Cronet API Refactoring

components/cronet/android/java/src/org/chromium/net/impl/CronetEngineBase.java

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+package org.chromium.net.impl;
+
+import static org.chromium.net.UrlRequest.Builder.REQUEST_PRIORITY_HIGHEST;
+import static org.chromium.net.UrlRequest.Builder.REQUEST_PRIORITY_IDLE;
+import static org.chromium.net.UrlRequest.Builder.REQUEST_PRIORITY_LOW;
+import static org.chromium.net.UrlRequest.Builder.REQUEST_PRIORITY_LOWEST;
+import static org.chromium.net.UrlRequest.Builder.REQUEST_PRIORITY_MEDIUM;
+
+import android.support.annotation.IntDef;
+
+import org.chromium.net.BidirectionalStream;
+import org.chromium.net.CronetEngine;
+import org.chromium.net.ExperimentalCronetEngine;
+import org.chromium.net.UrlRequest;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.reflect.Constructor;
+import java.net.URL;
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.Executor;
+
+/**
+ * Base class of {@link CronetUrlRequestContext} and {@link JavaCronetEngine} that contains
+ * shared logic.
+ */
+public abstract class CronetEngineBase extends ExperimentalCronetEngine {
+    private static final String CRONET_URL_REQUEST_CONTEXT =
+            "org.chromium.net.impl.CronetUrlRequestContext";
+
+    /**
+     * Creates a {@link UrlRequest} object. All callbacks will
+     * be called on {@code executor}'s thread. {@code executor} must not run
+     * tasks on the current thread to prevent blocking networking operations
+     * and causing exceptions during shutdown.
+     *
+     * @param url {@link URL} for the request.
+     * @param callback callback object that gets invoked on different events.
+     * @param executor {@link Executor} on which all callbacks will be invoked.
+     * @param priority priority of the request which should be one of the
+     *         {@link UrlRequest.Builder#REQUEST_PRIORITY_IDLE REQUEST_PRIORITY_*}
+     *         values.
+     * @param requestAnnotations Objects to pass on to
+     *        {@link org.chromium.net.RequestFinishedInfo.Listener}.
+     * @param disableCache disables cache for the request.
+     *         If context is not set up to use cache this param has no effect.
+     * @param disableConnectionMigration disables connection migration for this
+     *         request if it is enabled for the session.
+     * @param allowDirectExecutor whether executors used by this request are permitted
+     *         to execute submitted tasks inline.
+     * @return new request.
+     */
+    protected abstract UrlRequestBase createRequest(String url, UrlRequest.Callback callback,
+            Executor executor, int priority, Collection<Object> requestAnnotations,
+            boolean disableCache, boolean disableConnectionMigration, boolean allowDirectExecutor);
+
+    public abstract BidirectionalStream createBidirectionalStream(String url,
+            BidirectionalStream.Callback callback, Executor executor, String httpMethod,
+            List<Map.Entry<String, String>> requestHeaders,
+            @BidirectionalStreamBuilderImpl.StreamPriority int priority,
+            boolean delayRequestHeadersUntilFirstFlush);
+
+    /**
+     * @return {@code true} if the engine is enabled.
+     */
+    public abstract boolean isEnabled();
+
+    static CronetEngine createCronetEngine(CronetEngineBuilderImpl builder) {
+        CronetEngine cronetEngine = null;
+        try {
+            Class<? extends CronetEngineBase> engineClass =
+                    builder.getContext()
+                            .getClassLoader()
+                            .loadClass(CRONET_URL_REQUEST_CONTEXT)
+                            .asSubclass(CronetEngineBase.class);
+            Constructor<? extends CronetEngineBase> constructor =
+                    engineClass.getConstructor(CronetEngineBuilderImpl.class);
+            CronetEngineBase possibleEngine = constructor.newInstance(builder);
+            if (possibleEngine.isEnabled()) {
+                cronetEngine = possibleEngine;
+            }
+        } catch (ClassNotFoundException e) {
+            // Leave as null.
+        } catch (Exception e) {
+            throw new IllegalStateException("Cannot instantiate: " + CRONET_URL_REQUEST_CONTEXT, e);
+        }
+        return cronetEngine;
+    }
+
+    @Override
+    public UrlRequest.Builder newUrlRequestBuilder(
+            String url, UrlRequest.Callback callback, Executor executor) {
+        return new UrlRequestBuilderImpl(url, callback, executor, this);
+    }
+
+    @IntDef({
+            REQUEST_PRIORITY_IDLE, REQUEST_PRIORITY_LOWEST, REQUEST_PRIORITY_LOW,
+            REQUEST_PRIORITY_MEDIUM, REQUEST_PRIORITY_HIGHEST,
+    })
+    @Retention(RetentionPolicy.SOURCE)
+    public @interface RequestPriority {}
+}