From 78db6ea9dc1a872f9d07a36fe7aec700a5c963b9 Mon Sep 17 00:00:00 2001 From: Jeff King Date: Thu, 2 Feb 2012 03:18:29 -0500 Subject: [PATCH] grep: make locking flag global The low-level grep code traditionally didn't care about threading, as it doesn't do any threading itself and didn't call out to other non-thread-safe code. That changed with 0579f91 (grep: enable threading with -p and -W using lazy attribute lookup, 2011-12-12), which pushed the lookup of funcname attributes (which is not thread-safe) into the low-level grep code. As a result, the low-level code learned about a new global "grep_attr_mutex" to serialize access to the attribute code. A multi-threaded caller (e.g., builtin/grep.c) is expected to initialize the mutex and set "use_threads" in the grep_opt structure. The low-level code only uses the lock if use_threads is set. However, putting the use_threads flag into the grep_opt struct is not the most logical place. Whether threading is in use is not something that matters for each call to grep_buffer, but is instead global to the whole program (i.e., if any thread is doing multi-threaded grep, every other thread, even if it thinks it is doing its own single-threaded grep, would need to use the locking). In practice, this distinction isn't a problem for us, because the only user of multi-threaded grep is "git-grep", which does nothing except call grep. This patch turns the opt->use_threads flag into a global flag. More important than the nit-picking semantic argument above is that this means that the locking functions don't need to actually have access to a grep_opt to know whether to lock. Which in turn can make adding new locks simpler, as we don't need to pass around a grep_opt. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano --- builtin/grep.c | 4 ++-- grep.c | 18 ++++++++++-------- grep.h | 2 +- 3 files changed, 13 insertions(+), 11 deletions(-) diff --git a/builtin/grep.c b/builtin/grep.c index 9ce064ac11..5b881870f6 100644 --- a/builtin/grep.c +++ b/builtin/grep.c @@ -259,6 +259,7 @@ 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; for (i = 0; i < ARRAY_SIZE(todo); i++) { strbuf_init(&todo[i].out, 0); @@ -307,6 +308,7 @@ static int wait_all(void) pthread_cond_destroy(&cond_add); pthread_cond_destroy(&cond_write); pthread_cond_destroy(&cond_result); + grep_use_locks = 0; return hit; } @@ -1030,8 +1032,6 @@ int cmd_grep(int argc, const char **argv, const char *prefix) 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 || diff --git a/grep.c b/grep.c index 486230b511..7a67c2ff6f 100644 --- a/grep.c +++ b/grep.c @@ -807,26 +807,28 @@ static void show_line(struct grep_opt *opt, char *bol, char *eol, } #ifndef NO_PTHREADS +int grep_use_locks; + /* * 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) +static inline void grep_attr_lock(void) { - if (opt->use_threads) + if (grep_use_locks) pthread_mutex_lock(&grep_attr_mutex); } -static inline void grep_attr_unlock(struct grep_opt *opt) +static inline void grep_attr_unlock(void) { - if (opt->use_threads) + if (grep_use_locks) pthread_mutex_unlock(&grep_attr_mutex); } #else -#define grep_attr_lock(opt) -#define grep_attr_unlock(opt) +#define grep_attr_lock() +#define grep_attr_unlock() #endif static int match_funcname(struct grep_opt *opt, const char *name, char *bol, char *eol) @@ -834,9 +836,9 @@ static int match_funcname(struct grep_opt *opt, const char *name, char *bol, cha xdemitconf_t *xecfg = opt->priv; if (xecfg && !xecfg->find_func) { struct userdiff_driver *drv; - grep_attr_lock(opt); + grep_attr_lock(); drv = userdiff_find_by_path(name); - grep_attr_unlock(opt); + grep_attr_unlock(); if (drv && drv->funcname.pattern) { const struct userdiff_funcname *pe = &drv->funcname; xdiff_set_find_func(xecfg, pe->pattern, pe->cflags); diff --git a/grep.h b/grep.h index fb205f3542..3653bb333c 100644 --- a/grep.h +++ b/grep.h @@ -116,7 +116,6 @@ 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); @@ -138,6 +137,7 @@ extern int grep_threads_ok(const struct grep_opt *opt); * Mutex used around access to the attributes machinery if * opt->use_threads. Must be initialized/destroyed by callers! */ +extern int grep_use_locks; extern pthread_mutex_t grep_attr_mutex; #endif