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[PATCH 10/10] files_transaction_finish(): delete reflogs before references

From
Michael Haggerty <mhagger@alum.mit.edu>
Date
Aug 29, 2017, 08:20 UTC
Message-ID
<b147389b4abfbd8975fe651d956fded34f5b90cd.1503993268.git.mhagger@alum.mit.edu>
In-Reply-To
<cover.1503993268.git.mhagger@alum.mit.edu>

If the deletion steps unexpectedly fail, it is less bad to leave a reference without its reflog than it is to leave a reflog without its reference, since the latter is an invalid repository state.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
---
 refs/files-backend.c | 35 +++++++++++++++++++++--------------
 1 file changed, 21 insertions(+), 14 deletions(-)
diff --git a/refs/files-backend.c b/refs/files-backend.c
index 4f4c47b9db..36f81b4f28 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -2630,6 +2630,27 @@ static int files_transaction_finish(struct ref_store *ref_store,
 		}
 	}
 
+	/*
+	 * Now that updates are safely completed, we can perform
+	 * deletes. First delete the reflogs of any references that
+	 * will be deleted, since (in the unexpected event of an
+	 * error) leaving a reference without a reflog is less bad
+	 * than leaving a reflog without a reference (the latter is a
+	 * mildly invalid repository state):
+	 */
+	for (i = 0; i < transaction->nr; i++) {
+		struct ref_update *update = transaction->updates[i];
+		if (update->flags & REF_DELETING &&
+		    !(update->flags & REF_LOG_ONLY) &&
+		    !(update->flags & REF_ISPRUNING)) {
+			strbuf_reset(&sb);
+			files_reflog_path(refs, &sb, update->refname);
+			if (!unlink_or_warn(sb.buf))
+				try_remove_empty_parents(refs, update->refname,
+							 REMOVE_EMPTY_PARENTS_REFLOG);
+		}
+	}
+
 	/*
 	 * Perform deletes now that updates are safely completed.
 	 *
@@ -2666,20 +2687,6 @@ static int files_transaction_finish(struct ref_store *ref_store,
 		}
 	}
 
-	/* Delete the reflogs of any references that were deleted: */
-	for (i = 0; i < transaction->nr; i++) {
-		struct ref_update *update = transaction->updates[i];
-		if (update->flags & REF_DELETING &&
-		    !(update->flags & REF_LOG_ONLY) &&
-		    !(update->flags & REF_ISPRUNING)) {
-			strbuf_reset(&sb);
-			files_reflog_path(refs, &sb, update->refname);
-			if (!unlink_or_warn(sb.buf))
-				try_remove_empty_parents(refs, update->refname,
-							 REMOVE_EMPTY_PARENTS_REFLOG);
-		}
-	}
-
 	clear_loose_ref_cache(refs);
 
 cleanup:
-- 
2.14.1
Previous: Jeff KingNext: Michael Haggerty
Message 21 of 31 in “Implement transactions for the packed ref store”
  1. 00/10 Implement transactions for the packed ref storeMichael Haggerty, Aug 29, 2017
  2. 05/10 files_pack_refs(): use a reference transaction to write packed refsMichael Haggerty, Aug 29, 2017
  3. 04/10 packed_delete_refs(): implement methodMichael Haggerty, Aug 29, 2017
  4. Brandon WilliamsAug 29, 2017
  5. Michael HaggertyAug 30, 2017
  6. 06/10 files_initial_transaction_commit(): use a transaction for packed refsMichael Haggerty, Aug 29, 2017
  7. Jeff KingSep 8, 2017
  8. Michael HaggertySep 8, 2017
  9. 07/10 t1404: demonstrate two problems with reference transactionsMichael Haggerty, Aug 29, 2017
  10. Stefan BellerAug 30, 2017
  11. Michael HaggertyAug 31, 2017
  12. Junio C HamanoSep 8, 2017
  13. Jeff KingSep 8, 2017
  14. Michael HaggertySep 8, 2017
  15. 09/10 packed-backend: rip out some now-unused codeMichael Haggerty, Aug 29, 2017
  16. Brandon WilliamsAug 29, 2017
  17. 08/10 files_ref_store: use a transaction to update packed refsMichael Haggerty, Aug 29, 2017
  18. Jeff KingSep 8, 2017
  19. Michael HaggertySep 8, 2017
  20. Jeff KingSep 8, 2017
  21. 10/10 files_transaction_finish(): delete reflogs before referencesMichael Haggerty, Aug 29, 2017
  22. 01/10 packed-backend: don't adjust the reference count on lock/unlockMichael Haggerty, Aug 29, 2017
  23. Jeff KingSep 8, 2017
  24. Michael HaggertySep 8, 2017
  25. 02/10 struct ref_transaction: add a place for backends to store dataMichael Haggerty, Aug 29, 2017
  26. Jeff KingSep 8, 2017
  27. Michael HaggertySep 8, 2017
  28. Jeff KingSep 8, 2017
  29. 03/10 packed_ref_store: implement reference transactionsMichael Haggerty, Aug 29, 2017
  30. Brandon WilliamsAug 29, 2017
  31. Jeff KingSep 8, 2017

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