grep: clean up num_threads handling
When NO_PTHREADS is still used in this file, we have two separate code paths for thread and no thread support. The latter will always have num_threads remain zero while the former uses num_threads zero as "default number of threads". With recent changes blur the line between thread and no-thread support, this num_threads handling becomes a bit strange so let's redefine it like this: - num_threads == 0 means default number of threads and should become positive after all configuration and option parsing is done if multithread is supported. - num_threads <= 1 runs no threads. It does not matter if the platform supports threading or not. - num_threads > 1 will run multiple threads and is invalid if HAVE_THREADS is false. pthread API is only used in this case. PS. a new warning is also added when num_threads is forced back to one because a thread-incompatible option is specified. Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Nguyễn Thái Ngọc Duy committed
Nov 3, 2018 at 09:48 UTC
fd6263fb733e50cfbcf857136388bf47d9c5151f
1 file changed
+27
-31
builtin/grep.c
+27
-31
@@ -69,13 +69,11 @@ static pthread_mutex_t grep_mutex;
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static inline void grep_lock(void)
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{
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- assert(num_threads);
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pthread_mutex_lock(&grep_mutex);
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}
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static inline void grep_unlock(void)
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{
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- assert(num_threads);
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pthread_mutex_unlock(&grep_mutex);
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}
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@@ -234,7 +232,7 @@ static int wait_all(void)
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int i;
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if (!HAVE_THREADS)
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- return 0;
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+ BUG("Never call this function unless you have started threads");
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grep_lock();
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all_work_added = 1;
@@ -279,14 +277,14 @@ static int grep_cmd_config(const char *var, const char *value, void *cb)
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if (num_threads < 0)
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die(_("invalid number of threads specified (%d) for %s"),
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num_threads, var);
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- else if (!HAVE_THREADS && num_threads && num_threads != 1) {
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+ else if (!HAVE_THREADS && num_threads > 1) {
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/*
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* TRANSLATORS: %s is the configuration
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* variable for tweaking threads, currently
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* grep.threads
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*/
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warning(_("no threads support, ignoring %s"), var);
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- num_threads = 0;
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+ num_threads = 1;
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}
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}
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@@ -323,7 +321,7 @@ static int grep_oid(struct grep_opt *opt, const struct object_id *oid,
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grep_source_init(&gs, GREP_SOURCE_OID, pathbuf.buf, path, oid);
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strbuf_release(&pathbuf);
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- if (HAVE_THREADS && num_threads) {
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+ if (num_threads > 1) {
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/*
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* add_work() copies gs and thus assumes ownership of
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* its fields, so do not call grep_source_clear()
@@ -353,7 +351,7 @@ static int grep_file(struct grep_opt *opt, const char *filename)
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grep_source_init(&gs, GREP_SOURCE_FILE, buf.buf, filename, filename);
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strbuf_release(&buf);
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- if (HAVE_THREADS && num_threads) {
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+ if (num_threads > 1) {
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/*
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* add_work() copies gs and thus assumes ownership of
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* its fields, so do not call grep_source_clear()
@@ -1025,36 +1023,34 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
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pathspec.recursive = 1;
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pathspec.recurse_submodules = !!recurse_submodules;
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- if (HAVE_THREADS) {
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- if (list.nr || cached || show_in_pager)
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- num_threads = 0;
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- else if (num_threads == 0)
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- num_threads = GREP_NUM_THREADS_DEFAULT;
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- else if (num_threads < 0)
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- die(_("invalid number of threads specified (%d)"), num_threads);
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- if (num_threads == 1)
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- num_threads = 0;
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+ if (list.nr || cached || show_in_pager) {
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+ if (num_threads > 1)
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+ warning(_("invalid option combination, ignoring --threads"));
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+ num_threads = 1;
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+ } else if (!HAVE_THREADS && num_threads > 1) {
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+ warning(_("no threads support, ignoring --threads"));
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+ num_threads = 1;
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+ } else if (num_threads < 0)
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+ die(_("invalid number of threads specified (%d)"), num_threads);
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+ else if (num_threads == 0)
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+ num_threads = HAVE_THREADS ? GREP_NUM_THREADS_DEFAULT : 1;
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+
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+ if (num_threads > 1) {
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+ if (!HAVE_THREADS)
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+ BUG("Somebody got num_threads calculation wrong!");
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+ if (!(opt.name_only || opt.unmatch_name_only || opt.count)
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+ && (opt.pre_context || opt.post_context ||
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+ opt.file_break || opt.funcbody))
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+ skip_first_line = 1;
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+ start_threads(&opt);
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} else {
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- if (num_threads)
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- warning(_("no threads support, ignoring --threads"));
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- num_threads = 0;
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- }
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-
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- if (!num_threads)
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/*
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* The compiled patterns on the main path are only
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* used when not using threading. Otherwise
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- * start_threads() below calls compile_grep_patterns()
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+ * start_threads() above calls compile_grep_patterns()
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* for each thread.
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*/
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compile_grep_patterns(&opt);
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-
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- if (HAVE_THREADS && num_threads) {
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- if (!(opt.name_only || opt.unmatch_name_only || opt.count)
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- && (opt.pre_context || opt.post_context ||
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- opt.file_break || opt.funcbody))
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- skip_first_line = 1;
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- start_threads(&opt);
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}
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if (show_in_pager && (cached || list.nr))
@@ -1106,7 +1102,7 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
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hit = grep_objects(&opt, &pathspec, &list);
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}
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- if (num_threads)
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+ if (num_threads > 1)
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hit |= wait_all();
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if (hit && show_in_pager)
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run_pager(&opt, prefix);