For a command (like filter-branch --subdirectory-filter) that wants
to commit a lot of trees that already exist in the object db, writing
undeltified objects as loose files only to repack them later can
involve a significant amount of overhead.
(23% slow-down observed on Linux 2.6.35, worse on Mac OS X 10.6)
Fortunately we have fast-import (which is one of the only git commands
that will write to a pack directly) but there is not an advertised way
to tell fast-import to commit a given tree without unpacking it.
This patch changes that, by allowing
M 040000 <tree id> ""
as a filemodify line in a commit to reset to a particular tree without
any need to parse it. For example,
M 040000 4b825dc642cb6eb9a060e54bf8d69288fbee4904 ""
is a synonym for the deleteall command and the fast-import equivalent of
git read-tree 4b825dc642cb6eb9a060e54bf8d69288fbee4904
Commit-message-by: Jonathan Nieder <jrnieder@xxxxxxxxx>
Signed-off-by: David Barr <david.barr@xxxxxxxxxxxx>
---
fast-import.c | 9 +++++++++
1 files changed, 9 insertions(+), 0 deletions(-)
diff --git a/fast-import.c b/fast-import.c
index 2317b0f..8f68a89 100644
--- a/fast-import.c
+++ b/fast-import.c
@@ -1454,6 +1454,15 @@ static int tree_content_set(
n = slash1 - p;
else
n = strlen(p);
+ if (!slash1 && !n) {
+ if (!S_ISDIR(mode))
+ die("Root cannot be a non-directory");
+ hashcpy(root->versions[1].sha1, sha1);
+ if (root->tree)
+ release_tree_content_recursive(root->tree);
+ root->tree = subtree;
+ return 1;
+ }
if (!n)
die("Empty path component found in input");
if (!slash1 && !S_ISDIR(mode) && subtree)
--
1.7.3.4.g45608.dirty
--
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