[PATCH] fast-import: Do less work when given "from" matches current branch head
- From
Mike Hommey <mh@glandium.org>
- Date
- Jul 9, 2015, 06:50 UTC
- Message-ID
- <1436424609-26159-1-git-send-email-mh@glandium.org>
- In-Reply-To
- <20150709055227.GA32360@glandium.org>
When building a fast-import stream, it's easy to forget the fact that for non-merge commits happening on top of the current branch head, there is no need for a "from" command. That is corroborated by the fact that at least git-p4, hg-fast-export and felipec's git-remote-hg all unconditionally use a "from" command.
Unfortunately, giving a "from" command always resets the branch tree, forcing it to be re-read, and in many cases, the pack is also closed and reopened through gfi_unpack_entry. Both are extra unwanted overhead, and the latter is particularly slow at least on OSX.
So, avoid resetting the tree when it's unmodified, and avoid calling gfi_unpack_entry when the given mark points to the same commit as the current branch head.
Signed-off-by: Mike Hommey <mh@glandium.org> --- fast-import.c | 29 +++++++++++++++++------------ 1 file changed, 17 insertions(+), 12 deletions(-)
diff --git a/fast-import.c b/fast-import.c index e78ca10..372d63a 100644 --- a/fast-import.c +++ b/fast-import.c @@ -2588,14 +2588,12 @@ static int parse_from(struct branch *b) { const char *from; struct branch *s; + unsigned char sha1[20]; if (!skip_prefix(command_buf.buf, "from ", &from)) return 0; - if (b->branch_tree.tree) { - release_tree_content_recursive(b->branch_tree.tree); - b->branch_tree.tree = NULL; - } + hashcpy(sha1, b->branch_tree.versions[1].sha1); s = lookup_branch(from); if (b == s) @@ -2610,14 +2608,16 @@ static int parse_from(struct branch *b) struct object_entry *oe = find_mark(idnum); if (oe->type != OBJ_COMMIT) die("Mark :%" PRIuMAX " not a commit", idnum); - hashcpy(b->sha1, oe->idx.sha1); - if (oe->pack_id != MAX_PACK_ID) { - unsigned long size; - char *buf = gfi_unpack_entry(oe, &size); - parse_from_commit(b, buf, size); - free(buf); - } else - parse_from_existing(b); + if (hashcmp(b->sha1, oe->idx.sha1)) { + hashcpy(b->sha1, oe->idx.sha1); + if (oe->pack_id != MAX_PACK_ID) { + unsigned long size; + char *buf = gfi_unpack_entry(oe, &size); + parse_from_commit(b, buf, size); + free(buf); + } else + parse_from_existing(b); + } } else if (!get_sha1(from, b->sha1)) { parse_from_existing(b); if (is_null_sha1(b->sha1)) @@ -2626,6 +2626,11 @@ static int parse_from(struct branch *b) else die("Invalid ref name or SHA1 expression: %s", from); + if (b->branch_tree.tree && hashcmp(sha1, b->branch_tree.versions[1].sha1)) { + release_tree_content_recursive(b->branch_tree.tree); + b->branch_tree.tree = NULL; + } + read_next_command(); return 1; }
-- 2.4.3.2.gf0a024e.dirty