git/list[1] front-page[2] threads[3] people[4] search[5] about
 

[PATCH v4 31/31] grep: assert that threading is enabled when calling grep_{lock,unlock}

From
Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Date
May 25, 2017, 19:45 UTC
Message-ID
<20170525194535.9324-32-avarab@gmail.com>
In-Reply-To
<20170525194535.9324-1-avarab@gmail.com>

Change the grep_{lock,unlock} functions to assert that num_threads is true, instead of only locking & unlocking the pthread mutex lock when it is.

These functions are never called when num_threads isn't true, this logic has gone through multiple iterations since the initial introduction of grep threading in commit 5b594f457a ("Threaded grep", 2010-01-25), but ever since then they'd only be called if num_threads was true, so this check made the code confusing to read.

Replace the check with an assertion, so that it's clear to the reader that this code path is never taken unless we're spawning threads.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 builtin/grep.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/builtin/grep.c b/builtin/grep.c
index 3c721b75a5..b1095362fb 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -73,14 +73,14 @@ static pthread_mutex_t grep_mutex;
 
 static inline void grep_lock(void)
 {
-	if (num_threads)
-		pthread_mutex_lock(&grep_mutex);
+	assert(num_threads);
+	pthread_mutex_lock(&grep_mutex);
 }
 
 static inline void grep_unlock(void)
 {
-	if (num_threads)
-		pthread_mutex_unlock(&grep_mutex);
+	assert(num_threads);
+	pthread_mutex_unlock(&grep_mutex);
 }
 
 /* Signalled when a new work_item is added to todo. */

-- 
2.13.0.303.g4ebf302169
Previous: Ævar Arnfjörð BjarmasonNext: Ævar Arnfjörð Bjarmason
Message 29 of 32 in “Easy to review grep & pre-PCRE changes”
  1. 00/31 Easy to review grep & pre-PCRE changesÆvar Arnfjörð Bjarmason, May 25, 2017
  2. 01/31 Makefile & configure: reword inaccurate comment about PCREÆvar Arnfjörð Bjarmason, May 25, 2017
  3. 02/31 grep & rev-list doc: stop promising libpcre for --perl-regexpÆvar Arnfjörð Bjarmason, May 25, 2017
  4. 04/31 log: add exhaustive tests for pattern style options & configÆvar Arnfjörð Bjarmason, May 25, 2017
  5. 03/31 test-lib: rename the LIBPCRE prerequisite to PCREÆvar Arnfjörð Bjarmason, May 25, 2017
  6. 05/31 log: make --regexp-ignore-case work with --perl-regexpÆvar Arnfjörð Bjarmason, May 25, 2017
  7. 07/31 grep: add a test for backreferences in PCRE patternsÆvar Arnfjörð Bjarmason, May 25, 2017
  8. 08/31 grep: change non-ASCII -i test to stop using --debugÆvar Arnfjörð Bjarmason, May 25, 2017
  9. 06/31 grep: add a test asserting that --perl-regexp dies when !PCREÆvar Arnfjörð Bjarmason, May 25, 2017
  10. 09/31 grep: add tests for --threads=N and grep.threadsÆvar Arnfjörð Bjarmason, May 25, 2017
  11. 10/31 grep: amend submodule recursion test for regex engine testingÆvar Arnfjörð Bjarmason, May 25, 2017
  12. 11/31 grep: add tests for grep pattern types being passed to submodulesÆvar Arnfjörð Bjarmason, May 25, 2017
  13. 12/31 grep: add a test helper function for less verbose -f \0 testsÆvar Arnfjörð Bjarmason, May 25, 2017
  14. 13/31 grep: prepare for testing binary regexes containing rx metacharactersÆvar Arnfjörð Bjarmason, May 25, 2017
  15. 14/31 grep: add tests to fix blind spots with \0 patternsÆvar Arnfjörð Bjarmason, May 25, 2017
  16. 16/31 perf: emit progress output when unpacking & buildingÆvar Arnfjörð Bjarmason, May 25, 2017
  17. 18/31 perf: add a comparison test of grep regex engines with -FÆvar Arnfjörð Bjarmason, May 25, 2017
  18. 17/31 perf: add a comparison test of grep regex enginesÆvar Arnfjörð Bjarmason, May 25, 2017
  19. 15/31 perf: add a GIT_PERF_MAKE_COMMAND for when *_MAKE_OPTS won't doÆvar Arnfjörð Bjarmason, May 25, 2017
  20. 19/31 perf: add a comparison test of log --grep regex enginesÆvar Arnfjörð Bjarmason, May 25, 2017
  21. 20/31 perf: add a comparison test of log --grep regex engines with -FÆvar Arnfjörð Bjarmason, May 25, 2017
  22. 24/31 grep: change the internal PCRE macro names to be PCRE1Ævar Arnfjörð Bjarmason, May 25, 2017
  23. 23/31 grep: factor test for \0 in grep patterns into a functionÆvar Arnfjörð Bjarmason, May 25, 2017
  24. 21/31 grep: catch a missing enum in switch statementÆvar Arnfjörð Bjarmason, May 25, 2017
  25. 22/31 grep: remove redundant regflags assignmentsÆvar Arnfjörð Bjarmason, May 25, 2017
  26. 28/31 pack-objects & index-pack: add test for --threads warningÆvar Arnfjörð Bjarmason, May 25, 2017
  27. 30/31 grep: given --threads with NO_PTHREADS=YesPlease, warnÆvar Arnfjörð Bjarmason, May 25, 2017
  28. 25/31 grep: change internal *pcre* variable & function names to be *pcre1*Ævar Arnfjörð Bjarmason, May 25, 2017
  29. 31/31 grep: assert that threading is enabled when calling grep_{lock,unlock}Ævar Arnfjörð Bjarmason, May 25, 2017
  30. 29/31 pack-objects: fix buggy warning about threadsÆvar Arnfjörð Bjarmason, May 25, 2017
  31. 27/31 test-lib: add a PTHREADS prerequisiteÆvar Arnfjörð Bjarmason, May 25, 2017
  32. 26/31 grep: move is_fixed() earlier to avoid forward declarationÆvar Arnfjörð Bjarmason, May 25, 2017

Read the whole thread, see it on lore, or plain text.

$ cat FOOTERMessages come from the public archive at lore.kernel.org/git, fetched every hour. The front page is chosen and written each morning by an AI editor and can be wrong; the threads themselves are the record. About and API. For agents: an MCP server at https://gitlist.dev/mcp, and any thread, story or person page as Markdown by adding .md to its URL (or sending Accept: text/markdown). Details in /llms.txt.