JVMCBC-823: Add a global portion to the core ID.

This changeset adds a fixed somewhat globally unique
32 bit integer to the core id so that it now consist
of a global and a local section.

This allows helping identify an instance across logs
but also distinguish multiple core instances inside
the same JVM.

Output changed from "coreId": 1 to
"coreId":"0x47215cfa00000001"

Change-Id: Ic71bbb0030563d28625b6987604e9304fcbd9c76
Reviewed-on: http://review.couchbase.org/122391
Tested-by: Build Bot <[email protected]>
Reviewed-by: Graham Pople <[email protected]>

Author: daschl

core-io/src/main/java/com/couchbase/client/core/Core.java

@@ -57,15 +57,18 @@
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 
+import java.security.SecureRandom;
 import java.time.Duration;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Map;
 import java.util.Optional;
+import java.util.Random;
 import java.util.Set;
+import java.util.UUID;
 import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.concurrent.atomic.AtomicBoolean;
-import java.util.concurrent.atomic.AtomicLong;
+import java.util.concurrent.atomic.AtomicInteger;
 import java.util.stream.Stream;
 
 import static com.couchbase.client.core.util.CbCollections.isNullOrEmpty;
@@ -81,10 +84,15 @@
 @Stability.Volatile
 public class Core {
 
+  /**
+   * A reasonably unique instance ID.
+   */
+  private static final int GLOBAL_ID = new SecureRandom().nextInt();
+
   /**
    * Counts up core ids for each new instance.
    */
-  private static final AtomicLong CORE_IDS = new AtomicLong();
+  private static final AtomicInteger CORE_IDS = new AtomicInteger();
 
   /**
    * Locates the right node for the KV service.
@@ -192,7 +200,7 @@ protected Core(final CoreEnvironment environment, final Authenticator authentica
     }
 
     this.seedNodes = seedNodes;
-    this.coreContext = new CoreContext(this, CORE_IDS.incrementAndGet(), environment, authenticator);
+    this.coreContext = new CoreContext(this, createInstanceId(), environment, authenticator);
     this.configurationProvider = createConfigurationProvider();
     this.nodes = new CopyOnWriteArrayList<>();
     this.eventBus = environment.eventBus();
@@ -205,6 +213,21 @@ protected Core(final CoreEnvironment environment, final Authenticator authentica
     eventBus.publish(new CoreCreatedEvent(coreContext, environment));
   }
 
+  /**
+   * Creates a (somewhat) globally unique ID for this instance.
+   * <p>
+   * The 64 bit long is split up into an upper and lower 32 bit halves. The upper half
+   * is reusing the same global ID for all instances while the lower half is always
+   * incrementing for each instance. So it has a global and a local component which can
+   * be used to correlate instances across logs but also help distinguish multiple
+   * instances in the same JVM.
+   *
+   * @return the created instance ID.
+   */
+  private long createInstanceId() {
+    return (((long) GLOBAL_ID) << 32) | (CORE_IDS.incrementAndGet() & 0xffffffffL);
+  }
+
   /**
    * During testing this can be overridden so that a custom configuration provider is used
    * in the system.

core-io/src/main/java/com/couchbase/client/core/CoreContext.java

@@ -125,7 +125,7 @@ public Core core() {
 
   @Override
   public void injectExportableParams(final Map<String, Object> input) {
-    input.put("coreId", id);
+    input.put("coreId", "0x" + Long.toHexString(id));
     alternateAddress.ifPresent(a -> input.put("alternateIdentifier", a));
   }
 

core-io/src/test/java/com/couchbase/client/core/CoreContextTest.java

@@ -47,7 +47,7 @@ void getAndExportProperties() {
     assertEquals(authenticator, ctx.authenticator());
 
     String result = ctx.exportAsString(Context.ExportFormat.JSON);
-    assertEquals("{\"coreId\":12345}", result);
+    assertEquals("{\"coreId\":\"0x3039\"}", result);
   }
 
   @Test