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>
This commit is contained in:
Thomas Rast 2011-12-12 22:16:07 +01:00 committed by Junio C Hamano
parent b8ffedca6f
commit 0579f91dd7
3 changed files with 63 additions and 33 deletions

View File

@ -17,7 +17,6 @@
#include "grep.h"
#include "quote.h"
#include "dir.h"
#include "thread-utils.h"
static char const * const grep_usage[] = {
"git grep [options] [-e] <pattern> [<rev>...] [[--] <path>...]",
@ -256,6 +255,7 @@ static void start_threads(struct grep_opt *opt)
pthread_mutex_init(&grep_mutex, NULL);
pthread_mutex_init(&read_sha1_mutex, NULL);
pthread_mutex_init(&grep_attr_mutex, NULL);
pthread_cond_init(&cond_add, NULL);
pthread_cond_init(&cond_write, NULL);
pthread_cond_init(&cond_result, NULL);
@ -303,6 +303,7 @@ static int wait_all(void)
pthread_mutex_destroy(&grep_mutex);
pthread_mutex_destroy(&read_sha1_mutex);
pthread_mutex_destroy(&grep_attr_mutex);
pthread_cond_destroy(&cond_add);
pthread_cond_destroy(&cond_write);
pthread_cond_destroy(&cond_result);
@ -1002,17 +1003,21 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
opt.regflags |= REG_ICASE;
#ifndef NO_PTHREADS
if (online_cpus() == 1 || !grep_threads_ok(&opt))
if (online_cpus() == 1)
use_threads = 0;
#else
use_threads = 0;
#endif
opt.use_threads = use_threads;
#ifndef NO_PTHREADS
if (use_threads) {
if (opt.pre_context || opt.post_context || opt.file_break ||
opt.funcbody)
skip_first_line = 1;
start_threads(&opt);
}
#else
use_threads = 0;
#endif
compile_grep_patterns(&opt);

73
grep.c
View File

@ -806,10 +806,46 @@ static void show_line(struct grep_opt *opt, char *bol, char *eol,
opt->output(opt, "\n", 1);
}
static int match_funcname(struct grep_opt *opt, char *bol, char *eol)
#ifndef NO_PTHREADS
/*
* This lock protects access to the gitattributes machinery, which is
* not thread-safe.
*/
pthread_mutex_t grep_attr_mutex;
static inline void grep_attr_lock(struct grep_opt *opt)
{
if (opt->use_threads)
pthread_mutex_lock(&grep_attr_mutex);
}
static inline void grep_attr_unlock(struct grep_opt *opt)
{
if (opt->use_threads)
pthread_mutex_unlock(&grep_attr_mutex);
}
#else
#define grep_attr_lock(opt)
#define grep_attr_unlock(opt)
#endif
static int match_funcname(struct grep_opt *opt, const char *name, char *bol, char *eol)
{
xdemitconf_t *xecfg = opt->priv;
if (xecfg && xecfg->find_func) {
if (xecfg && !xecfg->find_func) {
struct userdiff_driver *drv;
grep_attr_lock(opt);
drv = userdiff_find_by_path(name);
grep_attr_unlock(opt);
if (drv && drv->funcname.pattern) {
const struct userdiff_funcname *pe = &drv->funcname;
xdiff_set_find_func(xecfg, pe->pattern, pe->cflags);
} else {
xecfg = opt->priv = NULL;
}
}
if (xecfg) {
char buf[1];
return xecfg->find_func(bol, eol - bol, buf, 1,
xecfg->find_func_priv) >= 0;
@ -835,7 +871,7 @@ static void show_funcname_line(struct grep_opt *opt, const char *name,
if (lno <= opt->last_shown)
break;
if (match_funcname(opt, bol, eol)) {
if (match_funcname(opt, name, bol, eol)) {
show_line(opt, bol, eol, name, lno, '=');
break;
}
@ -848,7 +884,7 @@ static void show_pre_context(struct grep_opt *opt, const char *name, char *buf,
unsigned cur = lno, from = 1, funcname_lno = 0;
int funcname_needed = !!opt->funcname;
if (opt->funcbody && !match_funcname(opt, bol, end))
if (opt->funcbody && !match_funcname(opt, name, bol, end))
funcname_needed = 2;
if (opt->pre_context < lno)
@ -864,7 +900,7 @@ static void show_pre_context(struct grep_opt *opt, const char *name, char *buf,
while (bol > buf && bol[-1] != '\n')
bol--;
cur--;
if (funcname_needed && match_funcname(opt, bol, eol)) {
if (funcname_needed && match_funcname(opt, name, bol, eol)) {
funcname_lno = cur;
funcname_needed = 0;
}
@ -942,19 +978,6 @@ static int look_ahead(struct grep_opt *opt,
return 0;
}
int grep_threads_ok(const struct grep_opt *opt)
{
/* If this condition is true, then we may use the attribute
* machinery in grep_buffer_1. The attribute code is not
* thread safe, so we disable the use of threads.
*/
if ((opt->funcname || opt->funcbody)
&& !opt->unmatch_name_only && !opt->status_only && !opt->name_only)
return 0;
return 1;
}
static void std_output(struct grep_opt *opt, const void *buf, size_t size)
{
fwrite(buf, size, 1, stdout);
@ -1008,16 +1031,8 @@ static int grep_buffer_1(struct grep_opt *opt, const char *name,
}
memset(&xecfg, 0, sizeof(xecfg));
if ((opt->funcname || opt->funcbody)
&& !opt->unmatch_name_only && !opt->status_only &&
!opt->name_only && !binary_match_only && !collect_hits) {
struct userdiff_driver *drv = userdiff_find_by_path(name);
if (drv && drv->funcname.pattern) {
const struct userdiff_funcname *pe = &drv->funcname;
xdiff_set_find_func(&xecfg, pe->pattern, pe->cflags);
opt->priv = &xecfg;
}
}
opt->priv = &xecfg;
try_lookahead = should_lookahead(opt);
while (left) {
@ -1093,7 +1108,7 @@ static int grep_buffer_1(struct grep_opt *opt, const char *name,
show_function = 1;
goto next_line;
}
if (show_function && match_funcname(opt, bol, eol))
if (show_function && match_funcname(opt, name, bol, eol))
show_function = 0;
if (show_function ||
(last_hit && lno <= last_hit + opt->post_context)) {

10
grep.h
View File

@ -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