revert: "feat: remove opencensus (googleapis#834)" (googleapis#837)

This reverts commit f16c777.

google-http-client/pom.xml

@@ -16,6 +16,18 @@
   </description>
 
   <build>
+    <pluginManagement>
+      <plugins>
+        <plugin>
+          <groupId>org.apache.maven.plugins</groupId>
+          <artifactId>maven-dependency-plugin</artifactId>
+          <version>3.1.1</version>
+          <configuration>
+            <ignoredUnusedDeclaredDependencies>io.opencensus:opencensus-impl</ignoredUnusedDeclaredDependencies>
+          </configuration>
+        </plugin>
+      </plugins>
+    </pluginManagement>
     <plugins>
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
@@ -97,6 +109,10 @@
       <groupId>org.apache.httpcomponents</groupId>
       <artifactId>httpcore</artifactId>
     </dependency>
+    <dependency>
+      <groupId>com.google.code.findbugs</groupId>
+      <artifactId>jsr305</artifactId>
+    </dependency>
     <dependency>
       <groupId>com.google.guava</groupId>
       <artifactId>guava</artifactId>
@@ -105,6 +121,14 @@
       <groupId>com.google.j2objc</groupId>
       <artifactId>j2objc-annotations</artifactId>
     </dependency>
+    <dependency>
+      <groupId>io.opencensus</groupId>
+      <artifactId>opencensus-api</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>io.opencensus</groupId>
+      <artifactId>opencensus-contrib-http-util</artifactId>
+    </dependency>
 
     <dependency>
       <groupId>com.google.guava</groupId>
@@ -126,5 +150,15 @@
       <artifactId>mockito-all</artifactId>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>io.opencensus</groupId>
+      <artifactId>opencensus-impl</artifactId>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>io.opencensus</groupId>
+      <artifactId>opencensus-testing</artifactId>
+      <scope>test</scope>
+    </dependency>
   </dependencies>
 </project>

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

@@ -23,6 +23,11 @@
 import com.google.api.client.util.StreamingContent;
 import com.google.api.client.util.StringUtils;
 import com.google.common.util.concurrent.ThreadFactoryBuilder;
+import io.opencensus.common.Scope;
+import io.opencensus.contrib.http.util.HttpTraceAttributeConstants;
+import io.opencensus.trace.AttributeValue;
+import io.opencensus.trace.Span;
+import io.opencensus.trace.Tracer;
 import java.io.IOException;
 import java.io.InputStream;
 import java.util.Properties;
@@ -192,6 +197,9 @@ public final class HttpRequest {
   /** Sleeper. */
   private Sleeper sleeper = Sleeper.DEFAULT;
 
+  /** OpenCensus tracing component. */
+  private final Tracer tracer = OpenCensusUtils.getTracer();
+
   /**
    * Determines whether {@link HttpResponse#getContent()} of this request should return raw input
    * stream or not.
@@ -835,7 +843,13 @@ public HttpResponse execute() throws IOException {
     Preconditions.checkNotNull(requestMethod);
     Preconditions.checkNotNull(url);
 
+    Span span =
+        tracer
+            .spanBuilder(OpenCensusUtils.SPAN_NAME_HTTP_REQUEST_EXECUTE)
+            .setRecordEvents(OpenCensusUtils.isRecordEvent())
+            .startSpan();
     do {
+      span.addAnnotation("retry #" + (numRetries - retriesRemaining));
       // Cleanup any unneeded response from a previous iteration
       if (response != null) {
         response.ignore();
@@ -850,6 +864,10 @@ public HttpResponse execute() throws IOException {
       }
       // build low-level HTTP request
       String urlString = url.build();
+      addSpanAttribute(span, HttpTraceAttributeConstants.HTTP_METHOD, requestMethod);
+      addSpanAttribute(span, HttpTraceAttributeConstants.HTTP_HOST, url.getHost());
+      addSpanAttribute(span, HttpTraceAttributeConstants.HTTP_PATH, url.getRawPath());
+      addSpanAttribute(span, HttpTraceAttributeConstants.HTTP_URL, urlString);
 
       LowLevelHttpRequest lowLevelHttpRequest = transport.buildRequest(requestMethod, urlString);
       Logger logger = HttpTransport.LOGGER;
@@ -879,11 +897,14 @@ public HttpResponse execute() throws IOException {
       if (!suppressUserAgentSuffix) {
         if (originalUserAgent == null) {
           headers.setUserAgent(USER_AGENT_SUFFIX);
+          addSpanAttribute(span, HttpTraceAttributeConstants.HTTP_USER_AGENT, USER_AGENT_SUFFIX);
         } else {
           String newUserAgent = originalUserAgent + " " + USER_AGENT_SUFFIX;
           headers.setUserAgent(newUserAgent);
+          addSpanAttribute(span, HttpTraceAttributeConstants.HTTP_USER_AGENT, newUserAgent);
         }
       }
+      OpenCensusUtils.propagateTracingContext(span, headers);
 
       // headers
       HttpHeaders.serializeHeaders(headers, logbuf, curlbuf, logger, lowLevelHttpRequest);
@@ -967,8 +988,15 @@ public HttpResponse execute() throws IOException {
       lowLevelHttpRequest.setTimeout(connectTimeout, readTimeout);
       lowLevelHttpRequest.setWriteTimeout(writeTimeout);
 
+      // switch tracing scope to current span
+      @SuppressWarnings("MustBeClosedChecker")
+      Scope ws = tracer.withSpan(span);
+      OpenCensusUtils.recordSentMessageEvent(span, lowLevelHttpRequest.getContentLength());
       try {
         LowLevelHttpResponse lowLevelHttpResponse = lowLevelHttpRequest.execute();
+        if (lowLevelHttpResponse != null) {
+          OpenCensusUtils.recordReceivedMessageEvent(span, lowLevelHttpResponse.getContentLength());
+        }
         // Flag used to indicate if an exception is thrown before the response is constructed.
         boolean responseConstructed = false;
         try {
@@ -986,13 +1014,17 @@ public HttpResponse execute() throws IOException {
         if (!retryOnExecuteIOException
             && (ioExceptionHandler == null
                 || !ioExceptionHandler.handleIOException(this, retryRequest))) {
+          // static analysis shows response is always null here
+          span.end(OpenCensusUtils.getEndSpanOptions(null));
           throw e;
         }
         // Save the exception in case the retries do not work and we need to re-throw it later.
         executeException = e;
         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
@@ -1049,6 +1081,8 @@ 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.
       throw executeException;
@@ -1163,6 +1197,12 @@ public HttpRequest setSleeper(Sleeper sleeper) {
     return this;
   }
 
+  private static void addSpanAttribute(Span span, String key, String value) {
+    if (value != null) {
+      span.putAttribute(key, AttributeValue.stringAttributeValue(value));
+    }
+  }
+
   private static String getVersion() {
     String version = HttpRequest.class.getPackage().getImplementationVersion();
     // in a non-packaged environment (local), there's no implementation version to read