X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=ext%2FTime%2FHiRes%2FHiRes.pm;h=72eed1c4a5da801bf94d73a6ee71d1d179e0021f;hb=0225372c57036b54771b8abce5d6355b7e7ed288;hp=eb4e41625d38e6a0e7dc8a348fbb92553296f451;hpb=a0c8e3cf5fa0fae52f31f219ff170d986966c18e;p=p5sagit%2Fp5-mst-13.2.git

diff --git a/ext/Time/HiRes/HiRes.pm b/ext/Time/HiRes/HiRes.pm
index eb4e416..72eed1c 100644
--- a/ext/Time/HiRes/HiRes.pm
+++ b/ext/Time/HiRes/HiRes.pm
@@ -15,7 +15,7 @@ require DynaLoader;
 		 d_usleep d_ualarm d_gettimeofday d_getitimer d_setitimer
 		 d_nanosleep);
 	
-$VERSION = '1.43';
+$VERSION = '1.54';
 $XS_VERSION = $VERSION;
 $VERSION = eval $VERSION;
 
@@ -83,31 +83,35 @@ Time::HiRes - High resolution alarm, sleep, gettimeofday, interval timers
 
 =head1 DESCRIPTION
 
-The C<Time::HiRes> module implements a Perl interface to the usleep,
-ualarm, gettimeofday, and setitimer/getitimer system calls. See the
-EXAMPLES section below and the test scripts for usage; see your system
-documentation for the description of the underlying nanosleep or usleep,
-ualarm, gettimeofday, and setitimer/getitimer calls.
+The C<Time::HiRes> module implements a Perl interface to the C<usleep>,
+C<ualarm>, C<gettimeofday>, and C<setitimer>/C<getitimer> system calls, in other
+words, high resolution time and timers. See the L</EXAMPLES> section below
+and the test scripts for usage; see your system documentation for the
+description of the underlying C<nanosleep> or C<usleep>, C<ualarm>,
+C<gettimeofday>, and C<setitimer>/C<getitimer> calls.
 
-If your system lacks gettimeofday(2) or an emulation of it you don't
-get gettimeofday() or the one-arg form of tv_interval().  If you don't
-have nanosleep() or usleep(3) or select(2) you don't get Time::HiRes::usleep()
-or sleep().  If your system don't have ualarm(3) or setitimer(2) you
-don't get Time::HiRes::ualarm() or alarm().
+If your system lacks C<gettimeofday()> or an emulation of it you don't
+get C<gettimeofday()> or the one-argument form of C<tv_interval()>.  If your system lacks all of 
+C<nanosleep()>, C<usleep()>, and C<select()>, you don't get
+C<Time::HiRes::usleep()> or C<Time::HiRes::sleep()>.  If your system lacks both
+C<ualarm()> and C<setitimer()> you don't get
+C<Time::HiRes::ualarm()> or C<Time::HiRes::alarm()>.
 
 If you try to import an unimplemented function in the C<use> statement
 it will fail at compile time.
 
-If your subsecond sleeping is implemented with nanosleep() instead of
-usleep(), you can mix subsecond sleeping with signals since
-nanosleep() does not use signals.  This, however, is unportable
-behavior, and you should first check for the truth value of
-C<&Time::HiRes::d_nanosleep> to see whether you have nanosleep,
-and then read carefully your nanosleep() C API documentation for
-any peculiarities.  (There is no separate interface to call nanosleep();
-just use Time::HiRes::sleep() or usleep() with small enough values.  Also,
-think twice whether using nanosecond accuracies in a Perl program is what
-you should be doing.)
+If your subsecond sleeping is implemented with C<nanosleep()> instead of
+C<usleep()>, you can mix subsecond sleeping with signals since
+C<nanosleep()> does not use signals.  This, however is unportable, and you
+should first check for the truth value of C<&Time::HiRes::d_nanosleep> to
+see whether you have nanosleep, and then carefully read your
+C<nanosleep()> C API documentation for any peculiarities.  (There is no
+separate interface to call C<nanosleep()>; just use C<Time::HiRes::sleep()>
+or C<Time::HiRes::usleep()> with small enough values.)
+
+Unless using C<nanosleep> for mixing sleeping with signals, give
+some thought to whether Perl is the tool you should be using for work
+requiring nanosecond accuracies.
 
 The following functions can be imported from this module.
 No functions are exported by default.
@@ -116,53 +120,53 @@ No functions are exported by default.
 
 =item gettimeofday ()
 
-In array context returns a 2 element array with the seconds and
+In array context returns a two-element array with the seconds and
 microseconds since the epoch.  In scalar context returns floating
-seconds like Time::HiRes::time() (see below).
+seconds like C<Time::HiRes::time()> (see below).
 
 =item usleep ( $useconds )
 
 Sleeps for the number of microseconds specified.  Returns the number
-of microseconds actually slept.  Can sleep for more than one second
-unlike the usleep system call. See also Time::HiRes::sleep() below.
+of microseconds actually slept.  Can sleep for more than one second,
+unlike the C<usleep> system call. See also C<Time::HiRes::sleep()> below.
 
 =item ualarm ( $useconds [, $interval_useconds ] )
 
-Issues a ualarm call; interval_useconds is optional and will be 0 if 
-unspecified, resulting in alarm-like behaviour.
+Issues a C<ualarm> call; the C<$interval_useconds> is optional and
+will be zero if unspecified, resulting in C<alarm>-like behaviour.
 
 =item tv_interval 
 
-C<tv_interval ( $ref_to_gettimeofday [, $ref_to_later_gettimeofday] )>
+tv_interval ( $ref_to_gettimeofday [, $ref_to_later_gettimeofday] )
 
 Returns the floating seconds between the two times, which should have
-been returned by gettimeofday(). If the second argument is omitted,
+been returned by C<gettimeofday()>. If the second argument is omitted,
 then the current time is used.
 
 =item time ()
 
 Returns a floating seconds since the epoch. This function can be
 imported, resulting in a nice drop-in replacement for the C<time>
-provided with core Perl, see the EXAMPLES below.
-
-B<NOTE 1>: this higher resolution timer can return values either less or
-more than the core time(), depending on whether your platforms rounds
-the higher resolution timer values up, down, or to the nearest to get
-the core time(), but naturally the difference should be never more than
-half a second.
-
-B<NOTE 2>: Since Sunday, September 9th, 2001 at 01:46:40 AM GMT
-(when the time() seconds since epoch rolled over to 1_000_000_000),
-the default floating point format of Perl and the seconds since epoch
-have conspired to produce an apparent bug: if you print the value of
-Time::HiRes::time() you seem to be getting only five decimals, not six
+provided with core Perl; see the L</EXAMPLES> below.
+
+B<NOTE 1>: This higher resolution timer can return values either less
+or more than the core C<time()>, depending on whether your platform
+rounds the higher resolution timer values up, down, or to the nearest second
+to get the core C<time()>, but naturally the difference should be never
+more than half a second.
+
+B<NOTE 2>: Since Sunday, September 9th, 2001 at 01:46:40 AM GMT, when
+the C<time()> seconds since epoch rolled over to 1_000_000_000, the
+default floating point format of Perl and the seconds since epoch have
+conspired to produce an apparent bug: if you print the value of
+C<Time::HiRes::time()> you seem to be getting only five decimals, not six
 as promised (microseconds).  Not to worry, the microseconds are there
-(assuming your platform supports such granularity).  What is going on
-is that the default floating point format of Perl only outputs 15
-digits.  In this case that means ten digits before the decimal
-separator and five after.  To see the microseconds you can use either
-printf/sprintf with C<%.6f>, or the gettimeofday() function in list
-context, which will give you the seconds and microseconds as two
+(assuming your platform supports such granularity in first place).
+What is going on is that the default floating point format of Perl
+only outputs 15 digits.  In this case that means ten digits before the
+decimal separator and five after.  To see the microseconds you can use
+either C<printf>/C<sprintf> with C<"%.6f">, or the C<gettimeofday()> function in
+list context, which will give you the seconds and microseconds as two
 separate values.
 
 =item sleep ( $floating_seconds )
@@ -170,73 +174,72 @@ separate values.
 Sleeps for the specified amount of seconds.  Returns the number of
 seconds actually slept (a floating point value).  This function can be
 imported, resulting in a nice drop-in replacement for the C<sleep>
-provided with perl, see the EXAMPLES below.
+provided with perl, see the L</EXAMPLES> below.
 
 =item alarm ( $floating_seconds [, $interval_floating_seconds ] )
 
-The SIGALRM signal is sent after the specified number of seconds.
-Implemented using ualarm().  The $interval_floating_seconds argument
-is optional and will be 0 if unspecified, resulting in alarm()-like
+The C<SIGALRM> signal is sent after the specified number of seconds.
+Implemented using C<ualarm()>.  The C<$interval_floating_seconds> argument
+is optional and will be zero if unspecified, resulting in C<alarm()>-like
 behaviour.  This function can be imported, resulting in a nice drop-in
-replacement for the C<alarm> provided with perl, see the EXAMPLES below.
-
-B<NOTE 1>: With some platform - Perl release combinations select()
-gets restarted by SIGALRM, instead of dropping out of select().
-This means that an alarm() followed by a select() may together take
-the sum of the times specified for the the alarm() and the select(),
-not just the time of the alarm().
+replacement for the C<alarm> provided with perl, see the L</EXAMPLES> below.
 
-=item setitimer 
+B<NOTE 1>: With some operating system and Perl release combinations
+C<SIGALRM> restarts C<select()>, instead of interuping it.  
+This means that an C<alarm()> followed by a C<select()>
+may together take the sum of the times specified for the the
+C<alarm()> and the C<select()>, not just the time of the C<alarm()>.
 
-C<setitimer ( $which, $floating_seconds [, $interval_floating_seconds ] )>
+=item setitimer ( $which, $floating_seconds [, $interval_floating_seconds ] )
 
 Start up an interval timer: after a certain time, a signal arrives,
-and more signals may keep arriving at certain intervals.  To disable
-a timer, use time of zero.  If interval is set to zero (or unspecified),
-the timer is disabled B<after> the next delivered signal.
+and more signals may keep arriving at certain intervals.  To disable a
+timer, use C<$floating_seconds> of zero.  If the C<$interval_floating_seconds>
+is set to zero (or unspecified), the timer is disabled B<after> the
+next delivered signal.
 
-Use of interval timers may interfere with alarm(), sleep(), and usleep().
-In standard-speak the "interaction is unspecified", which means that
-I<anything> may happen: it may work, it may not.
+Use of interval timers may interfere with C<alarm()>, C<sleep()>,
+and C<usleep()>.  In standard-speak the "interaction is unspecified",
+which means that I<anything> may happen: it may work, it may not.
 
 In scalar context, the remaining time in the timer is returned.
 
 In list context, both the remaining time and the interval are returned.
 
-There are usually three or four interval timers available: the $which
-can be ITIMER_REAL, ITIMER_VIRTUAL, ITIMER_PROF, or ITIMER_REALPROF.
-Note that which ones are available depends: true UNIX platforms have
-usually all first three, but for example Win32 and Cygwin only have
-ITIMER_REAL, and only Solaris seems to have ITIMER_REALPROF (which is
+There are usually three or four interval timers available: the C<$which>
+can be C<ITIMER_REAL>, C<ITIMER_VIRTUAL>, C<ITIMER_PROF>, or C<ITIMER_REALPROF>.
+Note that which ones are available depends: true UNIX platforms usually
+have the first three, but (for example) Win32 and Cygwin have only
+C<ITIMER_REAL>, and only Solaris seems to have C<ITIMER_REALPROF> (which is
 used to profile multithreaded programs).
 
-ITIMER_REAL results in alarm()-like behavior.  Time is counted in
-I<real time>, that is, wallclock time.  SIGALRM is delivered when
+C<ITIMER_REAL> results in C<alarm()>-like behavior.  Time is counted in
+I<real time>; that is, wallclock time.  C<SIGALRM> is delivered when
 the timer expires.
 
-ITIMER_VIRTUAL counts time in (process) I<virtual time>, that is, only
+C<ITIMER_VIRTUAL> counts time in (process) I<virtual time>; that is, only
 when the process is running.  In multiprocessor/user/CPU systems this
 may be more or less than real or wallclock time.  (This time is also
-known as the I<user time>.)  SIGVTALRM is delivered when the timer expires.
+known as the I<user time>.)  C<SIGVTALRM> is delivered when the timer expires.
 
-ITIMER_PROF counts time when either the process virtual time or when
-the operating system is running on behalf of the process (such as
-I/O).  (This time is also known as the I<system time>.)  (Collectively
-these times are also known as the I<CPU time>.)  SIGPROF is delivered
-when the timer expires.  SIGPROF can interrupt system calls.
+C<ITIMER_PROF> counts time when either the process virtual time or when
+the operating system is running on behalf of the process (such as I/O).
+(This time is also known as the I<system time>.)  (The sum of user
+time and system time is known as the I<CPU time>.)  C<SIGPROF> is
+delivered when the timer expires.  C<SIGPROF> can interrupt system calls.
 
 The semantics of interval timers for multithreaded programs are
 system-specific, and some systems may support additional interval
-timers.  See your setitimer() documentation.
+timers.  See your C<setitimer()> documentation.
 
 =item getitimer ( $which )
 
-Return the remaining time in the interval timer specified by $which.
+Return the remaining time in the interval timer specified by C<$which>.
 
 In scalar context, the remaining time is returned.
 
 In list context, both the remaining time and the interval are returned.
-The interval is always what you put in using setitimer().
+The interval is always what you put in using C<setitimer()>.
 
 =back
 
@@ -260,7 +263,7 @@ The interval is always what you put in using setitimer().
   $t1 = [gettimeofday];
   # do more stuff here
   $t0_t1 = tv_interval $t0, $t1;
-  
+
   $elapsed = tv_interval ($t0, [gettimeofday]);
   $elapsed = tv_interval ($t0);	# equivalent code
 
@@ -272,7 +275,7 @@ The interval is always what you put in using setitimer().
   $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);
@@ -283,7 +286,7 @@ The interval is always what you put in using setitimer().
 
   use Time::HiRes qw ( setitimer ITIMER_VIRTUAL time );
 
-  $SIG{VTLARM} = sub { print time, "\n" };
+  $SIG{VTALRM} = sub { print time, "\n" };
   setitimer(ITIMER_VIRTUAL, 10, 2.5);
 
 =head1 C API
@@ -300,9 +303,10 @@ modglobal hash:
 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 Un*x-centric.)
+(C<gettimeofday> is Unix-centric, though some platforms like VMS have
+emulations for it.)
 
-Here is an example of using NVtime from C:
+Here is an example of using C<NVtime> from C:
 
   double (*myNVtime)();
   SV **svp = hv_fetch(PL_modglobal, "Time::NVtime", 12, 0);
@@ -311,11 +315,22 @@ Here is an example of using NVtime from C:
   myNVtime = INT2PTR(double(*)(), SvIV(*svp));
   printf("The current time is: %f\n", (*myNVtime)());
 
+=head1 DIAGNOSTICS
+
+=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?
+
 =head1 CAVEATS
 
-Notice that the core time() maybe rounding rather than truncating.
-What this means that the core time() may be giving time one second
-later than gettimeofday(), also known as Time::HiRes::time().
+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()>.
 
 =head1 AUTHORS
 
@@ -328,7 +343,7 @@ G. Aas <gisle@aas.no>
 
 Copyright (c) 1996-2002 Douglas E. Wegscheid.  All rights reserved.
 
-Copyright (c) 2002 Jarkko Hietaniemi.  All rights reserved.
+Copyright (c) 2002,2003,2004 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.