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[PATCH] teach update-index --refresh about --data-unchanged

From
PWPete Wyckoff <pw@padd.com>
Date
Oct 31, 2010, 22:28 UTC
Message-ID
<20101031222805.GB31257@arf.padd.com>
In-Reply-To
<20101031222644.GA31257@arf.padd.com>

When a repository has been copied with rsync, or cloned using a volume manager, the index can be incorrect even though the data is unchanged. This new flag tells update-index --refresh that it is not necessary to reread the data contents. Without this flag, everything works, but it is much slower due to the need to read all files.

Signed-off-by: Pete Wyckoff <pw@padd.com>
---
 Documentation/git-update-index.txt |    9 +++++++++
 builtin/update-index.c             |    6 +++++-
 cache.h                            |    9 ++++++---
 read-cache.c                       |   16 ++++++++++------
 4 files changed, 30 insertions(+), 10 deletions(-)
diff --git a/Documentation/git-update-index.txt b/Documentation/git-update-index.txt
index 765d4b3..69aaaee 100644
--- a/Documentation/git-update-index.txt
+++ b/Documentation/git-update-index.txt
@@ -14,6 +14,7 @@ SYNOPSIS
 	     [--refresh] [-q] [--unmerged] [--ignore-missing]
 	     [--cacheinfo <mode> <object> <file>]\*
 	     [--chmod=(+|-)x]
+	     [--data-unchanged]
 	     [--assume-unchanged | --no-assume-unchanged]
 	     [--skip-worktree | --no-skip-worktree]
 	     [--ignore-submodules]
@@ -65,6 +66,14 @@ OPTIONS
 	behavior is to error out.  This option makes 'git update-index'
         continue anyway.
 
+--data-unchanged::
+	When refreshing the cache, do not re-read all data
+	files to verify that they are unchanged.  This flag
+	attests that even though the index may be invalid, file content
+	has not been changed.  This situation can happen when
+	a repository is copied with `rsync` or with a volume manager
+	clone command.
+
 --ignore-missing::
 	Ignores missing files during a --refresh
 
diff --git a/builtin/update-index.c b/builtin/update-index.c
index 3ab214d..dc609cc 100644
--- a/builtin/update-index.c
+++ b/builtin/update-index.c
@@ -398,7 +398,7 @@ static void read_index_info(int line_termination)
 }
 
 static const char update_index_usage[] =
-"git update-index [-q] [--add] [--replace] [--remove] [--unmerged] [--refresh] [--really-refresh] [--cacheinfo] [--chmod=(+|-)x] [--assume-unchanged] [--skip-worktree|--no-skip-worktree] [--info-only] [--force-remove] [--stdin] [--index-info] [--unresolve] [--again | -g] [--ignore-missing] [-z] [--verbose] [--] <file>...";
+"git update-index [-q] [--add] [--replace] [--remove] [--unmerged] [--data-unchanged] [--refresh] [--really-refresh] [--cacheinfo] [--chmod=(+|-)x] [--assume-unchanged] [--skip-worktree|--no-skip-worktree] [--info-only] [--force-remove] [--stdin] [--index-info] [--unresolve] [--again | -g] [--ignore-missing] [-z] [--verbose] [--] <file>...";
 
 static unsigned char head_sha1[20];
 static unsigned char merge_head_sha1[20];
@@ -635,6 +635,10 @@ int cmd_update_index(int argc, const char **argv, const char *prefix)
 				refresh_flags |= REFRESH_UNMERGED;
 				continue;
 			}
+			if (!strcmp(path, "--data-unchanged")) {
+				refresh_flags |= REFRESH_DATA_UNCHANGED;
+				continue;
+			}
 			if (!strcmp(path, "--refresh")) {
 				setup_work_tree();
 				has_errors |= refresh_cache(refresh_flags);
diff --git a/cache.h b/cache.h
index 1e690d1..b2e692c 100644
--- a/cache.h
+++ b/cache.h
@@ -485,11 +485,13 @@ extern int ce_same_name(struct cache_entry *a, struct cache_entry *b);
 extern int index_name_is_other(const struct index_state *, const char *, int);
 
 /* do stat comparison even if CE_VALID is true */
-#define CE_MATCH_IGNORE_VALID		01
+#define CE_MATCH_IGNORE_VALID		0x1
 /* do not check the contents but report dirty on racily-clean entries */
-#define CE_MATCH_RACY_IS_DIRTY		02
+#define CE_MATCH_RACY_IS_DIRTY		0x2
 /* do stat comparison even if CE_SKIP_WORKTREE is true */
-#define CE_MATCH_IGNORE_SKIP_WORKTREE	04
+#define CE_MATCH_IGNORE_SKIP_WORKTREE	0x4
+/* trust that the contents of files have not been modified */
+#define CE_MATCH_DATA_UNCHANGED		0x8
 extern int ie_match_stat(const struct index_state *, struct cache_entry *, struct stat *, unsigned int);
 extern int ie_modified(const struct index_state *, struct cache_entry *, struct stat *, unsigned int);
 
@@ -504,6 +506,7 @@ extern void fill_stat_cache_info(struct cache_entry *ce, struct stat *st);
 #define REFRESH_IGNORE_MISSING	0x0008	/* ignore non-existent */
 #define REFRESH_IGNORE_SUBMODULES	0x0010	/* ignore submodules */
 #define REFRESH_IN_PORCELAIN	0x0020	/* user friendly output, not "needs update" */
+#define REFRESH_DATA_UNCHANGED	0x0040	/* no need to read all files, trust unmodified */
 extern int refresh_index(struct index_state *, unsigned int flags, const char **pathspec, char *seen, char *header_msg);
 
 struct lock_file {
diff --git a/read-cache.c b/read-cache.c
index 1f42473..26d5d5f 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -137,12 +137,14 @@ static int ce_compare_gitlink(struct cache_entry *ce)
 	return hashcmp(sha1, ce->sha1);
 }
 
-static int ce_modified_check_fs(struct cache_entry *ce, struct stat *st)
+static int ce_modified_check_fs(struct cache_entry *ce, struct stat *st,
+				int options)
 {
 	switch (st->st_mode & S_IFMT) {
 	case S_IFREG:
-		if (ce_compare_data(ce, st))
-			return DATA_CHANGED;
+		if (!(options & CE_MATCH_DATA_UNCHANGED))
+			if (ce_compare_data(ce, st))
+				return DATA_CHANGED;
 		break;
 	case S_IFLNK:
 		if (ce_compare_link(ce, xsize_t(st->st_size)))
@@ -304,7 +306,7 @@ int ie_match_stat(const struct index_state *istate,
 		if (assume_racy_is_modified)
 			changed |= DATA_CHANGED;
 		else
-			changed |= ce_modified_check_fs(ce, st);
+			changed |= ce_modified_check_fs(ce, st, 0);
 	}
 
 	return changed;
@@ -343,7 +345,7 @@ int ie_modified(const struct index_state *istate,
 	    (S_ISGITLINK(ce->ce_mode) || ce->ce_size != 0))
 		return changed;
 
-	changed_fs = ce_modified_check_fs(ce, st);
+	changed_fs = ce_modified_check_fs(ce, st, options);
 	if (changed_fs)
 		return changed | changed_fs;
 	return 0;
@@ -1108,6 +1110,8 @@ int refresh_index(struct index_state *istate, unsigned int flags, const char **p
 
 	needs_update_fmt = (in_porcelain ? "M\t%s\n" : "%s: needs update\n");
 	needs_merge_fmt = (in_porcelain ? "U\t%s\n" : "%s: needs merge\n");
+	if (flags & REFRESH_DATA_UNCHANGED)
+	    options |= CE_MATCH_DATA_UNCHANGED;
 	for (i = 0; i < istate->cache_nr; i++) {
 		struct cache_entry *ce, *new;
 		int cache_errno = 0;
@@ -1481,7 +1485,7 @@ static void ce_smudge_racily_clean_entry(struct cache_entry *ce)
 		return;
 	if (ce_match_stat_basic(ce, &st))
 		return;
-	if (ce_modified_check_fs(ce, &st)) {
+	if (ce_modified_check_fs(ce, &st, 0)) {
 		/* This is "racily clean"; smudge it.  Note that this
 		 * is a tricky code.  At first glance, it may appear
 		 * that it can break with this sequence:

-- 
1.7.2.3
Previous: Pete WyckoffNext: Junio C Hamano
Message 7 of 16 in “index rebuild for cloned repo”
  1. Pete WyckoffOct 31, 2010
  2. Jonathan NiederOct 31, 2010
  3. cherry-pick/revert: transparently refresh indexJonathan Nieder, Oct 31, 2010
  4. Andreas SchwabOct 31, 2010
  5. Jonathan NiederOct 31, 2010
  6. Pete WyckoffOct 31, 2010
  7. teach update-index --refresh about --data-unchangedPete Wyckoff, Oct 31, 2010
  8. Junio C HamanoNov 3, 2010
  9. Jonathan NiederNov 3, 2010
  10. Pete WyckoffNov 3, 2010
  11. Pete WyckoffNov 14, 2010
  12. Jonathan NiederNov 14, 2010
  13. Johannes SixtNov 1, 2010
  14. Junio C HamanoNov 3, 2010
  15. Johannes SixtNov 3, 2010
  16. Nguyen Thai Ngoc DuyNov 1, 2010

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