Add long_running_traces.json to flare report

Synchronized accesses to traceArray in LongRunningTracesTracker
since the flare reporter can now access the array. This shouldn't
be a concern for blocking because addTrace and flushAndCompact are
the existing calls from PendingTraceBuffer's run() loop and
getTracesAsJson is called by the reporter thread and will complete
fairly quickly.

Author: deejgregor

dd-trace-core/src/main/java/datadog/trace/core/LongRunningTracesTracker.java

@@ -3,12 +3,16 @@
 import datadog.communication.ddagent.DDAgentFeaturesDiscovery;
 import datadog.communication.ddagent.SharedCommunicationObjects;
 import datadog.trace.api.Config;
+import datadog.trace.api.flare.TracerFlare;
+import datadog.trace.common.writer.TraceDumpJsonExporter;
 import datadog.trace.core.monitor.HealthMetrics;
+import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.TimeUnit;
+import java.util.zip.ZipOutputStream;
 
-public class LongRunningTracesTracker {
+public class LongRunningTracesTracker implements TracerFlare.Reporter {
   private final DDAgentFeaturesDiscovery features;
   private final HealthMetrics healthMetrics;
   private long lastFlushMilli = 0;
@@ -41,6 +45,8 @@ public LongRunningTracesTracker(
         (int) TimeUnit.SECONDS.toMillis(config.getLongRunningTraceFlushInterval());
     this.features = sharedCommunicationObjects.featuresDiscovery(config);
     this.healthMetrics = healthMetrics;
+
+    TracerFlare.addReporter(this);
   }
 
   public boolean add(PendingTraceBuffer.Element element) {
@@ -56,7 +62,7 @@ public boolean add(PendingTraceBuffer.Element element) {
     return true;
   }
 
-  private void addTrace(PendingTrace trace) {
+  private synchronized void addTrace(PendingTrace trace) {
     if (trace.empty()) {
       return;
     }
@@ -67,7 +73,7 @@ private void addTrace(PendingTrace trace) {
     traceArray.add(trace);
   }
 
-  public void flushAndCompact(long nowMilli) {
+  public synchronized void flushAndCompact(long nowMilli) {
     if (nowMilli < lastFlushMilli + TimeUnit.SECONDS.toMillis(1)) {
       return;
     }
@@ -139,4 +145,18 @@ private void flushStats() {
     write = 0;
     expired = 0;
   }
+
+  public synchronized String getTracesAsJson() {
+    try (TraceDumpJsonExporter writer = new TraceDumpJsonExporter()) {
+      for (PendingTrace trace : traceArray) {
+        writer.write(trace.getSpans());
+      }
+      return writer.getDumpJson();
+    }
+  }
+
+  @Override
+  public void addReportToFlare(ZipOutputStream zip) throws IOException {
+    TracerFlare.addText(zip, "long_running_traces.txt", getTracesAsJson());
+  }
 }

dd-trace-core/src/main/java/datadog/trace/core/PendingTraceBuffer.java

@@ -54,6 +54,7 @@ public interface Element {
   }
 
   private static class DelayingPendingTraceBuffer extends PendingTraceBuffer {
+    private static final Logger LOGGER = LoggerFactory.getLogger(DelayingPendingTraceBuffer.class);
     private static final long FORCE_SEND_DELAY_MS = TimeUnit.SECONDS.toMillis(5);
     private static final long SEND_DELAY_NS = TimeUnit.MILLISECONDS.toNanos(500);
     private static final long SLEEP_TIME_MS = 100;
@@ -315,6 +316,17 @@ public void run() {
       }
     }
 
+    @Override
+    public String getTracesAsJson() throws IOException {
+      dumpTraces();
+      String json = getDumpJson();
+      if (json.isEmpty()) {
+        return "[]";
+      } else {
+        return json;
+      }
+    }
+
     public DelayingPendingTraceBuffer(
         int bufferSize,
         TimeSource timeSource,
@@ -350,6 +362,11 @@ public void enqueue(Element pendingTrace) {
       log.debug(
           "PendingTrace enqueued but won't be reported. Root span: {}", pendingTrace.getRootSpan());
     }
+
+    @Override
+    public String getTracesAsJson() {
+      return "[]";
+    }
   }
 
   public static PendingTraceBuffer delaying(
@@ -374,6 +391,8 @@ public static PendingTraceBuffer discarding() {
 
   public abstract void enqueue(Element pendingTrace);
 
+  public abstract String getTracesAsJson() throws IOException;
+
   private static class TracerDump implements TracerFlare.Reporter {
     private final DelayingPendingTraceBuffer buffer;
 

dd-trace-core/src/test/groovy/datadog/trace/core/LongRunningTracesTrackerTest.groovy

@@ -192,4 +192,44 @@ class LongRunningTracesTrackerTest extends DDSpecification {
     PrioritySampling.USER_KEEP | 1 | LongRunningTracesTracker.WRITE_RUNNING_SPANS
     PrioritySampling.SAMPLER_KEEP | 1 | LongRunningTracesTracker.WRITE_RUNNING_SPANS
   }
+
+  def "getTracesAsJson with no traces"() {
+    when:
+    def json = tracker.getTracesAsJson()
+
+    then:
+    json == ""
+  }
+
+  def "getTracesAsJson with traces"() {
+    given:
+    def trace = newTraceToTrack()
+    tracker.add(trace)
+
+    when:
+    def json = tracker.getTracesAsJson()
+
+    then:
+    json != null
+    !json.isEmpty()
+    json.contains('"service"')
+    json.contains('"name"')
+  }
+
+  def "testing tracer flare dump with trace"() {
+    given:
+    def trace = newTraceToTrack()
+    tracker.add(trace)
+
+    when:
+    def entries = PendingTraceBufferTest.buildAndExtractZip()
+
+    then:
+    entries.size() == 1
+    entries.containsKey("long_running_traces.txt")
+
+    def jsonContent = entries["long_running_traces.txt"] as String
+    jsonContent.contains('"service"')
+    jsonContent.contains('"name"')
+  }
 }

dd-trace-core/src/test/groovy/datadog/trace/core/PendingTraceBufferTest.groovy

@@ -582,7 +582,7 @@ class PendingTraceBufferTest extends DDSpecification {
     return DDSpan.create("test", 0, context, null)
   }
 
-  def buildAndExtractZip() {
+  def static buildAndExtractZip() {
     TracerFlare.prepareForFlare()
     def out = new ByteArrayOutputStream()
     try (ZipOutputStream zip = new ZipOutputStream(out)) {