Fix LWT prepared statement routing failure in PRESERVE_REPLICA_ORDER mode #831
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| Original file line number | Diff line number | Diff line change |
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@@ -25,6 +25,7 @@ | |
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| import com.datastax.oss.driver.api.core.ConsistencyLevel; | ||
| import com.datastax.oss.driver.api.core.CqlIdentifier; | ||
| import com.datastax.oss.driver.api.core.RequestRoutingType; | ||
| 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.context.DriverContext; | ||
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@@ -63,6 +64,9 @@ | |
| import edu.umd.cs.findbugs.annotations.NonNull; | ||
| import edu.umd.cs.findbugs.annotations.Nullable; | ||
| import java.nio.ByteBuffer; | ||
| import java.util.ArrayList; | ||
| import java.util.Collections; | ||
| import java.util.LinkedHashMap; | ||
| import java.util.LinkedHashSet; | ||
| import java.util.List; | ||
| import java.util.Map; | ||
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@@ -71,8 +75,10 @@ | |
| import java.util.Queue; | ||
| import java.util.Set; | ||
| import java.util.UUID; | ||
| import java.util.concurrent.ThreadLocalRandom; | ||
| import java.util.concurrent.atomic.AtomicInteger; | ||
| import java.util.function.IntUnaryOperator; | ||
| import java.util.stream.Collectors; | ||
| import net.jcip.annotations.ThreadSafe; | ||
| import org.slf4j.Logger; | ||
| import org.slf4j.LoggerFactory; | ||
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@@ -113,6 +119,11 @@ | |
| @ThreadSafe | ||
| public class BasicLoadBalancingPolicy implements LoadBalancingPolicy { | ||
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| public enum RequestRoutingMethod { | ||
| REGULAR, | ||
| PRESERVE_REPLICA_ORDER | ||
| } | ||
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| private static final Logger LOG = LoggerFactory.getLogger(BasicLoadBalancingPolicy.class); | ||
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| protected static final IntUnaryOperator INCREMENT = i -> (i == Integer.MAX_VALUE) ? 0 : i + 1; | ||
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@@ -127,6 +138,7 @@ public class BasicLoadBalancingPolicy implements LoadBalancingPolicy { | |
| private final int maxNodesPerRemoteDc; | ||
| private final boolean allowDcFailoverForLocalCl; | ||
| private final ConsistencyLevel defaultConsistencyLevel; | ||
| private final RequestRoutingMethod lwtRequestRoutingMethod; | ||
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| // private because they should be set in init() and never be modified after | ||
| private volatile DistanceReporter distanceReporter; | ||
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@@ -154,6 +166,34 @@ public BasicLoadBalancingPolicy(@NonNull DriverContext context, @NonNull String | |
| new LinkedHashSet<>( | ||
| profile.getStringList( | ||
| DefaultDriverOption.LOAD_BALANCING_DC_FAILOVER_PREFERRED_REMOTE_DCS)); | ||
| this.lwtRequestRoutingMethod = parseLwtRequestRoutingMethod(); | ||
| } | ||
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| @NonNull | ||
| private RequestRoutingMethod parseLwtRequestRoutingMethod() { | ||
| String methodString = | ||
| profile.getString(DefaultDriverOption.LOAD_BALANCING_DEFAULT_LWT_REQUEST_ROUTING_METHOD); | ||
| try { | ||
| return RequestRoutingMethod.valueOf(methodString.toUpperCase()); | ||
| } catch (IllegalArgumentException e) { | ||
| LOG.warn( | ||
| "[{}] Unknown request routing method '{}', defaulting to PRESERVE_REPLICA_ORDER", | ||
| logPrefix, | ||
| methodString); | ||
| return RequestRoutingMethod.PRESERVE_REPLICA_ORDER; | ||
| } | ||
| } | ||
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| @NonNull | ||
| public RequestRoutingMethod getRequestRoutingMethod(@Nullable Request request) { | ||
| if (request == null) { | ||
| return RequestRoutingMethod.REGULAR; | ||
| } | ||
| if (request.getRequestRoutingType() == RequestRoutingType.LWT) { | ||
| return lwtRequestRoutingMethod; | ||
| } else { | ||
| return RequestRoutingMethod.REGULAR; | ||
| } | ||
| } | ||
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| /** | ||
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@@ -260,6 +300,17 @@ protected NodeDistanceEvaluator createNodeDistanceEvaluator( | |
| @NonNull | ||
| @Override | ||
| public Queue<Node> newQueryPlan(@Nullable Request request, @Nullable Session session) { | ||
| switch (getRequestRoutingMethod(request)) { | ||
| case PRESERVE_REPLICA_ORDER: | ||
| return newQueryPlanPreserveReplicas(request, session); | ||
| case REGULAR: | ||
| default: | ||
| return newQueryPlanRegular(request, session); | ||
| } | ||
| } | ||
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| @NonNull | ||
| protected Queue<Node> newQueryPlanRegular(@Nullable Request request, @Nullable Session session) { | ||
| // Take a snapshot since the set is concurrent: | ||
| Object[] currentNodes = liveNodes.dc(localDc).toArray(); | ||
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@@ -294,6 +345,116 @@ public Queue<Node> newQueryPlan(@Nullable Request request, @Nullable Session ses | |
| return maybeAddDcFailover(request, plan); | ||
| } | ||
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| /** | ||
| * Builds a query plan that preserves replica order: local replicas, remote replicas, local | ||
| * non-replicas (rotated), remote non-replicas (rotated). | ||
| */ | ||
| @NonNull | ||
| protected Queue<Node> newQueryPlanPreserveReplicas( | ||
| @Nullable Request request, @Nullable Session session) { | ||
| List<Node> replicas = getReplicas(request, session); | ||
| String localDc = getLocalDatacenter(); | ||
| List<Node> queryPlan = new ArrayList<>(); | ||
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| if (localDc == null) { | ||
| // No local DC: all replicas first, then rotated non-replicas | ||
| List<Node> allNodes = new ArrayList<>(); | ||
| for (Object obj : getLiveNodes().dc(null).toArray()) { | ||
| allNodes.add((Node) obj); | ||
| } | ||
| queryPlan.addAll(replicas); | ||
| addRotatedNonReplicas(queryPlan, allNodes, replicas, request); | ||
| } else { | ||
| // With local DC: prioritize local, then remote | ||
| Map<String, List<Node>> nodesByDc = getAllNodesByDc(); | ||
| addReplicasByDc(queryPlan, replicas, localDc); | ||
| addNonReplicasByDc(queryPlan, nodesByDc, replicas, localDc, request); | ||
| } | ||
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| return new SimpleQueryPlan(queryPlan.toArray()); | ||
| } | ||
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| /** Collect all live nodes grouped by DC, with preferred remote DCs ordered first. */ | ||
| private Map<String, List<Node>> getAllNodesByDc() { | ||
| Map<String, List<Node>> nodesByDc = new LinkedHashMap<>(); | ||
| Set<String> allDcs = getLiveNodes().dcs(); | ||
| // Add preferred remote DCs first (in configured order) | ||
| for (String dc : preferredRemoteDcs) { | ||
| if (allDcs.contains(dc)) { | ||
| nodesByDc.put(dc, dcNodeList(dc)); | ||
| } | ||
| } | ||
| // Add remaining DCs (sorted for deterministic ordering) | ||
| allDcs.stream() | ||
| .sorted() | ||
| .filter(dc -> !nodesByDc.containsKey(dc)) | ||
| .forEach(dc -> nodesByDc.put(dc, dcNodeList(dc))); | ||
| return nodesByDc; | ||
| } | ||
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| private List<Node> dcNodeList(String dc) { | ||
| List<Node> dcNodes = new ArrayList<>(); | ||
| for (Object obj : getLiveNodes().dc(dc).toArray()) { | ||
| dcNodes.add((Node) obj); | ||
| } | ||
| return dcNodes; | ||
| } | ||
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| /** Add replicas with local DC first, then remote DCs. */ | ||
| private void addReplicasByDc(List<Node> queryPlan, List<Node> replicas, String localDc) { | ||
| replicas.stream() | ||
| .filter(r -> Objects.equals(r.getDatacenter(), localDc)) | ||
| .forEach(queryPlan::add); | ||
| replicas.stream() | ||
| .filter(r -> !Objects.equals(r.getDatacenter(), localDc)) | ||
| .forEach(queryPlan::add); | ||
| } | ||
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| /** Add non-replicas with local DC first, then remote DCs (all rotated). */ | ||
| private void addNonReplicasByDc( | ||
| List<Node> queryPlan, | ||
| Map<String, List<Node>> nodesByDc, | ||
| List<Node> replicas, | ||
| String localDc, | ||
| Request request) { | ||
| // Local DC non-replicas first | ||
| List<Node> localNodes = nodesByDc.get(localDc); | ||
| if (localNodes != null) { | ||
| addRotatedNonReplicas(queryPlan, localNodes, replicas, request); | ||
| } | ||
| // Remote DC non-replicas | ||
| for (Map.Entry<String, List<Node>> entry : nodesByDc.entrySet()) { | ||
| if (!Objects.equals(entry.getKey(), localDc)) { | ||
| addRotatedNonReplicas(queryPlan, entry.getValue(), replicas, request); | ||
| } | ||
| } | ||
| } | ||
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| /** Add non-replica nodes from given list with rotation. */ | ||
| private void addRotatedNonReplicas( | ||
| List<Node> queryPlan, List<Node> nodes, List<Node> replicas, Request request) { | ||
| List<Node> nonReplicas = | ||
| nodes.stream().filter(n -> !replicas.contains(n)).collect(Collectors.toList()); | ||
| if (!nonReplicas.isEmpty()) { | ||
| rotateNonReplicas(nonReplicas, request); | ||
| queryPlan.addAll(nonReplicas); | ||
| } | ||
| } | ||
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| /** Rotates nodes based on routing key (consistent) or randomly. */ | ||
| private void rotateNonReplicas(List<Node> nodes, @Nullable Request request) { | ||
| if (nodes.size() <= 1) return; | ||
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| int rotationAmount = | ||
| (request != null && request.getRoutingKey() != null) | ||
| ? (request.getRoutingKey().hashCode() & 0x7fffffff) % nodes.size() | ||
| : randomNextInt(nodes.size()); | ||
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| if (rotationAmount > 0) { | ||
| Collections.rotate(nodes, -rotationAmount); | ||
| } | ||
| } | ||
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| @NonNull | ||
| protected List<Node> getReplicas(@Nullable Request request, @Nullable Session session) { | ||
| if (request == null || session == null) { | ||
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@@ -441,6 +602,11 @@ protected Object[] computeNodes() { | |
| return new CompositeQueryPlan(queryPlans); | ||
| } | ||
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| /** Exposed as a protected method so that it can be accessed by tests */ | ||
| protected int randomNextInt(int bound) { | ||
| return ThreadLocalRandom.current().nextInt(bound); | ||
| } | ||
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| /** Exposed as a protected method so that it can be accessed by tests */ | ||
| protected void shuffleHead(Object[] currentNodes, int headLength) { | ||
| ArrayUtils.shuffleHead(currentNodes, headLength); | ||
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The new preserve-replica-order logic adds explicit ordering for
preferredRemoteDcs, but the updated LWT routing tests don’t appear to assert that preferred remote DCs are actually prioritized ahead of other remote DCs in the resulting plan. Add a unit test that configures multiple remote DCs plusLOAD_BALANCING_DC_FAILOVER_PREFERRED_REMOTE_DCS, then asserts the remote non-replica portion of the plan respects that configured order.