Threaded grep

Make git grep use threads when it is available.

The results below are best of five runs in the Linux repository (on a
box with two cores).

With the patch:

git grep qwerty
1.58user 0.55system 0:01.16elapsed 183%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+800outputs (0major+5774minor)pagefaults 0swaps

Without:

git grep qwerty
1.59user 0.43system 0:02.02elapsed 100%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+800outputs (0major+3716minor)pagefaults 0swaps

And with a pattern with quite a few matches:

With the patch:

$ /usr/bin/time git grep void
5.61user 0.56system 0:03.44elapsed 179%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+800outputs (0major+5587minor)pagefaults 0swaps

Without:

$ /usr/bin/time git grep void
5.36user 0.51system 0:05.87elapsed 100%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+800outputs (0major+3693minor)pagefaults 0swaps

In either case we gain about 40% by the threading.

Signed-off-by: Fredrik Kuivinen <frekui@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin-grep.c b/builtin-grep.c
index 64cdfefdd1f701cdb1dbb7921e82cf16f2440668..6cc743d7c585fa443f18a700455a4da662dec49f 100644 (file)
--- a/builtin-grep.c
+++ b/builtin-grep.c
@@ -16,11 +16,274 @@
 #include "quote.h"
 #include "dir.h"
 
+#ifndef NO_PTHREADS
+#include "thread-utils.h"
+#include <pthread.h>
+#endif
+
 static char const * const grep_usage[] = {
        "git grep [options] [-e] <pattern> [<rev>...] [[--] path...]",
        NULL
 };
 
+static int use_threads = 1;
+
+#ifndef NO_PTHREADS
+#define THREADS 8
+static pthread_t threads[THREADS];
+
+static void *load_sha1(const unsigned char *sha1, unsigned long *size,
+                      const char *name);
+static void *load_file(const char *filename, size_t *sz);
+
+enum work_type {WORK_SHA1, WORK_FILE};
+
+/* We use one producer thread and THREADS consumer
+ * threads. The producer adds struct work_items to 'todo' and the
+ * consumers pick work items from the same array.
+ */
+struct work_item
+{
+       enum work_type type;
+       char *name;
+
+       /* if type == WORK_SHA1, then 'identifier' is a SHA1,
+        * otherwise type == WORK_FILE, and 'identifier' is a NUL
+        * terminated filename.
+        */
+       void *identifier;
+       char done;
+       struct strbuf out;
+};
+
+/* In the range [todo_done, todo_start) in 'todo' we have work_items
+ * that have been or are processed by a consumer thread. We haven't
+ * written the result for these to stdout yet.
+ *
+ * The work_items in [todo_start, todo_end) are waiting to be picked
+ * up by a consumer thread.
+ *
+ * The ranges are modulo TODO_SIZE.
+ */
+#define TODO_SIZE 128
+static struct work_item todo[TODO_SIZE];
+static int todo_start;
+static int todo_end;
+static int todo_done;
+
+/* Has all work items been added? */
+static int all_work_added;
+
+/* This lock protects all the variables above. */
+static pthread_mutex_t grep_mutex;
+
+/* Used to serialize calls to read_sha1_file. */
+static pthread_mutex_t read_sha1_mutex;
+
+#define grep_lock() pthread_mutex_lock(&grep_mutex)
+#define grep_unlock() pthread_mutex_unlock(&grep_mutex)
+#define read_sha1_lock() pthread_mutex_lock(&read_sha1_mutex)
+#define read_sha1_unlock() pthread_mutex_unlock(&read_sha1_mutex)
+
+/* Signalled when a new work_item is added to todo. */
+static pthread_cond_t cond_add;
+
+/* Signalled when the result from one work_item is written to
+ * stdout.
+ */
+static pthread_cond_t cond_write;
+
+/* Signalled when we are finished with everything. */
+static pthread_cond_t cond_result;
+
+static void add_work(enum work_type type, char *name, void *id)
+{
+       grep_lock();
+
+       while ((todo_end+1) % ARRAY_SIZE(todo) == todo_done) {
+               pthread_cond_wait(&cond_write, &grep_mutex);
+       }
+
+       todo[todo_end].type = type;
+       todo[todo_end].name = name;
+       todo[todo_end].identifier = id;
+       todo[todo_end].done = 0;
+       strbuf_reset(&todo[todo_end].out);
+       todo_end = (todo_end + 1) % ARRAY_SIZE(todo);
+
+       pthread_cond_signal(&cond_add);
+       grep_unlock();
+}
+
+static struct work_item *get_work(void)
+{
+       struct work_item *ret;
+
+       grep_lock();
+       while (todo_start == todo_end && !all_work_added) {
+               pthread_cond_wait(&cond_add, &grep_mutex);
+       }
+
+       if (todo_start == todo_end && all_work_added) {
+               ret = NULL;
+       } else {
+               ret = &todo[todo_start];
+               todo_start = (todo_start + 1) % ARRAY_SIZE(todo);
+       }
+       grep_unlock();
+       return ret;
+}
+
+static void grep_sha1_async(struct grep_opt *opt, char *name,
+                           const unsigned char *sha1)
+{
+       unsigned char *s;
+       s = xmalloc(20);
+       memcpy(s, sha1, 20);
+       add_work(WORK_SHA1, name, s);
+}
+
+static void grep_file_async(struct grep_opt *opt, char *name,
+                           const char *filename)
+{
+       add_work(WORK_FILE, name, xstrdup(filename));
+}
+
+static void work_done(struct work_item *w)
+{
+       int old_done;
+
+       grep_lock();
+       w->done = 1;
+       old_done = todo_done;
+       for(; todo[todo_done].done && todo_done != todo_start;
+           todo_done = (todo_done+1) % ARRAY_SIZE(todo)) {
+               w = &todo[todo_done];
+               write_or_die(1, w->out.buf, w->out.len);
+               free(w->name);
+               free(w->identifier);
+       }
+
+       if (old_done != todo_done)
+               pthread_cond_signal(&cond_write);
+
+       if (all_work_added && todo_done == todo_end)
+               pthread_cond_signal(&cond_result);
+
+       grep_unlock();
+}
+
+static void *run(void *arg)
+{
+       int hit = 0;
+       struct grep_opt *opt = arg;
+
+       while (1) {
+               struct work_item *w = get_work();
+               if (!w)
+                       break;
+
+               opt->output_priv = w;
+               if (w->type == WORK_SHA1) {
+                       unsigned long sz;
+                       void* data = load_sha1(w->identifier, &sz, w->name);
+
+                       if (data) {
+                               hit |= grep_buffer(opt, w->name, data, sz);
+                               free(data);
+                       }
+               } else if (w->type == WORK_FILE) {
+                       size_t sz;
+                       void* data = load_file(w->identifier, &sz);
+                       if (data) {
+                               hit |= grep_buffer(opt, w->name, data, sz);
+                               free(data);
+                       }
+               } else {
+                       assert(0);
+               }
+
+               work_done(w);
+       }
+
+       return (void*) (intptr_t) hit;
+}
+
+static void strbuf_out(struct grep_opt *opt, const void *buf, size_t size)
+{
+       struct work_item *w = opt->output_priv;
+       strbuf_add(&w->out, buf, size);
+}
+
+static void start_threads(struct grep_opt *opt)
+{
+       int i;
+
+       pthread_mutex_init(&grep_mutex, NULL);
+       pthread_mutex_init(&read_sha1_mutex, NULL);
+       pthread_cond_init(&cond_add, NULL);
+       pthread_cond_init(&cond_write, NULL);
+       pthread_cond_init(&cond_result, NULL);
+
+       for (i = 0; i < ARRAY_SIZE(todo); i++) {
+               strbuf_init(&todo[i].out, 0);
+       }
+
+       for (i = 0; i < ARRAY_SIZE(threads); i++) {
+               int err;
+               struct grep_opt *o = grep_opt_dup(opt);
+               o->output = strbuf_out;
+               compile_grep_patterns(o);
+               err = pthread_create(&threads[i], NULL, run, o);
+
+               if (err)
+                       die("grep: failed to create thread: %s",
+                           strerror(err));
+       }
+}
+
+static int wait_all(void)
+{
+       int hit = 0;
+       int i;
+
+       grep_lock();
+       all_work_added = 1;
+
+       /* Wait until all work is done. */
+       while (todo_done != todo_end)
+               pthread_cond_wait(&cond_result, &grep_mutex);
+
+       /* Wake up all the consumer threads so they can see that there
+        * is no more work to do.
+        */
+       pthread_cond_broadcast(&cond_add);
+       grep_unlock();
+
+       for (i = 0; i < ARRAY_SIZE(threads); i++) {
+               void *h;
+               pthread_join(threads[i], &h);
+               hit |= (int) (intptr_t) h;
+       }
+
+       pthread_mutex_destroy(&grep_mutex);
+       pthread_mutex_destroy(&read_sha1_mutex);
+       pthread_cond_destroy(&cond_add);
+       pthread_cond_destroy(&cond_write);
+       pthread_cond_destroy(&cond_result);
+
+       return hit;
+}
+#else /* !NO_PTHREADS */
+#define read_sha1_lock()
+#define read_sha1_unlock()
+
+static int wait_all(void)
+{
+       return 0;
+}
+#endif
+
 static int grep_config(const char *var, const char *value, void *cb)
 {
        struct grep_opt *opt = cb;
@@ -144,37 +407,64 @@ static int pathspec_matches(const char **paths, const char *name, int max_depth)
        return 0;
 }
 
-static int grep_sha1(struct grep_opt *opt, const unsigned char *sha1, const char *name, int tree_name_len)
+static void *load_sha1(const unsigned char *sha1, unsigned long *size,
+                      const char *name)
 {
-       unsigned long size;
-       char *data;
        enum object_type type;
-       int hit;
-       struct strbuf pathbuf = STRBUF_INIT;
+       char *data;
 
-       data = read_sha1_file(sha1, &type, &size);
-       if (!data) {
+       read_sha1_lock();
+       data = read_sha1_file(sha1, &type, size);
+       read_sha1_unlock();
+
+       if (!data)
                error("'%s': unable to read %s", name, sha1_to_hex(sha1));
-               return 0;
-       }
+
+       return data;
+}
+
+static int grep_sha1(struct grep_opt *opt, const unsigned char *sha1,
+                    const char *filename, int tree_name_len)
+{
+       struct strbuf pathbuf = STRBUF_INIT;
+       char *name;
+
        if (opt->relative && opt->prefix_length) {
-               quote_path_relative(name + tree_name_len, -1, &pathbuf, opt->prefix);
-               strbuf_insert(&pathbuf, 0, name, tree_name_len);
-               name = pathbuf.buf;
+               quote_path_relative(filename + tree_name_len, -1, &pathbuf,
+                                   opt->prefix);
+               strbuf_insert(&pathbuf, 0, filename, tree_name_len);
+       } else {
+               strbuf_addstr(&pathbuf, filename);
+       }
+
+       name = strbuf_detach(&pathbuf, NULL);
+
+#ifndef NO_PTHREADS
+       if (use_threads) {
+               grep_sha1_async(opt, name, sha1);
+               return 0;
+       } else
+#endif
+       {
+               int hit;
+               unsigned long sz;
+               void *data = load_sha1(sha1, &sz, name);
+               if (!data)
+                       hit = 0;
+               else
+                       hit = grep_buffer(opt, name, data, sz);
+
+               free(data);
+               free(name);
+               return hit;
        }
-       hit = grep_buffer(opt, name, data, size);
-       strbuf_release(&pathbuf);
-       free(data);
-       return hit;
 }
 
-static int grep_file(struct grep_opt *opt, const char *filename)
+static void *load_file(const char *filename, size_t *sz)
 {
        struct stat st;
-       int i;
        char *data;
-       size_t sz;
-       struct strbuf buf = STRBUF_INIT;
+       int i;
 
        if (lstat(filename, &st) < 0) {
        err_ret:
@@ -184,25 +474,52 @@ static int grep_file(struct grep_opt *opt, const char *filename)
        }
        if (!S_ISREG(st.st_mode))
                return 0;
-       sz = xsize_t(st.st_size);
+       *sz = xsize_t(st.st_size);
        i = open(filename, O_RDONLY);
        if (i < 0)
                goto err_ret;
-       data = xmalloc(sz + 1);
-       if (st.st_size != read_in_full(i, data, sz)) {
+       data = xmalloc(*sz + 1);
+       if (st.st_size != read_in_full(i, data, *sz)) {
                error("'%s': short read %s", filename, strerror(errno));
                close(i);
                free(data);
                return 0;
        }
        close(i);
-       data[sz] = 0;
+       data[*sz] = 0;
+       return data;
+}
+
+static int grep_file(struct grep_opt *opt, const char *filename)
+{
+       struct strbuf buf = STRBUF_INIT;
+       char *name;
+
        if (opt->relative && opt->prefix_length)
-               filename = quote_path_relative(filename, -1, &buf, opt->prefix);
-       i = grep_buffer(opt, filename, data, sz);
-       strbuf_release(&buf);
-       free(data);
-       return i;
+               quote_path_relative(filename, -1, &buf, opt->prefix);
+       else
+               strbuf_addstr(&buf, filename);
+       name = strbuf_detach(&buf, NULL);
+
+#ifndef NO_PTHREADS
+       if (use_threads) {
+               grep_file_async(opt, name, filename);
+               return 0;
+       } else
+#endif
+       {
+               int hit;
+               size_t sz;
+               void *data = load_file(filename, &sz);
+               if (!data)
+                       hit = 0;
+               else
+                       hit = grep_buffer(opt, name, data, sz);
+
+               free(data);
+               free(name);
+               return hit;
+       }
 }
 
 static int grep_cache(struct grep_opt *opt, const char **paths, int cached)
@@ -287,7 +604,10 @@ static int grep_tree(struct grep_opt *opt, const char **paths,
                        void *data;
                        unsigned long size;
 
+                       read_sha1_lock();
                        data = read_sha1_file(entry.sha1, &type, &size);
+                       read_sha1_unlock();
+
                        if (!data)
                                die("unable to read tree (%s)",
                                    sha1_to_hex(entry.sha1));
@@ -581,6 +901,17 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
                opt.regflags |= REG_ICASE;
        if ((opt.regflags != REG_NEWLINE) && opt.fixed)
                die("cannot mix --fixed-strings and regexp");
+
+#ifndef NO_PTHREADS
+       if (online_cpus() == 1 || !grep_threads_ok(&opt))
+               use_threads = 0;
+
+       if (use_threads)
+               start_threads(&opt);
+#else
+       use_threads = 0;
+#endif
+
        compile_grep_patterns(&opt);
 
        /* Check revs and then paths */
@@ -618,17 +949,26 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
        }
 
        if (!use_index) {
+               int hit;
                if (cached)
                        die("--cached cannot be used with --no-index.");
                if (list.nr)
                        die("--no-index cannot be used with revs.");
-               return !grep_directory(&opt, paths);
+               hit = grep_directory(&opt, paths);
+               if (use_threads)
+                       hit |= wait_all();
+               return !hit;
        }
 
        if (!list.nr) {
+               int hit;
                if (!cached)
                        setup_work_tree();
-               return !grep_cache(&opt, paths, cached);
+
+               hit = grep_cache(&opt, paths, cached);
+               if (use_threads)
+                       hit |= wait_all();
+               return !hit;
        }
 
        if (cached)
@@ -643,6 +983,9 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
                                break;
                }
        }
+
+       if (use_threads)
+               hit |= wait_all();
        free_grep_patterns(&opt);
        return !hit;
 }

diff --git a/grep.c b/grep.c
index 8e1f7de7717da95e8954491f5205547f2091aa35..d281a020e8452939d7dad0ab53876a8476a5cc89 100644 (file)
--- a/grep.c
+++ b/grep.c
@@ -29,6 +29,28 @@ void append_grep_pattern(struct grep_opt *opt, const char *pat,
        p->next = NULL;
 }
 
+struct grep_opt *grep_opt_dup(const struct grep_opt *opt)
+{
+       struct grep_pat *pat;
+       struct grep_opt *ret = xmalloc(sizeof(struct grep_opt));
+       *ret = *opt;
+
+       ret->pattern_list = NULL;
+       ret->pattern_tail = &ret->pattern_list;
+
+       for(pat = opt->pattern_list; pat != NULL; pat = pat->next)
+       {
+               if(pat->token == GREP_PATTERN_HEAD)
+                       append_header_grep_pattern(ret, pat->field,
+                                                  pat->pattern);
+               else
+                       append_grep_pattern(ret, pat->pattern, pat->origin,
+                                           pat->no, pat->token);
+       }
+
+       return ret;
+}
+
 static void compile_regexp(struct grep_pat *p, struct grep_opt *opt)
 {
        int err;
@@ -253,7 +275,8 @@ static int word_char(char ch)
 
 static void show_name(struct grep_opt *opt, const char *name)
 {
-       printf("%s%c", name, opt->null_following_name ? '\0' : '\n');
+       opt->output(opt, name, strlen(name));
+       opt->output(opt, opt->null_following_name ? "\0" : "\n", 1);
 }
 
 
@@ -490,24 +513,32 @@ static void show_line(struct grep_opt *opt, char *bol, char *eol,
                      const char *name, unsigned lno, char sign)
 {
        int rest = eol - bol;
+       char sign_str[1];
 
+       sign_str[0] = sign;
        if (opt->pre_context || opt->post_context) {
                if (opt->last_shown == 0) {
                        if (opt->show_hunk_mark)
-                               fputs("--\n", stdout);
+                               opt->output(opt, "--\n", 3);
                        else
                                opt->show_hunk_mark = 1;
                } else if (lno > opt->last_shown + 1)
-                       fputs("--\n", stdout);
+                       opt->output(opt, "--\n", 3);
        }
        opt->last_shown = lno;
 
        if (opt->null_following_name)
-               sign = '\0';
-       if (opt->pathname)
-               printf("%s%c", name, sign);
-       if (opt->linenum)
-               printf("%d%c", lno, sign);
+               sign_str[0] = '\0';
+       if (opt->pathname) {
+               opt->output(opt, name, strlen(name));
+               opt->output(opt, sign_str, 1);
+       }
+       if (opt->linenum) {
+               char buf[32];
+               snprintf(buf, sizeof(buf), "%d", lno);
+               opt->output(opt, buf, strlen(buf));
+               opt->output(opt, sign_str, 1);
+       }
        if (opt->color) {
                regmatch_t match;
                enum grep_context ctx = GREP_CONTEXT_BODY;
@@ -518,18 +549,22 @@ static void show_line(struct grep_opt *opt, char *bol, char *eol,
                while (next_match(opt, bol, eol, ctx, &match, eflags)) {
                        if (match.rm_so == match.rm_eo)
                                break;
-                       printf("%.*s%s%.*s%s",
-                              (int)match.rm_so, bol,
-                              opt->color_match,
-                              (int)(match.rm_eo - match.rm_so), bol + match.rm_so,
-                              GIT_COLOR_RESET);
+
+                       opt->output(opt, bol, match.rm_so);
+                       opt->output(opt, opt->color_match,
+                                   strlen(opt->color_match));
+                       opt->output(opt, bol + match.rm_so,
+                                   (int)(match.rm_eo - match.rm_so));
+                       opt->output(opt, GIT_COLOR_RESET,
+                                   strlen(GIT_COLOR_RESET));
                        bol += match.rm_eo;
                        rest -= match.rm_eo;
                        eflags = REG_NOTBOL;
                }
                *eol = ch;
        }
-       printf("%.*s\n", rest, bol);
+       opt->output(opt, bol, rest);
+       opt->output(opt, "\n", 1);
 }
 
 static int match_funcname(struct grep_opt *opt, char *bol, char *eol)
@@ -667,6 +702,32 @@ 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->unmatch_name_only && !opt->status_only &&
+           !opt->name_only)
+               return 0;
+
+       /* If we are showing hunk marks, we should not do it for the
+        * first match. The synchronization problem we get for this
+        * constraint is not yet solved, so we disable threading in
+        * this case.
+        */
+       if (opt->pre_context || opt->post_context)
+               return 0;
+
+       return 1;
+}
+
+static void std_output(struct grep_opt *opt, const void *buf, size_t size)
+{
+       fwrite(buf, size, 1, stdout);
+}
+
 static int grep_buffer_1(struct grep_opt *opt, const char *name,
                         char *buf, unsigned long size, int collect_hits)
 {
@@ -682,6 +743,9 @@ static int grep_buffer_1(struct grep_opt *opt, const char *name,
 
        opt->last_shown = 0;
 
+       if (!opt->output)
+               opt->output = std_output;
+
        if (buffer_is_binary(buf, size)) {
                switch (opt->binary) {
                case GREP_BINARY_DEFAULT:
@@ -754,7 +818,9 @@ static int grep_buffer_1(struct grep_opt *opt, const char *name,
                        if (opt->status_only)
                                return 1;
                        if (binary_match_only) {
-                               printf("Binary file %s matches\n", name);
+                               opt->output(opt, "Binary file ", 12);
+                               opt->output(opt, name, strlen(name));
+                               opt->output(opt, " matches\n", 9);
                                return 1;
                        }
                        if (opt->name_only) {
@@ -810,9 +876,13 @@ static int grep_buffer_1(struct grep_opt *opt, const char *name,
         * which feels mostly useless but sometimes useful.  Maybe
         * make it another option?  For now suppress them.
         */
-       if (opt->count && count)
-               printf("%s%c%u\n", name,
-                      opt->null_following_name ? '\0' : ':', count);
+       if (opt->count && count) {
+               char buf[32];
+               opt->output(opt, name, strlen(name));
+               snprintf(buf, sizeof(buf), "%c%u\n",
+                        opt->null_following_name ? '\0' : ':', count);
+               opt->output(opt, buf, strlen(buf));
+       }
        return !!last_hit;
 }
 

diff --git a/grep.h b/grep.h
index 0c61b00cbf3c4f059aedc02d487b4103eea31823..970308799664fe6a3871c0b8364c13e43cf96e1f 100644 (file)
--- a/grep.h
+++ b/grep.h
@@ -91,6 +91,9 @@ struct grep_opt {
        unsigned last_shown;
        int show_hunk_mark;
        void *priv;
+
+       void (*output)(struct grep_opt *opt, const void *data, size_t size);
+       void *output_priv;
 };
 
 extern void append_grep_pattern(struct grep_opt *opt, const char *pat, const char *origin, int no, enum grep_pat_token t);
@@ -99,4 +102,7 @@ extern void compile_grep_patterns(struct grep_opt *opt);
 extern void free_grep_patterns(struct grep_opt *opt);
 extern int grep_buffer(struct grep_opt *opt, const char *name, char *buf, unsigned long size);
 
+extern struct grep_opt *grep_opt_dup(const struct grep_opt *opt);
+extern int grep_threads_ok(const struct grep_opt *opt);
+
 #endif