Bigfile: teach "git add" to send a large file straight to a pack

When adding a new content to the repository, we have always slurped
the blob in its entirety in-core first, and computed the object name
and compressed it into a loose object file.  Handling large binary
files (e.g.  video and audio asset for games) has been problematic
because of this design.

At the middle level of "git add" callchain is an internal API
index_fd() that takes an open file descriptor to read from the
working tree file being added with its size. Teach it to call out to
fast-import when adding a large blob.

The write-out codepath in entry.c::write_entry() should be taught to
stream, instead of reading everything in core. This should not be so
hard to implement, especially if we limit ourselves only to loose
object files and non-delta representation in packfiles.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/t/t1050-large.sh b/t/t1050-large.sh
new file mode 100755
index 0000000000..deba111bd7
--- /dev/null
+++ b/t/t1050-large.sh
@@ -0,0 +1,27 @@
+#!/bin/sh
+# Copyright (c) 2011, Google Inc.
+
+test_description='adding and checking out large blobs'
+
+. ./test-lib.sh
+
+test_expect_success setup '
+	git config core.bigfilethreshold 200k &&
+	echo X | dd of=large bs=1k seek=2000
+'
+
+test_expect_success 'add a large file' '
+	git add large &&
+	# make sure we got a packfile and no loose objects
+	test -f .git/objects/pack/pack-*.pack &&
+	test ! -f .git/objects/??/??????????????????????????????????????
+'
+
+test_expect_success 'checkout a large file' '
+	large=$(git rev-parse :large) &&
+	git update-index --add --cacheinfo 100644 $large another &&
+	git checkout another &&
+	cmp large another ;# this must not be test_cmp
+'
+
+test_done