git/list[1] front-page[2] threads[3] people[4] search[5] about
 

[RFC PATCH v4 06/26] Add multi_ack_detailed capability to fetch-pack/upload-pack

From
Shawn O. Pearce <spearce@spearce.org>
Date
Oct 29, 2009, 00:00 UTC
Message-ID
<1256774448-7625-7-git-send-email-spearce@spearce.org>
In-Reply-To
<1256774448-7625-1-git-send-email-spearce@spearce.org>

When multi_ack_detailed is enabled the ACK continue messages returned by the remote upload-pack are broken out to describe the different states within the peer. This permits the client to better understand the server's in-memory state.

The fetch-pack/upload-pack protocol now looks like:
NAK
---------------------------------
  Always sent in response to "done" if there was no common base
  selected from the "have" lines (or no have lines were sent).
  * no multi_ack or multi_ack_detailed:
    Sent when the client has sent a pkt-line flush ("0000") and
    the server has not yet found a common base object.
  * either multi_ack or multi_ack_detailed:
    Always sent in response to a pkt-line flush.
ACK %s
-----------------------------------
  * no multi_ack or multi_ack_detailed:
    Sent in response to "have" when the object exists on the remote
    side and is therefore an object in common between the peers.
    The argument is the SHA-1 of the common object.
  * either multi_ack or multi_ack_detailed:
    Sent in response to "done" if there are common objects.
    The argument is the last SHA-1 determined to be common.
ACK %s continue
-----------------------------------
  * multi_ack only:
    Sent in response to "have".
    The remote side wants the client to consider this object as
    common, and immediately stop transmitting additional "have"
    lines for objects that are reachable from it.  The reason
    the client should stop is not given, but is one of the two
    cases below available under multi_ack_detailed.
ACK %s common
-----------------------------------
  * multi_ack_detailed only:
    Sent in response to "have".  Both sides have this object.
    Like with "ACK %s continue" above the client should stop
    sending have lines reachable for objects from the argument.
ACK %s ready
-----------------------------------
  * multi_ack_detailed only:
    Sent in response to "have".
    The client should stop transmitting objects which are reachable
    from the argument, and send "done" soon to get the objects.
    If the remote side has the specified object, it should
    first send an "ACK %s common" message prior to sending
    "ACK %s ready".
    Clients may still submit additional "have" lines if there are
    more side branches for the client to explore that might be added
    to the common set and reduce the number of objects to transfer.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
---
 builtin-fetch-pack.c |   41 ++++++++++++++++++++++++++++++++---------
 upload-pack.c        |   31 ++++++++++++++++++-------------
 2 files changed, 50 insertions(+), 22 deletions(-)
diff --git a/builtin-fetch-pack.c b/builtin-fetch-pack.c
index 7c09d46..615f549 100644
--- a/builtin-fetch-pack.c
+++ b/builtin-fetch-pack.c
@@ -157,7 +157,15 @@ static const unsigned char *get_rev(void)
 	return commit->object.sha1;
 }
 
-static int get_ack(int fd, unsigned char *result_sha1)
+enum ack_type {
+	NAK = 0,
+	ACK,
+	ACK_continue,
+	ACK_common,
+	ACK_ready
+};
+
+static enum ack_type get_ack(int fd, unsigned char *result_sha1)
 {
 	static char line[1000];
 	int len = packet_read_line(fd, line, sizeof(line));
@@ -167,12 +175,16 @@ static int get_ack(int fd, unsigned char *result_sha1)
 	if (line[len-1] == '\n')
 		line[--len] = 0;
 	if (!strcmp(line, "NAK"))
-		return 0;
+		return NAK;
 	if (!prefixcmp(line, "ACK ")) {
 		if (!get_sha1_hex(line+4, result_sha1)) {
 			if (strstr(line+45, "continue"))
-				return 2;
-			return 1;
+				return ACK_continue;
+			if (strstr(line+45, "common"))
+				return ACK_common;
+			if (strstr(line+45, "ready"))
+				return ACK_ready;
+			return ACK;
 		}
 	}
 	die("git fetch_pack: expected ACK/NAK, got '%s'", line);
@@ -218,7 +230,8 @@ static int find_common(int fd[2], unsigned char *result_sha1,
 		remote_hex = sha1_to_hex(remote);
 		if (!fetching) {
 			struct strbuf c = STRBUF_INIT;
-			if (multi_ack)          strbuf_addstr(&c, " multi_ack");
+			if (multi_ack == 2)     strbuf_addstr(&c, " multi_ack_detailed");
+			if (multi_ack == 1)     strbuf_addstr(&c, " multi_ack");
 			if (use_sideband == 2)  strbuf_addstr(&c, " side-band-64k");
 			if (use_sideband == 1)  strbuf_addstr(&c, " side-band");
 			if (args.use_thin_pack) strbuf_addstr(&c, " thin-pack");
@@ -298,18 +311,23 @@ static int find_common(int fd[2], unsigned char *result_sha1,
 				if (args.verbose && ack)
 					fprintf(stderr, "got ack %d %s\n", ack,
 							sha1_to_hex(result_sha1));
-				if (ack == 1) {
+				switch (ack) {
+				case ACK:
 					flushes = 0;
 					multi_ack = 0;
 					retval = 0;
 					goto done;
-				} else if (ack == 2) {
+				case ACK_common:
+				case ACK_ready:
+				case ACK_continue: {
 					struct commit *commit =
 						lookup_commit(result_sha1);
 					mark_common(commit, 0, 1);
 					retval = 0;
 					in_vain = 0;
 					got_continue = 1;
+					break;
+					}
 				}
 			} while (ack);
 			flushes--;
@@ -336,7 +354,7 @@ done:
 			if (args.verbose)
 				fprintf(stderr, "got ack (%d) %s\n", ack,
 					sha1_to_hex(result_sha1));
-			if (ack == 1)
+			if (ack == ACK)
 				return 0;
 			multi_ack = 1;
 			continue;
@@ -618,7 +636,12 @@ static struct ref *do_fetch_pack(int fd[2],
 
 	if (is_repository_shallow() && !server_supports("shallow"))
 		die("Server does not support shallow clients");
-	if (server_supports("multi_ack")) {
+	if (server_supports("multi_ack_detailed")) {
+		if (args.verbose)
+			fprintf(stderr, "Server supports multi_ack_detailed\n");
+		multi_ack = 2;
+	}
+	else if (server_supports("multi_ack")) {
 		if (args.verbose)
 			fprintf(stderr, "Server supports multi_ack\n");
 		multi_ack = 1;
diff --git a/upload-pack.c b/upload-pack.c
index 38ddac2..f1dc3a3 100644
--- a/upload-pack.c
+++ b/upload-pack.c
@@ -498,7 +498,7 @@ static int get_common_commits(void)
 {
 	static char line[1000];
 	unsigned char sha1[20];
-	char hex[41], last_hex[41];
+	char last_hex[41];
 
 	save_commit_buffer = 0;
 
@@ -515,19 +515,22 @@ static int get_common_commits(void)
 		if (!prefixcmp(line, "have ")) {
 			switch (got_sha1(line+5, sha1)) {
 			case -1: /* they have what we do not */
-				if (multi_ack && ok_to_give_up())
-					packet_write(1, "ACK %s continue\n",
-						     sha1_to_hex(sha1));
+				if (multi_ack && ok_to_give_up()) {
+					const char *hex = sha1_to_hex(sha1);
+					if (multi_ack == 2)
+						packet_write(1, "ACK %s ready\n", hex);
+					else
+						packet_write(1, "ACK %s continue\n", hex);
+				}
 				break;
 			default:
-				memcpy(hex, sha1_to_hex(sha1), 41);
-				if (multi_ack) {
-					const char *msg = "ACK %s continue\n";
-					packet_write(1, msg, hex);
-					memcpy(last_hex, hex, 41);
-				}
+				memcpy(last_hex, sha1_to_hex(sha1), 41);
+				if (multi_ack == 2)
+					packet_write(1, "ACK %s common\n", last_hex);
+				else if (multi_ack)
+					packet_write(1, "ACK %s continue\n", last_hex);
 				else if (have_obj.nr == 1)
-					packet_write(1, "ACK %s\n", hex);
+					packet_write(1, "ACK %s\n", last_hex);
 				break;
 			}
 			continue;
@@ -587,7 +590,9 @@ static void receive_needs(void)
 		    get_sha1_hex(line+5, sha1_buf))
 			die("git upload-pack: protocol error, "
 			    "expected to get sha, not '%s'", line);
-		if (strstr(line+45, "multi_ack"))
+		if (strstr(line+45, "multi_ack_detailed"))
+			multi_ack = 2;
+		else if (strstr(line+45, "multi_ack"))
 			multi_ack = 1;
 		if (strstr(line+45, "thin-pack"))
 			use_thin_pack = 1;
@@ -681,7 +686,7 @@ static int send_ref(const char *refname, const unsigned char *sha1, int flag, vo
 {
 	static const char *capabilities = "multi_ack thin-pack side-band"
 		" side-band-64k ofs-delta shallow no-progress"
-		" include-tag";
+		" include-tag multi_ack_detailed";
 	struct object *o = parse_object(sha1);
 
 	if (!o)

-- 
1.6.5.2.181.gd6f41
Previous: Shawn O. PearceNext: Junio C Hamano
Message 18 of 60 in “Return of smart HTTP”
  1. 00/26 Return of smart HTTPShawn O. Pearce, Oct 29, 2009
  2. 01/26 http-push: fix check condition on http.c::finish_http_pack_request()Shawn O. Pearce, Oct 29, 2009
  3. 02/26 pkt-line: Add strbuf based functionsShawn O. Pearce, Oct 29, 2009
  4. 03/26 pkt-line: Make packet_read_line easier to debugShawn O. Pearce, Oct 29, 2009
  5. Junio C HamanoOct 29, 2009
  6. Shawn O. PearceOct 29, 2009
  7. Junio C HamanoOct 29, 2009
  8. Shawn O. PearceOct 29, 2009
  9. Jeff KingOct 30, 2009
  10. Shawn O. PearceOct 30, 2009
  11. Jeff KingOct 30, 2009
  12. David BrownOct 30, 2009
  13. Junio C HamanoOct 30, 2009
  14. 04/26 fetch-pack: Use a strbuf to compose the want listShawn O. Pearce, Oct 29, 2009
  15. 05/26 Move "get_ack()" back to fetch-packShawn O. Pearce, Oct 29, 2009
  16. Junio C HamanoOct 29, 2009
  17. Shawn O. PearceOct 29, 2009
  18. 06/26 Add multi_ack_detailed capability to fetch-pack/upload-packShawn O. Pearce, Oct 29, 2009
  19. Junio C HamanoOct 29, 2009
  20. Shawn O. PearceOct 29, 2009
  21. 07/26 remote-curl: Refactor walker initializationShawn O. Pearce, Oct 29, 2009
  22. 08/26 fetch: Allow transport -v -v -v to set verbosity to 3Shawn O. Pearce, Oct 29, 2009
  23. 09/26 remote-helpers: Fetch more than one ref in a batchShawn O. Pearce, Oct 29, 2009
  24. 10/26 remote-helpers: Support custom transport optionsShawn O. Pearce, Oct 29, 2009
  25. 11/26 Move WebDAV HTTP push under remote-curlShawn O. Pearce, Oct 29, 2009
  26. Tay Ray ChuanOct 30, 2009
  27. Shawn O. PearceOct 31, 2009
  28. Tay Ray ChuanOct 30, 2009
  29. Clemens BuchacherOct 30, 2009
  30. Tay Ray ChuanOct 30, 2009
  31. 12/26 remote-helpers: return successfully if everything up-to-dateShawn O. Pearce, Oct 29, 2009
  32. 13/26 Git-aware CGI to provide dumb HTTP transportShawn O. Pearce, Oct 29, 2009
  33. 14/26 Add stateless RPC options to upload-pack, receive-packShawn O. Pearce, Oct 29, 2009
  34. Junio C HamanoOct 29, 2009
  35. Shawn O. PearceOct 29, 2009
  36. Junio C HamanoOct 29, 2009
  37. Shawn O. PearceOct 30, 2009
  38. 15/26 Smart fetch and push over HTTP: server sideShawn O. Pearce, Oct 29, 2009
  39. 16/26 http-backend: add GIT_PROJECT_ROOT environment varShawn O. Pearce, Oct 29, 2009
  40. 17/26 http-backend: reword some documentationShawn O. Pearce, Oct 29, 2009
  41. 18/26 http-backend: use mod_alias instead of mod_rewriteShawn O. Pearce, Oct 29, 2009
  42. 19/26 http-backend: add example for gitweb on same URLShawn O. Pearce, Oct 29, 2009
  43. 20/26 http-backend: more explict LocationMatchShawn O. Pearce, Oct 29, 2009
  44. 21/26 Discover refs via smart HTTP server when availableShawn O. Pearce, Oct 29, 2009
  45. 22/26 Smart push over HTTP: client sideShawn O. Pearce, Oct 29, 2009
  46. 23/26 Smart fetch over HTTP: client sideShawn O. Pearce, Oct 29, 2009
  47. 24/26 Smart HTTP fetch: gzip requestsShawn O. Pearce, Oct 29, 2009
  48. 25/26 t5540-http-push: remove redundant fetchesShawn O. Pearce, Oct 29, 2009
  49. 26/26 test smart http fetch and pushShawn O. Pearce, Oct 29, 2009
  50. Clemens BuchacherOct 29, 2009
  51. Shawn O. PearceOct 29, 2009
  52. Junio C HamanoOct 29, 2009
  53. Shawn O. PearceOct 29, 2009
  54. Shawn O. PearceOct 29, 2009
  55. Junio C HamanoOct 30, 2009
  56. Shawn O. PearceOct 30, 2009
  57. Tay Ray ChuanOct 30, 2009
  58. Shawn O. PearceOct 31, 2009
  59. Jakub NarebskiOct 29, 2009
  60. Shawn O. PearceOct 29, 2009

Read the whole thread, see it on lore, or plain text.

$ cat FOOTERMessages come from the public archive at lore.kernel.org/git, fetched every hour. The front page is chosen and written each morning by an AI editor and can be wrong; the threads themselves are the record. About and API. For agents: an MCP server at https://gitlist.dev/mcp, and any thread, story or person page as Markdown by adding .md to its URL (or sending Accept: text/markdown). Details in /llms.txt.