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[PATCH 21/31] refs.c allow multiple updates of the same ref in a transaction

From
Ronnie Sahlberg <sahlberg@google.com>
Date
May 14, 2014, 22:13 UTC
Message-ID
<1400105610-21194-22-git-send-email-sahlberg@google.com>
In-Reply-To
<1400105610-21194-1-git-send-email-sahlberg@google.com>

Allow multiple updates of a ref in the same transaction as long as each update has have_old and old_sha1 matches the new_sha1 of the previous update.

Add a test that verifies that a valid sequence such as
  create ref a
  update ref b a
  update ref c b
works and a test that an invalid sequence such as this still fails:
  update ref a c
  update ref b b
  update ref c c
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
---
 refs.c                | 23 +++++++++++++++++------
 t/t1400-update-ref.sh | 23 +++++++++++++++++++++--
 2 files changed, 38 insertions(+), 8 deletions(-)
diff --git a/refs.c b/refs.c
index 76cab6e..87cdd91 100644
--- a/refs.c
+++ b/refs.c
@@ -3455,12 +3455,6 @@ int transaction_update_sha1(struct ref_transaction *transaction,
 	if (update->lock)
 		return 0;
 
-	/* If we could not lock the ref it means we either collided with a
-	   different command or that we tried to perform a second update to
-	   the same ref from within the same transaction.
-	*/
-	transaction->status = REF_TRANSACTION_ERROR;
-
 	/* -1 is the update we just added. Start at -2 and find the most recent
 	   previous update for this ref.
 	*/
@@ -3472,6 +3466,23 @@ int transaction_update_sha1(struct ref_transaction *transaction,
 			    update->refname))
 			break;
 	}
+	/* If the current update has_old==1 and old_sha1 matches the new_sha1
+	 * of the previous update then merge the two updates into one.
+	 */
+	if (i >= 0 && update->have_old && !hashcmp(update->old_sha1,
+			   transaction->updates[i]->new_sha1)) {
+		hashcpy(transaction->updates[i]->new_sha1, update->new_sha1);
+		transaction->nr--;
+		free((char *)transaction->updates[transaction->nr]->msg);
+		free(transaction->updates[transaction->nr]);
+		return 0;
+	}
+	/* If we could not lock the ref it means we either collided with a
+	   different command or that we tried to perform a second update to
+	   the same ref from within the same transaction.
+	*/
+	transaction->status = REF_TRANSACTION_ERROR;
+
 	if (err)
 		if (i >= 0) {
 			const char *str =
diff --git a/t/t1400-update-ref.sh b/t/t1400-update-ref.sh
index f9b7bef..078cd4b 100755
--- a/t/t1400-update-ref.sh
+++ b/t/t1400-update-ref.sh
@@ -446,7 +446,7 @@ test_expect_success 'stdin fails option with unknown name' '
 	grep "fatal: option unknown: unknown" err
 '
 
-test_expect_success 'stdin fails with duplicate refs' '
+test_expect_success 'stdin fails with duplicate create refs' '
 	cat >stdin <<-EOF &&
 	create $a $m
 	create $b $m
@@ -464,6 +464,25 @@ test_expect_success 'stdin create ref works' '
 	test_cmp expect actual
 '
 
+test_expect_success 'stdin succeeds with correctly chained update refs' '
+	cat >stdin <<-EOF &&
+	update $a $A $m
+	update $a $B $A
+	update $a $C $B
+	EOF
+	git update-ref --stdin <stdin
+'
+
+test_expect_success 'stdin fails with incorrectly chained update refs' '
+	cat >stdin <<-EOF &&
+	update $a $A $C
+	update $a $B $B
+	update $a $B $B
+	EOF
+	test_must_fail git update-ref --stdin <stdin &&
+	grep "fatal: Multiple updates for ref '"'"'$a'"'"' not allowed." err
+'
+
 test_expect_success 'stdin succeeds with quoted argument' '
 	git update-ref -d $a &&
 	echo "create $a \"$m\"" >stdin &&
@@ -786,7 +805,7 @@ test_expect_success 'stdin -z fails option with unknown name' '
 	grep "fatal: option unknown: unknown" err
 '
 
-test_expect_success 'stdin -z fails with duplicate refs' '
+test_expect_success 'stdin -z fails with duplicate create refs' '
 	printf $F "create $a" "$m" "create $b" "$m" "create $a" "$m" >stdin &&
 	test_must_fail git update-ref -z --stdin <stdin 2>err &&
 	grep "fatal: Multiple updates for ref '"'"'$a'"'"' not allowed." err

-- 
2.0.0.rc3.506.g3739a35
Previous: Ronnie SahlbergNext: Ronnie Sahlberg
Message 33 of 43 in “Finish implementing ref and reflog transactions”
  1. 00/31 Finish implementing ref and reflog transactionsRonnie Sahlberg, May 14, 2014
  2. 01/31 refs.c make ref_transaction_create a wrapper to ref_transaction_updateRonnie Sahlberg, May 14, 2014
  3. 02/31 refs.c: make ref_transaction_delete a wrapper for ref_transaction_updateRonnie Sahlberg, May 14, 2014
  4. 03/31 refs.c: rename the transaction functionsRonnie Sahlberg, May 14, 2014
  5. Junio C HamanoMay 16, 2014
  6. Ronnie SahlbergMay 19, 2014
  7. Junio C HamanoMay 19, 2014
  8. 04/31 refs.c: add a new update_type field to ref_updateRonnie Sahlberg, May 14, 2014
  9. 05/31 refs.c: add a function to append a reflog entry to a fdRonnie Sahlberg, May 14, 2014
  10. 06/31 refs.c: add a transaction function to append a reflog entryRonnie Sahlberg, May 14, 2014
  11. 07/31 refs.c: add a flag to allow reflog updates to truncate the logRonnie Sahlberg, May 14, 2014
  12. Junio C HamanoMay 16, 2014
  13. Ronnie SahlbergMay 19, 2014
  14. 08/31 refs.c: only write reflog update if msg is non-NULLRonnie Sahlberg, May 14, 2014
  15. Junio C HamanoMay 16, 2014
  16. Ronnie SahlbergMay 19, 2014
  17. 09/31 refs.c: allow multiple reflog updates during a single transactionRonnie Sahlberg, May 14, 2014
  18. Junio C HamanoMay 16, 2014
  19. Eric SunshineMay 16, 2014
  20. Ronnie SahlbergMay 19, 2014
  21. Ronnie SahlbergMay 19, 2014
  22. 10/31 reflog.c: use a reflog transaction when writing during expireRonnie Sahlberg, May 14, 2014
  23. 11/31 refs.c: null terminate the string in copy_msgRonnie Sahlberg, May 14, 2014
  24. 12/31 refs.c: track the refnames we are deleting in the transaction structureRonnie Sahlberg, May 14, 2014
  25. 13/31 refs.c: update the list of deleted refs during _update instead of _commitRonnie Sahlberg, May 14, 2014
  26. 14/31 refs.c: return error instead of dying when locking fails during transactionRonnie Sahlberg, May 14, 2014
  27. 15/31 refs.c: lock the ref during _update instead of during _commitRonnie Sahlberg, May 14, 2014
  28. 16/31 refs.c: add an error argument to create/delete/update just like commitRonnie Sahlberg, May 14, 2014
  29. 17/31 refs.c: make _update_reflog take an error argumentRonnie Sahlberg, May 14, 2014
  30. 18/31 refs.c: return immediately from _commit if the transaction has an errorRonnie Sahlberg, May 14, 2014
  31. 19/31 tests: move tests for -z update/delete/verify to after the ref is createdRonnie Sahlberg, May 14, 2014
  32. 20/31 refs.c: check for lock conflicts already in _updateRonnie Sahlberg, May 14, 2014
  33. 21/31 refs.c allow multiple updates of the same ref in a transactionRonnie Sahlberg, May 14, 2014
  34. 22/31 refs.c: release all remaining locks during transaction_freeRonnie Sahlberg, May 14, 2014
  35. 23/31 reflog.c: use the existing transaction to also lock and update the refRonnie Sahlberg, May 14, 2014
  36. 24/31 refs.c: make unlock_ref staticRonnie Sahlberg, May 14, 2014
  37. 25/31 refs.c: make close_ref staticRonnie Sahlberg, May 14, 2014
  38. 26/31 refs.c: make commit_ref staticRonnie Sahlberg, May 14, 2014
  39. 27/31 refs.c: remove the function lock_any_ref_for_updateRonnie Sahlberg, May 14, 2014
  40. 28/31 refs.c: make struct ref_lock private to refs.cRonnie Sahlberg, May 14, 2014
  41. 29/31 refs.c: allow passing raw git_committer_info as email to _update_reflogRonnie Sahlberg, May 14, 2014
  42. 30/31 refs.c: move ref_update and other definitions to earlier in the fileRonnie Sahlberg, May 14, 2014
  43. 31/31 refs.c: use the transaction to manage the reflog in rename_refsRonnie Sahlberg, May 14, 2014

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