Restore "generate" method and add defaults for generateSpanId and generateTraceId

Author: worldtiki

core/src/main/java/com/expedia/www/haystack/client/idgenerators/IdGenerator.java

@@ -17,7 +17,25 @@
 package com.expedia.www.haystack.client.idgenerators;
 
 public interface IdGenerator {
-    Object generateTraceId();
 
-    Object generateSpanId();
+    /**
+     * Generates a unique id
+     * @deprecated This method was deprecated in 0.3.1. Use {@link #generateTraceId()}  and {@link #generateSpanId()} instead
+     */
+    @Deprecated
+    Object generate();
+
+    /**
+     * Generates a random unique identifier for a trace.
+     */
+    default Object generateTraceId() {
+        return generate();
+    }
+
+    /**
+     * Generates a random identifier for a span. It should be unique within a trace.
+     */
+    default Object generateSpanId() {
+        return generate();
+    }
 }

core/src/main/java/com/expedia/www/haystack/client/idgenerators/LongIdGenerator.java

@@ -16,20 +16,15 @@
  */
 package com.expedia.www.haystack.client.idgenerators;
 
-
-import com.expedia.www.haystack.client.idgenerators.IdGenerator;
-
 import java.util.concurrent.ThreadLocalRandom;
 
+/**
+ * Generates random and unique Longs as ids for Traces and Spans.
+ */
 public class LongIdGenerator implements IdGenerator {
 
     @Override
-    public Long generateTraceId() {
-        return ThreadLocalRandom.current().nextLong(Long.MAX_VALUE);
-    }
-
-    @Override
-    public Long generateSpanId() {
+    public Long generate() {
         return ThreadLocalRandom.current().nextLong(Long.MAX_VALUE);
     }
 }

core/src/main/java/com/expedia/www/haystack/client/idgenerators/RandomUUIDGenerator.java

@@ -19,10 +19,20 @@
 
 import java.util.UUID;
 
+/**
+ * Generates UUIDs as ids for Traces and Spans.
+ * <p/>
+ * Given that the span only needs to be unique within a trace, the UUID for spans will only contain the least
+ * significant bits and will be left padded with zeroes.
+ * <p/>
+ * Consider using the TimeBasedUUIDGenerator which is more performant.
+ * <p/>
+ * @see com.expedia.www.haystack.client.idgenerators.TimeBasedUUIDGenerator
+ */
 public class RandomUUIDGenerator implements IdGenerator {
 
     @Override
-    public UUID generateTraceId() {
+    public UUID generate() {
         return UUID.randomUUID();
     }
 

core/src/main/java/com/expedia/www/haystack/client/idgenerators/TimeBasedUUIDGenerator.java

@@ -17,19 +17,25 @@
 package com.expedia.www.haystack.client.idgenerators;
 
 
-import com.fasterxml.uuid.Generators;
-
 import java.util.UUID;
 
+import static com.fasterxml.uuid.Generators.timeBasedGenerator;
+
+/**
+ * Generates UUIDs as ids for Traces and Spans.
+ * <p/>
+ * Given that the span only needs to be unique within a trace, the UUID for spans will only contain the least
+ * significant bits and will be left padded with zeroes.
+ */
 public class TimeBasedUUIDGenerator implements IdGenerator {
 
     @Override
-    public UUID generateTraceId() {
-        return Generators.timeBasedGenerator().generate();
+    public UUID generate() {
+        return timeBasedGenerator().generate();
     }
 
     @Override
-    public Object generateSpanId() {
-        return Generators.timeBasedGenerator().generate();
+    public UUID generateSpanId() {
+        return new UUID(0, timeBasedGenerator().generate().getLeastSignificantBits());
     }
 }