[bug#60807] [PATCH v2] tests: reuse am_cv_filesystem_timestamp_resolution

[Mike Frysinger]

Rather than assume such coarse delays, re-use existing logic for
probing the current filesystem resolution.  This speeds up the
testsuite significantly.  On my system, it speeds -j1 up quite a
lot -- by ~30%.  While I didn't gather many samples to produce a
statistically significant distribution, my runs seem to be fairly
consistent with the values below with deviations of <1 minute.

$ time make -j1
    Before                After
real  33m17.182s      real  23m33.557s
user  12m12.145s      user  12m12.763s
sys   1m52.308s       sys   1m52.853s

$ time make -j32
    Before                After
real  1m35.874s       real  1m4.908s
user  14m24.664s      user  15m58.663s
sys   2m9.297s        sys   2m27.393s

* configure.ac: Set test delays to am_cv_filesystem_timestamp_resolution.
* t/aclocal-no-force.sh: Use slower sleep if subsecond APIs are missing.
* t/ax/test-defs.in: Split sleep settings into separate variables.
---
 configure.ac          | 10 +---------
 t/aclocal-no-force.sh | 12 ++++++++++++
 t/ax/test-defs.in     |  5 ++---
 3 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/configure.ac b/configure.ac
index dcf2d95566a0..d3a67d5ffec9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -172,15 +172,7 @@ result=no
 test "x$am_cv_prog_ln" = xln && result=yes
 AC_MSG_RESULT([$result])
 
-# The amount we should wait after modifying files depends on the platform.
-# On Windows '95, '98 and ME, files modifications have 2-seconds
-# granularity and can be up to 3 seconds in the future w.r.t. the
-# system clock.  When it is important to ensure one file is older
-# than another we wait at least 5 seconds between creations.
-case $build in
-  *-pc-msdosdjgpp) MODIFICATION_DELAY=5;;
-  *)               MODIFICATION_DELAY=2;;
-esac
+MODIFICATION_DELAY=$am_cv_filesystem_timestamp_resolution
 AC_SUBST([MODIFICATION_DELAY])
 
 ## ------------------------------------------- ##
diff --git a/t/aclocal-no-force.sh b/t/aclocal-no-force.sh
index 3e0c04d12f18..2e139d75cf74 100644
--- a/t/aclocal-no-force.sh
+++ b/t/aclocal-no-force.sh
@@ -19,6 +19,18 @@
 
 . test-init.sh
 
+# Automake relies on high resolution timestamps in perl.  If support isn't
+# available (see lib/Automake/FileUtils.pm), then fallback to coarse sleeps.
+# The creative quoting is to avoid spuriously triggering a failure in
+# the maintainer checks.
+case ${sleep_delay} in
+0*)
+  if ! $PERL -e 'use Time::HiRes' 2>/dev/null; then
+    sleep='sleep ''2'
+  fi
+  ;;
+esac
+
 cat >> configure.ac << 'END'
 SOME_DEFS
 AC_CONFIG_FILES([sub/Makefile])
diff --git a/t/ax/test-defs.in b/t/ax/test-defs.in
index e09a387cd0a6..321602cfdd0b 100644
--- a/t/ax/test-defs.in
+++ b/t/ax/test-defs.in
@@ -180,9 +180,8 @@ TEX=${AM_TESTSUITE_TEX-'@TEX@'}
 # The amount we should wait after modifying files depends on the platform.
 # For instance, Windows '95, '98 and ME have 2-second granularity
 # and can be up to 3 seconds in the future w.r.t. the system clock.
-# The creative quoting is to avoid spuriously triggering a failure in
-# the maintainer checks,
-sleep='sleep ''@MODIFICATION_DELAY@'
+sleep_delay=@MODIFICATION_DELAY@
+sleep="sleep ${sleep_delay}"
 
 # An old timestamp that can be given to a file, in "touch -t" format.
 # The time stamp should be portable to all file systems of interest.
-- 
2.39.0