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[GSoC][PATCH 2/4] grep: allow locks to be enabled individually

From
Matheus Tavares <matheus.bernardino@usp.br>
Date
Aug 10, 2019, 20:27 UTC
Message-ID
<235de7de2874bd089b106be75121e1616308ed55.1565468806.git.matheus.bernardino@usp.br>
In-Reply-To
<cover.1565468806.git.matheus.bernardino@usp.br>

git-grep has some internal locks to protect thread-unsafe operations when running with threads. The usage of these locks can be toggled through the variable 'grep_use_locks'. However, it's not currently possible to enable each lock individually. And since object reading has its own locks now, it is desirable to disable the respective grep lock (and only that) in cases where we can do so. To do that, transform 'grep_use_locks' from a binary variable to a bitmask, which controls each lock individually.

The actual disabling of grep_read_lock, when possible, will be done in the following patch.

Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br>
---
 builtin/grep.c | 2 +-
 grep.c         | 4 ++--
 grep.h         | 8 ++++++--
 3 files changed, 9 insertions(+), 5 deletions(-)
diff --git a/builtin/grep.c b/builtin/grep.c
index 560051784e..a871bad8ad 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -205,7 +205,7 @@ static void start_threads(struct grep_opt *opt)
 	pthread_cond_init(&cond_add, NULL);
 	pthread_cond_init(&cond_write, NULL);
 	pthread_cond_init(&cond_result, NULL);
-	grep_use_locks = 1;
+	grep_use_locks = GREP_USE_ALL_LOCKS;
 
 	for (i = 0; i < ARRAY_SIZE(todo); i++) {
 		strbuf_init(&todo[i].out, 0);
diff --git a/grep.c b/grep.c
index cd952ef5d3..3aca0db435 100644
--- a/grep.c
+++ b/grep.c
@@ -1523,13 +1523,13 @@ pthread_mutex_t grep_attr_mutex;
 
 static inline void grep_attr_lock(void)
 {
-	if (grep_use_locks)
+	if (grep_use_locks & GREP_USE_ATTR_LOCK)
 		pthread_mutex_lock(&grep_attr_mutex);
 }
 
 static inline void grep_attr_unlock(void)
 {
-	if (grep_use_locks)
+	if (grep_use_locks & GREP_USE_ATTR_LOCK)
 		pthread_mutex_unlock(&grep_attr_mutex);
 }
 
diff --git a/grep.h b/grep.h
index 1875880f37..02bffacfa2 100644
--- a/grep.h
+++ b/grep.h
@@ -229,6 +229,10 @@ int grep_source(struct grep_opt *opt, struct grep_source *gs);
 struct grep_opt *grep_opt_dup(const struct grep_opt *opt);
 int grep_threads_ok(const struct grep_opt *opt);
 
+#define GREP_USE_READ_LOCK (1 << 0)
+#define GREP_USE_ATTR_LOCK (1 << 1)
+#define GREP_USE_ALL_LOCKS (~0)
+
 /*
  * Mutex used around access to the attributes machinery if
  * opt->use_threads.  Must be initialized/destroyed by callers!
@@ -239,13 +243,13 @@ extern pthread_mutex_t grep_read_mutex;
 
 static inline void grep_read_lock(void)
 {
-	if (grep_use_locks)
+	if (grep_use_locks & GREP_USE_READ_LOCK)
 		pthread_mutex_lock(&grep_read_mutex);
 }
 
 static inline void grep_read_unlock(void)
 {
-	if (grep_use_locks)
+	if (grep_use_locks & GREP_USE_READ_LOCK)
 		pthread_mutex_unlock(&grep_read_mutex);
 }
 

-- 
2.22.0
Previous: Matheus TavaresNext: Matheus Tavares
Message 3 of 47 in “grep: re-enable threads when cached, w/ parallel inflation”
  1. Matheus TavaresAug 10, 2019
  2. [GSoC][PATCH 1/4] object-store: add lock to read_object_file_extended()Matheus Tavares, Aug 10, 2019
  3. [GSoC][PATCH 2/4] grep: allow locks to be enabled individuallyMatheus Tavares, Aug 10, 2019
  4. [GSoC][PATCH 3/4] grep: disable grep_read_mutex when possibleMatheus Tavares, Aug 10, 2019
  5. [GSoC][PATCH 4/4] grep: re-enable threads in some non-worktree casesMatheus Tavares, Aug 10, 2019
  6. 00/11 grep: improve threading and fix race conditionsMatheus Tavares, Sep 30, 2019
  7. 01/11 grep: fix race conditions on userdiff callsMatheus Tavares, Sep 30, 2019
  8. 02/11 grep: fix race conditions at grep_submodule()Matheus Tavares, Sep 30, 2019
  9. 03/11 grep: fix racy calls in grep_objects()Matheus Tavares, Sep 30, 2019
  10. 04/11 replace-object: make replace operations thread-safeMatheus Tavares, Sep 30, 2019
  11. 05/11 object-store: allow threaded access to object readingMatheus Tavares, Sep 30, 2019
  12. Jonathan TanNov 12, 2019
  13. Jeff KingNov 13, 2019
  14. Matheus Tavares BernardinoNov 14, 2019
  15. Jeff KingNov 14, 2019
  16. Jonathan TanNov 14, 2019
  17. Jeff KingNov 15, 2019
  18. Matheus Tavares BernardinoDec 19, 2019
  19. Matheus Tavares BernardinoJan 9, 2020
  20. Christian CouderJan 10, 2020
  21. 06/11 grep: replace grep_read_mutex by internal obj read lockMatheus Tavares, Sep 30, 2019
  22. squash! grep: replace grep_read_mutex by internal obj read lockMatheus Tavares, Oct 1, 2019
  23. 07/11 submodule-config: add skip_if_read option to repo_read_gitmodules()Matheus Tavares, Sep 30, 2019
  24. 08/11 grep: allow submodule functions to run in parallelMatheus Tavares, Sep 30, 2019
  25. 09/11 grep: protect packed_git [re-]initializationMatheus Tavares, Sep 30, 2019
  26. 10/11 grep: re-enable threads in non-worktree caseMatheus Tavares, Sep 30, 2019
  27. 11/11 grep: move driver pre-load out of critical sectionMatheus Tavares, Sep 30, 2019
  28. 00/12 grep: improve threading and fix race conditionsMatheus Tavares, Jan 16, 2020
  29. 01/12 grep: fix race conditions on userdiff callsMatheus Tavares, Jan 16, 2020
  30. 02/12 grep: fix race conditions at grep_submodule()Matheus Tavares, Jan 16, 2020
  31. 03/12 grep: fix racy calls in grep_objects()Matheus Tavares, Jan 16, 2020
  32. 04/12 replace-object: make replace operations thread-safeMatheus Tavares, Jan 16, 2020
  33. 05/12 object-store: allow threaded access to object readingMatheus Tavares, Jan 16, 2020
  34. 06/12 grep: replace grep_read_mutex by internal obj read lockMatheus Tavares, Jan 16, 2020
  35. 07/12 submodule-config: add skip_if_read option to repo_read_gitmodules()Matheus Tavares, Jan 16, 2020
  36. 08/12 grep: allow submodule functions to run in parallelMatheus Tavares, Jan 16, 2020
  37. SZEDER GáborJan 29, 2020
  38. Junio C HamanoJan 29, 2020
  39. Junio C HamanoJan 29, 2020
  40. Matheus Tavares BernardinoJan 29, 2020
  41. Philippe BlainJan 30, 2020
  42. 09/12 grep: protect packed_git [re-]initializationMatheus Tavares, Jan 16, 2020
  43. 10/12 grep: re-enable threads in non-worktree caseMatheus Tavares, Jan 16, 2020
  44. 11/12 grep: move driver pre-load out of critical sectionMatheus Tavares, Jan 16, 2020
  45. 12/12 grep: use no. of cores as the default no. of threadsMatheus Tavares, Jan 16, 2020
  46. Victor LeschukJan 16, 2020
  47. Matheus TavaresJan 16, 2020

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