dir.c: git-status --ignored: don't scan the work tree twice

'git-status --ignored' still scans the work tree twice to collect
untracked and ignored files, respectively.

fill_directory / read_directory already supports collecting untracked and
ignored files in a single directory scan. However, the DIR_COLLECT_IGNORED
flag to enable this has some git-add specific side-effects (e.g. it
doesn't recurse into ignored directories, so listing ignored files with
--untracked=all doesn't work).

The DIR_SHOW_IGNORED flag doesn't list untracked files and returns ignored
files in dir_struct.entries[] (instead of dir_struct.ignored[] as
DIR_COLLECT_IGNORED). DIR_SHOW_IGNORED is used all throughout git.

We don't want to break the existing API, so lets introduce a new flag
DIR_SHOW_IGNORED_TOO that lists untracked as well as ignored files similar
to DIR_COLLECT_FILES, but will recurse into sub-directories based on the
other flags as DIR_SHOW_IGNORED does.

In dir.c::read_directory_recursive, add ignored files to either
dir_struct.entries[] or dir_struct.ignored[] based on the flags. Also move
the DIR_COLLECT_IGNORED case here so that filling result lists is in a
common place.

In wt-status.c::wt_status_collect_untracked, use the new flag and read
results from dir_struct.ignored[]. Remove the extra fill_directory call.

builtin/check-ignore.c doesn't call fill_directory, setting the git-add
specific DIR_COLLECT_IGNORED flag has no effect here. Remove for clarity.

Update API documentation to reflect the changes.

Performance: with this patch, 'git-status --ignored' is typically as fast
as 'git-status'.

Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 22 insertions, 3 deletions

diff --git a/Documentation/technical/api-directory-listing.txt b/Documentation/technical/api-directory-listing.txt
index 1f349b28a..7f8e78d91 100644
--- a/Documentation/technical/api-directory-listing.txt
+++ b/Documentation/technical/api-directory-listing.txt
@@ -22,12 +22,23 @@ The notable options are:
 
 `flags`::
 
-	A bit-field of options:
+	A bit-field of options (the `*IGNORED*` flags are mutually exclusive):
 
 `DIR_SHOW_IGNORED`:::
 
-	The traversal is for finding just ignored files, not unignored
-	files.
+	Return just ignored files in `entries[]`, not untracked files.
+
+`DIR_SHOW_IGNORED_TOO`:::
+
+	Similar to `DIR_SHOW_IGNORED`, but return ignored files in `ignored[]`
+	in addition to untracked files in `entries[]`.
+
+`DIR_COLLECT_IGNORED`:::
+
+	Special mode for git-add. Return ignored files in `ignored[]` and
+	untracked files in `entries[]`. Only returns ignored files that match
+	pathspec exactly (no wildcards). Does not recurse into ignored
+	directories.
 
 `DIR_SHOW_OTHER_DIRECTORIES`:::
 
@@ -57,6 +68,14 @@ The result of the enumeration is left in these fields:
 
 	Internal use; keeps track of allocation of `entries[]` array.
 
+`ignored[]`::
+
+	An array of `struct dir_entry`, used for ignored paths with the
+	`DIR_SHOW_IGNORED_TOO` and `DIR_COLLECT_IGNORED` flags.
+
+`ignored_nr`::
+
+	The number of members in `ignored[]` array.
 
 Calling sequence
 ----------------