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;
+import java.util.concurrent.atomic.AtomicInteger;
+
+/**
+ * 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;
+    private AtomicInteger mActiveRequestCount = new AtomicInteger(0);
+
+    public CronetUrlRequestContext(Context context,
+                                   UrlRequestContextConfig config) {
+        nativeSetMinLogLevel(getLoggingLevel());

[mmenke, 2014/11/06 17:31:29]

Does it really make sense to call this whenever we create a context, rather than
during startup or something?

[mef, 2014/11/06 22:51:47]

Good question. Theoretically log level could change over time. :)
Practically I think it is ok to do it during global initialization, along side
with porting Helen's changes for proxies, NCN, etc to the new interface.

+        mUrlRequestContextAdapter = nativeCreateRequestContextAdapter(
+                context, config.toString());
+        if (mUrlRequestContextAdapter == 0) {
+            throw new NullPointerException("Context Adapter creation failed");
+        }
+    }
+
+    @Override
+    public UrlRequest createRequest(String url, UrlRequestListener listener,
+                                    Executor executor) {
+        if (mUrlRequestContextAdapter == 0) {
+            throw new IllegalStateException(
+                    "Cannot create requests on shutdown context.");
+        }
+        return new CronetUrlRequest(this, mUrlRequestContextAdapter, url,
+                UrlRequest.REQUEST_PRIORITY_MEDIUM, listener, executor);
+    }
+
+    @Override
+    public boolean isEnabled() {
+        return Build.VERSION.SDK_INT >= 14;
+    }
+
+    @Override
+    public String getVersionString() {
+        return "Cronet/" + Version.getVersion();
+    }
+
+    @Override
+    public void shutdown() {
+        if (mActiveRequestCount.get() != 0) {
+            throw new IllegalStateException(
+                    "Cannot shutdown with active requests.");
+        }
+        // Destroying adapter stops the network thread, so it cannot be called
+        // on network thread.
+        if (Thread.currentThread() == mNetworkThread) {
+            throw new IllegalThreadStateException(
+                    "Cannot shutdown from network thread.");
+        }
+        nativeDestroyRequestContextAdapter(mUrlRequestContextAdapter);
+        mUrlRequestContextAdapter = 0;
+    }
+
+    /**
+     * Mark request as started to prevent shutdown when there are active
+     * requests.
+     */
+    void onRequestStarted(UrlRequest urlRequest) {
+        mActiveRequestCount.incrementAndGet();
+    }
+
+    /**
+     * Mark request as completed to allow shutdown when there are no active
+     * requests.
+     */
+    void onRequestDestroyed(UrlRequest urlRequest) {
+        mActiveRequestCount.decrementAndGet();
+    }
+
+    long getUrlRequestContextAdapter() {
+        if (mUrlRequestContextAdapter == 0) {
+            throw new IllegalStateException("Context Adapter is destroyed.");
+        }
+        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

[mmenke, 2014/11/06 17:31:29]

Why isn't @SuppressWarnings("unused") needed?

[mef, 2014/11/06 22:51:47]

Done.

+    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,
+            String config);
+
+    private native void nativeDestroyRequestContextAdapter(
+            long urlRequestContextAdapter);
+
+    private native void nativeInitializeStatistics();
+
+    private native String nativeGetStatisticsJSON(String filter);
+
+    private native void nativeStartNetLogToFile(
+            long urlRequestContextAdapter, String fileName);
+
+    private native void nativeStopNetLog(long urlRequestContextAdapter);
+
+    private native int nativeSetMinLogLevel(int loggingLevel);
+}