Client config reporting (3.x) — stage 2: full DRIVER_CONFIG report

driver-core/pom.xml

@@ -187,6 +187,11 @@
             <scope>test</scope>
         </dependency>
 
+        <dependency>
+            <groupId>com.networknt</groupId>
+            <artifactId>json-schema-validator</artifactId>
+            <scope>test</scope>
+        </dependency>
 
     </dependencies>
 

driver-core/src/main/java/com/datastax/driver/core/DriverConfigReporter.java

@@ -39,7 +39,10 @@ public interface DriverConfigReporter {
    *
    * <p><b>Implementations must not throw:</b> a failure to build the report must be swallowed (and
    * logged) rather than propagated, so that a diagnostic aid can never break cluster
-   * initialization.
+   * initialization. For the same reason they must return {@code null} rather than a report that
+   * exceeds {@code DefaultDriverConfigReporter.MAX_DRIVER_CONFIG_LENGTH}: {@code STARTUP} option
+   * values carry an unchecked 16-bit length prefix, so an oversized one corrupts the frame instead
+   * of merely being useless.
    *
    * @return the report to send under the {@code DRIVER_CONFIG} startup option, or {@code null} to
    *     send nothing.

driver-core/src/main/java/com/datastax/driver/core/policies/DCAwareRoundRobinPolicy.java

@@ -77,6 +77,7 @@ public static Builder builder() {
 
   private final int usedHostsPerRemoteDc;
   private final boolean dontHopForLocalCL;
+  private final boolean localDcExplicit;
 
   private volatile Configuration configuration;
 
@@ -90,6 +91,40 @@ private DCAwareRoundRobinPolicy(
     this.localDc = localDc == null ? UNSET : localDc;
     this.usedHostsPerRemoteDc = usedHostsPerRemoteDc;
     this.dontHopForLocalCL = !allowRemoteDCsForLocalConsistencyLevel;
+    this.localDcExplicit = !Strings.isNullOrEmpty(localDc);
+  }
+
+  /**
+   * The datacenter this policy considers local, or {@code null} if it has neither been configured
+   * explicitly nor inferred yet. When {@link #isLocalDcExplicit()} is {@code false}, this is the
+   * datacenter inferred from the first contacted node, which is only available once the policy has
+   * been initialized.
+   *
+   * @return the local datacenter name, or {@code null}.
+   */
+  public String getLocalDc() {
+    String dc = localDc;
+    return Strings.isNullOrEmpty(dc) ? null : dc;
+  }
+
+  /**
+   * Whether the local datacenter was configured explicitly (as opposed to being inferred from the
+   * first contacted node).
+   *
+   * @return {@code true} if the local datacenter was set explicitly.
+   */
+  public boolean isLocalDcExplicit() {
+    return localDcExplicit;
+  }
+
+  /**
+   * The number of hosts per remote datacenter that this policy considers for failover (0 means no
+   * remote failover).
+   *
+   * @return the number of used hosts per remote datacenter.
+   */
+  public int getUsedHostsPerRemoteDc() {
+    return usedHostsPerRemoteDc;
   }
 
   @Override

driver-core/src/main/java/com/datastax/driver/core/policies/PagingOptimizingLoadBalancingPolicy.java

@@ -12,14 +12,19 @@
 import java.util.Iterator;
 import java.util.concurrent.CopyOnWriteArrayList;
 
-public class PagingOptimizingLoadBalancingPolicy implements LoadBalancingPolicy {
+public class PagingOptimizingLoadBalancingPolicy implements ChainableLoadBalancingPolicy {
   private final LoadBalancingPolicy wrapped;
   private volatile CopyOnWriteArrayList<Host> hosts;
 
   public PagingOptimizingLoadBalancingPolicy(LoadBalancingPolicy loadBalancingPolicy) {
     wrapped = loadBalancingPolicy;
   }
 
+  @Override
+  public LoadBalancingPolicy getChildPolicy() {
+    return wrapped;
+  }
+
   @Override
   public void init(Cluster cluster, Collection<Host> hosts) {
     this.hosts = new CopyOnWriteArrayList<Host>(hosts);

driver-core/src/main/java/com/datastax/driver/core/policies/RackAwareRoundRobinPolicy.java

@@ -90,6 +90,8 @@ public static Builder builder() {
 
   private final int usedHostsPerRemoteDc;
   private final boolean dontHopForLocalCL;
+  private final boolean localDcExplicit;
+  private final boolean localRackExplicit;
 
   private volatile Configuration configuration;
 
@@ -109,6 +111,62 @@ public RackAwareRoundRobinPolicy(
     this.localRack = localRack == null ? UNSET : localRack;
     this.usedHostsPerRemoteDc = usedHostsPerRemoteDc;
     this.dontHopForLocalCL = !allowRemoteDCsForLocalConsistencyLevel;
+    this.localDcExplicit = !Strings.isNullOrEmpty(localDc);
+    this.localRackExplicit = !Strings.isNullOrEmpty(localRack);
+  }
+
+  /**
+   * The datacenter this policy considers local, or {@code null} if it has neither been configured
+   * explicitly nor inferred yet. When {@link #isLocalDcExplicit()} is {@code false}, this is the
+   * datacenter inferred from the first contacted node, which is only available once the policy has
+   * been initialized.
+   *
+   * @return the local datacenter name, or {@code null}.
+   */
+  public String getLocalDc() {
+    String dc = localDc;
+    return Strings.isNullOrEmpty(dc) ? null : dc;
+  }
+
+  /**
+   * The rack this policy considers local, or {@code null} if it has neither been configured
+   * explicitly nor inferred yet.
+   *
+   * @return the local rack name, or {@code null}.
+   */
+  public String getLocalRack() {
+    String rack = localRack;
+    return Strings.isNullOrEmpty(rack) ? null : rack;
+  }
+
+  /**
+   * Whether the local datacenter was configured explicitly (as opposed to being inferred from the
+   * first contacted node).
+   *
+   * @return {@code true} if the local datacenter was set explicitly.
+   */
+  public boolean isLocalDcExplicit() {
+    return localDcExplicit;
+  }
+
+  /**
+   * Whether the local rack was configured explicitly (as opposed to being inferred from the first
+   * contacted node).
+   *
+   * @return {@code true} if the local rack was set explicitly.
+   */
+  public boolean isLocalRackExplicit() {
+    return localRackExplicit;
+  }
+
+  /**
+   * The number of hosts per remote datacenter that this policy considers for failover (0 means no
+   * remote failover).
+   *
+   * @return the number of used hosts per remote datacenter.
+   */
+  public int getUsedHostsPerRemoteDc() {
+    return usedHostsPerRemoteDc;
   }
 
   @Override