_gettime) ||
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($i eq 'clock_nanosleep' && !&d_clock_nanosleep) ||
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($i eq 'clock' && !&d_clock) ||
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($i eq 'nanosleep' && !&d_nanosleep) ||
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($i eq 'usleep' && !&d_usleep) ||
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($i eq 'ualarm' && !&d_ualarm)) {
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require Carp;
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Carp::croak("Time::HiRes::$i(): unimplemented in this platform");
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}
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}
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Time::HiRes->export_to_level(1, $this, @_);
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}
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bootstrap Time::HiRes;
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# Preloaded methods go here.
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sub tv_interval {
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# probably could have been done in C
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my ($a, $b) = @_;
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$b = [gettimeofday()] unless defined($b);
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(${$b}[0] - ${$a}[0]) + ((${$b}[1] - ${$a}[1]) / 1_000_000);
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}
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# Autoload methods go after =cut, and are processed by the autosplit program.
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1;
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__END__
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=head1 NAME
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Time::HiRes - High resolution alarm, sleep, gettimeofday, interval timers
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=head1 SYNOPSIS
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use Time::HiRes qw( usleep ualarm gettimeofday tv_interval nanosleep
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clock_gettime clock_getres clock_nanosleep clock
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stat );
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usleep ($microseconds);
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nanosleep ($nanoseconds);
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ualarm ($microseconds);
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ualarm ($microseconds, $interval_microseconds);
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$t0 = [gettimeofday];
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($seconds, $microseconds) = gettimeofday;
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$elapsed = tv_interval ( $t0, [$seconds, $microseconds]);
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$elapsed = tv_interval ( $t0, [gettimeofday]);
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$elapsed = tv_interval ( $t0 );
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use Time::HiRes qw ( time alarm sleep );
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$now_fractions = time;
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sleep ($floating_seconds);
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alarm ($floating_seconds);
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alarm ($floating_seconds, $floating_interval);
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use Time::HiRes qw( setitimer getitimer );
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setitimer ($which, $floating_seconds, $floating_interval );
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getitimer ($which);
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use Time::HiRes qw( clock_gettime clock_getres clock_nanosleep
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ITIMER_REAL ITIMER_VIRTUAL ITIMER_PROF ITIMER_REALPROF );
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$realtime = clock_gettime(CLOCK_REALTIME);
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$resolution = clock_getres(CLOCK_REALTIME);
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clock_nanosleep(CLOCK_REALTIME, 1.5e9);
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clock_nanosleep(CLOCK_REALTIME, time()*1e9 + 10e9, TIMER_ABSTIME);
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my $ticktock = clock();
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use Time::HiRes qw( stat );
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my @stat = stat("file");
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my @stat = stat(FH);
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=head1 DESCRIPTION
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The C<Time::HiRes> module implements a Perl interface to the
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C<usleep>, C<nanosleep>, C<ualarm>, C<gettimeofday>, and
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C<setitimer>/C<getitimer> system calls, in other words, high
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resolution time and timers. See the L</EXAMPLES> section below and the
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test scripts for usage; see your system documentation for the
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description of the underlying C<nanosleep> or C<usleep>, C<ualarm>,
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C<gettimeofday>, and C<setitimer>/C<getitimer> calls.
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If your system lacks C<gettimeofday()> or an emulation of it you don't
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get C<gettimeofday()> or the one-argument form of C<tv_interval()>.
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If your system lacks all of C<nanosleep()>, C<usleep()>,
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C<select()>, and C<poll>, you don't get C<Time::HiRes::usleep()>,
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C<Time::HiRes::nanosleep()>, or C<Time::HiRes::sleep()>.
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If your system lacks both C<ualarm()> and C<setitimer()> you don't get
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C<Time::HiRes::ualarm()> or C<Time::HiRes::alarm()>.
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If you try to import an unimplemented function in the C<use> statement
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it will fail at compile time.
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If your subsecond sleeping is implemented with C<nanosleep()> instead
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of C<usleep()>, you can mix subsecond sleeping with signals since
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C<nanosleep()> does not use signals. This, however, is not portable,
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and you should first check for the truth value of
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C<&Time::HiRes::d_nanosleep> to see whether you have nanosleep, and
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then carefully read your C<nanosleep()> C API documentation for any
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peculiarities.
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If you are using C<nanosleep> for something else than mixing sleeping
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with signals, give some thought to whether Perl is the tool you should
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be using for work requiring nanosecond accuracies.
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Remember that unless you are working on a I<hard realtime> system,
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any clocks and timers will be imprecise, especially so if you are working
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in a pre-emptive multiuser system. Understand the difference between
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I<wallclock time> and process time (in UNIX-like systems the sum of
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I<user> and I<system> times). Any attempt to sleep for X seconds will
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most probably end up sleeping B<more> than that, but don't be surpised
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if you end up sleeping slightly B<less>.
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The following functions can be imported from this module.
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No functions are exported by default.
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=over 4
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=item gettimeofday ()
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In array context returns a two-element array with the seconds and
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microseconds since the epoch. In scalar context returns floating
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seconds like C<Time::HiRes::time()> (see below).
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=item usleep ( $useconds )
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Sleeps for the number of microseconds (millionths of a second)
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specified. Returns the number of microseconds actually slept.
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Can sleep for more than one second, unlike the C<usleep> system call.
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Can also sleep for zero seconds, which often works like a I<thread yield>.
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See also C<Time::HiRes::usleep()>, C<Time::HiRes::sleep()>, and
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C<Time::HiRes::clock_nanosleep()>.
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Do not expect usleep() to be exact down to one microsecond.
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=item nanosleep ( $nanoseconds )
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Sleeps for the number of nanoseconds (1e9ths of a second) specified.
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Returns the number of nanoseconds actually slept (accurate only to
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microseconds, the nearest thousand of them). Can sleep for more than
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one second. Can also sleep for zero seconds, which often works like
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a I<thread yield>. See also C<Time::HiRes::sleep()>,
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C<Time::HiRes::usleep()>, and C<Time::HiRes::clock_nanosleep()>.
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Do not expect nanosleep() to be exact down to one nanosecond.
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Getting even accuracy of one thousand nanoseconds is good.
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=item ualarm ( $useconds [, $interval_useconds ] )
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Issues a C<ualarm> call; the C<$interval_useconds> is optional and
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will be zero if unspecified, resulting in C<alarm>-like behaviour.
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Returns the remaining time in the alarm in microseconds, or C<undef>
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if an error occurred.
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ualarm(0) will cancel an outstanding ualarm().
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Note that the interaction between alarms and sleeps is unspecified.
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=item tv_interval
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tv_interval ( $ref_to_gettimeofday [, $ref_to_later_gettimeofday] )
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Returns the floating seconds between the two times, which should have
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been returned by C<gettimeofday()>. If the second argument is omitted,
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then the current time is used.
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=item time ()
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Returns a floating seconds since the epoch. This function can be
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imported, resulting in a nice drop-in replacement for the C<time>
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provided with core Perl; see the L</EXAMPLES> below.
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B<NOTE 1>: This higher resolution timer can return values either less
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or more than the core C<time()>, depending on whether your platform
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rounds the higher resolution timer values up, down, or to the nearest second
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to get the core C<time()>, but naturally the difference should be never
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more than half a second. See also L</clock_getres>, if available
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in your system.
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B<NOTE 2>: Since Sunday, September 9th, 2001 at 01:46:40 AM GMT, when
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the C<time()> seconds since epoch rolled over to 1_000_000_000, the
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default floating point format of Perl and the seconds since epoch have
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conspired to produce an apparent bug: if you print the value of
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C<Time::HiRes::time()> you seem to be getting only five decimals, not
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six as promised (microseconds). Not to worry, the microseconds are
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there (assuming your platform supports such granularity in the first
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place). What is going on is that the default floating point format of
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Perl only outputs 15 digits. In this case that means ten digits
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before the decimal separator and five after. To see the microseconds
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you can use either C<printf>/C<sprintf> with C<"%.6f">, or the
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C<gettimeofday()> function in list context, which will give you the
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seconds and microseconds as two separate values.
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=item sleep ( $floating_seconds )
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Sleeps for the specified amount of seconds. Returns the number of
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seconds actually slept (a floating point value). This function can
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be imported, resulting in a nice drop-in replacement for the C<sleep>
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provided with perl, see the L</EXAMPLES> below.
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Note that the interaction between alarms and sleeps is unspecified.
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=item alarm ( $floating_seconds [, $interval_floating_seconds ] )
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The C<SIGALRM> signal is sent after the specified number of seconds.
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Implemented using C<setitimer()> if available, C<ualarm()> if not.
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The C<$interval_floating_seconds> argument is optional and will be
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zero if unspecified, resulting in C<alarm()>-like behaviour. This
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function can be imported, resulting in a nice drop-in replacement for
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the C<alarm> provided with perl, see the L</EXAMPLES> below.
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Returns the remaining time in the alarm in seconds, or C<undef>
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if an error occurred.
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B<NOTE 1>: With some combinations of operating systems and Perl
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releases C<SIGALRM> restarts C<select()>, instead of interrupting it.
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This means that an C<alarm()> followed by a C<select()> may together
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take the sum of the times specified for the the C<alarm()> and the
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C<select()>, not just the time of the C<alarm()>.
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Note that the interaction between alarms and sleeps is unspecified.
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=item setitimer ( $which, $floating_seconds [, $interval_floating_seconds ] )
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Start up an interval timer: after a certain time, a signal ($which) arrives,
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and more signals may keep arriving at certain intervals. To disable
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an "itimer", use C<$floating_seconds> of zero. If the
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C<$interval_floating_seconds> is set to zero (or unspecified), the
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timer is disabled B<after> the next delivered signal.
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Use of interval timers may interfere with C<alarm()>, C<sleep()>,
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and C<usleep()>. In standard-speak the "interaction is unspecified",
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which means that I<anything> may happen: it may work, it may not.
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In scalar context, the remaining time in the timer is returned.
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In list context, both the remaining time and the interval are returned.
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There are usually three or four interval timers (signals) available: the
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C<$which> can be C<ITIMER_REAL>, C<ITIMER_VIRTUAL>, C<ITIMER_PROF>, or
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C<ITIMER_REALPROF>. Note that which ones are available depends: true
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UNIX platforms usually have the first three, but only Solaris seems to
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have C<ITIMER_REALPROF> (which is used to profile multithreaded programs).
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Win32 unfortunately does not haveinterval timers.
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C<ITIMER_REAL> results in C<alarm()>-like behaviour. Time is counted in
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I<real time>; that is, wallclock time. C<SIGALRM> is delivered when
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the timer expires.
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C<ITIMER_VIRTUAL> counts time in (process) I<virtual time>; that is,
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only when the process is running. In multiprocessor/user/CPU systems
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this may be more or less than real or wallclock time. (This time is
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also known as the I<user time>.) C<SIGVTALRM> is delivered when the
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timer expires.
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C<ITIMER_PROF> counts time when either the process virtual time or when
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the operating system is running on behalf of the process (such as I/O).
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(This time is also known as the I<system time>.) (The sum of user
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time and system time is known as the I<CPU time>.) C<SIGPROF> is
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delivered when the timer expires. C<SIGPROF> can interrupt system calls.
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The semantics of interval timers for multithreaded programs are
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system-specific, and some systems may support additional interval
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timers. For example, it is unspecified which thread gets the signals.
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See your C<setitimer()> documentation.
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=item getitimer ( $which )
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Return the remaining time in the interval timer specified by C<$which>.
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In scalar context, the remaining time is returned.
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In list context, both the remaining time and the interval are returned.
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The interval is always what you put in using C<setitimer()>.
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=item clock_gettime ( $which )
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Return as seconds the current value of the POSIX high resolution timer
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specified by C<$which>. All implementations that support POSIX high
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resolution timers are supposed to support at least the C<$which> value
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of C<CLOCK_REALTIME>, which is supposed to return results close to the
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results of C<gettimeofday>, or the number of seconds since 00:00:00:00
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January 1, 1970 Greenwich Mean Time (GMT). Do not assume that
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CLOCK_REALTIME is zero, it might be one, or something else.
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Another potentially useful (but not available everywhere) value is
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C<CLOCK_MONOTONIC>, which guarantees a monotonically increasing time
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value (unlike time() or gettimeofday(), which can be adjusted).
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See your system documentation for other possibly supported values.
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=item clock_getres ( $which )
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Return as seconds the resolution of the POSIX high resolution timer
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specified by C<$which>. All implementations that support POSIX high
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resolution timers are supposed to support at least the C<$which> value
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of C<CLOCK_REALTIME>, see L</clock_gettime>.
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=item clock_nanosleep ( $which, $nanoseconds, $flags = 0)
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Sleeps for the number of nanoseconds (1e9ths of a second) specified.
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Returns the number of nanoseconds actually slept. The $which is the
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"clock id", as with clock_gettime() and clock_getres(). The flags
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default to zero but C<TIMER_ABSTIME> can specified (must be exported
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explicitly) which means that C<$nanoseconds> is not a time interval
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(as is the default) but instead an absolute time. Can sleep for more
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than one second. Can also sleep for zero seconds, which often works
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like a I<thread yield>. See also C<Time::HiRes::sleep()>,
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C<Time::HiRes::usleep()>, and C<Time::HiRes::nanosleep()>.
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Do not expect clock_nanosleep() to be exact down to one nanosecond.
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Getting even accuracy of one thousand nanoseconds is good.
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=item clock()
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Return as seconds the I<process time> (user + system time) spent by
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the process since the first call to clock() (the definition is B<not>
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"since the start of the process", though if you are lucky these times
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may be quite close to each other, depending on the system). What this
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means is that you probably need to store the result of your first call
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to clock(), and subtract that value from the following results of clock().
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The time returned also includes the process times of the terminated
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child processes for which wait() has been executed. This value is
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somewhat like the second value returned by the times() of core Perl,
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but not necessarily identical. Note that due to backward
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compatibility limitations the returned value may wrap around at about
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2147 seconds or at about 36 minutes.
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=item stat
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=item stat FH
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=item stat EXPR
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As L<perlfunc/stat> but with the access/modify/change file timestamps
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in subsecond resolution, if the operating system and the filesystem
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both support such timestamps. To override the standard stat():
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use Time::HiRes qw(stat);
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Test for the value of &Time::HiRes::d_hires_stat to find out whether
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the operating system supports subsecond file timestamps: a value
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larger than zero means yes. There are unfortunately no easy
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ways to find out whether the filesystem supports such timestamps.
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UNIX filesystems often do; NTFS does; FAT doesn't (FAT timestamp
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granularity is B<two> seconds).
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A zero return value of &Time::HiRes::d_hires_stat means that
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Time::HiRes::stat is a no-op passthrough for CORE::stat(),
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and therefore the timestamps will stay integers. The same
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thing will happen if the filesystem does not do subsecond timestamps,
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even if the &Time::HiRes::d_hires_stat is non-zero.
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In any case do not expect nanosecond resolution, or even a microsecond
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resolution. Also note that the modify/access timestamps might have
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different resolutions, and that they need not be synchronized, e.g.
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if the operations are
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write
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stat # t1
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read
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stat # t2
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the access time stamp from t2 need not be greater-than the modify
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time stamp from t1: it may be equal or I<less>.
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=back
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=head1 EXAMPLES
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use Time::HiRes qw(usleep ualarm gettimeofday tv_interval);
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$microseconds = 750_000;
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usleep($microseconds);
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# signal alarm in 2.5s & every .1s thereafter
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ualarm(2_500_000, 100_000);
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# cancel that ualarm
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ualarm(0);
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# get seconds and microseconds since the epoch
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($s, $usec) = gettimeofday();
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# measure elapsed time
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# (could also do by subtracting 2 gettimeofday return values)
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$t0 = [gettimeofday];
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# do bunch of stuff here
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$t1 = [gettimeofday];
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# do more stuff here
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$t0_t1 = tv_interval $t0, $t1;
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$elapsed = tv_interval ($t0, [gettimeofday]);
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$elapsed = tv_interval ($t0); # equivalent code
|
|
|
|
#
|
|
# replacements for time, alarm and sleep that know about
|
|
# floating seconds
|
|
#
|
|
use Time::HiRes;
|
|
$now_fractions = Time::HiRes::time;
|
|
Time::HiRes::sleep (2.5);
|
|
Time::HiRes::alarm (10.6666666);
|
|
|
|
use Time::HiRes qw ( time alarm sleep );
|
|
$now_fractions = time;
|
|
sleep (2.5);
|
|
alarm (10.6666666);
|
|
|
|
# Arm an interval timer to go off first at 10 seconds and
|
|
# after that every 2.5 seconds, in process virtual time
|
|
|
|
use Time::HiRes qw ( setitimer ITIMER_VIRTUAL time );
|
|
|
|
$SIG{VTALRM} = sub { print time, "\n" };
|
|
setitimer(ITIMER_VIRTUAL, 10, 2.5);
|
|
|
|
use Time::HiRes qw( clock_gettime clock_getres CLOCK_REALTIME );
|
|
# Read the POSIX high resolution timer.
|
|
my $high = clock_getres(CLOCK_REALTIME);
|
|
# But how accurate we can be, really?
|
|
my $reso = clock_getres(CLOCK_REALTIME);
|
|
|
|
use Time::HiRes qw( clock_nanosleep TIMER_ABSTIME );
|
|
clock_nanosleep(CLOCK_REALTIME, 1e6);
|
|
clock_nanosleep(CLOCK_REALTIME, 2e9, TIMER_ABSTIME);
|
|
|
|
use Time::HiRes qw( clock );
|
|
my $clock0 = clock();
|
|
... # Do something.
|
|
my $clock1 = clock();
|
|
my $clockd = $clock1 - $clock0;
|
|
|
|
use Time::HiRes qw( stat );
|
|
my ($atime, $mtime, $ctime) = (stat("istics"))[8, 9, 10];
|
|
|
|
=head1 C API
|
|
|
|
In addition to the perl API described above, a C API is available for
|
|
extension writers. The following C functions are available in the
|
|
modglobal hash:
|
|
|
|
name C prototype
|
|
--------------- ----------------------
|
|
Time::NVtime double (*)()
|
|
Time::U2time void (*)(pTHX_ UV ret[2])
|
|
|
|
Both functions return equivalent information (like C<gettimeofday>)
|
|
but with different representations. The names C<NVtime> and C<U2time>
|
|
were selected mainly because they are operating system independent.
|
|
(C<gettimeofday> is Unix-centric, though some platforms like Win32 and
|
|
VMS have emulations for it.)
|
|
|
|
Here is an example of using C<NVtime> from C:
|
|
|
|
double (*myNVtime)(); /* Returns -1 on failure. */
|
|
SV **svp = hv_fetch(PL_modglobal, "Time::NVtime", 12, 0);
|
|
if (!svp) croak("Time::HiRes is required");
|
|
if (!SvIOK(*svp)) croak("Time::NVtime isn't a function pointer");
|
|
myNVtime = INT2PTR(double(*)(), SvIV(*svp));
|
|
printf("The current time is: %f\n", (*myNVtime)());
|
|
|
|
=head1 DIAGNOSTICS
|
|
|
|
=head2 useconds or interval more than ...
|
|
|
|
In ualarm() you tried to use number of microseconds or interval (also
|
|
in microseconds) more than 1_000_000 and setitimer() is not available
|
|
in your system to emulate that case.
|
|
|
|
=head2 negative time not invented yet
|
|
|
|
You tried to use a negative time argument.
|
|
|
|
=head2 internal error: useconds < 0 (unsigned ... signed ...)
|
|
|
|
Something went horribly wrong-- the number of microseconds that cannot
|
|
become negative just became negative. Maybe your compiler is broken?
|
|
|
|
=head2 useconds or uinterval equal to or more than 1000000
|
|
|
|
In some platforms it is not possible to get an alarm with subsecond
|
|
resolution and later than one second.
|
|
|
|
=head2 unimplemented in this platform
|
|
|
|
Some calls simply aren't available, real or emulated, on every platform.
|
|
|
|
=head1 CAVEATS
|
|
|
|
Notice that the core C<time()> maybe rounding rather than truncating.
|
|
What this means is that the core C<time()> may be reporting the time
|
|
as one second later than C<gettimeofday()> and C<Time::HiRes::time()>.
|
|
|
|
Adjusting the system clock (either manually or by services like ntp)
|
|
may cause problems, especially for long running programs that assume
|
|
a monotonously increasing time (note that all platforms do not adjust
|
|
time as gracefully as UNIX ntp does). For example in Win32 (and derived
|
|
platforms like Cygwin and MinGW) the Time::HiRes::time() may temporarily
|
|
drift off from the system clock (and the original time()) by up to 0.5
|
|
seconds. Time::HiRes will notice this eventually and recalibrate.
|
|
Note that since Time::HiRes 1.77 the clock_gettime(CLOCK_MONOTONIC)
|
|
might help in this (in case your system supports CLOCK_MONOTONIC).
|
|
|
|
Some systems have APIs but not implementations: for example QNX and Haiku
|
|
have the interval timer APIs but not the functionality.
|
|
|
|
=head1 SEE ALSO
|
|
|
|
Perl modules L<BSD::Resource>, L<Time::TAI64>.
|
|
|
|
Your system documentation for C<clock>, C<clock_gettime>,
|
|
C<clock_getres>, C<clock_nanosleep>, C<clock_settime>, C<getitimer>,
|
|
C<gettimeofday>, C<setitimer>, C<sleep>, C<stat>, C<ualarm>.
|
|
|
|
=head1 AUTHORS
|
|
|
|
D. Wegscheid <wegscd@whirlpool.com>
|
|
R. Schertler <roderick@argon.org>
|
|
J. Hietaniemi <jhi@iki.fi>
|
|
G. Aas <gisle@aas.no>
|
|
|
|
=head1 COPYRIGHT AND LICENSE
|
|
|
|
Copyright (c) 1996-2002 Douglas E. Wegscheid. All rights reserved.
|
|
|
|
Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008 Jarkko Hietaniemi.
|
|
All rights reserved.
|
|
|
|
This program is free software; you can redistribute it and/or modify
|
|
it under the same terms as Perl itself.
|
|
|
|
=cut
|