From e3701746f3c339944ad80236b6aec5f41e243e7f Mon Sep 17 00:00:00 2001
From: astrubel <66489232+astrubel@users.noreply.github.com>
Date: Tue, 9 Jun 2020 19:27:32 +0200
Subject: [PATCH] GH-3294: Retry JdbcLock.unlock for TransDataAccEx

Fixes https://github.com/spring-projects/spring-integration/issues/3294

A `DeadlockLoserDataAccessException` occurs at `JdbcLockRegistry$JdbcLock.unlock()` -
better to retry like in the `lock()`

**Cherry-pick to 5.3.x, 5.2.x, 5.1.x & 4.3.x**
---
 .../jdbc/lock/JdbcLockRegistry.java           | 22 ++++++++++++-------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/spring-integration-jdbc/src/main/java/org/springframework/integration/jdbc/lock/JdbcLockRegistry.java b/spring-integration-jdbc/src/main/java/org/springframework/integration/jdbc/lock/JdbcLockRegistry.java
index 18a15ae19ac..4a523233696 100644
--- a/spring-integration-jdbc/src/main/java/org/springframework/integration/jdbc/lock/JdbcLockRegistry.java
+++ b/spring-integration-jdbc/src/main/java/org/springframework/integration/jdbc/lock/JdbcLockRegistry.java
@@ -236,14 +236,20 @@ public void unlock() {
 				this.delegate.unlock();
 				return;
 			}
-			try {
-				this.mutex.delete(this.path);
-			}
-			catch (Exception e) {
-				throw new DataAccessResourceFailureException("Failed to release mutex at " + this.path, e);
-			}
-			finally {
-				this.delegate.unlock();
+			while (true) {
+				try {
+					this.mutex.delete(this.path);
+					return;
+				}
+				catch (TransientDataAccessException e) {
+					// try again
+				}
+				catch (Exception e) {
+					throw new DataAccessResourceFailureException("Failed to release mutex at " + this.path, e);
+				}
+				finally {
+					this.delegate.unlock();
+				}
 			}
 		}