Add OpenCensus tracing instrumentation in google-http-client module.

google-http-client/pom.xml

@@ -164,5 +164,15 @@
       <artifactId>commons-codec</artifactId>
       <scope>provided</scope>
     </dependency>
+    <dependency>
+      <groupId>io.opencensus</groupId>
+      <artifactId>opencensus-api</artifactId>
+      <version>0.11.1</version>
+    </dependency>
+    <dependency>
+      <groupId>io.opencensus</groupId>
+      <artifactId>opencensus-contrib-http-util</artifactId>
+      <version>0.11.1</version>
+    </dependency>
   </dependencies>
 </project>

google-http-client/src/main/java/com/google/api/client/http/HttpRequest.java

@@ -18,11 +18,16 @@
 import com.google.api.client.util.IOUtils;
 import com.google.api.client.util.LoggingStreamingContent;
 import com.google.api.client.util.ObjectParser;
+import com.google.api.client.util.OpenCensusUtils;
 import com.google.api.client.util.Preconditions;
 import com.google.api.client.util.Sleeper;
 import com.google.api.client.util.StreamingContent;
 import com.google.api.client.util.StringUtils;
 
+import io.opencensus.common.Scope;
+import io.opencensus.trace.Span;
+import io.opencensus.trace.Tracer;
+
 import java.io.IOException;
 import java.io.InputStream;
 import java.util.concurrent.Callable;
@@ -210,6 +215,12 @@ static String executeAndGetValueOfSomeCustomHeader(HttpRequest request) {
   /** Sleeper. */
   private Sleeper sleeper = Sleeper.DEFAULT;
 
+  /** OpenCensus tracing component. */
+  private Tracer tracer = OpenCensusUtils.getTracer();
+
+  /** Prefix for tracing span name. */
+  private static final String traceSpanNamePrefix = "Sent." + HttpRequest.class.getName() + ".";
+
   /**
    * @param transport HTTP transport
    * @param requestMethod HTTP request method or {@code null} for none
@@ -854,7 +865,9 @@ public HttpResponse execute() throws IOException {
     Preconditions.checkNotNull(requestMethod);
     Preconditions.checkNotNull(url);
 
+    Span span = tracer.spanBuilder(traceSpanNamePrefix + "execute").startSpan();
     do {
+      span.addAnnotation("retry #" + numRetries);
       // Cleanup any unneeded response from a previous iteration
       if (response != null) {
         response.ignore();
@@ -898,6 +911,8 @@ public HttpResponse execute() throws IOException {
           headers.setUserAgent(originalUserAgent + " " + USER_AGENT_SUFFIX);
         }
       }
+      OpenCensusUtils.propagateTracingContext(headers);
+
       // headers
       HttpHeaders.serializeHeaders(headers, logbuf, curlbuf, logger, lowLevelHttpRequest);
       if (!suppressUserAgentSuffix) {
@@ -977,6 +992,8 @@ public HttpResponse execute() throws IOException {
 
       // execute
       lowLevelHttpRequest.setTimeout(connectTimeout, readTimeout);
+      // switch tracing scope to current span
+      Scope ws = tracer.withSpan(span);
       try {
         LowLevelHttpResponse lowLevelHttpResponse = lowLevelHttpRequest.execute();
         // Flag used to indicate if an exception is thrown before the response is constructed.
@@ -1002,6 +1019,8 @@ public HttpResponse execute() throws IOException {
         if (loggable) {
           logger.log(Level.WARNING, "exception thrown while executing request", e);
         }
+      } finally {
+        ws.close();
       }
 
       // Flag used to indicate if an exception is thrown before the response has completed
@@ -1057,6 +1076,7 @@ public HttpResponse execute() throws IOException {
         }
       }
     } while (retryRequest);
+    span.end(OpenCensusUtils.getEndSpanOptions(response == null ? null : response.getStatusCode()));
 
     if (response == null) {
       // Retries did not help resolve the execute exception, re-throw it.

google-http-client/src/main/java/com/google/api/client/util/OpenCensusUtils.java

@@ -0,0 +1,157 @@
+/*
+ * Copyright (c) 2018 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License
+ * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+package com.google.api.client.util;
+
+import com.google.api.client.http.HttpHeaders;
+import com.google.api.client.http.HttpResponse;
+import com.google.api.client.http.HttpStatusCodes;
+
+import io.opencensus.contrib.http.util.HttpPropagationUtil;
+import io.opencensus.trace.BlankSpan;
+import io.opencensus.trace.EndSpanOptions;
+import io.opencensus.trace.Span;
+import io.opencensus.trace.Status;
+import io.opencensus.trace.Tracer;
+import io.opencensus.trace.Tracing;
+import io.opencensus.trace.propagation.TextFormat;
+
+import java.io.IOException;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+import javax.annotation.Nullable;
+
+/**
+ * Utilities for Census monitoring and tracing.
+ *
+ * @since 1.24
+ * @author Hailong Wen
+ */
+public class OpenCensusUtils {
+
+  private static final Logger LOGGER = Logger.getLogger(OpenCensusUtils.class.getName());
+
+  /**
+   * OpenCensus tracing component.
+   * When no OpenCensus implementation is provided, it will return a no-op tracer.
+   */
+  static Tracer tracer = Tracing.getTracer();
+
+  /**
+   * {@link TextFormat} used in tracing context propagation.
+   */
+  @Nullable
+  static TextFormat propagationTextFormat = null;
+
+  /**
+   * {@link TextFormat.Setter} for {@link activeTextFormat}.
+   */
+  @Nullable
+  static TextFormat.Setter propagationTextFormatSetter = null;
+
+  /**
+   * Sets the {@link TextFormat} used in context propagation.
+   * @param textFormat the text format.
+   */
+  public static void setPropagationTextFormat(@Nullable TextFormat textFormat) {
+    propagationTextFormat = textFormat;
+  }
+
+  /**
+   * Sets the {@link TextFormat.Setter} used in context propagation.
+   * @param textFormatSetter the {@code TextFormat.Setter} for the text format.
+   */
+  public static void setPropagationTextFormatSetter(@Nullable TextFormat.Setter textFormatSetter) {
+    propagationTextFormatSetter = textFormatSetter;
+  }
+
+  /**
+   * Returns the tracing component of OpenCensus.
+   *
+   * @return the tracing component of OpenCensus.
+   */
+  public static Tracer getTracer() {
+    return tracer;
+  }
+
+  /**
+   * Propagate information of current tracing context. This information will be injected into HTTP
+   * header.
+   */
+  public static void propagateTracingContext(HttpHeaders headers) {
+    Preconditions.checkNotNull(headers);
+    if (propagationTextFormat != null && propagationTextFormatSetter != null) {
+      Span span = tracer.getCurrentSpan();
+      if (span != null && !span.equals(BlankSpan.INSTANCE)) {
+        propagationTextFormat.inject(span.getContext(), headers, propagationTextFormatSetter);
+      }
+    }
+  }
+
+  /**
+   * Returns an {@link EndSpanOptions} to end a http span according to the status code.
+   *
+   * @param statusCode the status code, can be null to represent no valid response is returned.
+   * @return an {@code EndSpanOptions} that best suits the status code.
+   */
+  public static EndSpanOptions getEndSpanOptions(@Nullable Integer statusCode) {
+    // Always sample the span, but optionally export it.
+    EndSpanOptions.Builder builder = EndSpanOptions.builder().setSampleToLocalSpanStore(true);
+    if (statusCode == null) {
+      builder.setStatus(Status.UNKNOWN);
+    } else if (!HttpStatusCodes.isSuccess(statusCode)) {
+      switch (statusCode) {
+        case HttpStatusCodes.STATUS_CODE_BAD_REQUEST:
+          builder.setStatus(Status.INVALID_ARGUMENT);
+          break;
+        case HttpStatusCodes.STATUS_CODE_UNAUTHORIZED:
+          builder.setStatus(Status.UNAUTHENTICATED);
+          break;
+        case HttpStatusCodes.STATUS_CODE_FORBIDDEN:
+          builder.setStatus(Status.PERMISSION_DENIED);
+          break;
+        case HttpStatusCodes.STATUS_CODE_NOT_FOUND:
+          builder.setStatus(Status.NOT_FOUND);
+          break;
+        case HttpStatusCodes.STATUS_CODE_PRECONDITION_FAILED:
+          builder.setStatus(Status.FAILED_PRECONDITION);
+          break;
+        case HttpStatusCodes.STATUS_CODE_SERVER_ERROR:
+          builder.setStatus(Status.UNAVAILABLE);
+          break;
+        default:
+          builder.setStatus(Status.UNKNOWN);
+      }
+    } else {
+      builder.setStatus(Status.OK);
+    }
+    return builder.build();
+  }
+
+  static {
+    try {
+      propagationTextFormat = HttpPropagationUtil.getCloudTraceFormat();
+      propagationTextFormatSetter = new TextFormat.Setter<HttpHeaders>() {
+        @Override
+        public void put(HttpHeaders carrier, String key, String value) {
+          carrier.set(key, value);
+        }
+      };
+    } catch (Exception e) {
+      LOGGER.log(Level.WARNING, "Cannot initiate OpenCensus modules, tracing disabled", e);
+    }
+  }
+
+  private OpenCensusUtils() {}
+}