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Add high resolution time support (nanoseconds) to Time::HiRes via a new method: hrtime() #24471

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Add high resolution time support (nanoseconds) to Time::HiRes via a new method: hrtime() #24471

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b733a0c
First pass at hrtime() in `Time::HiRes`
scottchiefbaker Jun 12, 2026
30fa55f
Add POD documentation for `hrtime()`
scottchiefbaker Jun 12, 2026
c44f3fe
Target a simpler return path
scottchiefbaker Jun 13, 2026
195c1c8
Add an optional parameter to hrtime() to make it return an array
scottchiefbaker Jun 15, 2026
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31 changes: 29 additions & 2 deletions dist/Time-HiRes/HiRes.pm
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Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,7 @@ our @EXPORT = qw( );
# More or less this same list is in Makefile.PL. Should unify.
our @EXPORT_OK = qw (usleep sleep ualarm alarm gettimeofday time tv_interval
getitimer setitimer nanosleep clock_gettime clock_getres
clock clock_nanosleep
clock clock_nanosleep hrtime
CLOCKS_PER_SEC
CLOCK_BOOTTIME
CLOCK_HIGHRES
Expand Down Expand Up @@ -45,7 +45,7 @@ our @EXPORT_OK = qw (usleep sleep ualarm alarm gettimeofday time tv_interval
TIMER_ABSTIME
d_usleep d_ualarm d_gettimeofday d_getitimer d_setitimer
d_nanosleep d_clock_gettime d_clock_getres
d_clock d_clock_nanosleep d_hires_stat
d_clock d_clock_nanosleep d_hrtime d_hires_stat
d_futimens d_utimensat d_hires_utime
stat lstat utime
);
Expand Down Expand Up @@ -82,6 +82,7 @@ sub import {
($i eq 'nanosleep' && !&d_nanosleep) ||
($i eq 'usleep' && !&d_usleep) ||
($i eq 'utime' && !&d_hires_utime) ||
($i eq 'hrtime' && !&d_hrtime) ||
($i eq 'ualarm' && !&d_ualarm)) {
require Carp;
Carp::croak("Time::HiRes::$i(): unimplemented in this platform");
Expand Down Expand Up @@ -153,6 +154,11 @@ Time::HiRes - High resolution alarm, sleep, gettimeofday, interval timers

my $ticktock = clock();

use Time::HiRes qw( hrtime );

my $nanoseconds = hrtime();
my ($seconds, $nanosec) = hrtime(1);

use Time::HiRes qw( stat lstat );

my @stat = stat("file");
Expand Down Expand Up @@ -429,6 +435,27 @@ but not necessarily identical. Note that due to backward
compatibility limitations the returned value may wrap around at about
2147 seconds or at about 36 minutes.

=item hrtime ()

=item hrtime ($as_array)

Returns a 64-bit unsigned integer representing the value of the
CLOCK_MONOTONIC clock in nanoseconds. When called with a true
argument, returns a two-element array of (seconds, nanoseconds)
from the same clock.

This is a monotonic clock, meaning that it is unaffected by system
clock adjustments. The reference epoch of this clock is not
specified, so only I<differences> between hrtime() values are
meaningful.

On 64bit systems the counter will roll after 584 years. On 32bit
systems the counter will roll after ~4.2 seconds.

This function was added in Time::HiRes 1.9780 and requires a
system that supports clock_gettime() (i.e., a POSIX-like system
or equivalent).

=item stat

=item stat FH
Expand Down
36 changes: 36 additions & 0 deletions dist/Time-HiRes/HiRes.xs
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Expand Up @@ -1409,6 +1409,42 @@ clock_gettime(clock_id = 0)

#endif /* #if defined(TIME_HIRES_CLOCK_GETTIME) */

#if defined(TIME_HIRES_CLOCK_GETTIME)

void
hrtime(as_array = 0)
bool as_array

@bulk88 bulk88 Jun 24, 2026

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This argument is illogical in the Perl 5 language and shows zero knowledge of Perl coding.

Either call PP wantarray or C GIMME_V to learn this information the PP Grammar correct way.

PREINIT:
struct timespec ts;
int status;
PPCODE:
# ifdef TIME_HIRES_CLOCK_GETTIME_SYSCALL
status = syscall(SYS_clock_gettime, CLOCK_MONOTONIC, &ts);
# else
status = clock_gettime(CLOCK_MONOTONIC, &ts);
# endif
if (status != 0)
XSRETURN_EMPTY;

@bulk88 bulk88 Jun 24, 2026

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XSRETURN_EMPTY should not be used in a PPCODE: block. XSRETURN_FOOs are intended for CODE: blocks where local nor global SP has never been rewound to zero, or the validity/non-SEGV Ness of local var SP is unknown, such as in EU::PXS codegen blocks that can not determine if call_sv() indirectly ever got executed in the body of a XSUB thus causing a possible Perl stack realloc grow event, and the end dev was sloppy or careless in writing SPAGAIN in the correct locations. PPCODE: puts a XSprePuSH: in the codegen at the top, rewinding local SP to 0. "PUTBACK; return;" is all that is needed to return an empty list in a PPCODE block.

if (as_array) {
EXTEND(sp, 2);
PUSHs(sv_2mortal(newSViv(ts.tv_sec)));
PUSHs(sv_2mortal(newSViv(ts.tv_nsec)));
} else {
EXTEND(sp, 1);

@bulk88 bulk88 Jun 24, 2026

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Eliminate EXTEND 1, it's not needed, all XSUBs are guaranteed 1 slot on PL_stack_sp bc pp_entersub removes 1 SV* from the stack to invoke your CV*. The alternative is to do EXTEND 2 on all paths, the Perl stack is incapable of shrinking for the life of the process. If 8 bytes of malloc() space is the difference between the kernel OOM killing Perl and a successful app run, there r much bigger problems going on. It's not worth the code space or CPU wall Time to bother branching between bounds check of 1 and 2. just do 2 always, or check for 2 on the list return path and no check on scalar return path.

PUSHs(sv_2mortal(newSVuv((UV)ts.tv_sec * (UV)IV_1E9 + (UV)ts.tv_nsec)));
}

@bulk88 bulk88 Jun 24, 2026

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What if UV is size 32bits such as on i386 Perl? You might want type U64 math here or throw a C syntax error. Truncate to 32 bits 3 times silently is a bad idea here if all 3 inputs are size 64b. Even Visual C 6.0 can be beaten with a heavy stick to cough up support for types U64 and I64 .


#else /* if defined(TIME_HIRES_CLOCK_GETTIME) */

void
hrtime(as_array = 0)
bool as_array
PPCODE:
PERL_UNUSED_ARG(as_array);
croak("Time::HiRes::hrtime(): unimplemented in this platform");

@bulk88 bulk88 Jun 24, 2026

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     croak("Time::HiRes::hrtime(): unimplemented in this platform");

Replace with "%s" and Split off string "Time::HiRes::hrtime" into arg 1 of croak(), nobody needs ASCII string "Time::HiRes::hrtime" to appear twice in the .so/.dll file.


#endif /* #if defined(TIME_HIRES_CLOCK_GETTIME) */

#if defined(TIME_HIRES_CLOCK_GETRES)

NV
Expand Down
7 changes: 6 additions & 1 deletion dist/Time-HiRes/Makefile.PL
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Expand Up @@ -984,7 +984,7 @@ sub doConstants {
);
foreach (qw (d_usleep d_ualarm d_gettimeofday d_getitimer d_setitimer
d_nanosleep d_clock_gettime d_clock_getres
d_clock d_clock_nanosleep d_hires_stat
d_clock d_clock_nanosleep d_hrtime d_hires_stat
d_futimens d_utimensat d_hires_utime)) {
my $macro = $_;
if ($macro =~ /^(d_nanosleep|d_clock)$/) {
Expand All @@ -1003,6 +1003,11 @@ sub doConstants {
push @names, {name => $_, macro => "TIME_HIRES_UTIME", value => $d_hires_utime,
default => ["IV", "0"]};
next;
} elsif ($macro =~ /^d_hrtime$/) {
my $d_hrtime = ($DEFINE =~ /-DTIME_HIRES_CLOCK_GETTIME\b/) ? 1 : 0;
push @names, {name => $_, macro => "TIME_HIRES_CLOCK_GETTIME", value => $d_hrtime,
default => ["IV", "0"]};
next;
} elsif ($macro =~ /^(d_clock_gettime|d_clock_getres|d_clock_nanosleep)$/) {
$macro =~ s/^d_(.+)/TIME_HIRES_\U$1/;
my $val = ($DEFINE =~ /-D$macro\b/) ? 1 : 0;
Expand Down
14 changes: 13 additions & 1 deletion dist/Time-HiRes/t/clock.t
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@@ -1,6 +1,6 @@
use strict;

use Test::More tests => 5;
use Test::More tests => 6;
BEGIN { push @INC, '.' }
use t::Watchdog;

Expand All @@ -18,6 +18,7 @@ printf("# have_clock_gettime = %d\n", &Time::HiRes::d_clock_gettime);
printf("# have_clock_getres = %d\n", &Time::HiRes::d_clock_getres);
printf("# have_clock_nanosleep = %d\n", &Time::HiRes::d_clock_nanosleep);
printf("# have_clock = %d\n", &Time::HiRes::d_clock);
printf("# have_hrtime = %d\n", &Time::HiRes::d_hrtime);

# Ideally, we'd like to test that the timers are rather precise.
# However, if the system is busy, there are no guarantees on how
Expand Down Expand Up @@ -97,3 +98,14 @@ SKIP: {
$clock[2] > $clock[1] &&
$clock[3] > $clock[2];
}

SKIP: {
skip "no hrtime", 1 unless &Time::HiRes::d_hrtime;
my @got = Time::HiRes::hrtime(1);
my $ok = @got == 2
&& $got[0] >= 0
&& $got[1] >= 0
&& $got[1] < 1_000_000_000;
ok $ok
or print("# got: @got, size: " . scalar(@got) . "\n");
}
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