Recording http metrics at host level (#1926)

* Recording http metrics at host level

* Always adding hsot

* Revert "Always adding hsot"

This reverts commit c02d008.

* reverting back to default views

Author: iamgr0ot

contrib/http_jaxrs/src/main/java/io/opencensus/contrib/http/jaxrs/JaxrsClientExtractor.java

@@ -44,7 +44,13 @@ public String getUrl(ClientRequestContext request) {
   @Nullable
   @Override
   public String getHost(ClientRequestContext request) {
-    return request.getUri().getHost();
+    if (request == null) {
+      return "null_request";
+    } else if (request.getUri() == null) {
+      return "null_uri";
+    } else {
+      return request.getUri().getHost();
+    }
   }
 
   @Nullable

contrib/http_util/src/main/java/io/opencensus/contrib/http/HttpClientHandler.java

@@ -18,6 +18,7 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 import static io.opencensus.contrib.http.HttpRequestContext.METADATA_NO_PROPAGATION;
+import static io.opencensus.contrib.http.util.HttpMeasureConstants.HTTP_CLIENT_HOST;
 import static io.opencensus.contrib.http.util.HttpMeasureConstants.HTTP_CLIENT_METHOD;
 import static io.opencensus.contrib.http.util.HttpMeasureConstants.HTTP_CLIENT_RECEIVED_BYTES;
 import static io.opencensus.contrib.http.util.HttpMeasureConstants.HTTP_CLIENT_ROUNDTRIP_LATENCY;
@@ -156,9 +157,15 @@ private void recordStats(HttpRequestContext context, @Nullable Q request, int ht
     double requestLatency = NANOSECONDS.toMillis(System.nanoTime() - context.requestStartTime);
 
     String methodStr = request == null ? "" : extractor.getMethod(request);
+    String host = request == null ? "null_request" : extractor.getHost(request);
+
     TagContext startCtx =
         tagger
             .toBuilder(context.tagContext)
+            .put(
+                HTTP_CLIENT_HOST,
+                TagValue.create(host == null ? "null_host" : host),
+                METADATA_NO_PROPAGATION)
             .put(
                 HTTP_CLIENT_METHOD,
                 TagValue.create(methodStr == null ? "" : methodStr),