jni: update java library interfaces (#326)

Updating java library layer to conform to the streaming interfaces changes. Also, tweaks to make the java layer more consistent with the ObjC layer in envoyproxy/envoy-mobile#327

Signed-off-by: Alan Chiu <achiu@lyft.com>

For an explanation of how to fill out the fields, please see the relevant section
in [PULL_REQUESTS.md](https://github.com/envoyproxy/envoy/blob/master/PULL_REQUESTS.md)

Description: Updating java library interfaces
Risk Level: low
Testing: n/a
Docs Changes: n/a
Release Notes: n/a
[Optional Fixes #Issue]
[Optional Deprecated:]

Signed-off-by: JP Simard <jp@jpsim.com>

mobile/library/java/src/io/envoyproxy/envoymobile/engine/AndroidEngine.java → mobile/library/java/src/io/envoyproxy/envoymobile/engine/AndroidEngineImpl.java

@@ -2,22 +2,21 @@
 
 import android.content.Context;
 import android.net.ConnectivityManager;
-import io.envoyproxy.envoymobile.engine.types.EnvoyStatus;
 
-public class AndroidEngine {
+public class AndroidEngineImpl {
 
   // Internal reference to helper object used to load and initialize the native library.
   // Volatile to ensure double-checked locking works correctly.
-  private static volatile AndroidEngine loader = null;
+  private static volatile AndroidEngineImpl loader = null;
 
-  private final Engine engine;
+  private final EnvoyEngine envoyEngine;
 
   // Private helper class used by the load method to ensure the native library and its
   // dependencies are loaded and initialized at most once.
-  private AndroidEngine(Context context) {
+  private AndroidEngineImpl(Context context) {
     System.loadLibrary("envoy_jni");
     initialize((ConnectivityManager)context.getSystemService(Context.CONNECTIVITY_SERVICE));
-    engine = new EnvoyEngine();
+    envoyEngine = new EnvoyEngineImpl();
   }
 
   // Load and initialize Envoy and its dependencies, but only once.
@@ -26,17 +25,18 @@ public static void load(Context context) {
       return;
     }
 
-    synchronized (AndroidEngine.class) {
+    synchronized (AndroidEngineImpl.class) {
       if (loader != null) {
         return;
       }
 
-      loader = new AndroidEngine(context);
+      loader = new AndroidEngineImpl(context);
     }
   }
 
-  public static EnvoyStatus run(String config, String logLevel) {
-    return loader.engine.runEngine(config, logLevel);
+  public static int run(String config, String logLevel) {
+    // TODO: Resolve the static loader instance
+    return loader.envoyEngine.runWithConfig(config, logLevel);
   }
 
   private static native int initialize(ConnectivityManager connectivityManager);

mobile/library/java/src/io/envoyproxy/envoymobile/engine/BUILD

@@ -5,7 +5,7 @@ load("//bazel:kotlin_lib.bzl", "envoy_mobile_android_library", "envoy_mobile_jav
 envoy_mobile_android_library(
     name = "envoy_engine_lib",
     srcs = [
-        "AndroidEngine.java",
+        "AndroidEngineImpl.java",
     ],
     custom_package = "io.envoyproxy.envoymobile.engine",
     manifest = "AndroidEngineManifest.xml",
@@ -20,8 +20,9 @@ envoy_mobile_android_library(
 envoy_mobile_java_library(
     name = "envoy_base_engine_lib",
     srcs = [
-        "Engine.java",
         "EnvoyEngine.java",
+        "EnvoyEngineImpl.java",
+        "EnvoyStream.java",
         "JniLibrary.java",
     ],
     visibility = ["//visibility:public"],

mobile/library/java/src/io/envoyproxy/envoymobile/engine/EnvoyEngine.java

@@ -1,117 +1,30 @@
 package io.envoyproxy.envoymobile.engine;
 
-import io.envoyproxy.envoymobile.engine.types.EnvoyData;
-import io.envoyproxy.envoymobile.engine.types.EnvoyHeaders;
 import io.envoyproxy.envoymobile.engine.types.EnvoyObserver;
-import io.envoyproxy.envoymobile.engine.types.EnvoyStatus;
-import io.envoyproxy.envoymobile.engine.types.EnvoyStream;
 
-public class EnvoyEngine implements Engine {
+public interface EnvoyEngine {
   /**
-   * Open an underlying HTTP stream.
+   * Creates a new stream with the provided observer.
    *
-   * @param observer, the observer that will run the stream callbacks.
-   * @return EnvoyStream, with a stream handle and a success status, or a failure status.
+   * @param observer The observer for receiving callbacks from the stream.
+   * @return A stream that may be used for sending data.
    */
-  @Override
-  public EnvoyStream startStream(EnvoyObserver observer) {
-    // TODO: Implement
-    throw new UnsupportedOperationException("TODO: Implement me");
-  }
+  EnvoyStream startStream(EnvoyObserver observer);
 
   /**
-   * Send headers over an open HTTP stream. This method can be invoked once and needs to be called
-   * before send_data.
+   * Run the Envoy engine with the provided config and log level.
    *
-   * @param stream,    the stream to send headers over.
-   * @param headers,   the headers to send.
-   * @param endStream, supplies whether this is headers only.
-   * @return EnvoyStatus, the resulting status of the operation.
+   * @param config The configuration file with which to start Envoy.
+   * @return A status indicating if the action was successful.
    */
-  @Override
-  public EnvoyStatus sendHeaders(EnvoyStream stream, EnvoyHeaders headers, boolean endStream) {
-    // TODO: Implement
-    throw new UnsupportedOperationException("TODO: Implement me");
-  }
+  int runWithConfig(String config);
 
   /**
-   * Send data over an open HTTP stream. This method can be invoked multiple times.
+   * Run the Envoy engine with the provided config and log level.
    *
-   * @param stream,    the stream to send data over.
-   * @param data,      the data to send.
-   * @param endStream, supplies whether this is the last data in the stream.
-   * @return EnvoyStatus, the resulting status of the operation.
+   * @param config   The configuration file with which to start Envoy.
+   * @param logLevel The log level to use when starting Envoy.
+   * @return int A status indicating if the action was successful.
    */
-  @Override
-  public EnvoyStatus sendData(EnvoyStream stream, EnvoyData data, boolean endStream) {
-    // TODO: Implement
-    throw new UnsupportedOperationException("TODO: Implement me");
-  }
-
-  /**
-   * Send metadata over an HTTP stream. This method can be invoked multiple times.
-   *
-   * @param stream,    the stream to send metadata over.
-   * @param metadata,  the metadata to send.
-   * @param endStream, supplies whether this is the last data in the stream.
-   * @return EnvoyStatus, the resulting status of the operation.
-   */
-  @Override
-  public EnvoyStatus sendMetadata(EnvoyStream stream, EnvoyHeaders metadata, boolean endStream) {
-    // TODO: Implement
-    throw new UnsupportedOperationException("TODO: Implement me");
-  }
-
-  /**
-   * Send trailers over an open HTTP stream. This method can only be invoked once per stream.
-   * Note that this method implicitly ends the stream.
-   *
-   * @param stream,   the stream to send trailers over.
-   * @param trailers, the trailers to send.
-   * @return EnvoyStatus, the resulting status of the operation.
-   */
-  @Override
-  public EnvoyStatus sendTrailers(EnvoyStream stream, EnvoyHeaders trailers) {
-    // TODO: Implement
-    throw new UnsupportedOperationException("TODO: Implement me");
-  }
-
-  /**
-   * Half-close an HTTP stream. The stream will be observable and may return further data
-   * via the observer callbacks. However, nothing further may be sent.
-   *
-   * @param stream, the stream to close.
-   * @return EnvoyStatus, the resulting status of the operation.
-   */
-  @Override
-  public EnvoyStatus locallyCloseStream(EnvoyStream stream) {
-    // TODO: Implement
-    throw new UnsupportedOperationException("TODO: Implement me");
-  }
-
-  /**
-   * Detach all observers from a stream and send an EnvoyStatuserrupt upstream if supported by
-   * transport.
-   *
-   * @param stream, the stream to evict.
-   * @return EnvoyStatus, the resulting status of the operation.
-   */
-  @Override
-  public EnvoyStatus resetStream(EnvoyStream stream) {
-    // TODO: Implement
-    throw new UnsupportedOperationException("TODO: Implement me");
-  }
-
-  /**
-   * External entry poEnvoyStatus for library.
-   *
-   * @param config,   the configuration blob to run envoy with.
-   * @param logLevel, the logging level to run envoy with.
-   * @return EnvoyStatus, the resulting status of the operation.
-   */
-  @Override
-  public EnvoyStatus runEngine(String config, String logLevel) {
-    int status = JniLibrary.runEngine(config, logLevel);
-    return status == 0 ? EnvoyStatus.ENVOY_SUCCESS : EnvoyStatus.ENVOY_FAILURE;
-  }
+  int runWithConfig(String config, String logLevel);
 }

mobile/library/java/src/io/envoyproxy/envoymobile/engine/EnvoyEngineImpl.java

@@ -0,0 +1,50 @@
+package io.envoyproxy.envoymobile.engine;
+
+import io.envoyproxy.envoymobile.engine.types.EnvoyObserver;
+
+public class EnvoyEngineImpl implements EnvoyEngine {
+
+  private final long engineHandle;
+
+  public EnvoyEngineImpl() { this.engineHandle = JniLibrary.initEngine(); }
+
+  /**
+   * Creates a new stream with the provided observer.
+   *
+   * @param observer The observer for receiving callbacks from the stream.
+   * @return A stream that may be used for sending data.
+   */
+  @Override
+  public EnvoyStream startStream(EnvoyObserver observer) {
+    long streamHandle = JniLibrary.initStream(engineHandle);
+    return new EnvoyStream(streamHandle, observer);
+  }
+
+  /**
+   * Run the Envoy engine with the provided config and log level.
+   *
+   * @param config The configuration file with which to start Envoy.
+   * @return A status indicating if the action was successful.
+   */
+  @Override
+  public int runWithConfig(String config) {
+    return runWithConfig(config, "info");
+  }
+
+  /**
+   * Run the Envoy engine with the provided config and log level.
+   *
+   * @param config   The configuration file with which to start Envoy.
+   * @param logLevel The log level to use when starting Envoy.
+   * @return int A status indicating if the action was successful.
+   */
+  @Override
+  public int runWithConfig(String config, String logLevel) {
+    try {
+      return JniLibrary.runEngine(config, logLevel);
+    } catch (Throwable throwable) {
+      // TODO: Need to have a way to log the exception somewhere
+      return 1;
+    }
+  }
+}