Rename trace exporters that have inconsistent naming. (#942)

* Rename trace exporters [Logging|Stackdriver|Zipkin]Exporter to [Logging|Stackdriver|Zipkin]TraceExporter.

* Add old [Logging|Stackdriver|Zipkin]Exporter back and deprecate them to maintain compatibility.

* Implement old trace exporters using renamed ones.

3 files changed, 175 insertions, 44 deletions

diff --git a/exporters/trace/stackdriver/src/main/java/io/opencensus/exporter/trace/stackdriver/StackdriverExporter.java b/exporters/trace/stackdriver/src/main/java/io/opencensus/exporter/trace/stackdriver/StackdriverExporter.java
index efe1c85b..2a77541f 100644
--- a/exporters/trace/stackdriver/src/main/java/io/opencensus/exporter/trace/stackdriver/StackdriverExporter.java
+++ b/exporters/trace/stackdriver/src/main/java/io/opencensus/exporter/trace/stackdriver/StackdriverExporter.java
@@ -16,18 +16,13 @@
 
 package io.opencensus.exporter.trace.stackdriver;
 
-import static com.google.common.base.Preconditions.checkState;
-
 import com.google.auth.Credentials;
 import com.google.auth.oauth2.GoogleCredentials;
 import com.google.cloud.ServiceOptions;
 import com.google.common.annotations.VisibleForTesting;
-import io.opencensus.trace.Tracing;
 import io.opencensus.trace.export.SpanExporter;
 import io.opencensus.trace.export.SpanExporter.Handler;
 import java.io.IOException;
-import javax.annotation.Nullable;
-import javax.annotation.concurrent.GuardedBy;
 
 /**
  * An OpenCensus span exporter implementation which exports data to Stackdriver Trace.
@@ -40,16 +35,12 @@ import javax.annotation.concurrent.GuardedBy;
  *   ... // Do work.
  * }
  * }</pre>
+ *
+ * @deprecated Deprecated due to inconsistent naming. Use {@link StackdriverTraceExporter}.
  */
+@Deprecated
 public final class StackdriverExporter {
 
-  private static final String REGISTER_NAME = StackdriverExporter.class.getName();
-  private static final Object monitor = new Object();
-
-  @GuardedBy("monitor")
-  @Nullable
-  private static Handler handler = null;
-
   /**
    * Creates and registers the Stackdriver Trace exporter to the OpenCensus library for an explicit
    * project ID and using explicit credentials. Only one Stackdriver exporter can be registered at
@@ -61,10 +52,7 @@ public final class StackdriverExporter {
    */
   public static void createAndRegisterWithCredentialsAndProjectId(
       Credentials credentials, String projectId) throws IOException {
-    synchronized (monitor) {
-      checkState(handler == null, "Stackdriver exporter is already registered.");
-      registerInternal(StackdriverV2ExporterHandler.createWithCredentials(credentials, projectId));
-    }
+    StackdriverTraceExporter.createAndRegisterWithCredentialsAndProjectId(credentials, projectId);
   }
 
   /**
@@ -85,10 +73,7 @@ public final class StackdriverExporter {
    * @throws IllegalStateException if a Stackdriver exporter is already registered.
    */
   public static void createAndRegisterWithProjectId(String projectId) throws IOException {
-    synchronized (monitor) {
-      checkState(handler == null, "Stackdriver exporter is already registered.");
-      registerInternal(StackdriverV2ExporterHandler.create(projectId));
-    }
+    StackdriverTraceExporter.createAndRegisterWithProjectId(projectId);
   }
 
   /**
@@ -109,17 +94,7 @@ public final class StackdriverExporter {
    * @throws IllegalStateException if a Stackdriver exporter is already registered.
    */
   public static void createAndRegister() throws IOException {
-    synchronized (monitor) {
-      checkState(handler == null, "Stackdriver exporter is already registered.");
-      registerInternal(StackdriverV2ExporterHandler.create(ServiceOptions.getDefaultProjectId()));
-    }
-  }
-
-  private static void registerInternal(Handler newHandler) {
-    synchronized (monitor) {
-      handler = newHandler;
-      register(Tracing.getExportComponent().getSpanExporter(), newHandler);
-    }
+    StackdriverTraceExporter.createAndRegister();
   }
 
   /**
@@ -129,7 +104,7 @@ public final class StackdriverExporter {
    */
   @VisibleForTesting
   static void register(SpanExporter spanExporter, Handler handler) {
-    spanExporter.registerHandler(REGISTER_NAME, handler);
+    StackdriverTraceExporter.register(spanExporter, handler);
   }
 
   /**
@@ -138,11 +113,7 @@ public final class StackdriverExporter {
    * @throws IllegalStateException if a Stackdriver exporter is not registered.
    */
   public static void unregister() {
-    synchronized (monitor) {
-      checkState(handler != null, "Stackdriver exporter is not registered.");
-      unregister(Tracing.getExportComponent().getSpanExporter());
-      handler = null;
-    }
+    StackdriverTraceExporter.unregister();
   }
 
   /**
@@ -153,7 +124,7 @@ public final class StackdriverExporter {
    */
   @VisibleForTesting
   static void unregister(SpanExporter spanExporter) {
-    spanExporter.unregisterHandler(REGISTER_NAME);
+    StackdriverTraceExporter.unregister(spanExporter);
   }
 
   private StackdriverExporter() {}
diff --git a/exporters/trace/stackdriver/src/main/java/io/opencensus/exporter/trace/stackdriver/StackdriverTraceExporter.java b/exporters/trace/stackdriver/src/main/java/io/opencensus/exporter/trace/stackdriver/StackdriverTraceExporter.java
new file mode 100644
index 00000000..6ad17c66
--- /dev/null
+++ b/exporters/trace/stackdriver/src/main/java/io/opencensus/exporter/trace/stackdriver/StackdriverTraceExporter.java
@@ -0,0 +1,160 @@
+/*
+ * Copyright 2017, OpenCensus Authors
+ *
+ * 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 io.opencensus.exporter.trace.stackdriver;
+
+import static com.google.common.base.Preconditions.checkState;
+
+import com.google.auth.Credentials;
+import com.google.auth.oauth2.GoogleCredentials;
+import com.google.cloud.ServiceOptions;
+import com.google.common.annotations.VisibleForTesting;
+import io.opencensus.trace.Tracing;
+import io.opencensus.trace.export.SpanExporter;
+import io.opencensus.trace.export.SpanExporter.Handler;
+import java.io.IOException;
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.GuardedBy;
+
+/**
+ * An OpenCensus span exporter implementation which exports data to Stackdriver Trace.
+ *
+ * <p>Example of usage on Google Cloud VMs:
+ *
+ * <pre>{@code
+ * public static void main(String[] args) {
+ *   StackdriverTraceExporter.createAndRegisterWithProjectId("MyStackdriverProjectId");
+ *   ... // Do work.
+ * }
+ * }</pre>
+ */
+public final class StackdriverTraceExporter {
+
+  private static final String REGISTER_NAME = StackdriverTraceExporter.class.getName();
+  private static final Object monitor = new Object();
+
+  @GuardedBy("monitor")
+  @Nullable
+  private static Handler handler = null;
+
+  /**
+   * Creates and registers the Stackdriver Trace exporter to the OpenCensus library for an explicit
+   * project ID and using explicit credentials. Only one Stackdriver exporter can be registered at
+   * any point.
+   *
+   * @param credentials a credentials used to authenticate API calls.
+   * @param projectId the cloud project id.
+   * @throws IllegalStateException if a Stackdriver exporter is already registered.
+   */
+  public static void createAndRegisterWithCredentialsAndProjectId(
+      Credentials credentials, String projectId) throws IOException {
+    synchronized (monitor) {
+      checkState(handler == null, "Stackdriver exporter is already registered.");
+      registerInternal(StackdriverV2ExporterHandler.createWithCredentials(credentials, projectId));
+    }
+  }
+
+  /**
+   * Creates and registers the Stackdriver Trace exporter to the OpenCensus library for an explicit
+   * project ID. Only one Stackdriver exporter can be registered at any point.
+   *
+   * <p>This uses the default application credentials see {@link
+   * GoogleCredentials#getApplicationDefault}.
+   *
+   * <p>This is equivalent with:
+   *
+   * <pre>{@code
+   * StackdriverExporter.createAndRegisterWithCredentialsAndProjectId(
+   *     GoogleCredentials.getApplicationDefault(), projectId);
+   * }</pre>
+   *
+   * @param projectId the cloud project id.
+   * @throws IllegalStateException if a Stackdriver exporter is already registered.
+   */
+  public static void createAndRegisterWithProjectId(String projectId) throws IOException {
+    synchronized (monitor) {
+      checkState(handler == null, "Stackdriver exporter is already registered.");
+      registerInternal(StackdriverV2ExporterHandler.create(projectId));
+    }
+  }
+
+  /**
+   * Creates and registers the Stackdriver Trace exporter to the OpenCensus library. Only one
+   * Stackdriver exporter can be registered at any point.
+   *
+   * <p>This uses the default application credentials see {@link
+   * GoogleCredentials#getApplicationDefault}.
+   *
+   * <p>This uses the default project ID configured see {@link ServiceOptions#getDefaultProjectId}.
+   *
+   * <p>This is equivalent with:
+   *
+   * <pre>{@code
+   * StackdriverExporter.createAndRegisterWithProjectId(ServiceOptions.getDefaultProjectId());
+   * }</pre>
+   *
+   * @throws IllegalStateException if a Stackdriver exporter is already registered.
+   */
+  public static void createAndRegister() throws IOException {
+    synchronized (monitor) {
+      checkState(handler == null, "Stackdriver exporter is already registered.");
+      registerInternal(StackdriverV2ExporterHandler.create(ServiceOptions.getDefaultProjectId()));
+    }
+  }
+
+  private static void registerInternal(Handler newHandler) {
+    synchronized (monitor) {
+      handler = newHandler;
+      register(Tracing.getExportComponent().getSpanExporter(), newHandler);
+    }
+  }
+
+  /**
+   * Registers the {@code StackdriverExporter}.
+   *
+   * @param spanExporter the instance of the {@code SpanExporter} where this service is registered.
+   */
+  @VisibleForTesting
+  static void register(SpanExporter spanExporter, Handler handler) {
+    spanExporter.registerHandler(REGISTER_NAME, handler);
+  }
+
+  /**
+   * Unregisters the Stackdriver Trace exporter from the OpenCensus library.
+   *
+   * @throws IllegalStateException if a Stackdriver exporter is not registered.
+   */
+  public static void unregister() {
+    synchronized (monitor) {
+      checkState(handler != null, "Stackdriver exporter is not registered.");
+      unregister(Tracing.getExportComponent().getSpanExporter());
+      handler = null;
+    }
+  }
+
+  /**
+   * Unregisters the {@code StackdriverExporter}.
+   *
+   * @param spanExporter the instance of the {@code SpanExporter} from where this service is
+   *     unregistered.
+   */
+  @VisibleForTesting
+  static void unregister(SpanExporter spanExporter) {
+    spanExporter.unregisterHandler(REGISTER_NAME);
+  }
+
+  private StackdriverTraceExporter() {}
+}
diff --git a/exporters/trace/stackdriver/src/test/java/io/opencensus/exporter/trace/stackdriver/StackdriverExporterTest.java b/exporters/trace/stackdriver/src/test/java/io/opencensus/exporter/trace/stackdriver/StackdriverTraceExporterTest.java
index 71790586..6a12a899 100644
--- a/exporters/trace/stackdriver/src/test/java/io/opencensus/exporter/trace/stackdriver/StackdriverExporterTest.java
+++ b/exporters/trace/stackdriver/src/test/java/io/opencensus/exporter/trace/stackdriver/StackdriverTraceExporterTest.java
@@ -29,9 +29,9 @@ import org.junit.runners.JUnit4;
 import org.mockito.Mock;
 import org.mockito.MockitoAnnotations;
 
-/** Unit tests for {@link StackdriverExporter}. */
+/** Unit tests for {@link StackdriverTraceExporter}. */
 @RunWith(JUnit4.class)
-public class StackdriverExporterTest {
+public class StackdriverTraceExporterTest {
   @Mock private SpanExporter spanExporter;
   @Mock private Handler handler;
 
@@ -42,12 +42,12 @@ public class StackdriverExporterTest {
 
   @Test
   public void registerUnregisterStackdriverExporter() {
-    StackdriverExporter.register(spanExporter, handler);
+    StackdriverTraceExporter.register(spanExporter, handler);
     verify(spanExporter)
         .registerHandler(
-            eq("io.opencensus.exporter.trace.stackdriver.StackdriverExporter"), same(handler));
-    StackdriverExporter.unregister(spanExporter);
+            eq("io.opencensus.exporter.trace.stackdriver.StackdriverTraceExporter"), same(handler));
+    StackdriverTraceExporter.unregister(spanExporter);
     verify(spanExporter)
-        .unregisterHandler(eq("io.opencensus.exporter.trace.stackdriver.StackdriverExporter"));
+        .unregisterHandler(eq("io.opencensus.exporter.trace.stackdriver.StackdriverTraceExporter"));
   }
 }