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[PATCH v3 10/11] bundle-uri: store fetch.bundleCreationToken

From
Derrick Stolee via GitGitGadget <gitgitgadget@gmail.com>
Date
Jan 31, 2023, 13:29 UTC
Message-ID
<4e0465efd19798e7a14d653440233b9b3319b6de.1675171760.git.gitgitgadget@gmail.com>
In-Reply-To
<pull.1454.v3.git.1675171759.gitgitgadget@gmail.com>
From: Derrick Stolee <derrickstolee@github.com>

When a bundle list specifies the "creationToken" heuristic, the Git client downloads the list and then starts downloading bundles in descending creationToken order. This process stops as soon as all downloaded bundles can be applied to the repository (because all required commits are present in the repository or in the downloaded bundles).

When checking the same bundle list twice, this strategy requires downloading the bundle with the maximum creationToken again, which is wasteful. The creationToken heuristic promises that the client will not have a use for that bundle if its creationToken value is at most the previous creationToken value.

To prevent these wasteful downloads, create a fetch.bundleCreationToken config setting that the Git client sets after downloading bundles. This value allows skipping that maximum bundle download when this config value is the same value (or larger).

To test that this works correctly, we can insert some "duplicate" fetches into existing tests and demonstrate that only the bundle list is downloaded.

The previous logic for downloading bundles by creationToken worked even if the bundle list was empty, but now we have logic that depends on the first entry of the list. Terminate early in the (non-sensical) case of an empty bundle list.

Signed-off-by: Derrick Stolee <derrickstolee@github.com>
---
 Documentation/config/fetch.txt | 16 ++++++++++++
 bundle-uri.c                   | 48 ++++++++++++++++++++++++++++++++--
 t/t5558-clone-bundle-uri.sh    | 29 +++++++++++++++++++-
 3 files changed, 90 insertions(+), 3 deletions(-)
diff --git a/Documentation/config/fetch.txt b/Documentation/config/fetch.txt
index 244f44d460f..568f0f75b30 100644
--- a/Documentation/config/fetch.txt
+++ b/Documentation/config/fetch.txt
@@ -104,3 +104,19 @@ fetch.bundleURI::
 	linkgit:git-clone[1]. `git clone --bundle-uri` will set the
 	`fetch.bundleURI` value if the supplied bundle URI contains a bundle
 	list that is organized for incremental fetches.
++
+If you modify this value and your repository has a `fetch.bundleCreationToken`
+value, then remove that `fetch.bundleCreationToken` value before fetching from
+the new bundle URI.
+
+fetch.bundleCreationToken::
+	When using `fetch.bundleURI` to fetch incrementally from a bundle
+	list that uses the "creationToken" heuristic, this config value
+	stores the maximum `creationToken` value of the downloaded bundles.
+	This value is used to prevent downloading bundles in the future
+	if the advertised `creationToken` is not strictly larger than this
+	value.
++
+The creation token values are chosen by the provider serving the specific
+bundle URI. If you modify the URI at `fetch.bundleURI`, then be sure to
+remove the value for the `fetch.bundleCreationToken` value before fetching.
diff --git a/bundle-uri.c b/bundle-uri.c
index 7a1b6d94bf5..d6f7df7350f 100644
--- a/bundle-uri.c
+++ b/bundle-uri.c
@@ -481,6 +481,8 @@ static int fetch_bundles_by_token(struct repository *r,
 {
 	int cur;
 	int move_direction = 0;
+	const char *creationTokenStr;
+	uint64_t maxCreationToken = 0, newMaxCreationToken = 0;
 	struct bundle_list_context ctx = {
 		.r = r,
 		.list = list,
@@ -494,8 +496,27 @@ static int fetch_bundles_by_token(struct repository *r,
 
 	for_all_bundles_in_list(list, append_bundle, &bundles);
 
+	if (!bundles.nr) {
+		free(bundles.items);
+		return 0;
+	}
+
 	QSORT(bundles.items, bundles.nr, compare_creation_token_decreasing);
 
+	/*
+	 * If fetch.bundleCreationToken exists, parses to a uint64t, and
+	 * is not strictly smaller than the maximum creation token in the
+	 * bundle list, then do not download any bundles.
+	 */
+	if (!repo_config_get_value(r,
+				   "fetch.bundlecreationtoken",
+				   &creationTokenStr) &&
+	    sscanf(creationTokenStr, "%"PRIu64, &maxCreationToken) == 1 &&
+	    bundles.items[0]->creationToken <= maxCreationToken) {
+		free(bundles.items);
+		return 0;
+	}
+
 	/*
 	 * Attempt to download and unbundle the minimum number of bundles by
 	 * creationToken in decreasing order. If we fail to unbundle (after
@@ -516,6 +537,16 @@ static int fetch_bundles_by_token(struct repository *r,
 	cur = 0;
 	while (cur >= 0 && cur < bundles.nr) {
 		struct remote_bundle_info *bundle = bundles.items[cur];
+
+		/*
+		 * If we need to dig into bundles below the previous
+		 * creation token value, then likely we are in an erroneous
+		 * state due to missing or invalid bundles. Halt the process
+		 * instead of continuing to download extra data.
+		 */
+		if (bundle->creationToken <= maxCreationToken)
+			break;
+
 		if (!bundle->file) {
 			/*
 			 * Not downloaded yet. Try downloading.
@@ -555,6 +586,9 @@ static int fetch_bundles_by_token(struct repository *r,
 				 */
 				move_direction = -1;
 				bundle->unbundled = 1;
+
+				if (bundle->creationToken > newMaxCreationToken)
+					newMaxCreationToken = bundle->creationToken;
 			}
 		}
 
@@ -569,14 +603,24 @@ move:
 		cur += move_direction;
 	}
 
-	free(bundles.items);
-
 	/*
 	 * We succeed if the loop terminates because 'cur' drops below
 	 * zero. The other case is that we terminate because 'cur'
 	 * reaches the end of the list, so we have a failure no matter
 	 * which bundles we apply from the list.
 	 */
+	if (cur < 0) {
+		struct strbuf value = STRBUF_INIT;
+		strbuf_addf(&value, "%"PRIu64"", newMaxCreationToken);
+		if (repo_config_set_multivar_gently(ctx.r,
+						    "fetch.bundleCreationToken",
+						    value.buf, NULL, 0))
+			warning(_("failed to store maximum creation token"));
+
+		strbuf_release(&value);
+	}
+
+	free(bundles.items);
 	return cur >= 0;
 }
 
diff --git a/t/t5558-clone-bundle-uri.sh b/t/t5558-clone-bundle-uri.sh
index 7deeb4b8ad1..9c2b7934b9b 100755
--- a/t/t5558-clone-bundle-uri.sh
+++ b/t/t5558-clone-bundle-uri.sh
@@ -433,6 +433,7 @@ test_expect_success 'clone incomplete bundle list (http, creationToken)' '
 		"$HTTPD_URL/smart/fetch.git" clone-token-http &&
 
 	test_cmp_config -C clone-token-http "$HTTPD_URL/bundle-list" fetch.bundleuri &&
+	test_cmp_config -C clone-token-http 1 fetch.bundlecreationtoken &&
 
 	cat >expect <<-EOF &&
 	$HTTPD_URL/bundle-list
@@ -468,6 +469,7 @@ test_expect_success 'clone incomplete bundle list (http, creationToken)' '
 	GIT_TRACE2_EVENT="$(pwd)/trace1.txt" \
 		git -C clone-token-http fetch origin --no-tags \
 		refs/heads/merge:refs/heads/merge &&
+	test_cmp_config -C clone-token-http 4 fetch.bundlecreationtoken &&
 
 	cat >expect <<-EOF &&
 	$HTTPD_URL/bundle-list
@@ -511,6 +513,7 @@ test_expect_success 'http clone with bundle.heuristic creates fetch.bundleURI' '
 		"$HTTPD_URL/smart/fetch.git" fetch-http-4 &&
 
 	test_cmp_config -C fetch-http-4 "$HTTPD_URL/bundle-list" fetch.bundleuri &&
+	test_cmp_config -C fetch-http-4 1 fetch.bundlecreationtoken &&
 
 	cat >expect <<-EOF &&
 	$HTTPD_URL/bundle-list
@@ -538,6 +541,7 @@ test_expect_success 'http clone with bundle.heuristic creates fetch.bundleURI' '
 		git -C fetch-http-4 fetch origin --no-tags \
 		refs/heads/left:refs/heads/left \
 		refs/heads/right:refs/heads/right &&
+	test_cmp_config -C fetch-http-4 2 fetch.bundlecreationtoken &&
 
 	cat >expect <<-EOF &&
 	$HTTPD_URL/bundle-list
@@ -555,6 +559,18 @@ test_expect_success 'http clone with bundle.heuristic creates fetch.bundleURI' '
 	EOF
 	test_cmp expect refs &&
 
+	# No-op fetch
+	GIT_TRACE2_EVENT="$(pwd)/trace1b.txt" \
+		git -C fetch-http-4 fetch origin --no-tags \
+		refs/heads/left:refs/heads/left \
+		refs/heads/right:refs/heads/right &&
+
+	cat >expect <<-EOF &&
+	$HTTPD_URL/bundle-list
+	EOF
+	test_remote_https_urls <trace1b.txt >actual &&
+	test_cmp expect actual &&
+
 	cat >>"$HTTPD_DOCUMENT_ROOT_PATH/bundle-list" <<-EOF &&
 	[bundle "bundle-3"]
 		uri = bundle-3.bundle
@@ -570,6 +586,7 @@ test_expect_success 'http clone with bundle.heuristic creates fetch.bundleURI' '
 	GIT_TRACE2_EVENT="$(pwd)/trace2.txt" \
 		git -C fetch-http-4 fetch origin --no-tags \
 		refs/heads/merge:refs/heads/merge &&
+	test_cmp_config -C fetch-http-4 4 fetch.bundlecreationtoken &&
 
 	cat >expect <<-EOF &&
 	$HTTPD_URL/bundle-list
@@ -588,7 +605,17 @@ test_expect_success 'http clone with bundle.heuristic creates fetch.bundleURI' '
 	refs/bundles/left
 	refs/bundles/merge
 	EOF
-	test_cmp expect refs
+	test_cmp expect refs &&
+
+	# No-op fetch
+	GIT_TRACE2_EVENT="$(pwd)/trace2b.txt" \
+		git -C fetch-http-4 fetch origin &&
+
+	cat >expect <<-EOF &&
+	$HTTPD_URL/bundle-list
+	EOF
+	test_remote_https_urls <trace2b.txt >actual &&
+	test_cmp expect actual
 '
 
 # Do not add tests here unless they use the HTTP server, as they will

-- 
gitgitgadget
Previous: Derrick Stolee via GitGitGadgetNext: Junio C Hamano
Message 78 of 79 in “Bundle URIs V: creationToken heuristic for incremental fetches”
  1. 0/8 Bundle URIs V: creationToken heuristic for incremental fetchesDerrick Stolee via GitGitGadget, Jan 6, 2023
  2. 2/8 bundle-uri: parse bundle.heuristic=creationTokenDerrick Stolee via GitGitGadget, Jan 6, 2023
  3. Junio C HamanoJan 9, 2023
  4. Derrick StoleeJan 9, 2023
  5. Victoria DyeJan 17, 2023
  6. 1/8 t5558: add tests for creationToken heuristicDerrick Stolee via GitGitGadget, Jan 6, 2023
  7. Victoria DyeJan 17, 2023
  8. Derrick StoleeJan 17, 2023
  9. 6/8 bundle-uri: drop bundle.flag from design docDerrick Stolee via GitGitGadget, Jan 6, 2023
  10. Victoria DyeJan 19, 2023
  11. 5/8 clone: set fetch.bundleURI if appropriateDerrick Stolee via GitGitGadget, Jan 6, 2023
  12. Victoria DyeJan 19, 2023
  13. Derrick StoleeJan 20, 2023
  14. 7/8 fetch: fetch from an external bundle URIDerrick Stolee via GitGitGadget, Jan 6, 2023
  15. Victoria DyeJan 19, 2023
  16. Derrick StoleeJan 20, 2023
  17. 4/8 bundle-uri: download in creationToken orderDerrick Stolee via GitGitGadget, Jan 6, 2023
  18. Junio C HamanoJan 9, 2023
  19. Derrick StoleeJan 9, 2023
  20. Victoria DyeJan 19, 2023
  21. Derrick StoleeJan 20, 2023
  22. 8/8 bundle-uri: store fetch.bundleCreationTokenDerrick Stolee via GitGitGadget, Jan 6, 2023
  23. Victoria DyeJan 19, 2023
  24. Derrick StoleeJan 20, 2023
  25. 3/8 bundle-uri: parse bundle.<id>.creationToken valuesDerrick Stolee via GitGitGadget, Jan 6, 2023
  26. Junio C HamanoJan 9, 2023
  27. Derrick StoleeJan 9, 2023
  28. Victoria DyeJan 17, 2023
  29. 00/10 Bundle URIs V: creationToken heuristic for incremental fetchesDerrick Stolee via GitGitGadget, Jan 23, 2023
  30. 01/10 bundle: optionally skip reachability walkDerrick Stolee via GitGitGadget, Jan 23, 2023
  31. Junio C HamanoJan 23, 2023
  32. Derrick StoleeJan 23, 2023
  33. Junio C HamanoJan 23, 2023
  34. Junio C HamanoJan 23, 2023
  35. Derrick StoleeJan 24, 2023
  36. 01/11 bundle: test unbundling with incomplete historyDerrick Stolee, Jan 24, 2023
  37. Junio C HamanoJan 24, 2023
  38. 02/11 bundle: verify using connected()Derrick Stolee, Jan 24, 2023
  39. Junio C HamanoJan 24, 2023
  40. Derrick StoleeJan 24, 2023
  41. Junio C HamanoJan 24, 2023
  42. Junio C HamanoJan 24, 2023
  43. Junio C HamanoJan 23, 2023
  44. 02/10 t5558: add tests for creationToken heuristicDerrick Stolee via GitGitGadget, Jan 23, 2023
  45. Victoria DyeJan 27, 2023
  46. 04/10 bundle-uri: parse bundle.<id>.creationToken valuesDerrick Stolee via GitGitGadget, Jan 23, 2023
  47. 03/10 bundle-uri: parse bundle.heuristic=creationTokenDerrick Stolee via GitGitGadget, Jan 23, 2023
  48. 05/10 bundle-uri: download in creationToken orderDerrick Stolee via GitGitGadget, Jan 23, 2023
  49. Victoria DyeJan 27, 2023
  50. Junio C HamanoJan 27, 2023
  51. Derrick StoleeJan 30, 2023
  52. Junio C HamanoJan 30, 2023
  53. Derrick StoleeJan 30, 2023
  54. 06/10 clone: set fetch.bundleURI if appropriateDerrick Stolee via GitGitGadget, Jan 23, 2023
  55. 07/10 bundle-uri: drop bundle.flag from design docDerrick Stolee via GitGitGadget, Jan 23, 2023
  56. 09/10 bundle-uri: store fetch.bundleCreationTokenDerrick Stolee via GitGitGadget, Jan 23, 2023
  57. 10/10 bundle-uri: test missing bundles with heuristicDerrick Stolee via GitGitGadget, Jan 23, 2023
  58. Victoria DyeJan 27, 2023
  59. Derrick StoleeJan 30, 2023
  60. 08/10 fetch: fetch from an external bundle URIDerrick Stolee via GitGitGadget, Jan 23, 2023
  61. Victoria DyeJan 27, 2023
  62. Victoria DyeJan 27, 2023
  63. 00/11 Bundle URIs V: creationToken heuristic for incremental fetchesDerrick Stolee via GitGitGadget, Jan 31, 2023
  64. 01/11 bundle: test unbundling with incomplete historyDerrick Stolee via GitGitGadget, Jan 31, 2023
  65. 02/11 bundle: verify using check_connected()Derrick Stolee via GitGitGadget, Jan 31, 2023
  66. Junio C HamanoJan 31, 2023
  67. Derrick StoleeJan 31, 2023
  68. Junio C HamanoJan 31, 2023
  69. 03/11 t5558: add tests for creationToken heuristicDerrick Stolee via GitGitGadget, Jan 31, 2023
  70. 04/11 bundle-uri: parse bundle.heuristic=creationTokenDerrick Stolee via GitGitGadget, Jan 31, 2023
  71. 05/11 bundle-uri: parse bundle.<id>.creationToken valuesDerrick Stolee via GitGitGadget, Jan 31, 2023
  72. Junio C HamanoJan 31, 2023
  73. 07/11 clone: set fetch.bundleURI if appropriateDerrick Stolee via GitGitGadget, Jan 31, 2023
  74. 06/11 bundle-uri: download in creationToken orderDerrick Stolee via GitGitGadget, Jan 31, 2023
  75. 08/11 bundle-uri: drop bundle.flag from design docDerrick Stolee via GitGitGadget, Jan 31, 2023
  76. 09/11 fetch: fetch from an external bundle URIDerrick Stolee via GitGitGadget, Jan 31, 2023
  77. 11/11 bundle-uri: test missing bundles with heuristicDerrick Stolee via GitGitGadget, Jan 31, 2023
  78. 10/11 bundle-uri: store fetch.bundleCreationTokenDerrick Stolee via GitGitGadget, Jan 31, 2023
  79. Junio C HamanoJan 31, 2023

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