Optimize directory listing with pathspec limiter.

The way things are set up, you can now pass a "pathspec" to the
"read_directory()" function. If you pass NULL, it acts exactly
like it used to do (read everything). If you pass a non-NULL
pointer, it will simplify it into a "these are the prefixes
without any special characters", and stop any readdir() early if
the path in question doesn't match any of the prefixes.

NOTE! This does *not* obviate the need for the caller to do the *exact*
pathspec match later. It's a first-level filter on "read_directory()", but
it does not do the full pathspec thing. Maybe it should. But in the
meantime, builtin-add.c really does need to do first

	read_directory(dir, .., pathspec);
	if (pathspec)
		prune_directory(dir, pathspec, baselen);

ie the "prune_directory()" part will do the *exact* pathspec pruning,
while the "read_directory()" will use the pathspec just to do some quick
high-level pruning of the directories it will recurse into.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/builtin-add.c b/builtin-add.c
index 9fcf514dbc4cb76e15b47142e77c4019997ecd5d..871e23f0f60398418f52a9c9a63e6198b5d10c15 100644 (file)
--- a/builtin-add.c
+++ b/builtin-add.c
@@ -87,7 +87,7 @@ static void fill_directory(struct dir_struct *dir, const char **pathspec)
        }
 
        /* Read the directory and prune it */
-       read_directory(dir, path, base, baselen);
+       read_directory(dir, path, base, baselen, pathspec);
        if (pathspec)
                prune_directory(dir, pathspec, baselen);
 }

diff --git a/builtin-ls-files.c b/builtin-ls-files.c
index 4e1d5af634a1280288d7c8110571f1136343bf3e..74a6acacc15b416a6149a519f3a69c5facfa5067 100644 (file)
--- a/builtin-ls-files.c
+++ b/builtin-ls-files.c
@@ -216,7 +216,7 @@ static void show_files(struct dir_struct *dir, const char *prefix)
 
                if (baselen)
                        path = base = prefix;
-               read_directory(dir, path, base, baselen);
+               read_directory(dir, path, base, baselen, pathspec);
                if (show_others)
                        show_other_files(dir);
                if (show_killed)

diff --git a/dir.c b/dir.c
index b48e19dc09fff7d7fb1d5b48673fe4448b69a7c3..7426fde330a200e3137e722c4b9adbc5ce6bdd90 100644 (file)
--- a/dir.c
+++ b/dir.c
@@ -8,6 +8,11 @@
 #include "cache.h"
 #include "dir.h"
 
+struct path_simplify {
+       int len;
+       const char *path;
+};
+
 int common_prefix(const char **pathspec)
 {
        const char *path, *slash, *next;
@@ -292,6 +297,31 @@ static int dir_exists(const char *dirname, int len)
        return !strncmp(active_cache[pos]->name, dirname, len);
 }
 
+/*
+ * This is an inexact early pruning of any recursive directory
+ * reading - if the path cannot possibly be in the pathspec,
+ * return true, and we'll skip it early.
+ */
+static int simplify_away(const char *path, int pathlen, const struct path_simplify *simplify)
+{
+       if (simplify) {
+               for (;;) {
+                       const char *match = simplify->path;
+                       int len = simplify->len;
+
+                       if (!match)
+                               break;
+                       if (len > pathlen)
+                               len = pathlen;
+                       if (!memcmp(path, match, len))
+                               return 0;
+                       simplify++;
+               }
+               return 1;
+       }
+       return 0;
+}
+
 /*
  * Read a directory tree. We currently ignore anything but
  * directories, regular files and symlinks. That's because git
@@ -301,7 +331,7 @@ static int dir_exists(const char *dirname, int len)
  * Also, we ignore the name ".git" (even if it is not a directory).
  * That likely will not change.
  */
-static int read_directory_recursive(struct dir_struct *dir, const char *path, const char *base, int baselen, int check_only)
+static int read_directory_recursive(struct dir_struct *dir, const char *path, const char *base, int baselen, int check_only, const struct path_simplify *simplify)
 {
        DIR *fdir = opendir(path);
        int contents = 0;
@@ -324,6 +354,8 @@ static int read_directory_recursive(struct dir_struct *dir, const char *path, co
                                continue;
                        len = strlen(de->d_name);
                        memcpy(fullname + baselen, de->d_name, len+1);
+                       if (simplify_away(fullname, baselen + len, simplify))
+                               continue;
                        if (excluded(dir, fullname) != dir->show_ignored) {
                                if (!dir->show_ignored || DTYPE(de) != DT_DIR) {
                                        continue;
@@ -350,13 +382,13 @@ static int read_directory_recursive(struct dir_struct *dir, const char *path, co
                                        if (dir->hide_empty_directories &&
                                            !read_directory_recursive(dir,
                                                    fullname, fullname,
-                                                   baselen + len, 1))
+                                                   baselen + len, 1, simplify))
                                                continue;
                                        break;
                                }
 
                                contents += read_directory_recursive(dir,
-                                       fullname, fullname, baselen + len, 0);
+                                       fullname, fullname, baselen + len, 0, simplify);
                                continue;
                        case DT_REG:
                        case DT_LNK:
@@ -386,8 +418,61 @@ static int cmp_name(const void *p1, const void *p2)
                                  e2->name, e2->len);
 }
 
-int read_directory(struct dir_struct *dir, const char *path, const char *base, int baselen)
+/*
+ * Return the length of the "simple" part of a path match limiter.
+ */
+static int simple_length(const char *match)
 {
+       const char special[256] = {
+               [0] = 1, ['?'] = 1,
+               ['\\'] = 1, ['*'] = 1,
+               ['['] = 1
+       };
+       int len = -1;
+
+       for (;;) {
+               unsigned char c = *match++;
+               len++;
+               if (special[c])
+                       return len;
+       }
+}
+
+static struct path_simplify *create_simplify(const char **pathspec)
+{
+       int nr, alloc = 0;
+       struct path_simplify *simplify = NULL;
+
+       if (!pathspec)
+               return NULL;
+
+       for (nr = 0 ; ; nr++) {
+               const char *match;
+               if (nr >= alloc) {
+                       alloc = alloc_nr(alloc);
+                       simplify = xrealloc(simplify, alloc * sizeof(*simplify));
+               }
+               match = *pathspec++;
+               if (!match)
+                       break;
+               simplify[nr].path = match;
+               simplify[nr].len = simple_length(match);
+       }
+       simplify[nr].path = NULL;
+       simplify[nr].len = 0;
+       return simplify;
+}
+
+static void free_simplify(struct path_simplify *simplify)
+{
+       if (simplify)
+               free(simplify);
+}
+
+int read_directory(struct dir_struct *dir, const char *path, const char *base, int baselen, const char **pathspec)
+{
+       struct path_simplify *simplify = create_simplify(pathspec);
+
        /*
         * Make sure to do the per-directory exclude for all the
         * directories leading up to our base.
@@ -414,7 +499,8 @@ int read_directory(struct dir_struct *dir, const char *path, const char *base, i
                }
        }
 
-       read_directory_recursive(dir, path, base, baselen, 0);
+       read_directory_recursive(dir, path, base, baselen, 0, simplify);
+       free_simplify(simplify);
        qsort(dir->entries, dir->nr, sizeof(struct dir_entry *), cmp_name);
        return dir->nr;
 }

diff --git a/dir.h b/dir.h
index 7233d65bbd393f1d34d75538dd0e39e4a86383f2..33c31f25fbabc36db26e6fdf9f33381f166d2d7f 100644 (file)
--- a/dir.h
+++ b/dir.h
@@ -48,7 +48,7 @@ extern int common_prefix(const char **pathspec);
 #define MATCHED_EXACTLY 3
 extern int match_pathspec(const char **pathspec, const char *name, int namelen, int prefix, char *seen);
 
-extern int read_directory(struct dir_struct *, const char *path, const char *base, int baselen);
+extern int read_directory(struct dir_struct *, const char *path, const char *base, int baselen, const char **pathspec);
 extern int push_exclude_per_directory(struct dir_struct *, const char *, int);
 extern void pop_exclude_per_directory(struct dir_struct *, int);
 

diff --git a/wt-status.c b/wt-status.c
index a25632bc87867748016e32a4ba4652918c8705a3..a0559905a0b7072f4a4b44ea321c1316cfc84414 100644 (file)
--- a/wt-status.c
+++ b/wt-status.c
@@ -260,7 +260,7 @@ static void wt_status_print_untracked(struct wt_status *s)
        if (file_exists(x))
                add_excludes_from_file(&dir, x);
 
-       read_directory(&dir, ".", "", 0);
+       read_directory(&dir, ".", "", 0, NULL);
        for(i = 0; i < dir.nr; i++) {
                /* check for matching entry, which is unmerged; lifted from
                 * builtin-ls-files:show_other_files */