From: Stephan Bosch <stephan.bosch@open-xchange.com>
Date: Tue, 13 Jul 2021 02:15:14 +0000 (+0200)
Subject: lib-storage: mail-duplicate - Implement separate error code for deadlock.
X-Git-Tag: 2.3.17~49
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2d32ee8b548eb36ccf5c26962e754d38dbf7a5a6;p=thirdparty%2Fdovecot%2Fcore.git

lib-storage: mail-duplicate - Implement separate error code for deadlock.
---

diff --git a/src/lib-storage/mail-duplicate.c b/src/lib-storage/mail-duplicate.c
index 7eb1123ee4..6940ede19c 100644
--- a/src/lib-storage/mail-duplicate.c
+++ b/src/lib-storage/mail-duplicate.c
@@ -34,6 +34,7 @@ enum mail_duplicate_lock_result {
 	MAIL_DUPLICATE_LOCK_IO_ERROR,
 	MAIL_DUPLICATE_LOCK_TIMEOUT,
 	MAIL_DUPLICATE_LOCK_TOO_MANY,
+	MAIL_DUPLICATE_LOCK_DEADLOCK,
 };
 
 struct mail_duplicate_lock {
@@ -131,7 +132,10 @@ duplicate_lock_failed(struct mail_duplicate_transaction *trans,
 	i_assert(lock->fd == -1);
 	i_assert(lock->lock == NULL);
 
-	if (errno != EAGAIN) {
+	if (errno == EDEADLK) {
+		/* deadlock */
+		result = MAIL_DUPLICATE_LOCK_DEADLOCK;
+	} else if (errno != EAGAIN) {
 		/* not a lock timeout */
 		result = MAIL_DUPLICATE_LOCK_IO_ERROR;
 	} else {
@@ -541,6 +545,10 @@ mail_duplicate_check(struct mail_duplicate_transaction *trans,
 		e_debug(trans->event,
 			"Check ID: too many IDs locked");
 		return MAIL_DUPLICATE_CHECK_RESULT_TOO_MANY_LOCKS;
+	case MAIL_DUPLICATE_LOCK_DEADLOCK:
+		e_debug(trans->event,
+			"Check ID: deadlock detected while locking");
+		return MAIL_DUPLICATE_CHECK_RESULT_DEADLOCK;
 	}
 
 	mail_duplicate_update(trans);
diff --git a/src/lib-storage/mail-duplicate.h b/src/lib-storage/mail-duplicate.h
index 4bbeaaba28..c414893385 100644
--- a/src/lib-storage/mail-duplicate.h
+++ b/src/lib-storage/mail-duplicate.h
@@ -14,6 +14,10 @@ enum mail_duplicate_check_result {
 	MAIL_DUPLICATE_CHECK_RESULT_LOCK_TIMEOUT,
 	/* Too many locks held. */
 	MAIL_DUPLICATE_CHECK_RESULT_TOO_MANY_LOCKS,
+	/* Locking detected a deadlock. The caller should rollback the
+	   transaction to release all locks, do a short random sleep, retry
+	   and hope that the next attempt succeeds. */
+	MAIL_DUPLICATE_CHECK_RESULT_DEADLOCK,
 };
 
 #define MAIL_DUPLICATE_DEFAULT_KEEP (3600 * 24)