grep: enable threading with -p and -W using lazy attribute lookup

Lazily load the userdiff attributes in match_funcname().  Use a
separate mutex around this loading to protect the (not thread-safe)
attributes machinery.  This lets us re-enable threading with -p and
-W while reducing the overhead caused by looking up attributes.

Signed-off-by: Thomas Rast <trast@student.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/grep.h b/grep.h
index a65280026d..fb205f3542 100644
--- a/grep.h
+++ b/grep.h
@@ -8,6 +8,7 @@ typedef int pcre;
 typedef int pcre_extra;
 #endif
 #include "kwset.h"
+#include "thread-utils.h"
 
 enum grep_pat_token {
 	GREP_PATTERN,
@@ -115,6 +116,7 @@ struct grep_opt {
 	int show_hunk_mark;
 	int file_break;
 	int heading;
+	int use_threads;
 	void *priv;
 
 	void (*output)(struct grep_opt *opt, const void *data, size_t size);
@@ -131,4 +133,12 @@ extern int grep_buffer(struct grep_opt *opt, const char *name, char *buf, unsign
 extern struct grep_opt *grep_opt_dup(const struct grep_opt *opt);
 extern int grep_threads_ok(const struct grep_opt *opt);
 
+#ifndef NO_PTHREADS
+/*
+ * Mutex used around access to the attributes machinery if
+ * opt->use_threads.  Must be initialized/destroyed by callers!
+ */
+extern pthread_mutex_t grep_attr_mutex;
+#endif
+
 #endif