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[PATCH v16 34/48] walker.c: use ref transaction for ref updates

From
Ronnie Sahlberg <sahlberg@google.com>
Date
Jun 12, 2014, 17:21 UTC
Message-ID
<1402593699-13983-35-git-send-email-sahlberg@google.com>
In-Reply-To
<1402593699-13983-1-git-send-email-sahlberg@google.com>

Switch to using ref transactions in walker_fetch(). As part of the refactoring to use ref transactions we also fix a potential memory leak where in the original code if write_ref_sha1() would fail we would end up returning from the function without free()ing the msg string.

Note that this function is only called when fetching from a remote HTTP repository onto the local (most of the time single-user) repository which likely means that the type of collissions that the previous locking would protect against and cause the fetch to fail for to be even more rare.

Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
---
 walker.c | 59 +++++++++++++++++++++++++++++++++++------------------------
 1 file changed, 35 insertions(+), 24 deletions(-)
diff --git a/walker.c b/walker.c
index 1dd86b8..60d9f9e 100644
--- a/walker.c
+++ b/walker.c
@@ -251,39 +251,36 @@ void walker_targets_free(int targets, char **target, const char **write_ref)
 int walker_fetch(struct walker *walker, int targets, char **target,
 		 const char **write_ref, const char *write_ref_log_details)
 {
-	struct ref_lock **lock = xcalloc(targets, sizeof(struct ref_lock *));
+	struct strbuf ref_name = STRBUF_INIT;
+	struct strbuf err = STRBUF_INIT;
+	struct ref_transaction *transaction = NULL;
 	unsigned char *sha1 = xmalloc(targets * 20);
-	char *msg;
-	int ret;
+	char *msg = NULL;
 	int i;
 
 	save_commit_buffer = 0;
 
-	for (i = 0; i < targets; i++) {
-		if (!write_ref || !write_ref[i])
-			continue;
-
-		lock[i] = lock_ref_sha1(write_ref[i], NULL);
-		if (!lock[i]) {
-			error("Can't lock ref %s", write_ref[i]);
-			goto unlock_and_fail;
+	if (write_ref) {
+		transaction = ref_transaction_begin(&err);
+		if (!transaction) {
+			error("%s", err.buf);
+			goto rollback_and_fail;
 		}
 	}
-
 	if (!walker->get_recover)
 		for_each_ref(mark_complete, NULL);
 
 	for (i = 0; i < targets; i++) {
 		if (interpret_target(walker, target[i], &sha1[20 * i])) {
 			error("Could not interpret response from server '%s' as something to pull", target[i]);
-			goto unlock_and_fail;
+			goto rollback_and_fail;
 		}
 		if (process(walker, lookup_unknown_object(&sha1[20 * i])))
-			goto unlock_and_fail;
+			goto rollback_and_fail;
 	}
 
 	if (loop(walker))
-		goto unlock_and_fail;
+		goto rollback_and_fail;
 
 	if (write_ref_log_details) {
 		msg = xmalloc(strlen(write_ref_log_details) + 12);
@@ -294,19 +291,33 @@ int walker_fetch(struct walker *walker, int targets, char **target,
 	for (i = 0; i < targets; i++) {
 		if (!write_ref || !write_ref[i])
 			continue;
-		ret = write_ref_sha1(lock[i], &sha1[20 * i], msg ? msg : "fetch (unknown)");
-		lock[i] = NULL;
-		if (ret)
-			goto unlock_and_fail;
+		strbuf_reset(&ref_name);
+		strbuf_addf(&ref_name, "refs/%s", write_ref[i]);
+		if (ref_transaction_update(transaction, ref_name.buf,
+					   &sha1[20 * i], NULL, 0, 0,
+					   &err)) {
+			error("%s", err.buf);
+			goto rollback_and_fail;
+		}
+	}
+	if (write_ref) {
+		if (ref_transaction_commit(transaction,
+					   msg ? msg : "fetch (unknown)",
+					   &err)) {
+			error("%s", err.buf);
+			goto rollback_and_fail;
+		}
+		ref_transaction_free(transaction);
 	}
-	free(msg);
 
+	free(msg);
 	return 0;
 
-unlock_and_fail:
-	for (i = 0; i < targets; i++)
-		if (lock[i])
-			unlock_ref(lock[i]);
+rollback_and_fail:
+	ref_transaction_free(transaction);
+	free(msg);
+	strbuf_release(&err);
+	strbuf_release(&ref_name);
 
 	return -1;
 }

-- 
2.0.0.599.g83ced0e
Previous: Ronnie SahlbergNext: Ronnie Sahlberg
Message 35 of 49 in “Use ref transactions”
  1. 00/48 Use ref transactionsRonnie Sahlberg, Jun 12, 2014
  2. 01/48 refs.c: remove ref_transaction_rollbackRonnie Sahlberg, Jun 12, 2014
  3. 02/48 refs.c: ref_transaction_commit should not free the transactionRonnie Sahlberg, Jun 12, 2014
  4. 03/48 refs.c: constify the sha arguments for ref_transaction_create|delete|updateRonnie Sahlberg, Jun 12, 2014
  5. 04/48 refs.c: allow passing NULL to ref_transaction_freeRonnie Sahlberg, Jun 12, 2014
  6. 05/48 refs.c: add a strbuf argument to ref_transaction_commit for error loggingRonnie Sahlberg, Jun 12, 2014
  7. 06/48 lockfile.c: add a new public function unable_to_lock_messageRonnie Sahlberg, Jun 12, 2014
  8. 07/48 lockfile.c: make lock_file return a meaningful errno on failureiRonnie Sahlberg, Jun 12, 2014
  9. 08/48 refs.c: add an err argument to repack_without_refsRonnie Sahlberg, Jun 12, 2014
  10. 09/48 refs.c: make sure log_ref_setup returns a meaningful errnoRonnie Sahlberg, Jun 12, 2014
  11. 10/48 refs.c: verify_lock should set errno to something meaningfulRonnie Sahlberg, Jun 12, 2014
  12. 11/48 refs.c: make remove_empty_directories alwasy set errno to something saneRonnie Sahlberg, Jun 12, 2014
  13. 12/48 refs.c: commit_packed_refs to return a meaningful errno on failureRonnie Sahlberg, Jun 12, 2014
  14. 13/48 refs.c: make resolve_ref_unsafe set errno to something meaningful on errorRonnie Sahlberg, Jun 12, 2014
  15. 14/48 refs.c: log_ref_write should try to return meaningful errnoRonnie Sahlberg, Jun 12, 2014
  16. 15/48 refs.c: make ref_update_reject_duplicates take a strbuf argument for errorsRonnie Sahlberg, Jun 12, 2014
  17. 16/48 refs.c: add an err argument to delete_ref_looseRonnie Sahlberg, Jun 12, 2014
  18. 17/48 refs.c: make update_ref_write update a strbuf on failureRonnie Sahlberg, Jun 12, 2014
  19. 18/48 update-ref: use err argument to get error from ref_transaction_commitRonnie Sahlberg, Jun 12, 2014
  20. 19/48 refs.c: remove the onerr argument to ref_transaction_commitRonnie Sahlberg, Jun 12, 2014
  21. 20/48 refs.c: change ref_transaction_update() to do error checking and return statusRonnie Sahlberg, Jun 12, 2014
  22. 21/48 refs.c: change ref_transaction_create to do error checking and return statusRonnie Sahlberg, Jun 12, 2014
  23. 22/48 refs.c: update ref_transaction_delete to check for error and return statusRonnie Sahlberg, Jun 12, 2014
  24. 23/48 refs.c: make ref_transaction_begin take an err argumentRonnie Sahlberg, Jun 12, 2014
  25. 24/48 refs.c: add transaction.status and track OPEN/CLOSED/ERRORRonnie Sahlberg, Jun 12, 2014
  26. 25/48 tag.c: use ref transactions when doing updatesRonnie Sahlberg, Jun 12, 2014
  27. 26/48 replace.c: use the ref transaction functions for updatesRonnie Sahlberg, Jun 12, 2014
  28. 27/48 commit.c: use ref transactions for updatesRonnie Sahlberg, Jun 12, 2014
  29. 28/48 sequencer.c: use ref transactions for all ref updatesRonnie Sahlberg, Jun 12, 2014
  30. 29/48 fast-import.c: change update_branch to use ref transactionsRonnie Sahlberg, Jun 12, 2014
  31. 30/48 branch.c: use ref transaction for all ref updatesRonnie Sahlberg, Jun 12, 2014
  32. 31/48 refs.c: change update_ref to use a transactionRonnie Sahlberg, Jun 12, 2014
  33. 32/48 receive-pack.c: use a reference transaction for updating the refsRonnie Sahlberg, Jun 12, 2014
  34. 33/48 fast-import.c: use a ref transaction when dumping tagsRonnie Sahlberg, Jun 12, 2014
  35. 34/48 walker.c: use ref transaction for ref updatesRonnie Sahlberg, Jun 12, 2014
  36. 35/48 refs.c: make lock_ref_sha1 staticRonnie Sahlberg, Jun 12, 2014
  37. 36/48 refs.c: remove the update_ref_lock functionRonnie Sahlberg, Jun 12, 2014
  38. 37/48 refs.c: remove the update_ref_write functionRonnie Sahlberg, Jun 12, 2014
  39. 38/48 refs.c: remove lock_ref_sha1Ronnie Sahlberg, Jun 12, 2014
  40. 39/48 refs.c: make prune_ref use a transaction to delete the refRonnie Sahlberg, Jun 12, 2014
  41. 40/48 refs.c: make delete_ref use a transactionRonnie Sahlberg, Jun 12, 2014
  42. 41/48 refs.c: pass the ref log message to _create/delete/update instead of _commitRonnie Sahlberg, Jun 12, 2014
  43. 42/48 refs.c: pass NULL as *flags to read_ref_fullRonnie Sahlberg, Jun 12, 2014
  44. 43/48 refs.c: move the check for valid refname to lock_ref_sha1_basicRonnie Sahlberg, Jun 12, 2014
  45. 44/48 refs.c: call lock_ref_sha1_basic directly from commitRonnie Sahlberg, Jun 12, 2014
  46. 45/48 refs.c: pass a skip list to name_conflict_fnRonnie Sahlberg, Jun 12, 2014
  47. 46/48 refs.c: propagate any errno==ENOTDIR from _commit back to the callersRonnie Sahlberg, Jun 12, 2014
  48. 47/48 fetch.c: change s_update_ref to use a ref transactionRonnie Sahlberg, Jun 12, 2014
  49. 48/48 refs.c: make write_ref_sha1 staticRonnie Sahlberg, Jun 12, 2014

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