Initial implementation of Cronet Async API.

components/cronet/android/java/src/org/chromium/net/CronetUrlRequestContext.java

+// Copyright 2014 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;
+
+import android.content.Context;
+import android.os.Build;
+import android.os.Process;
+import android.util.Log;
+
+import org.chromium.base.CalledByNative;
+import org.chromium.base.JNINamespace;
+
+import java.util.concurrent.Executor;
+
+/**
+ * UrlRequest context using Chromium HTTP stack implementation.
+ */
+@JNINamespace("cronet")
+public class CronetUrlRequestContext extends UrlRequestContext  {
+    private static final int LOG_NONE = 3;  // LOG(FATAL), no VLOG.
+    private static final int LOG_DEBUG = -1;  // LOG(FATAL...INFO), VLOG(1)
+    private static final int LOG_VERBOSE = -2;  // LOG(FATAL...INFO), VLOG(2)
+    static final String LOG_TAG = "ChromiumNetwork";
+
+    private long mUrlRequestContextAdapter = 0;
+    private Thread mNetworkThread;
+
+    public CronetUrlRequestContext(Context context,
+                                   UrlRequestContextConfig config) {
+        mUrlRequestContextAdapter = nativeCreateRequestContextAdapter(
+                context, getLoggingLevel(), config.toString());
+        if (mUrlRequestContextAdapter == 0) {
+            throw new NullPointerException("Context Adapter creation failed");
+        }
+    }
+
+    @Override
+    public UrlRequest createRequest(String url, UrlRequestListener listener,
+                                    Executor executor) {
+        return new CronetUrlRequest(this, url,
+                UrlRequest.REQUEST_PRIORITY_MEDIUM, listener, executor);
+    }
+
+    @Override
+    public boolean isEnabled() {
+        return Build.VERSION.SDK_INT >= 14;
+    }
+
+    @Override
+    public String getName() {
+        return "Cronet/" + Version.getVersion();
+    }
+
+    long getCronetUrlRequestContextAdapter() {

[xunjieli, 2014/10/23 14:04:33]

nit: is this method private or public?

[mef, 2014/10/24 03:31:45]

Package as it needs to be accessed by CronetUrlRequest.

+        return mUrlRequestContextAdapter;
+    }
+
+    /**
+     * @return loggingLevel see {@link #LOG_NONE}, {@link #LOG_DEBUG} and
+     *         {@link #LOG_VERBOSE}.
+     */
+    private int getLoggingLevel() {
+        int loggingLevel;
+        if (Log.isLoggable(LOG_TAG, Log.VERBOSE)) {
+            loggingLevel = LOG_VERBOSE;
+        } else if (Log.isLoggable(LOG_TAG, Log.DEBUG)) {
+            loggingLevel = LOG_DEBUG;
+        } else {
+            loggingLevel = LOG_NONE;
+        }
+        return loggingLevel;
+    }
+
+    @CalledByNative
+    private void initNetworkThread() {
+        mNetworkThread = Thread.currentThread();
+        Thread.currentThread().setName("ChromiumNet");
+        Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND);
+    }
+
+    // Native methods are implemented in cronet_url_request_context.cc.
+    private native long nativeCreateRequestContextAdapter(Context context,
+            int loggingLevel, String config);
+
+    private native void nativeReleaseRequestContextAdapter(
+            long urlRequestContextAdapter);

[mmenke, 2014/10/23 16:26:01]

This is never called.

Seems like we have two options:  Call it on finalize, or make a Shutdown method
- neither is great (And what happens to in-progress requests when Shutdown is
called?)

[mef, 2014/10/24 03:31:45]

Previous interface did it in finalize, but I guess that's discouraged, so I've
added an explicit 'shutdown' method.

Should we track (number) of open requests on Java side and throw an exception on
shutdown if that number is not 0,
or should we cancel them when shutdown is called? Later behavior may make it
easier to do bulk cancelation, but OTOH we don't notify listeners when request
is canceled...

[mmenke, 2014/10/24 03:46:19]

My suggestion is go with the exception, and if we need better behavior, can
implement it later (Easy to go from throwing an exception to being nice, not so
easy to go the other way around)

[mef, 2014/10/24 19:57:55]

Sounds good. We can also set a 'shutdown' flag, so new requests would not be
created,
but native release would only happen after all active requests are destroyed.

+
+    private native void nativeInitializeStatistics();
+
+    private native String nativeGetStatisticsJSON(String filter);
+
+    private native void nativeStartNetLogToFile(
+            long urlRequestContextAdapter, String fileName);
+
+    private native void nativeStopNetLog(long urlRequestContextAdapter);
+}