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[PATCH 01/12] grep: add ability to disable threading with --threads=0 or grep.threads=0

From
Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Date
Apr 8, 2017, 13:24 UTC
Message-ID
<20170408132506.5415-2-avarab@gmail.com>
In-Reply-To
<20170408132506.5415-1-avarab@gmail.com>

Add the ability to entirely disable threading by having grep.threads=0 in the config or --threads=0 on the command-line.

This was made configurable in commit 89f09dd34e ("grep: add --threads=<num> option and grep.threads configuration", 2015-12-15). Before that change there was no way to disable threaded grep other than to recompile Git.

It's very useful for testing & debugging to be able to entirely disable threading without recompiling with NO_PTHREADS=YesPlease, so support setting the value to 0 to disable threading.

There was no reason this wasn't the case already other than an implementation detail in how OPT_INTEGER() works. When it's used there's no way to tell the difference between an unset value & the default value. Use OPT_CALLBACK() instead using the same pattern as in commit b16a991c1b ("cherry-pick: detect bogus arguments to --mainline", 2017-03-15).

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 Documentation/git-grep.txt |  4 ++--
 builtin/grep.c             | 26 ++++++++++++++++++++++----
 t/t7810-grep.sh            | 10 ++++++++++
 3 files changed, 34 insertions(+), 6 deletions(-)
diff --git a/Documentation/git-grep.txt b/Documentation/git-grep.txt
index 71f32f3508..7b52e3fbc4 100644
--- a/Documentation/git-grep.txt
+++ b/Documentation/git-grep.txt
@@ -56,8 +56,8 @@ grep.extendedRegexp::
 	other than 'default'.
 
 grep.threads::
-	Number of grep worker threads to use.  If unset (or set to 0),
-	8 threads are used by default (for now).
+	Number of grep worker threads to use.  If unset, 8 threads are
+	used by default (for now). Set to 0 to disable threading.
 
 grep.fullName::
 	If set to true, enable `--full-name` option by default.
diff --git a/builtin/grep.c b/builtin/grep.c
index 65070c52fc..9478ab5dff 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -35,7 +35,7 @@ static int grep_submodule_launch(struct grep_opt *opt,
 				 const struct grep_source *gs);
 
 #define GREP_NUM_THREADS_DEFAULT 8
-static int num_threads;
+static int num_threads = -1;
 
 #ifndef NO_PTHREADS
 static pthread_t *threads;
@@ -897,6 +897,24 @@ static int context_callback(const struct option *opt, const char *arg,
 	return 0;
 }
 
+static int thread_callback(const struct option *opt,
+			   const char *arg, int unset)
+{
+	int *threads = (int*)opt->value;
+	char *end;
+
+	if (unset) {
+		*threads = GREP_NUM_THREADS_DEFAULT;
+		return 0;
+	}
+
+	*threads = strtol(arg, &end, 10);
+	if (*end || *threads < 0)
+		return opterror(opt, "invalid number of threads specified", 0);
+
+	return 0;
+}
+
 static int file_callback(const struct option *opt, const char *arg, int unset)
 {
 	struct grep_opt *grep_opt = opt->value;
@@ -1049,8 +1067,8 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 			N_("show <n> context lines before matches")),
 		OPT_INTEGER('A', "after-context", &opt.post_context,
 			N_("show <n> context lines after matches")),
-		OPT_INTEGER(0, "threads", &num_threads,
-			N_("use <n> worker threads")),
+		OPT_CALLBACK(0, "threads", &num_threads, N_("n"),
+			N_("use <n> worker threads"), thread_callback),
 		OPT_NUMBER_CALLBACK(&opt, N_("shortcut for -C NUM"),
 			context_callback),
 		OPT_BOOL('p', "show-function", &opt.funcname,
@@ -1222,7 +1240,7 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 #ifndef NO_PTHREADS
 	if (list.nr || cached || show_in_pager)
 		num_threads = 0;
-	else if (num_threads == 0)
+	else if (num_threads == -1)
 		num_threads = GREP_NUM_THREADS_DEFAULT;
 	else if (num_threads < 0)
 		die(_("invalid number of threads specified (%d)"), num_threads);
diff --git a/t/t7810-grep.sh b/t/t7810-grep.sh
index cee42097b0..53c2ca05c4 100755
--- a/t/t7810-grep.sh
+++ b/t/t7810-grep.sh
@@ -1505,4 +1505,14 @@ test_expect_success 'grep does not report i-t-a and assume unchanged with -L' '
 	test_cmp expected actual
 '
 
+test_expect_success 'grep with thread options' '
+	git -c grep.threads=4 grep st.*dio &&
+	git grep --threads=4 st.*dio &&
+	git -c grep.threads=4 grep --threads=6 st.*dio &&
+	test_must_fail git -c grep.threads=-1 grep st.*dio &&
+	test_must_fail git -c grep.threads=-1 grep --threads=-1 st.*dio &&
+	test_must_fail git -c grep.threads=-1 grep --threads=1 st.*dio &&
+	test_must_fail git -c grep.threads=1 grep --threads=-1 st.*dio
+'
+
 test_done

-- 
2.11.0
Previous: Ævar Arnfjörð BjarmasonNext: Jeff King
Message 2 of 43 in “PCREv2 & more”
  1. 00/12 PCREv2 & moreÆvar Arnfjörð Bjarmason, Apr 8, 2017
  2. 01/12 grep: add ability to disable threading with --threads=0 or grep.threads=0Ævar Arnfjörð Bjarmason, Apr 8, 2017
  3. Jeff KingApr 11, 2017
  4. Ævar Arnfjörð BjarmasonApr 11, 2017
  5. Jeff KingApr 11, 2017
  6. Ævar Arnfjörð BjarmasonApr 11, 2017
  7. Jeff KingApr 14, 2017
  8. Ævar Arnfjörð BjarmasonApr 16, 2017
  9. 02/12 grep: remove redundant regflags assignment under PCREÆvar Arnfjörð Bjarmason, Apr 8, 2017
  10. Jeff KingApr 11, 2017
  11. 03/12 Makefile & configure: reword outdated comment about PCREÆvar Arnfjörð Bjarmason, Apr 8, 2017
  12. Jeff KingApr 11, 2017
  13. Ævar Arnfjörð BjarmasonApr 15, 2017
  14. 04/12 grep: add a test for backreferences in PCRE patternsÆvar Arnfjörð Bjarmason, Apr 8, 2017
  15. 05/12 log: add exhaustive tests for pattern style options & configÆvar Arnfjörð Bjarmason, Apr 8, 2017
  16. Jeff KingApr 11, 2017
  17. Ævar Arnfjörð BjarmasonApr 11, 2017
  18. Jeff KingApr 11, 2017
  19. 06/12 log: add -P as a synonym for --perl-regexpÆvar Arnfjörð Bjarmason, Apr 8, 2017
  20. Junio C HamanoApr 10, 2017
  21. Jeff KingApr 11, 2017
  22. 08/12 grep: make grep.patternType=[pcre|pcre1] a synonym for "perl"Ævar Arnfjörð Bjarmason, Apr 8, 2017
  23. Jeff KingApr 11, 2017
  24. 07/12 grep & rev-list doc: stop promising libpcre for --perl-regexpÆvar Arnfjörð Bjarmason, Apr 8, 2017
  25. 09/12 test-lib: rename the LIBPCRE prerequisite to PCREÆvar Arnfjörð Bjarmason, Apr 8, 2017
  26. Jeff KingApr 11, 2017
  27. 10/12 grep: change the internal PCRE macro names to be PCRE1Ævar Arnfjörð Bjarmason, Apr 8, 2017
  28. Jeff KingApr 11, 2017
  29. Ævar Arnfjörð BjarmasonApr 11, 2017
  30. Jeff KingApr 11, 2017
  31. 12/12 grep: add support for PCRE v2Ævar Arnfjörð Bjarmason, Apr 8, 2017
  32. Jeff KingApr 11, 2017
  33. 11/12 grep: change the internal PCRE code & header names to be PCRE1Ævar Arnfjörð Bjarmason, Apr 8, 2017
  34. Jeff KingApr 11, 2017
  35. Ævar Arnfjörð BjarmasonApr 11, 2017
  36. Jeff KingApr 11, 2017
  37. Ævar Arnfjörð BjarmasonApr 11, 2017
  38. Jeff KingApr 11, 2017
  39. Brandon WilliamsApr 11, 2017
  40. Ævar Arnfjörð BjarmasonApr 11, 2017
  41. Jeff KingApr 11, 2017
  42. Junio C HamanoApr 15, 2017
  43. Ævar Arnfjörð BjarmasonApr 15, 2017

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