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[PATCH v3 1/7] negotiator/noop: add noop fetch negotiator

From
JTJonathan Tan <jonathantanmy@google.com>
Date
Aug 18, 2020, 04:01 UTC
Message-ID
<5b3b49d1236756dc65479f7e6c062479f2e19b3c.1597722941.git.jonathantanmy@google.com>
In-Reply-To
<cover.1597722941.git.jonathantanmy@google.com>

Add a noop fetch negotiator. This is introduced to allow partial clones to skip the unneeded negotiation step when fetching missing objects using a "git fetch" subprocess. (The implementation of spawning a "git fetch" subprocess will be done in a subsequent patch.) But this can also be useful for end users, e.g. as a blunt fix for object corruption.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
---
 Documentation/config/fetch.txt   |  5 +++-
 Makefile                         |  1 +
 fetch-negotiator.c               |  5 ++++
 negotiator/noop.c                | 44 ++++++++++++++++++++++++++++++++
 negotiator/noop.h                |  8 ++++++
 repo-settings.c                  |  2 ++
 repository.h                     |  1 +
 t/t5554-noop-fetch-negotiator.sh | 22 ++++++++++++++++
 8 files changed, 87 insertions(+), 1 deletion(-)
 create mode 100644 negotiator/noop.c
 create mode 100644 negotiator/noop.h
 create mode 100755 t/t5554-noop-fetch-negotiator.sh
diff --git a/Documentation/config/fetch.txt b/Documentation/config/fetch.txt
index 0aaa05e8c0..19383ddf7b 100644
--- a/Documentation/config/fetch.txt
+++ b/Documentation/config/fetch.txt
@@ -60,7 +60,10 @@ fetch.negotiationAlgorithm::
 	sent when negotiating the contents of the packfile to be sent by the
 	server. Set to "skipping" to use an algorithm that skips commits in an
 	effort to converge faster, but may result in a larger-than-necessary
-	packfile; The default is "default" which instructs Git to use the default algorithm
+	packfile; or set to "noop" to not send any information at all, which
+	will almost certainly result in a larger-than-necessary packfile, but
+	will skip the negotiation step.
+	The default is "default" which instructs Git to use the default algorithm
 	that never skips commits (unless the server has acknowledged it or one
 	of its descendants). If `feature.experimental` is enabled, then this
 	setting defaults to "skipping".
diff --git a/Makefile b/Makefile
index 372139f1f2..94a8fb54d1 100644
--- a/Makefile
+++ b/Makefile
@@ -917,6 +917,7 @@ LIB_OBJS += mergesort.o
 LIB_OBJS += midx.o
 LIB_OBJS += name-hash.o
 LIB_OBJS += negotiator/default.o
+LIB_OBJS += negotiator/noop.o
 LIB_OBJS += negotiator/skipping.o
 LIB_OBJS += notes-cache.o
 LIB_OBJS += notes-merge.o
diff --git a/fetch-negotiator.c b/fetch-negotiator.c
index 0a1357dc9d..57ed5784e1 100644
--- a/fetch-negotiator.c
+++ b/fetch-negotiator.c
@@ -2,6 +2,7 @@
 #include "fetch-negotiator.h"
 #include "negotiator/default.h"
 #include "negotiator/skipping.h"
+#include "negotiator/noop.h"
 #include "repository.h"
 
 void fetch_negotiator_init(struct repository *r,
@@ -13,6 +14,10 @@ void fetch_negotiator_init(struct repository *r,
 		skipping_negotiator_init(negotiator);
 		return;
 
+	case FETCH_NEGOTIATION_NOOP:
+		noop_negotiator_init(negotiator);
+		return;
+
 	case FETCH_NEGOTIATION_DEFAULT:
 	default:
 		default_negotiator_init(negotiator);
diff --git a/negotiator/noop.c b/negotiator/noop.c
new file mode 100644
index 0000000000..60569b8350
--- /dev/null
+++ b/negotiator/noop.c
@@ -0,0 +1,44 @@
+#include "cache.h"
+#include "noop.h"
+#include "../commit.h"
+#include "../fetch-negotiator.h"
+
+static void known_common(struct fetch_negotiator *n, struct commit *c)
+{
+	/* do nothing */
+}
+
+static void add_tip(struct fetch_negotiator *n, struct commit *c)
+{
+	/* do nothing */
+}
+
+static const struct object_id *next(struct fetch_negotiator *n)
+{
+	return NULL;
+}
+
+static int ack(struct fetch_negotiator *n, struct commit *c)
+{
+	/*
+	 * This negotiator does not emit any commits, so there is no commit to
+	 * be acknowledged. If there is any ack, there is a bug.
+	 */
+	BUG("ack with noop negotiator, which does not emit any commits");
+	return 0;
+}
+
+static void release(struct fetch_negotiator *n)
+{
+	/* nothing to release */
+}
+
+void noop_negotiator_init(struct fetch_negotiator *negotiator)
+{
+	negotiator->known_common = known_common;
+	negotiator->add_tip = add_tip;
+	negotiator->next = next;
+	negotiator->ack = ack;
+	negotiator->release = release;
+	negotiator->data = NULL;
+}
diff --git a/negotiator/noop.h b/negotiator/noop.h
new file mode 100644
index 0000000000..2b4ec5d07a
--- /dev/null
+++ b/negotiator/noop.h
@@ -0,0 +1,8 @@
+#ifndef NEGOTIATOR_NOOP_H
+#define NEGOTIATOR_NOOP_H
+
+struct fetch_negotiator;
+
+void noop_negotiator_init(struct fetch_negotiator *negotiator);
+
+#endif
diff --git a/repo-settings.c b/repo-settings.c
index 0918408b34..aa61a35338 100644
--- a/repo-settings.c
+++ b/repo-settings.c
@@ -39,6 +39,8 @@ void prepare_repo_settings(struct repository *r)
 	if (!repo_config_get_string(r, "fetch.negotiationalgorithm", &strval)) {
 		if (!strcasecmp(strval, "skipping"))
 			r->settings.fetch_negotiation_algorithm = FETCH_NEGOTIATION_SKIPPING;
+		else if (!strcasecmp(strval, "noop"))
+			r->settings.fetch_negotiation_algorithm = FETCH_NEGOTIATION_NOOP;
 		else
 			r->settings.fetch_negotiation_algorithm = FETCH_NEGOTIATION_DEFAULT;
 	}
diff --git a/repository.h b/repository.h
index 3c1f7d54bd..628c834367 100644
--- a/repository.h
+++ b/repository.h
@@ -23,6 +23,7 @@ enum fetch_negotiation_setting {
 	FETCH_NEGOTIATION_NONE = 0,
 	FETCH_NEGOTIATION_DEFAULT = 1,
 	FETCH_NEGOTIATION_SKIPPING = 2,
+	FETCH_NEGOTIATION_NOOP = 3,
 };
 
 struct repo_settings {
diff --git a/t/t5554-noop-fetch-negotiator.sh b/t/t5554-noop-fetch-negotiator.sh
new file mode 100755
index 0000000000..2ac7b5859e
--- /dev/null
+++ b/t/t5554-noop-fetch-negotiator.sh
@@ -0,0 +1,22 @@
+#!/bin/sh
+
+test_description='test noop fetch negotiator'
+. ./test-lib.sh
+
+test_expect_success 'noop negotiator does not emit any "have"' '
+	rm -f trace &&
+
+	test_create_repo server &&
+	test_commit -C server to_fetch &&
+
+	test_create_repo client &&
+	test_commit -C client we_have &&
+
+	test_config -C client fetch.negotiationalgorithm noop &&
+	GIT_TRACE_PACKET="$(pwd)/trace" git -C client fetch "$(pwd)/server" &&
+
+	! grep "fetch> have" trace &&
+	grep "fetch> done" trace
+'
+
+test_done

-- 
2.28.0.220.ged08abb693-goog
Previous: Jonathan TanNext: Jonathan Tan
Message 47 of 57 in “Modify fetch-pack to no longer die on error?”
  1. Modify fetch-pack to no longer die on error?Jonathan Tan, Jul 24, 2020
  2. Junio C HamanoJul 24, 2020
  3. Junio C HamanoJul 24, 2020
  4. Jeff KingJul 25, 2020
  5. Junio C HamanoJul 25, 2020
  6. Jeff KingJul 27, 2020
  7. Jonathan TanJul 28, 2020
  8. Jeff KingJul 28, 2020
  9. Jonathan TanJul 29, 2020
  10. Jeff KingJul 29, 2020
  11. Junio C HamanoJul 29, 2020
  12. Jonathan TanJul 29, 2020
  13. 0/7 Lazy fetch with subprocessJonathan Tan, Aug 5, 2020
  14. 1/7 fetch-pack: allow NULL negotiator->add_tipJonathan Tan, Aug 5, 2020
  15. Junio C HamanoAug 5, 2020
  16. Jonathan TanAug 7, 2020
  17. 3/7 negotiator/null: add null fetch negotiatorJonathan Tan, Aug 5, 2020
  18. 2/7 fetch-pack: allow NULL negotiator->known_commonJonathan Tan, Aug 5, 2020
  19. Junio C HamanoAug 5, 2020
  20. Junio C HamanoAug 5, 2020
  21. Jonathan TanAug 7, 2020
  22. 4/7 fetch: --stdinJonathan Tan, Aug 5, 2020
  23. Junio C HamanoAug 5, 2020
  24. Jonathan TanAug 7, 2020
  25. Junio C HamanoAug 7, 2020
  26. Jonathan TanAug 7, 2020
  27. 5/7 fetch: submodule configJonathan Tan, Aug 5, 2020
  28. 7/7 promisor-remote: use subprocess to fetchJonathan Tan, Aug 5, 2020
  29. 6/7 fetch: only populate existing_refs if neededJonathan Tan, Aug 5, 2020
  30. 0/7 Lazy fetch with subprocessJonathan Tan, Aug 11, 2020
  31. 1/7 negotiator/null: add null fetch negotiatorJonathan Tan, Aug 11, 2020
  32. Derrick StoleeAug 12, 2020
  33. Junio C HamanoAug 12, 2020
  34. Jonathan TanAug 12, 2020
  35. 2/7 fetch: allow refspecs specified through stdinJonathan Tan, Aug 11, 2020
  36. 3/7 fetch: avoid reading submodule config until neededJonathan Tan, Aug 11, 2020
  37. Junio C HamanoAug 12, 2020
  38. 4/7 fetch: only populate existing_refs if neededJonathan Tan, Aug 11, 2020
  39. Junio C HamanoAug 12, 2020
  40. 5/7 fetch-pack: do not lazy-fetch during ref iterationJonathan Tan, Aug 11, 2020
  41. Junio C HamanoAug 12, 2020
  42. 6/7 promisor-remote: lazy-fetch objects in subprocessJonathan Tan, Aug 11, 2020
  43. Junio C HamanoAug 12, 2020
  44. 7/7 fetch-pack: remove no_dependents codeJonathan Tan, Aug 11, 2020
  45. Derrick StoleeAug 12, 2020
  46. 0/7 Lazy fetch with subprocessJonathan Tan, Aug 18, 2020
  47. 1/7 negotiator/noop: add noop fetch negotiatorJonathan Tan, Aug 18, 2020
  48. 2/7 fetch: allow refspecs specified through stdinJonathan Tan, Aug 18, 2020
  49. 4/7 fetch: only populate existing_refs if neededJonathan Tan, Aug 18, 2020
  50. 5/7 fetch-pack: do not lazy-fetch during ref iterationJonathan Tan, Aug 18, 2020
  51. 3/7 fetch: avoid reading submodule config until neededJonathan Tan, Aug 18, 2020
  52. 6/7 promisor-remote: lazy-fetch objects in subprocessJonathan Tan, Aug 18, 2020
  53. 7/7 fetch-pack: remove no_dependents codeJonathan Tan, Aug 18, 2020
  54. Junio C HamanoAug 18, 2020
  55. Junio C HamanoAug 18, 2020
  56. fixup! promisor-remote: lazy-fetch objects in subprocessJonathan Tan, Aug 18, 2020
  57. Junio C HamanoAug 18, 2020

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