@@ -42,9 +42,9 @@ private DefaultRetryPolicy() {
4242 }
4343
4444 /**
45- * Defines whether to retry and at which consistency level on a read timeout.
45+ * {@inheritDoc}
4646 * <p/>
47- * This method triggers a maximum of one retry, and only if enough
47+ * This implementation triggers a maximum of one retry, and only if enough
4848 * replicas had responded to the read request but data was not retrieved
4949 * amongst those. Indeed, that case usually means that enough replica
5050 * are alive to satisfy the consistency but the coordinator picked a
@@ -53,15 +53,6 @@ private DefaultRetryPolicy() {
5353 * timeout the dead replica will likely have been detected as dead and
5454 * the retry has a high chance of success.
5555 *
56- * @param statement the original query that timed out.
57- * @param cl the original consistency level of the read that timed out.
58- * @param requiredResponses the number of responses that were required to
59- * achieve the requested consistency level.
60- * @param receivedResponses the number of responses that had been received
61- * by the time the timeout exception was raised.
62- * @param dataRetrieved whether actual data (by opposition to data checksum)
63- * was present in the received responses.
64- * @param nbRetry the number of retries already performed for this operation.
6556 * @return {@code RetryDecision.retry(cl)} if no retry attempt has yet been tried and
6657 * {@code receivedResponses >= requiredResponses && !dataRetrieved}, {@code RetryDecision.rethrow()} otherwise.
6758 */
@@ -74,9 +65,9 @@ public RetryDecision onReadTimeout(Statement statement, ConsistencyLevel cl, int
7465 }
7566
7667 /**
77- * Defines whether to retry and at which consistency level on a write timeout.
68+ * {@inheritDoc}
7869 * <p/>
79- * This method triggers a maximum of one retry, and only in the case of
70+ * This implementation triggers a maximum of one retry, and only in the case of
8071 * a {@code WriteType.BATCH_LOG} write. The reasoning for the retry in
8172 * that case is that write to the distributed batch log is tried by the
8273 * coordinator of the write against a small subset of all the nodes alive
@@ -86,14 +77,6 @@ public RetryDecision onReadTimeout(Statement statement, ConsistencyLevel cl, int
8677 * nodes will likely have been detected as dead and the retry has thus a
8778 * high chance of success.
8879 *
89- * @param statement the original query that timed out.
90- * @param cl the original consistency level of the write that timed out.
91- * @param writeType the type of the write that timed out.
92- * @param requiredAcks the number of acknowledgments that were required to
93- * achieve the requested consistency level.
94- * @param receivedAcks the number of acknowledgments that had been received
95- * by the time the timeout exception was raised.
96- * @param nbRetry the number of retry already performed for this operation.
9780 * @return {@code RetryDecision.retry(cl)} if no retry attempt has yet been tried and
9881 * {@code writeType == WriteType.BATCH_LOG}, {@code RetryDecision.rethrow()} otherwise.
9982 */
@@ -103,37 +86,27 @@ public RetryDecision onWriteTimeout(Statement statement, ConsistencyLevel cl, Wr
10386 return RetryDecision .rethrow ();
10487
10588 // If the batch log write failed, retry the operation as this might just be we were unlucky at picking candidates
89+ // JAVA-764: testing the write type automatically filters out serial consistency levels as these have always WriteType.CAS.
10690 return writeType == WriteType .BATCH_LOG ? RetryDecision .retry (cl ) : RetryDecision .rethrow ();
10791 }
10892
10993 /**
110- * Defines whether to retry and at which consistency level on an
111- * unavailable exception.
94+ * {@inheritDoc}
11295 * <p/>
113- * This method triggers a retry iff no retry has been executed before
114- * (nbRetry == 0), with
115- * {@link RetryPolicy.RetryDecision#tryNextHost(ConsistencyLevel) RetryDecision.tryNextHost(cl)},
116- * otherwise it throws an exception. The retry will be processed on the next host
117- * in the query plan according to the current Load Balancing Policy.
118- * Where retrying on the same host in the event of an Unavailable exception
119- * has almost no chance of success, if the first replica tried happens to
120- * be "network" isolated from all the other nodes but can still answer to
121- * the client, it makes sense to retry the query on another node.
122- *
123- * @param statement the original query for which the consistency level cannot
124- * be achieved.
125- * @param cl the original consistency level for the operation.
126- * @param requiredReplica the number of replica that should have been
127- * (known) alive for the operation to be attempted.
128- * @param aliveReplica the number of replica that were know to be alive by
129- * the coordinator of the operation.
130- * @param nbRetry the number of retry already performed for this operation.
131- * @return {@code RetryDecision.rethrow()}.
96+ * This implementation does the following:
97+ * <ul>
98+ * <li>if this is the first retry ({@code nbRetry == 0}), it triggers a retry on the next host in the query plan
99+ * with the same consistency level ({@link RetryPolicy.RetryDecision#tryNextHost(ConsistencyLevel) RetryDecision#tryNextHost(null)}.
100+ * The rationale is that the first coordinator might have been network-isolated from all other nodes (thinking
101+ * they're down), but still able to communicate with the client; in that case, retrying on the same host has almost
102+ * no chance of success, but moving to the next host might solve the issue.</li>
103+ * <li>otherwise, the exception is rethrow.</li>
104+ * </ul>
132105 */
133106 @ Override
134107 public RetryDecision onUnavailable (Statement statement , ConsistencyLevel cl , int requiredReplica , int aliveReplica , int nbRetry ) {
135108 return (nbRetry == 0 )
136- ? RetryDecision .tryNextHost (cl )
109+ ? RetryDecision .tryNextHost (null )
137110 : RetryDecision .rethrow ();
138111 }
139112
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