add ..."metrics":{"_dd.measured":1}... to every span (#1336)

* add ..."metrics":{"_dd.measured":1}... to every span

* update tests to always have "metrics":{"_dd.measured":1} in every span

Authored-by: Lev Priima <lev.priima@data.dog>

dd-trace-api/src/main/java/datadog/trace/api/Config.java

@@ -837,7 +837,7 @@ public class Config {
    * @return
    * @deprecated This method should only be used internally. Use the explicit getter instead.
    */
-  public static String getSettingFromEnvironment(final String name, final String defaultValue) {
+  private static String getSettingFromEnvironment(final String name, final String defaultValue) {
     String value;
 
     // System properties and properties provided from command line have the highest precedence

dd-trace-ot/src/main/java/datadog/opentracing/DDSpanContext.java

@@ -25,8 +25,11 @@ public class DDSpanContext implements io.opentracing.SpanContext {
   public static final String PRIORITY_SAMPLING_KEY = "_sampling_priority_v1";
   public static final String SAMPLE_RATE_KEY = "_sample_rate";
   public static final String ORIGIN_KEY = "_dd.origin";
+  public static final String DD_MEASURED = "_dd.measured";
+  public static final Number DD_MEASURED_DEFAULT = 1;
 
-  private static final Map<String, Number> EMPTY_METRICS = Collections.emptyMap();
+  private static final Map<String, Number> DEFAULT_METRICS =
+      Collections.singletonMap(DD_MEASURED, DD_MEASURED_DEFAULT);
 
   // Shared with other span contexts
   /** For technical reasons, the ref to the original tracer */
@@ -307,12 +310,12 @@ public class DDSpanContext implements io.opentracing.SpanContext {
 
   public Map<String, Number> getMetrics() {
     final Map<String, Number> metrics = this.metrics.get();
-    return metrics == null ? EMPTY_METRICS : metrics;
+    return metrics == null ? DEFAULT_METRICS : metrics;
   }
 
   public void setMetric(final String key, final Number value) {
     if (metrics.get() == null) {
-      metrics.compareAndSet(null, new ConcurrentHashMap<String, Number>());
+      metrics.compareAndSet(null, new ConcurrentHashMap<>(DEFAULT_METRICS));
     }
     if (value instanceof Float) {
       metrics.get().put(key, value.doubleValue());

dd-trace-ot/src/test/groovy/datadog/opentracing/DDSpanSerializationTest.groovy

@@ -20,6 +20,7 @@ class DDSpanSerializationTest extends DDSpecification {
     def jsonAdapter = new Moshi.Builder().build().adapter(Map)
 
     final Map<String, Number> metrics = ["_sampling_priority_v1": 1]
+    metrics.putAll(DDSpanContext.DEFAULT_METRICS)
     if (samplingPriority == PrioritySampling.UNSET) {  // RateByServiceSampler sets priority
       metrics.put("_dd.agent_psr", 1.0d)
     }

dd-trace-ot/src/test/groovy/datadog/opentracing/decorators/SpanDecoratorTest.groovy

@@ -279,10 +279,13 @@ class SpanDecoratorTest extends DDSpecification {
 
   def "span metrics starts empty but added with rate limiting value of #rate"() {
     expect:
-    span.metrics == [:]
+    span.metrics == DDSpanContext.DEFAULT_METRICS
 
     when:
     span.setTag(ANALYTICS_SAMPLE_RATE, rate)
+    // these 2 lines to avoid checking for {@code DDSpanContext.DD_MEASURED} for every metric:
+    span.context().setMetric(DDSpanContext.DD_MEASURED, 42)
+    span.metrics.remove(DDSpanContext.DD_MEASURED, 42)
 
     then:
     span.metrics == result

dd-trace-ot/src/test/groovy/datadog/trace/DDSpanContextTest.groovy

@@ -1,5 +1,6 @@
 package datadog.trace
 
+import datadog.opentracing.DDSpanContext
 import datadog.opentracing.SpanFactory
 import datadog.trace.api.DDTags
 import datadog.trace.util.test.DDSpecification
@@ -18,7 +19,7 @@ class DDSpanContextTest extends DDSpecification {
     context.serviceName == "fakeService"
     context.resourceName == "fakeResource"
     context.spanType == "fakeType"
-    context.toString() == "DDSpan [ t_id=1, s_id=1, p_id=0] trace=fakeService/fakeOperation/fakeResource metrics={} *errored* tags={${extra}${tags.containsKey(DDTags.SPAN_TYPE) ? "span.type=${context.getSpanType()}, " : ""}thread.id=${Thread.currentThread().id}, thread.name=${Thread.currentThread().name}}"
+    context.toString() == "DDSpan [ t_id=1, s_id=1, p_id=0] trace=fakeService/fakeOperation/fakeResource metrics=${defaultMetrics()} *errored* tags={${extra}${tags.containsKey(DDTags.SPAN_TYPE) ? "span.type=${context.getSpanType()}, " : ""}thread.id=${Thread.currentThread().id}, thread.name=${Thread.currentThread().name}}"
 
     where:
     name                 | extra             | tags
@@ -35,7 +36,7 @@ class DDSpanContextTest extends DDSpecification {
     def thread = Thread.currentThread()
 
     def expectedTags = [(DDTags.THREAD_NAME): thread.name, (DDTags.THREAD_ID): thread.id]
-    def expectedTrace = "DDSpan [ t_id=1, s_id=1, p_id=0] trace=$details metrics={} tags={thread.id=$thread.id, thread.name=$thread.name}"
+    def expectedTrace = "DDSpan [ t_id=1, s_id=1, p_id=0] trace=$details metrics=${defaultMetrics()} tags={thread.id=$thread.id, thread.name=$thread.name}"
 
     expect:
     context.getTags() == expectedTags
@@ -61,7 +62,7 @@ class DDSpanContextTest extends DDSpecification {
       (DDTags.THREAD_NAME): thread.name,
       (DDTags.THREAD_ID)  : thread.id
     ]
-    context.toString() == "DDSpan [ t_id=1, s_id=1, p_id=0] trace=fakeService/fakeOperation/fakeResource metrics={} tags={$name=$value, thread.id=$thread.id, thread.name=$thread.name}"
+    context.toString() == "DDSpan [ t_id=1, s_id=1, p_id=0] trace=fakeService/fakeOperation/fakeResource metrics=${defaultMetrics()} tags={$name=$value, thread.id=$thread.id, thread.name=$thread.name}"
 
     where:
     name             | value
@@ -98,4 +99,8 @@ class DDSpanContextTest extends DDSpecification {
     Double  | 0.5d
     Integer | 0x55
   }
+
+  static String defaultMetrics() {
+    return DDSpanContext.DEFAULT_METRICS
+  }
 }

dd-trace-ot/src/test/groovy/datadog/trace/api/writer/DDAgentApiTest.groovy

@@ -2,6 +2,7 @@ package datadog.trace.api.writer
 
 import com.fasterxml.jackson.core.type.TypeReference
 import com.fasterxml.jackson.databind.ObjectMapper
+import datadog.opentracing.DDSpanContext
 import datadog.opentracing.SpanFactory
 import datadog.trace.common.writer.ddagent.DDAgentApi
 import datadog.trace.common.writer.ddagent.DDAgentResponseListener
@@ -101,7 +102,8 @@ class DDAgentApiTest extends DDSpecification {
       "duration" : 0,
       "error"    : 0,
       "meta"     : ["thread.name": Thread.currentThread().getName(), "thread.id": "${Thread.currentThread().id}"],
-      "metrics"  : [:],
+      //TODO : use DDSpanContext.DD_MEASURED as a key
+      "metrics"  : ["_dd.measured": DDSpanContext.DD_MEASURED_DEFAULT],
       "name"     : "fakeOperation",
       "parent_id": 0,
       "resource" : "fakeResource",
@@ -115,7 +117,7 @@ class DDAgentApiTest extends DDSpecification {
       "duration" : 0,
       "error"    : 0,
       "meta"     : ["thread.name": Thread.currentThread().getName(), "thread.id": "${Thread.currentThread().id}"],
-      "metrics"  : [:],
+      "metrics"  : ["_dd.measured": DDSpanContext.DD_MEASURED_DEFAULT],
       "name"     : "fakeOperation",
       "parent_id": 0,
       "resource" : "my-resource",

dd-trace-ot/src/test/groovy/datadog/trace/api/writer/LoggingWriterTest.groovy

@@ -16,6 +16,6 @@ class LoggingWriterTest extends DDSpecification {
 
   def "test toString"() {
     expect:
-    writer.toString(sampleTrace).startsWith('[{"service":"fakeService","name":"fakeOperation","resource":"fakeResource","trace_id":1,"span_id":1,"parent_id":0,"start":1000,"duration":0,"type":"fakeType","error":0,"metrics":{},"meta":{')
+    writer.toString(sampleTrace).startsWith('[{"service":"fakeService","name":"fakeOperation","resource":"fakeResource","trace_id":1,"span_id":1,"parent_id":0,"start":1000,"duration":0,"type":"fakeType","error":0,"metrics":{"_dd.measured":1},"meta":{')
   }
 }