[PATCH] Implement timestamp'ed output on "make check"

[Sergio Durigan Junior <sergiodj at redhat dot com>]

It is unfortunately not uncommon to have tests hanging on some of the
BuildBot workers.  For example, the ppc64be/ppc64le+gdbserver builders
are especially in a bad state when it comes to testing GDB/gdbserver,
and we can have builds that take an absurd amount of time to
finish (almost 1 week for one single build, for example).

It may be hard to diagnose these failures, because sometimes we don't
have access to the faulty systems, and other times we're just too busy
to wait and check which test is actually hanging.  During one of our
conversations about the topic, someone proposed that it would be a
good idea to have a timestamp put together with stdout output, so that
we can come back later and examine which tests are taking too long to
complete.

Here's my proposal to do this.  The very first thing I tried to do was
to use "ts(1)" to achieve this feature, and it obviously worked, but
the problem is that I'm afraid "ts(1)" may not be widely available on
every system we support.  Therefore, I decided to implement a *very*
simple version of "ts(1)", in Python 3, which basically does the same
thing: iterate over the stdin lines, and prepend a timestamp onto
them.

As for testsuite/Makefile.in, the user can now specify two new
variables to enable timestamp'ed output: TS (which enables the
output), and TS_FORMAT (optional, used to specify another timestamp
format according to "strftime").

Here's an example of how the output looks like:

  ...
  [Nov 22 17:07:19] Running binutils-gdb/gdb/testsuite/gdb.base/call-strs.exp ...
  [Nov 22 17:07:19] Running binutils-gdb/gdb/testsuite/gdb.base/step-over-no-symbols.exp ...
  [Nov 22 17:07:20] Running binutils-gdb/gdb/testsuite/gdb.base/all-architectures-6.exp ...
  [Nov 22 17:07:20] Running binutils-gdb/gdb/testsuite/gdb.base/hashline3.exp ...
  [Nov 22 17:07:20] Running binutils-gdb/gdb/testsuite/gdb.base/max-value-size.exp ...
  [Nov 22 17:07:20] Running binutils-gdb/gdb/testsuite/gdb.base/quit-live.exp ...
  [Nov 22 17:07:46] Running binutils-gdb/gdb/testsuite/gdb.base/paginate-bg-execution.exp ...
  [Nov 22 17:07:56] Running binutils-gdb/gdb/testsuite/gdb.base/gcore-buffer-overflow.exp ...
  [Nov 22 17:07:56] Running binutils-gdb/gdb/testsuite/gdb.base/gcore-relro.exp ...
  [Nov 22 17:07:56] Running binutils-gdb/gdb/testsuite/gdb.base/watchpoint-delete.exp ...
  [Nov 22 17:07:56] Running binutils-gdb/gdb/testsuite/gdb.base/breakpoint-in-ro-region.exp ...
  [Nov 22 17:07:56] Running binutils-gdb/gdb/testsuite/gdb.base/vla-sideeffect.exp ...
  [Nov 22 17:07:57] Running binutils-gdb/gdb/testsuite/gdb.base/unload.exp ...
  ...

(What, gdb.base/quit-live.exp is taking 26 seconds to complete?!)

I've also tested this with FORCE_PARALLEL=1 -j8, and the output still
looks clean (i.e., not intertwined).

Output to stderr is not timestamp'ed, but I don't think that will be a
problem for us.  If it is, we can revisit the solution and extend it.

gdb/testsuite/ChangeLog:
2018-11-22  Sergio Durigan Junior  <sergiodj@redhat.com>

	* Makefile.in (TIMESTAMP): New variable.
	(check-single): Add $(TIMESTAMP) to the end of $(DO_RUNTEST)
	command.
	(check-single-racy): Likewise.
	(check/%.exp): Likewise.
	(check-racy/%.exp): Likewise.
	(workers/%.worker): Likewise.
	(build-perf): Likewise.
	(check-perf): Likewise.
	* README: Describe new "TS" and "TS_FORMAT" variables.
	* print-ts.py: New file.
---
 gdb/testsuite/Makefile.in | 20 ++++++++++-------
 gdb/testsuite/README      | 20 +++++++++++++++++
 gdb/testsuite/print-ts.py | 45 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 77 insertions(+), 8 deletions(-)
 create mode 100755 gdb/testsuite/print-ts.py

diff --git a/gdb/testsuite/Makefile.in b/gdb/testsuite/Makefile.in
index ece7e252c5..b526f579be 100644
--- a/gdb/testsuite/Makefile.in
+++ b/gdb/testsuite/Makefile.in
@@ -158,6 +158,10 @@ check: all $(abs_builddir)/site.exp
 check-read1:
 	$(MAKE) READ1="1" check
 
+# Check whether we need to print the timestamp for each line of
+# status.
+TIMESTAMP = $(if $(TS),| $(srcdir)/print-ts.py $(if $(TS_FORMAT),$(TS_FORMAT),),)
+
 # All the hair to invoke dejagnu.  A given invocation can just append
 # $(RUNTESTFLAGS)
 DO_RUNTEST = \
@@ -192,7 +196,7 @@ check-gdb.%:
 	$(MAKE) check TESTS="gdb.$*/*.exp"
 
 check-single:
-	$(DO_RUNTEST) $(RUNTESTFLAGS) $(expanded_tests_or_none)
+	$(DO_RUNTEST) $(RUNTESTFLAGS) $(expanded_tests_or_none) $(TIMESTAMP)
 
 check-single-racy:
 	-rm -rf cache racy_outputs temp
@@ -208,7 +212,7 @@ check-single-racy:
 	for n in `seq $$racyiter` ; do \
 	  mkdir -p racy_outputs/$$n; \
 	  $(DO_RUNTEST) --outdir=racy_outputs/$$n $(RUNTESTFLAGS) \
-	    $(expanded_tests_or_none); \
+	    $(expanded_tests_or_none) $(TIMESTAMP); \
 	done; \
 	$(srcdir)/analyze-racy-logs.py \
 	  `ls racy_outputs/*/gdb.sum` > racy.sum; \
@@ -273,7 +277,7 @@ do-check-parallel: $(TEST_TARGETS)
 
 check/%.exp:
 	-mkdir -p outputs/$*
-	@$(DO_RUNTEST) GDB_PARALLEL=yes --outdir=outputs/$* $*.exp $(RUNTESTFLAGS)
+	@$(DO_RUNTEST) GDB_PARALLEL=yes --outdir=outputs/$* $*.exp $(RUNTESTFLAGS) $(TIMESTAMP)
 
 do-check-parallel-racy: $(TEST_TARGETS)
 	@:
@@ -282,7 +286,7 @@ check-racy/%.exp:
 	-mkdir -p racy_outputs/$(RACY_OUTPUT_N)/$*
 	$(DO_RUNTEST) GDB_PARALLEL=yes \
 	  --outdir=racy_outputs/$(RACY_OUTPUT_N)/$* $*.exp \
-	  $(RUNTESTFLAGS)
+	  $(RUNTESTFLAGS) $(TIMESTAMP)
 
 check/no-matching-tests-found:
 	@echo ""
@@ -292,7 +296,7 @@ check/no-matching-tests-found:
 # Utility rule invoked by step 2 of the build-perf rule.
 workers/%.worker:
 	mkdir -p gdb.perf/outputs/$*
-	$(DO_RUNTEST) --outdir=gdb.perf/outputs/$* lib/build-piece.exp WORKER=$* GDB_PARALLEL=gdb.perf $(RUNTESTFLAGS) GDB_PERFTEST_MODE=compile GDB_PERFTEST_SUBMODE=build-pieces
+	$(DO_RUNTEST) --outdir=gdb.perf/outputs/$* lib/build-piece.exp WORKER=$* GDB_PARALLEL=gdb.perf $(RUNTESTFLAGS) GDB_PERFTEST_MODE=compile GDB_PERFTEST_SUBMODE=build-pieces $(TIMESTAMP)
 
 # Utility rule to build tests that support it in parallel.
 # The build is broken into 3 steps distinguished by GDB_PERFTEST_SUBMODE:
@@ -312,18 +316,18 @@ build-perf: $(abs_builddir)/site.exp
 	rm -rf gdb.perf/workers
 	mkdir -p gdb.perf/workers
 	@: Step 1: Generate the build .worker files.
-	$(DO_RUNTEST) --directory=gdb.perf --outdir gdb.perf/workers GDB_PARALLEL=gdb.perf $(RUNTESTFLAGS) GDB_PERFTEST_MODE=compile GDB_PERFTEST_SUBMODE=gen-workers
+	$(DO_RUNTEST) --directory=gdb.perf --outdir gdb.perf/workers GDB_PARALLEL=gdb.perf $(RUNTESTFLAGS) GDB_PERFTEST_MODE=compile GDB_PERFTEST_SUBMODE=gen-workers $(TIMESTAMP)
 	@: Step 2: Compile the pieces.  Here is the build parallelism.
 	$(MAKE) $$(cd gdb.perf && echo workers/*/*.worker)
 	@: Step 3: Do the final link.
-	$(DO_RUNTEST) --directory=gdb.perf --outdir gdb.perf GDB_PARALLEL=gdb.perf $(RUNTESTFLAGS) GDB_PERFTEST_MODE=compile GDB_PERFTEST_SUBMODE=final
+	$(DO_RUNTEST) --directory=gdb.perf --outdir gdb.perf GDB_PARALLEL=gdb.perf $(RUNTESTFLAGS) GDB_PERFTEST_MODE=compile GDB_PERFTEST_SUBMODE=final $(TIMESTAMP)
 
 # The default is to both compile and run the tests.
 GDB_PERFTEST_MODE = both
 
 check-perf: all $(abs_builddir)/site.exp
 	@if test ! -d gdb.perf; then mkdir gdb.perf; fi
-	$(DO_RUNTEST) --directory=gdb.perf --outdir gdb.perf GDB_PERFTEST_MODE=$(GDB_PERFTEST_MODE) $(RUNTESTFLAGS)
+	$(DO_RUNTEST) --directory=gdb.perf --outdir gdb.perf GDB_PERFTEST_MODE=$(GDB_PERFTEST_MODE) $(RUNTESTFLAGS) $(TIMESTAMP)
 
 force:;
 
diff --git a/gdb/testsuite/README b/gdb/testsuite/README
index 55abfb3254..723d8ba5eb 100644
--- a/gdb/testsuite/README
+++ b/gdb/testsuite/README
@@ -273,6 +273,26 @@ can do:
 Note that only a hostname/address can be provided, without a port
 number.
 
+TS
+
+This variable turns on the timestamp printing for each line of "make
+check".  Note that the timestamp will be printed on stdout output
+only.  In other words, there will be no timestamp output on either
+gdb.sum and gdb.log files.  If you would like to enable timestamp
+printing, you can do:
+
+	make check TS=1
+
+TS_FORMAT
+
+You can provide a custom format for timestamp printing with this
+variable.  The format must be a string compatible with "strftime".
+This variable is only useful when the TS variable is also provided.
+If you would like to change the output format of the timestamp, you
+can do:
+
+	make check TS=1 TS_FORMAT='[%b %H:%S]'
+
 Race detection
 **************
 
diff --git a/gdb/testsuite/print-ts.py b/gdb/testsuite/print-ts.py
new file mode 100755
index 0000000000..58127f5716
--- /dev/null
+++ b/gdb/testsuite/print-ts.py
@@ -0,0 +1,45 @@
+#!/usr/bin/env python3
+
+# Copyright (C) 2018 Free Software Foundation, Inc.
+#
+# This file is part of GDB.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# This is a simple program that can be used to print timestamps on
+# standard output.  The inspiration for it was ts(1)
+# (<https://joeyh.name/code/moreutils/>).  We have our own version
+# because unfortunately ts(1) is or may not be available on all
+# systems that GDB supports.
+#
+# The usage is simple:
+#
+#   #> some_command | print-ts.py [FORMAT]
+#
+# FORMAT must be a string compatible with "strftime".  If nothing is
+# provided, we choose a reasonable format.
+
+import fileinput
+import datetime
+import sys
+
+if len (sys.argv) > 1:
+    fmt = sys.argv[1]
+else:
+    fmt = '[%b %d %H:%M:%S]'
+
+for line in fileinput.input ('-'):
+    print ("{} {}".format (datetime.datetime.now ().strftime (fmt),
+                           line),
+           end = '', flush = True)
-- 
2.17.2