Revert "Add OpenCensus tracing instrument."

This reverts commit 2f67205.

Author: jeanbza

google-http-client/pom.xml

@@ -169,15 +169,5 @@
       <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

@@ -18,16 +18,11 @@
 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;
@@ -215,12 +210,6 @@ 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
@@ -865,9 +854,7 @@ 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();
@@ -911,8 +898,6 @@ public HttpResponse execute() throws IOException {
           headers.setUserAgent(originalUserAgent + " " + USER_AGENT_SUFFIX);
         }
       }
-      OpenCensusUtils.propagateTracingContext(headers);
-
       // headers
       HttpHeaders.serializeHeaders(headers, logbuf, curlbuf, logger, lowLevelHttpRequest);
       if (!suppressUserAgentSuffix) {
@@ -992,9 +977,6 @@ public HttpResponse execute() throws IOException {
 
       // execute
       lowLevelHttpRequest.setTimeout(connectTimeout, readTimeout);
-      // switch tracing scope to current span
-      @SuppressWarnings("MustBeClosedChecker")
-      Scope ws = tracer.withSpan(span);
       try {
         LowLevelHttpResponse lowLevelHttpResponse = lowLevelHttpRequest.execute();
         // Flag used to indicate if an exception is thrown before the response is constructed.
@@ -1020,8 +1002,6 @@ 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
@@ -1077,7 +1057,6 @@ 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.