receive-pack: handle reference deletions separately
In 9d2962a7c4 (receive-pack: use batched reference updates, 2025-05-19) we updated the 'git-receive-pack(1)' command to use batched reference updates. One edge case which was missed during this implementation was when a user pushes multiple branches such as: delete refs/heads/branch/conflict create refs/heads/branch Before using batched updates, the references would be applied sequentially and hence no conflicts would arise. With batched updates, while the first update applies, the second fails due to D/F conflict. A similar issue was present in 'git-fetch(1)' and was fixed by separating out reference pruning into a separate transaction in the commit 'fetch: use batched reference updates'. Apply a similar mechanism for 'git-receive-pack(1)' and separate out reference deletions into its own batch. This means 'git-receive-pack(1)' will now use up to two transactions, whereas before using batched updates it would use _at least_ two transactions. So using batched updates is still the better option. Add a test to validate this behavior. Signed-off-by: Karthik Nayak <karthik.188@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Karthik Nayak committed
Jun 20, 2025 at 09:15 UTC
5c697f0b7ddbc85965bcba00c29d4b823bd221b7
2 files changed
+81
-38
builtin/receive-pack.c
+68
-34
@@ -1866,47 +1866,81 @@ static void execute_commands_non_atomic(struct command *commands,
1866
const char *reported_error = NULL;
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struct strmap failed_refs = STRMAP_INIT;
1868
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- transaction = ref_store_transaction_begin(get_main_ref_store(the_repository),
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- REF_TRANSACTION_ALLOW_FAILURE, &err);
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- if (!transaction) {
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- rp_error("%s", err.buf);
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- strbuf_reset(&err);
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- reported_error = "transaction failed to start";
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- goto failure;
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- }
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+ /*
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+ * Reference updates, where D/F conflicts shouldn't arise due to
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+ * one reference being deleted, while the other being created
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+ * are treated as conflicts in batched updates. This is because
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+ * we don't do conflict resolution inside a transaction. To
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+ * mitigate this, delete references in a separate batch.
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+ *
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+ * NEEDSWORK: Add conflict resolution between deletion and creation
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+ * of reference updates within a transaction. With that, we can
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+ * combine the two phases.
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+ */
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+ enum processing_phase {
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+ PHASE_DELETIONS,
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+ PHASE_OTHERS
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+ };
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- for (cmd = commands; cmd; cmd = cmd->next) {
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- if (!should_process_cmd(cmd) || cmd->run_proc_receive)
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- continue;
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+ for (enum processing_phase phase = PHASE_DELETIONS; phase <= PHASE_OTHERS; phase++) {
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+ for (cmd = commands; cmd; cmd = cmd->next) {
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+ if (!should_process_cmd(cmd) || cmd->run_proc_receive)
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+ continue;
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- cmd->error_string = update(cmd, si);
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- }
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+ if (phase == PHASE_DELETIONS && !is_null_oid(&cmd->new_oid))
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+ continue;
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+ else if (phase == PHASE_OTHERS && is_null_oid(&cmd->new_oid))
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+ continue;
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- if (ref_transaction_commit(transaction, &err)) {
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- rp_error("%s", err.buf);
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- reported_error = "failed to update refs";
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- goto failure;
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- }
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+ /*
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+ * Lazily create a transaction only when we know there are
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+ * updates to be added.
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+ */
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+ if (!transaction) {
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+ transaction = ref_store_transaction_begin(get_main_ref_store(the_repository),
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+ REF_TRANSACTION_ALLOW_FAILURE, &err);
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+ if (!transaction) {
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+ rp_error("%s", err.buf);
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+ strbuf_reset(&err);
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+ reported_error = "transaction failed to start";
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+ goto failure;
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+ }
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+ }
1909
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- ref_transaction_for_each_rejected_update(transaction,
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- ref_transaction_rejection_handler,
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- &failed_refs);
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+ cmd->error_string = update(cmd, si);
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+ }
1912
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- if (strmap_empty(&failed_refs))
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- goto cleanup;
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+ /* No transaction, so nothing to commit */
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+ if (!transaction)
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+ goto cleanup;
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-failure:
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- for (cmd = commands; cmd; cmd = cmd->next) {
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- if (reported_error)
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- cmd->error_string = reported_error;
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- else if (strmap_contains(&failed_refs, cmd->ref_name))
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- cmd->error_string = strmap_get(&failed_refs, cmd->ref_name);
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- }
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+ if (ref_transaction_commit(transaction, &err)) {
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+ rp_error("%s", err.buf);
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+ reported_error = "failed to update refs";
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+ goto failure;
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+ }
1922
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-cleanup:
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- ref_transaction_free(transaction);
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- strmap_clear(&failed_refs, 0);
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- strbuf_release(&err);
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+ ref_transaction_for_each_rejected_update(transaction,
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+ ref_transaction_rejection_handler,
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+ &failed_refs);
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+
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+ if (strmap_empty(&failed_refs))
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+ goto cleanup;
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+
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+ failure:
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+ for (cmd = commands; cmd; cmd = cmd->next) {
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+ if (reported_error)
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+ cmd->error_string = reported_error;
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+ else if (strmap_contains(&failed_refs, cmd->ref_name))
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+ cmd->error_string = strmap_get(&failed_refs, cmd->ref_name);
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+ }
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+
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+ cleanup:
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+ ref_transaction_free(transaction);
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+ transaction = NULL;
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+ strmap_clear(&failed_refs, 0);
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+ strbuf_release(&err);
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+ }
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}
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static void execute_commands_atomic(struct command *commands,
t/t5516-fetch-push.sh
+13
-4
@@ -744,8 +744,8 @@ test_expect_success 'pushing valid refs triggers post-receive and post-update ho
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EOF
745
746
cat >update.expect <<-EOF &&
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- refs/heads/main $orgmain $newmain
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refs/heads/next $orgnext $newnext
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+ refs/heads/main $orgmain $newmain
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EOF
750
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cat >post-receive.expect <<-EOF &&
@@ -808,8 +808,8 @@ test_expect_success 'deletion of a non-existent ref is not fed to post-receive a
808
EOF
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cat >update.expect <<-EOF &&
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- refs/heads/main $orgmain $newmain
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refs/heads/nonexistent $ZERO_OID $ZERO_OID
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+ refs/heads/main $orgmain $newmain
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EOF
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815
cat >post-receive.expect <<-EOF &&
@@ -868,10 +868,10 @@ test_expect_success 'mixed ref updates, deletes, invalid deletes trigger hooks w
868
EOF
869
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cat >update.expect <<-EOF &&
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- refs/heads/main $orgmain $newmain
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refs/heads/next $orgnext $newnext
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- refs/heads/seen $orgseen $newseen
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refs/heads/nonexistent $ZERO_OID $ZERO_OID
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+ refs/heads/main $orgmain $newmain
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+ refs/heads/seen $orgseen $newseen
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EOF
876
877
cat >post-receive.expect <<-EOF &&
@@ -1909,4 +1909,13 @@ test_expect_success 'push with config push.useBitmaps' '
1909
--thin --delta-base-offset -q --no-use-bitmap-index <false
1910
'
1911
1912
+test_expect_success 'push with F/D conflict with deletion and creation' '
1913
+ test_when_finished "git branch -D branch" &&
1914
+ git branch branch/conflict &&
1915
+ mk_test testrepo heads/branch/conflict &&
1916
+ git branch -D branch/conflict &&
1917
+ git branch branch &&
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+ git push testrepo :refs/heads/branch/conflict refs/heads/branch
1919
+'
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+
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test_done