Remove phantom copy of expiring data when source gets persisted.

This commit makes sure to clean up resources when a previously expiring entity is persisted by setting the time to live to zero or negative.
In case a phantom copy exists for the changed entity, it is removed to free space on the server and prevent expiration events from being sent.

Closes #1955
Original Pull Request: #1961

Author: muchnik

src/main/java/org/springframework/data/redis/core/RedisKeyValueAdapter.java

@@ -99,6 +99,7 @@
  *
  * @author Christoph Strobl
  * @author Mark Paluch
+ * @author Andrey Muchnik
  * @since 1.7
  */
 public class RedisKeyValueAdapter extends AbstractKeyValueAdapter
@@ -248,6 +249,11 @@ public Object put(Object id, Object item, String keyspace) {
 				}
 			}
 
+			boolean isNoExpire = rdo.getTimeToLive() == null || rdo.getTimeToLive() != null && rdo.getTimeToLive() < 0;
+			if (isNoExpire && !isNew && keepShadowCopy()){
+				connection.del(ByteUtils.concat(objectKey, BinaryKeyspaceIdentifier.PHANTOM_SUFFIX));
+			}
+
 			connection.sAdd(toBytes(rdo.getKeyspace()), key);
 
 			IndexWriter indexWriter = new IndexWriter(connection, converter);
@@ -492,7 +498,7 @@ public void update(PartialUpdate<?> update) {
 				} else {
 
 					connection.persist(redisKey);
-					connection.persist(ByteUtils.concat(redisKey, BinaryKeyspaceIdentifier.PHANTOM_SUFFIX));
+					connection.del(ByteUtils.concat(redisKey, BinaryKeyspaceIdentifier.PHANTOM_SUFFIX));
 				}
 			}
 

src/test/java/org/springframework/data/redis/core/RedisKeyValueAdapterTests.java

@@ -54,6 +54,7 @@
  *
  * @author Christoph Strobl
  * @author Mark Paluch
+ * @author Andrey Muchnik
  */
 @ExtendWith(LettuceConnectionFactoryExtension.class)
 public class RedisKeyValueAdapterTests {
@@ -705,6 +706,41 @@ void phantomKeyInsertedOnPutWhenShadowCopyIsInDefaultAndKeyspaceNotificationEnab
 		assertThat(template.hasKey("persons:1:phantom")).isTrue();
 	}
 
+	@Test // DATAREDIS-1955
+	void phantomKeyIsDeletedWhenPutWithNegativeTimeToLiveAndOldEntryTimeToLiveWasPositiveAndWhenShadowCopyIsTurnedOn() {
+		ExpiringPerson rand = new ExpiringPerson();
+		rand.id = "1";
+		rand.ttl = 3000L;
+
+		adapter.put("1", rand, "persons");
+
+		assertThat(template.getExpire("persons:1:phantom")).isPositive();
+
+		rand.ttl = -1L;
+
+		adapter.put("1", rand, "persons");
+
+		assertThat(template.hasKey("persons:1:phantom")).isFalse();
+	}
+
+	@Test // DATAREDIS-1955
+	void updateWithRefreshTtlAndWithoutPositiveTtlShouldDeletePhantomKey() {
+		ExpiringPerson person = new ExpiringPerson();
+		person.id = "1";
+		person.ttl = 100L;
+
+		adapter.put("1", person, "persons");
+
+		assertThat(template.getExpire("persons:1:phantom")).isPositive();
+
+		PartialUpdate<ExpiringPerson> update = new PartialUpdate<>("1", ExpiringPerson.class) //
+				.refreshTtl(true);
+
+		adapter.update(update);
+
+		assertThat(template.hasKey("persons:1:phantom")).isFalse();
+	}
+
 	/**
 	 * Wait up to 5 seconds until {@code key} is no longer available in Redis.
 	 *