adutra commented on code in PR #1896:
URL:
https://github.com/apache/cassandra-java-driver/pull/1896#discussion_r1435650327
##########
core/src/main/java/com/datastax/oss/driver/api/core/config/TypedDriverOption.java:
##########
@@ -886,6 +886,16 @@ public String toString() {
DefaultDriverOption.LOAD_BALANCING_DC_FAILOVER_ALLOW_FOR_LOCAL_CONSISTENCY_LEVELS,
GenericType.BOOLEAN);
+ /**
+ * Ordered preference list of remote dc's optionally supplied for automatic
failover and included
+ * in query plan. This feature is enabled only when max-nodes-per-remote-dc
is greater than 0
Review Comment:
```suggestion
* in query plan. This feature is enabled only when
max-nodes-per-remote-dc is greater than 0.
```
##########
core/src/main/java/com/datastax/oss/driver/internal/core/loadbalancing/BasicLoadBalancingPolicy.java:
##########
@@ -131,6 +135,15 @@ public BasicLoadBalancingPolicy(@NonNull DriverContext
context, @NonNull String
this.context
.getConsistencyLevelRegistry()
.nameToLevel(profile.getString(DefaultDriverOption.REQUEST_CONSISTENCY));
+
+ final List<String> remoteDcs =
Review Comment:
For improved efficiency, I'd suggest that you store the preferred DCs in a
`String[]`:
```java
Set<String> remoteDcs =
new LinkedHashSet<>(
Objects.requireNonNull(
profile.getStringList(
DefaultDriverOption.LOAD_BALANCING_DC_FAILOVER_PREFERRED_REMOTE_DCS,
new ArrayList<>())));
preferredRemoteDcs = remoteDcs.toArray(new String[0]);
```
##########
core/src/main/java/com/datastax/oss/driver/internal/core/loadbalancing/BasicLoadBalancingPolicy.java:
##########
@@ -117,6 +120,7 @@ public class BasicLoadBalancingPolicy implements
LoadBalancingPolicy {
private volatile NodeDistanceEvaluator nodeDistanceEvaluator;
private volatile String localDc;
private volatile NodeSet liveNodes;
+ private volatile Set<String> preferredRemoteLocalDcs = new LinkedHashSet<>();
Review Comment:
Rename to `preferredRemoteDcs`. Also, the field should be final.
##########
core/src/main/java/com/datastax/oss/driver/internal/core/loadbalancing/BasicLoadBalancingPolicy.java:
##########
@@ -325,24 +338,63 @@ protected Queue<Node> maybeAddDcFailover(@Nullable
Request request, @NonNull Que
@Override
protected Object[] computeNodes() {
- Object[] remoteNodes =
- liveNodes.dcs().stream()
- .filter(Predicates.not(Predicates.equalTo(localDc)))
- .flatMap(dc ->
liveNodes.dc(dc).stream().limit(maxNodesPerRemoteDc))
- .toArray();
-
- int remoteNodesLength = remoteNodes.length;
- if (remoteNodesLength == 0) {
- return EMPTY_NODES;
+ if (!preferredRemoteLocalDcs.isEmpty()) {
Review Comment:
Isn't this unnecessarily complex? I think the same effect could be achieved
with a sorted stream:
```java
Object[] remoteNodes =
liveNodes.dcs().stream()
.filter(Predicates.not(Predicates.equalTo(localDc)))
.sorted(
Comparator.comparingInt(
dc -> {
int i = Arrays.binarySearch(preferredRemoteDcs, dc);
return i < 0 ? Integer.MAX_VALUE : i;
}))
.flatMap(dc -> liveNodes.dc(dc).stream().limit(maxNodesPerRemoteDc))
.toArray();
```
And indeed, in presence of preferred dcs, it probably doesn't make sense to
shuffle the remote nodes:
```java
if (preferredRemoteDcs.length == 0) {
shuffleHead(remoteNodes, remoteNodesLength);
}
```
##########
core/src/test/java/com/datastax/oss/driver/internal/core/loadbalancing/BasicLoadBalancingPolicyRemoteDcTest.java:
##########
@@ -0,0 +1,189 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.datastax.oss.driver.internal.core.loadbalancing;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyInt;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.BDDMockito.then;
+import static org.mockito.Mockito.atLeast;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.spy;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import com.datastax.oss.driver.api.core.config.DefaultDriverOption;
+import com.datastax.oss.driver.api.core.config.DriverExecutionProfile;
+import com.datastax.oss.driver.api.core.metadata.Node;
+import com.datastax.oss.driver.internal.core.metadata.DefaultNode;
+import com.datastax.oss.driver.shaded.guava.common.collect.ImmutableMap;
+import com.datastax.oss.driver.shaded.guava.common.collect.ImmutableSet;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+import java.util.UUID;
+import org.junit.Test;
+import org.mockito.Mock;
+
+public class BasicLoadBalancingPolicyRemoteDcTest extends
BasicLoadBalancingPolicyQueryPlanTest {
Review Comment:
Rename to `BasicLoadBalancingPolicyPreferredRemoteDcsTest`. Also, maybe it
would have been simpler to extend `BasicLoadBalancingPolicyDcFailoverTest`.
##########
core/src/main/java/com/datastax/oss/driver/internal/core/loadbalancing/BasicLoadBalancingPolicy.java:
##########
@@ -325,24 +338,63 @@ protected Queue<Node> maybeAddDcFailover(@Nullable
Request request, @NonNull Que
@Override
protected Object[] computeNodes() {
- Object[] remoteNodes =
- liveNodes.dcs().stream()
- .filter(Predicates.not(Predicates.equalTo(localDc)))
- .flatMap(dc ->
liveNodes.dc(dc).stream().limit(maxNodesPerRemoteDc))
- .toArray();
-
- int remoteNodesLength = remoteNodes.length;
- if (remoteNodesLength == 0) {
- return EMPTY_NODES;
+ if (!preferredRemoteLocalDcs.isEmpty()) {
+ final List<Object> nodes = new ArrayList<>();
+
+ preferredRemoteLocalDcs.forEach(dc -> addRemoteNodes(nodes, dc));
+
+ liveNodes
+ .dcs()
+ .forEach(
+ dc -> {
+ if (!preferredRemoteLocalDcs.contains(dc) &&
!dc.equals(localDc)) {
+ addRemoteNodes(nodes, dc);
+ }
+ });
+
+ if (!nodes.isEmpty()) {
+ return nodes.toArray();
+ } else {
+ return EMPTY_NODES;
+ }
+ } else {
+ Object[] remoteNodes =
+ liveNodes.dcs().stream()
+ .filter(Predicates.not(Predicates.equalTo(localDc)))
+ .flatMap(dc ->
liveNodes.dc(dc).stream().limit(maxNodesPerRemoteDc))
+ .toArray();
+
+ int remoteNodesLength = remoteNodes.length;
+ if (remoteNodesLength == 0) {
+ return EMPTY_NODES;
+ }
+ shuffleHead(remoteNodes, remoteNodesLength);
+ return remoteNodes;
+ }
+ }
+
+ private void addRemoteNodes(final List<Object> nodes, final String
dc) {
+ final Object[] remoteNodesPerDc =
+ liveNodes.dc(dc).stream().limit(maxNodesPerRemoteDc).toArray();
+ int remoteNodesLength = remoteNodesPerDc.length;
+ if (remoteNodesLength > 0) {
+ shuffleHeadRemote(remoteNodesPerDc, remoteNodesLength);
+
+ for (int i = 0; i < remoteNodesLength; i++) {
+ nodes.add(remoteNodesPerDc[i]);
+ }
}
- shuffleHead(remoteNodes, remoteNodesLength);
- return remoteNodes;
}
};
return new CompositeQueryPlan(local, remote);
}
+ /** Exposed as a protected method so that it can be accessed by tests */
+ protected void shuffleHeadRemote(Object[] currentNodes, int headLength) {
Review Comment:
Not a huge fan of this tbh. I believe you can distinguish calls to
`shuffleHead` by inspecting their arguments. See here for an example:
https://github.com/apache/cassandra-java-driver/blob/16260261d3df50fcf24fac1fc2d37896c4a111bf/core/src/test/java/com/datastax/oss/driver/internal/core/loadbalancing/BasicLoadBalancingPolicyDcFailoverTest.java#L67-L70
##########
core/src/test/java/com/datastax/oss/driver/internal/core/loadbalancing/BasicLoadBalancingPolicyRemoteDcTest.java:
##########
@@ -0,0 +1,189 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.datastax.oss.driver.internal.core.loadbalancing;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyInt;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.BDDMockito.then;
+import static org.mockito.Mockito.atLeast;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.spy;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import com.datastax.oss.driver.api.core.config.DefaultDriverOption;
+import com.datastax.oss.driver.api.core.config.DriverExecutionProfile;
+import com.datastax.oss.driver.api.core.metadata.Node;
+import com.datastax.oss.driver.internal.core.metadata.DefaultNode;
+import com.datastax.oss.driver.shaded.guava.common.collect.ImmutableMap;
+import com.datastax.oss.driver.shaded.guava.common.collect.ImmutableSet;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+import java.util.UUID;
+import org.junit.Test;
+import org.mockito.Mock;
+
+public class BasicLoadBalancingPolicyRemoteDcTest extends
BasicLoadBalancingPolicyQueryPlanTest {
+
+ @Mock protected DefaultNode node6;
+ @Mock protected DefaultNode node7;
+ @Mock protected DefaultNode node8;
+ @Mock protected DefaultNode node9;
+ @Mock protected DefaultNode node10;
+ @Mock protected DefaultNode node11;
+ @Mock protected DefaultNode node12;
+
+ @Override
+ @Test
+ public void
+
should_use_round_robin_when_token_map_returns_no_replicas_using_request_keyspace_and_routing_key()
{
+ when(request.getRoutingKeyspace()).thenReturn(KEYSPACE);
+ when(request.getRoutingKey()).thenReturn(ROUTING_KEY);
+ when(tokenMap.getReplicas(KEYSPACE,
ROUTING_KEY)).thenReturn(Collections.emptySet());
+
+ assertRoundRobinQueryPlans();
+
+ then(tokenMap).should(atLeast(1)).getReplicas(KEYSPACE, ROUTING_KEY);
+ }
+
+ @Override
+ @Test
+ public void should_prioritize_and_shuffle_replicas() {
+ when(request.getRoutingKeyspace()).thenReturn(KEYSPACE);
+ when(request.getRoutingKey()).thenReturn(ROUTING_KEY);
+ when(tokenMap.getReplicas(KEYSPACE,
ROUTING_KEY)).thenReturn(ImmutableSet.of(node3, node5));
+
+ assertThat(policy.newQueryPlan(request, session))
+ .containsExactly(node3, node5, node1, node2, node4, node9, node10,
node6, node7, node12);
+ assertThat(policy.newQueryPlan(request, session))
+ .containsExactly(node3, node5, node2, node4, node1, node9, node10,
node6, node7, node12);
+ assertThat(policy.newQueryPlan(request, session))
+ .containsExactly(node3, node5, node4, node1, node2, node9, node10,
node6, node7, node12);
+
+ verify(policy, times(3)).shuffleHead(any(), eq(2));
+ // No power of two choices with only two replicas
+ verify(session, never()).getPools();
+ }
+
+ @Override
+ @Test
+ public void should_prioritize_single_replica() {
+ when(request.getRoutingKeyspace()).thenReturn(KEYSPACE);
+ when(request.getRoutingKey()).thenReturn(ROUTING_KEY);
+ when(tokenMap.getReplicas(KEYSPACE,
ROUTING_KEY)).thenReturn(ImmutableSet.of(node3));
+
+ // node3 always first, round-robin on the rest
+ assertThat(policy.newQueryPlan(request, session))
+ .containsExactly(node3, node1, node2, node4, node5, node9, node10,
node6, node7, node12);
+ assertThat(policy.newQueryPlan(request, session))
+ .containsExactly(node3, node2, node4, node5, node1, node9, node10,
node6, node7, node12);
+ assertThat(policy.newQueryPlan(request, session))
+ .containsExactly(node3, node4, node5, node1, node2, node9, node10,
node6, node7, node12);
+ assertThat(policy.newQueryPlan(request, session))
+ .containsExactly(node3, node5, node1, node2, node4, node9, node10,
node6, node7, node12);
+
+ // Should not shuffle replicas since there is only one
+ verify(policy, never()).shuffleHead(any(), anyInt());
+ }
+
+ @Override
+ protected void assertRoundRobinQueryPlans() {
+ for (int i = 0; i < 3; i++) {
+ assertThat(policy.newQueryPlan(request, session))
+ .containsExactly(node1, node2, node3, node4, node5, node9, node10,
node6, node7, node12);
+ assertThat(policy.newQueryPlan(request, session))
+ .containsExactly(node2, node3, node4, node5, node1, node9, node10,
node6, node7, node12);
+ assertThat(policy.newQueryPlan(request, session))
+ .containsExactly(node3, node4, node5, node1, node2, node9, node10,
node6, node7, node12);
+ assertThat(policy.newQueryPlan(request, session))
+ .containsExactly(node4, node5, node1, node2, node3, node9, node10,
node6, node7, node12);
+ assertThat(policy.newQueryPlan(request, session))
+ .containsExactly(node5, node1, node2, node3, node4, node9, node10,
node6, node7, node12);
+ }
+ }
+
+ @Override
+ protected BasicLoadBalancingPolicy createAndInitPolicy() {
+ when(node4.getDatacenter()).thenReturn("dc1");
+ when(node5.getDatacenter()).thenReturn("dc1");
+ when(node6.getDatacenter()).thenReturn("dc2");
+ when(node7.getDatacenter()).thenReturn("dc2");
+ when(node8.getDatacenter()).thenReturn("dc2");
+ when(node9.getDatacenter()).thenReturn("dc3");
+ when(node10.getDatacenter()).thenReturn("dc3");
+ when(node11.getDatacenter()).thenReturn("dc3");
+ when(node12.getDatacenter()).thenReturn("dc4");
+
+ // Accept 2 nodes per remote DC
+ when(defaultProfile.getInt(
+
DefaultDriverOption.LOAD_BALANCING_DC_FAILOVER_MAX_NODES_PER_REMOTE_DC))
+ .thenReturn(2);
+ when(defaultProfile.getBoolean(
+
DefaultDriverOption.LOAD_BALANCING_DC_FAILOVER_ALLOW_FOR_LOCAL_CONSISTENCY_LEVELS))
+ .thenReturn(false);
+
+ final List<String> preferredDcs = new ArrayList<>();
+ preferredDcs.add("dc3");
+ preferredDcs.add("dc2");
+ when(defaultProfile.getStringList(
+
DefaultDriverOption.LOAD_BALANCING_DC_FAILOVER_PREFERRED_REMOTE_DCS, new
ArrayList<>()))
+ .thenReturn(preferredDcs);
Review Comment:
```suggestion
when(defaultProfile.getStringList(
DefaultDriverOption.LOAD_BALANCING_DC_FAILOVER_PREFERRED_REMOTE_DCS, new
ArrayList<>()))
.thenReturn(ImmutableList.of("dc3","dc2"));
```
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