[automake-commit] branch master updated: automake: omit 1s test in _AM_FILESYSTEM_TIMESTAMP_RESOLUTION, for speed.

[Karl Berry]

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View the commit online:
https://git.savannah.gnu.org/gitweb/?p=automake.git;a=commitdiff;h=fad36f78a34cd20af0e0dc185a350a315e2aca0d

The following commit(s) were added to refs/heads/master by this push:
     new fad36f78a automake: omit 1s test in 
_AM_FILESYSTEM_TIMESTAMP_RESOLUTION, for speed.
fad36f78a is described below

commit fad36f78a34cd20af0e0dc185a350a315e2aca0d
Author: Bruno Haible <bruno@clisp.org>
AuthorDate: Mon Jun 17 15:38:11 2024 -0700

    automake: omit 1s test in _AM_FILESYSTEM_TIMESTAMP_RESOLUTION, for speed.
    
    From https://lists.gnu.org/archive/html/automake/2024-06/msg00055.html
    plus https://lists.gnu.org/archive/html/automake/2024-06/msg00054.html.
    
    * m4/sanity.m4 (_AM_FILESYSTEM_TIMESTAMP_RESOLUTION): Don't test
    whether 1 sec works; instead just accept the 2 sec delay in the
    Automake test $sleep in exchange for not incurring the 2s delay of
    running the test for all packages on 1s-resolution platforms.
    Platforms that support subsecond mtimes will still use them.
---
 m4/sanity.m4 | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/m4/sanity.m4 b/m4/sanity.m4
index 68fbf36f7..7452c1aef 100644
--- a/m4/sanity.m4
+++ b/m4/sanity.m4
@@ -32,8 +32,17 @@ AC_CACHE_CHECK([filesystem timestamp resolution],
 # Default to the worst case.
 am_cv_filesystem_timestamp_resolution=2
 
-# Only try to go finer than 1s if sleep can do it.
-am_try_resolutions=1
+# Only try to go finer than 1 sec if sleep can do it.
+# Don't try 1 sec, because if 0.01 sec and 0.1 sec don't work,
+# - 1 sec is not much of a win compared to 2 sec, and
+# - it takes 2 seconds to perform the test whether 1 sec works.
+# 
+# Instead, just use the default 2s on platforms that have 1s resolution,
+# accept the extra 1s delay when using $sleep in the Automake tests, in
+# exchange for not incurring the 2s delay for running the test for all
+# packages.
+#
+am_try_resolutions=
 if $am_cv_sleep_fractional_seconds; then
   # Even a millisecond often causes a bunch of false positives,
   # so just try a hundredth of a second. The time saved between .001 and