Merge pull request #994 from jeffhostetler/jeffhostetler/fscache_nfd

fscache: add not-found directory cache to fscache

Author: dscho

compat/win32/fscache.c

@@ -7,6 +7,7 @@ static int initialized;
 static volatile long enabled;
 static struct hashmap map;
 static CRITICAL_SECTION mutex;
+static struct trace_key trace_fscache = TRACE_KEY_INIT(FSCACHE);
 
 /*
  * An entry in the file system cache. Used for both entire directory listings
@@ -163,7 +164,8 @@ static struct fsentry *fseentry_create_entry(struct fsentry *list,
  * Dir should not contain trailing '/'. Use an empty string for the current
  * directory (not "."!).
  */
-static struct fsentry *fsentry_create_list(const struct fsentry *dir)
+static struct fsentry *fsentry_create_list(const struct fsentry *dir,
+					   int *dir_not_found)
 {
 	wchar_t pattern[MAX_LONG_PATH + 2]; /* + 2 for "\*" */
 	WIN32_FIND_DATAW fdata;
@@ -172,6 +174,8 @@ static struct fsentry *fsentry_create_list(const struct fsentry *dir)
 	struct fsentry *list, **phead;
 	DWORD err;
 
+	*dir_not_found = 0;
+
 	/* convert name to UTF-16 and check length */
 	if ((wlen = xutftowcs_path_ex(pattern, dir->name, MAX_LONG_PATH,
 			dir->len, MAX_PATH - 2, core_long_paths)) < 0)
@@ -190,12 +194,16 @@ static struct fsentry *fsentry_create_list(const struct fsentry *dir)
 	h = FindFirstFileW(pattern, &fdata);
 	if (h == INVALID_HANDLE_VALUE) {
 		err = GetLastError();
+		*dir_not_found = 1; /* or empty directory */
 		errno = (err == ERROR_DIRECTORY) ? ENOTDIR : err_win_to_posix(err);
+		trace_printf_key(&trace_fscache, "fscache: error(%d) '%.*s'\n",
+						 errno, dir->len, dir->name);
 		return NULL;
 	}
 
 	/* allocate object to hold directory listing */
 	list = fsentry_alloc(NULL, dir->name, dir->len);
+	list->st_mode = S_IFDIR;
 
 	/* walk directory and build linked list of fsentry structures */
 	phead = &list->next;
@@ -296,12 +304,16 @@ static struct fsentry *fscache_get_wait(struct fsentry *key)
 static struct fsentry *fscache_get(struct fsentry *key)
 {
 	struct fsentry *fse, *future, *waiter;
+	int dir_not_found;
 
 	EnterCriticalSection(&mutex);
 	/* check if entry is in cache */
 	fse = fscache_get_wait(key);
 	if (fse) {
-		fsentry_addref(fse);
+		if (fse->st_mode)
+			fsentry_addref(fse);
+		else
+			fse = NULL; /* non-existing directory */
 		LeaveCriticalSection(&mutex);
 		return fse;
 	}
@@ -310,7 +322,10 @@ static struct fsentry *fscache_get(struct fsentry *key)
 		fse = fscache_get_wait(key->list);
 		if (fse) {
 			LeaveCriticalSection(&mutex);
-			/* dir entry without file entry -> file doesn't exist */
+			/*
+			 * dir entry without file entry, or dir does not
+			 * exist -> file doesn't exist
+			 */
 			errno = ENOENT;
 			return NULL;
 		}
@@ -324,7 +339,7 @@ static struct fsentry *fscache_get(struct fsentry *key)
 
 	/* create the directory listing (outside mutex!) */
 	LeaveCriticalSection(&mutex);
-	fse = fsentry_create_list(future);
+	fse = fsentry_create_list(future, &dir_not_found);
 	EnterCriticalSection(&mutex);
 
 	/* remove future entry and signal waiting threads */
@@ -338,6 +353,17 @@ static struct fsentry *fscache_get(struct fsentry *key)
 
 	/* leave on error (errno set by fsentry_create_list) */
 	if (!fse) {
+		if (dir_not_found && key->list) {
+			/*
+			 * Record that the directory does not exist (or is
+			 * empty, which for all practical matters is the same
+			 * thing as far as fscache is concerned).
+			 */
+			fse = fsentry_alloc(key->list->list,
+					    key->list->name, key->list->len);
+			fse->st_mode = 0;
+			hashmap_add(&map, fse);
+		}
 		LeaveCriticalSection(&mutex);
 		return NULL;
 	}
@@ -349,6 +375,9 @@ static struct fsentry *fscache_get(struct fsentry *key)
 	if (key->list)
 		fse = hashmap_get(&map, key, NULL);
 
+	if (fse && !fse->st_mode)
+		fse = NULL; /* non-existing directory */
+
 	/* return entry or ENOENT */
 	if (fse)
 		fsentry_addref(fse);
@@ -392,6 +421,7 @@ int fscache_enable(int enable)
 		fscache_clear();
 		LeaveCriticalSection(&mutex);
 	}
+	trace_printf_key(&trace_fscache, "fscache: enable(%d)\n", enable);
 	return result;
 }
 

t/t1090-sparse-checkout-scope.sh

@@ -49,4 +49,24 @@ test_expect_success 'return to full checkout of master' '
 	test "$(cat b)" = "modified"
 '
 
+test_expect_success 'no unnecessary opendir() with fscache' '
+	git clone . fscache-test &&
+	(
+		cd fscache-test &&
+		git config core.fscache 1 &&
+		echo "/excluded/*" >.git/info/sparse-checkout &&
+		for f in $(test_seq 10)
+		do
+			sha1=$(echo $f | git hash-object -w --stdin) &&
+			git update-index --add \
+				--cacheinfo 100644,$sha1,excluded/$f || break
+		done &&
+		test_tick &&
+		git commit -m excluded &&
+		GIT_TRACE_FSCACHE=1 git status >out 2>err &&
+		grep excluded err >grep.out &&
+		test_line_count = 1 grep.out
+	)
+'
+
 test_done