From: Junio C Hamano <gitster@pobox.com>
Date: Mon, 3 Aug 2015 18:01:24 +0000 (-0700)
Subject: Merge branch 'mh/fast-import-optimize-current-from'
X-Git-Tag: v2.6.0-rc0~96
X-Git-Url: https://git.lorimer.id.au/gitweb.git/diff_plain/3ecca8879a07889884dcdc90066c76c4e948856a?hp=-c

Merge branch 'mh/fast-import-optimize-current-from'

Often a fast-import stream builds a new commit on top of the
previous commit it built, and it often unconditionally emits a
"from" command to specify the first parent, which can be omitted in
such a case.  This caused fast-import to forget the tree of the
previous commit and then re-read it from scratch, which was
inefficient.  Optimize for this common case.

* mh/fast-import-optimize-current-from:
fast-import: do less work when given "from" matches current branch head
---

3ecca8879a07889884dcdc90066c76c4e948856a
diff --combined fast-import.c
index 9d949d1f77,ece0096623..6a0c0ac570
--- a/fast-import.c
+++ b/fast-import.c
@@@ -134,17 -134,16 +134,17 @@@ Format of STDIN stream
    ts    ::= # time since the epoch in seconds, ascii base10 notation;
    tz    ::= # GIT style timezone;
  
 -     # note: comments, ls and cat requests may appear anywhere
 -     # in the input, except within a data command.  Any form
 -     # of the data command always escapes the related input
 -     # from comment processing.
 +     # note: comments, get-mark, ls-tree, and cat-blob requests may
 +     # appear anywhere in the input, except within a data command. Any
 +     # form of the data command always escapes the related input from
 +     # comment processing.
       #
       # In case it is not clear, the '#' that starts the comment
       # must be the first character on that line (an lf
       # preceded it).
       #
  
 +  get_mark ::= 'get-mark' sp idnum lf;
    cat_blob ::= 'cat-blob' sp (hexsha1 | idnum) lf;
    ls_tree  ::= 'ls' sp (hexsha1 | idnum) sp path_str lf;
  
@@@ -373,7 -372,6 +373,7 @@@ static volatile sig_atomic_t checkpoint
  static int cat_blob_fd = STDOUT_FILENO;
  
  static void parse_argv(void);
 +static void parse_get_mark(const char *p);
  static void parse_cat_blob(const char *p);
  static void parse_ls(const char *p, struct branch *b);
  
@@@ -1694,13 -1692,13 +1694,13 @@@ static int update_branch(struct branch 
  	unsigned char old_sha1[20];
  	struct strbuf err = STRBUF_INIT;
  
 -	if (read_ref(b->name, old_sha1))
 -		hashclr(old_sha1);
  	if (is_null_sha1(b->sha1)) {
  		if (b->delete)
 -			delete_ref(b->name, old_sha1, 0);
 +			delete_ref(b->name, NULL, 0);
  		return 0;
  	}
 +	if (read_ref(b->name, old_sha1))
 +		hashclr(old_sha1);
  	if (!force_update && !is_null_sha1(old_sha1)) {
  		struct commit *old_cmit, *new_cmit;
  
@@@ -1909,10 -1907,6 +1909,10 @@@ static int read_next_command(void
  			rc->prev->next = rc;
  			cmd_tail = rc;
  		}
 +		if (skip_prefix(command_buf.buf, "get-mark ", &p)) {
 +			parse_get_mark(p);
 +			continue;
 +		}
  		if (skip_prefix(command_buf.buf, "cat-blob ", &p)) {
  			parse_cat_blob(p);
  			continue;
@@@ -2594,14 -2588,12 +2594,12 @@@ 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)
@@@ -2616,14 -2608,16 +2614,16 @@@
  		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))
@@@ -2632,6 -2626,11 +2632,11 @@@
  	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;
  }
@@@ -2925,23 -2924,6 +2930,23 @@@ static void cat_blob(struct object_entr
  		free(buf);
  }
  
 +static void parse_get_mark(const char *p)
 +{
 +	struct object_entry *oe = oe;
 +	char output[42];
 +
 +	/* get-mark SP <object> LF */
 +	if (*p != ':')
 +		die("Not a mark: %s", p);
 +
 +	oe = find_mark(parse_mark_ref_eol(p));
 +	if (!oe)
 +		die("Unknown mark: %s", command_buf.buf);
 +
 +	snprintf(output, sizeof(output), "%s\n", sha1_to_hex(oe->idx.sha1));
 +	cat_blob_write(output, 41);
 +}
 +
  static void parse_cat_blob(const char *p)
  {
  	struct object_entry *oe = oe;
@@@ -3263,8 -3245,6 +3268,8 @@@ static int parse_one_feature(const cha
  		option_import_marks(arg, from_stream, 1);
  	} else if (skip_prefix(feature, "export-marks=", &arg)) {
  		option_export_marks(arg);
 +	} else if (!strcmp(feature, "get-mark")) {
 +		; /* Don't die - this feature is supported */
  	} else if (!strcmp(feature, "cat-blob")) {
  		; /* Don't die - this feature is supported */
  	} else if (!strcmp(feature, "relative-marks")) {