[dynamic control] Add identity to existing policy classes (open-telemetry#2942)

Author: jackshirazi

dynamic-control/src/main/java/io/opentelemetry/contrib/dynamic/policy/tracesampling/TraceSamplingRatePolicy.java

@@ -7,6 +7,7 @@
 
 import io.opentelemetry.contrib.dynamic.policy.PolicyImplementer;
 import io.opentelemetry.contrib.dynamic.policy.TelemetryPolicy;
+import io.opentelemetry.contrib.dynamic.policy.TelemetryPolicyIdentity;
 import io.opentelemetry.contrib.dynamic.policy.registry.PolicyInit;
 import io.opentelemetry.sdk.autoconfigure.spi.AutoConfigurationCustomizer;
 import io.opentelemetry.sdk.extension.incubator.trace.samplers.ComposableSampler;
@@ -17,16 +18,24 @@
 
 public final class TraceSamplingRatePolicy extends TelemetryPolicy {
   public static final String POLICY_TYPE = "trace-sampling";
+  public static final TelemetryPolicyIdentity DEFAULT_IDENTITY =
+      new TelemetryPolicyIdentity("trace-sampling", "Trace sampling rate");
 
   @Nullable private static volatile DelegatingSampler initializedSampler;
 
+  private final TelemetryPolicyIdentity identity;
   private final double probability;
 
   public TraceSamplingRatePolicy(double probability) {
     super(POLICY_TYPE);
+    this.identity = DEFAULT_IDENTITY;
     this.probability = normalizeProbability(probability);
   }
 
+  public TelemetryPolicyIdentity getIdentity() {
+    return identity;
+  }
+
   public double getProbability() {
     return probability;
   }
@@ -90,11 +99,13 @@ public boolean equals(Object obj) {
       return false;
     }
     TraceSamplingRatePolicy that = (TraceSamplingRatePolicy) obj;
-    return Double.compare(probability, that.probability) == 0;
+    return Double.compare(probability, that.probability) == 0 && identity.equals(that.identity);
   }
 
   @Override
   public int hashCode() {
-    return Double.hashCode(probability);
+    int result = identity.hashCode();
+    result = 31 * result + Double.hashCode(probability);
+    return result;
   }
 }

dynamic-control/src/test/java/io/opentelemetry/contrib/dynamic/policy/tracesampling/TraceSamplingRatePolicyTest.java

@@ -21,6 +21,7 @@ class TraceSamplingRatePolicyTest {
   void constructorStoresProbabilityAndType() {
     TraceSamplingRatePolicy policy = new TraceSamplingRatePolicy(0.25);
 
+    assertThat(policy.getIdentity()).isEqualTo(TraceSamplingRatePolicy.DEFAULT_IDENTITY);
     assertThat(policy.getProbability()).isEqualTo(0.25);
     assertThat(policy.getType()).isEqualTo(TraceSamplingRatePolicy.POLICY_TYPE);
   }

dynamic-control/src/test/java/io/opentelemetry/contrib/dynamic/policy/tracesampling/TraceSamplingValidatorTest.java

@@ -34,6 +34,8 @@ void testValidate_ValidJson() {
     assertThat(policy).isNotNull();
     assertThat(policy.getType()).isEqualTo(TRACE_SAMPLING_POLICY_TYPE);
     assertThat(policy).isInstanceOf(TraceSamplingRatePolicy.class);
+    assertThat(((TraceSamplingRatePolicy) policy).getIdentity())
+        .isEqualTo(TraceSamplingRatePolicy.DEFAULT_IDENTITY);
     assertThat(((TraceSamplingRatePolicy) policy).getProbability()).isCloseTo(0.5, within(1e-9));
   }
 
@@ -61,6 +63,8 @@ void testValidate_ValidJson_LegacyObjectShapeWithProbabilityField() {
     assertThat(policy).isNotNull();
     assertThat(policy.getType()).isEqualTo(TRACE_SAMPLING_POLICY_TYPE);
     assertThat(policy).isInstanceOf(TraceSamplingRatePolicy.class);
+    assertThat(((TraceSamplingRatePolicy) policy).getIdentity())
+        .isEqualTo(TraceSamplingRatePolicy.DEFAULT_IDENTITY);
     assertThat(((TraceSamplingRatePolicy) policy).getProbability()).isCloseTo(0.5, within(1e-9));
   }
 
@@ -121,6 +125,8 @@ void testValidate_ValidKeyValue() {
     assertThat(policy).isNotNull();
     assertThat(policy.getType()).isEqualTo(TRACE_SAMPLING_POLICY_TYPE);
     assertThat(policy).isInstanceOf(TraceSamplingRatePolicy.class);
+    assertThat(((TraceSamplingRatePolicy) policy).getIdentity())
+        .isEqualTo(TraceSamplingRatePolicy.DEFAULT_IDENTITY);
     assertThat(((TraceSamplingRatePolicy) policy).getProbability()).isCloseTo(0.5, within(1e-9));
   }