Tracing: added request status codes and exceptions

After a request is completed, its status code (OK or ERROR) is added
to trace data, as well as exception information (if one occured).

Author: wprzytula

driver-core/src/main/java/com/datastax/driver/core/RequestHandler.java

@@ -281,6 +281,11 @@ private void setFinalResult(
         logServerWarnings(response.warnings);
       }
       callback.onSet(connection, response, info, statement, System.nanoTime() - startTime);
+
+      tracingInfo.setStatus(
+          response.type == Message.Response.Type.ERROR
+              ? TracingInfo.StatusCode.ERROR
+              : TracingInfo.StatusCode.OK);
       tracingInfo.tracingFinished();
     } catch (Exception e) {
       callback.onException(
@@ -290,6 +295,8 @@ private void setFinalResult(
           System.nanoTime() - startTime, /*unused*/
           0);
 
+      tracingInfo.recordException(e);
+      tracingInfo.setStatus(TracingInfo.StatusCode.ERROR, e.toString());
       tracingInfo.tracingFinished();
     }
   }
@@ -315,6 +322,8 @@ private void setFinalException(
 
     cancelPendingExecutions(execution);
 
+    tracingInfo.recordException(exception);
+    tracingInfo.setStatus(TracingInfo.StatusCode.ERROR, exception.toString());
     tracingInfo.tracingFinished();
 
     try {
@@ -327,6 +336,7 @@ private void setFinalException(
   // Triggered when an execution reaches the end of the query plan.
   // This is only a failure if there are no other running executions.
   private void reportNoMoreHosts(SpeculativeExecution execution) {
+    execution.parentTracingInfo.setStatus(TracingInfo.StatusCode.ERROR);
     execution.parentTracingInfo.tracingFinished();
     runningExecutions.remove(execution);
     if (runningExecutions.isEmpty())
@@ -669,6 +679,7 @@ void cancel() {
                 CancelledSpeculativeExecutionException.INSTANCE,
                 System.nanoTime() - startTime);
           }
+          parentTracingInfo.setStatus(TracingInfo.StatusCode.OK);
           parentTracingInfo.tracingFinished();
           return;
         } else if (!previous.inProgress
@@ -682,6 +693,7 @@ void cancel() {
                 CancelledSpeculativeExecutionException.INSTANCE,
                 System.nanoTime() - startTime);
           }
+          parentTracingInfo.setStatus(TracingInfo.StatusCode.OK);
           parentTracingInfo.tracingFinished();
           return;
         }
@@ -698,6 +710,7 @@ public Message.Request request() {
     @Override
     public void onSet(
         Connection connection, Message.Response response, long latency, int retryCount) {
+      currentChildTracingInfo.setStatus(TracingInfo.StatusCode.OK);
       currentChildTracingInfo.tracingFinished();
 
       QueryState queryState = queryStateRef.get();
@@ -1008,6 +1021,8 @@ public boolean onTimeout(Connection connection, long latency, int retryCount) {
     @Override
     public void onException(
         Connection connection, Exception exception, long latency, int retryCount) {
+      currentChildTracingInfo.recordException(exception);
+      currentChildTracingInfo.setStatus(TracingInfo.StatusCode.ERROR);
       currentChildTracingInfo.tracingFinished();
 
       QueryState queryState = queryStateRef.get();
@@ -1047,6 +1062,7 @@ public void onException(
 
     @Override
     public boolean onTimeout(Connection connection, long latency, int retryCount) {
+      currentChildTracingInfo.setStatus(TracingInfo.StatusCode.ERROR, "timeout");
       currentChildTracingInfo.tracingFinished();
 
       QueryState queryState = queryStateRef.get();
@@ -1090,11 +1106,13 @@ public int retryCount() {
     }
 
     private void setFinalException(Connection connection, Exception exception) {
+      parentTracingInfo.setStatus(TracingInfo.StatusCode.ERROR);
       parentTracingInfo.tracingFinished();
       RequestHandler.this.setFinalException(this, connection, exception);
     }
 
     private void setFinalResult(Connection connection, Message.Response response) {
+      parentTracingInfo.setStatus(TracingInfo.StatusCode.OK);
       parentTracingInfo.tracingFinished();
       RequestHandler.this.setFinalResult(this, connection, response);
     }

driver-core/src/main/java/com/datastax/driver/core/tracing/NoopTracingInfoFactory.java

@@ -22,6 +22,15 @@ private static class NoopTracingInfo implements TracingInfo {
     @Override
     public void setNameAndStartTime(String name) {}
 
+    @Override
+    public void recordException(Exception exception) {}
+
+    @Override
+    public void setStatus(StatusCode code, String description) {}
+
+    @Override
+    public void setStatus(StatusCode code) {}
+
     @Override
     public void tracingFinished() {}
   }

driver-core/src/main/java/com/datastax/driver/core/tracing/TracingInfo.java

@@ -22,6 +22,12 @@
  */
 public interface TracingInfo {
 
+  /** Final status of the traced execution. */
+  enum StatusCode {
+    OK,
+    ERROR,
+  }
+
   /**
    * Starts a span corresponding to this {@link TracingInfo} object. Must be called exactly once,
    * before any other method, at the beginning of the traced execution.
@@ -30,6 +36,28 @@ public interface TracingInfo {
    */
   void setNameAndStartTime(String name);
 
+  /**
+   * Records in the trace that the provided exception occured.
+   *
+   * @param exception the exception to be recorded.
+   */
+  void recordException(Exception exception);
+
+  /**
+   * Sets the final status of the traced execution.
+   *
+   * @param code the status code to be set.
+   */
+  void setStatus(StatusCode code);
+
+  /**
+   * Sets the final status of the traced execution, with additional description.
+   *
+   * @param code the status code to be set.
+   * @param description the additional description of the status.
+   */
+  void setStatus(StatusCode code, String description);
+
   /** Must be always called exactly once at the logical end of traced execution. */
   void tracingFinished();
 }