[Cronet] Hook up library loader, system proxy and network change notifier to 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.ConditionVariable;
+import android.os.Handler;
+import android.os.Looper;
 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";
 
+    /**
+     * Synchronize access to mUrlRequestContextAdapter and shutdown routine.
+     */
+    private final Object mLock = new Object();
+    private final ConditionVariable mInitCompleted = new ConditionVariable(false);
+    private final AtomicInteger mActiveRequestCount = new AtomicInteger(0);
+
     private long mUrlRequestContextAdapter = 0;

[pauljensen, 2015/02/04 14:33:20]

nit: part of me feels like this variable would be better typed as a boolean so
we don't have so many comparisons to a magical "0".  Perhaps "boolean
mHaveUrlRequestContextAdapter" or "boolean
mUrlRequestContextAdapterInitialized".

[mmenke, 2015/02/04 16:18:25]

We do need the long to actually talk to the adapter, though, so if we went with
a bool, we'd need both the bool and this.

I'm not a big fan of redundant variables (The more things you have that have to
be kept consistent, the more chance you have of getting into an inconsistent
state).  Maybe a method?  private bool HaveRequestContextAdapter() { return
mUrlRequestContextAdapter != 0; }?

[pauljensen, 2015/02/04 16:22:11]

Oops, I didn't see the use of it to talk to the adaper, you can ignore my
comment, though I do like the use of a method to hide all the inlined constant
0's.

[mef, 2015/02/04 17:35:01]

Done.

     private Thread mNetworkThread;
-    private AtomicInteger mActiveRequestCount = new AtomicInteger(0);
 
     public CronetUrlRequestContext(Context context,
                                    UrlRequestContextConfig config) {
+        CronetLibraryLoader.ensureInitialized(context, config);
         nativeSetMinLogLevel(getLoggingLevel());
         mUrlRequestContextAdapter = nativeCreateRequestContextAdapter(
                 context, config.toString());
         if (mUrlRequestContextAdapter == 0) {
             throw new NullPointerException("Context Adapter creation failed");
         }
+
+        // Init native Chromium URLRequestContext on main UI thread.
+        Runnable task = new Runnable() {
+            @Override
+            public void run() {
+                synchronized (mLock) {
+                    // mUrlRequestContextAdapter is guaranteed to exist until
+                    // initialization on main and network threads completes and
+                    // initNetworkThread is called back on network thread.
+                    nativeInitRequestContextOnMainThread(mUrlRequestContextAdapter);
+                }
+            }
+        };
+        // Run task immediately or post it to the UI thread.
+        if (Looper.getMainLooper() == Looper.myLooper()) {
+            task.run();
+        } else {
+            new Handler(Looper.getMainLooper()).post(task);
+        }
     }
 
     @Override
     public UrlRequest createRequest(String url, UrlRequestListener listener,
                                     Executor executor) {
-        if (mUrlRequestContextAdapter == 0) {
-            throw new IllegalStateException(
-                    "Cannot create requests on shutdown context.");
+        synchronized (mLock) {
+            if (mUrlRequestContextAdapter == 0) {
+                throw new IllegalStateException("Context is shut down.");
+            }
+            return new CronetUrlRequest(this, mUrlRequestContextAdapter, url,
+                    UrlRequest.REQUEST_PRIORITY_MEDIUM, listener, executor);
         }
-        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.");
+        synchronized (mLock) {
+            if (mUrlRequestContextAdapter == 0) {
+                throw new IllegalStateException(
+                        "Context is already 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.");
+            }
         }
-        // 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.");
+        // Wait for init to complete on main and network thread (without lock,
+        // so other thread could access it).
+        mInitCompleted.block();
+
+        synchronized (mLock) {
+            // It is possible that adapter is already destroyed on another thread.
+            if (mUrlRequestContextAdapter == 0) {
+                return;
+            }
+            nativeDestroyRequestContextAdapter(mUrlRequestContextAdapter);
+            mUrlRequestContextAdapter = 0;
         }
-        nativeDestroyRequestContextAdapter(mUrlRequestContextAdapter);
-        mUrlRequestContextAdapter = 0;
     }
 
     @Override
     public void startNetLogToFile(String fileName) {
-        nativeStartNetLogToFile(mUrlRequestContextAdapter, fileName);
+        synchronized (mLock) {
+            if (mUrlRequestContextAdapter == 0) {
+                throw new IllegalStateException(
+                        "Context is shut down.");
+            }
+            nativeStartNetLogToFile(mUrlRequestContextAdapter, fileName);
+        }
     }
 
     @Override
     public void stopNetLog() {
-        nativeStopNetLog(mUrlRequestContextAdapter);
+        synchronized (mLock) {
+            if (mUrlRequestContextAdapter == 0) {
+                throw new IllegalStateException(
+                        "Context is shut down.");
+            }
+            nativeStopNetLog(mUrlRequestContextAdapter);
+        }
     }
 
     /**
      * 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.");
+        synchronized (mLock) {
+            if (mUrlRequestContextAdapter == 0) {
+                throw new IllegalStateException("Context is shut down.");
+            }
+            return mUrlRequestContextAdapter;
         }
-        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;
     }
 
     @SuppressWarnings("unused")
     @CalledByNative
     private void initNetworkThread() {
-        mNetworkThread = Thread.currentThread();
+        synchronized (mLock) {
+            mNetworkThread = Thread.currentThread();
+            mInitCompleted.open();
+        }
         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 nativeStartNetLogToFile(
             long urlRequestContextAdapter, String fileName);
 
     private native void nativeStopNetLog(long urlRequestContextAdapter);
 
     private native int nativeSetMinLogLevel(int loggingLevel);
+
+    private native void nativeInitRequestContextOnMainThread(
+            long urlRequestContextAdapter);
 }