projects/syncpingpong/PingPongApp/app/src/main/java/io/v/pingpongapp/MainActivity.java - release.java - Git at Google

 // Copyright 2016 The Vanadium 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 io.v.pingpongapp;

 import android.graphics.Color;
 import android.os.Bundle;
 import android.support.v7.app.AppCompatActivity;
 import android.util.Log;
 import android.view.View;
 import android.widget.Button;
 import android.widget.TextView;

 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.util.concurrent.FutureCallback;
 import com.google.common.util.concurrent.Futures;

 import java.util.Arrays;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;

 import io.v.android.security.BlessingsManager;
 import io.v.android.v23.V;
 import io.v.impl.google.services.syncbase.SyncbaseServer;
 import io.v.v23.InputChannels;
 import io.v.v23.OptionDefs;
 import io.v.v23.Options;
 import io.v.v23.VIterable;
 import io.v.v23.context.VContext;
 import io.v.v23.rpc.Server;
 import io.v.v23.security.BlessingPattern;
 import io.v.v23.security.Blessings;
 import io.v.v23.security.access.AccessList;
 import io.v.v23.security.access.Constants;
 import io.v.v23.security.access.Permissions;
 import io.v.v23.services.syncbase.Id;
 import io.v.v23.services.syncbase.SyncgroupMemberInfo;
 import io.v.v23.services.syncbase.SyncgroupSpec;
 import io.v.v23.syncbase.Syncbase;
 import io.v.v23.syncbase.SyncbaseService;
 import io.v.v23.syncbase.Database;
 import io.v.v23.syncbase.Syncgroup;
 import io.v.v23.syncbase.Collection;
 import io.v.v23.syncbase.WatchChange;
 import io.v.v23.syncbase.util.Util;
 import io.v.v23.verror.VException;

 import static io.v.v23.VFutures.sync;

 public class MainActivity extends AppCompatActivity {
     // Syncgroup-related names for where the mounttable is and the syncgroup name's suffix.
     public static final String MT_PREFIX = "/ns.dev.v.io:8101/tmp/benchmark/pingpong/";
     public static final String SG_SUFFIX = "_sg";

     // Syncbase-related names for the db/cx hierarchy and where to write data.
     public static final String DB_NAME = "db";
     public static final String CX_NAME = "cx";

     // Allow each asynchronous operation to take at most this amount of time.
     private static final long TEST_TIMEOUT = 5;
     private static final TimeUnit TEST_TIMEUNIT = TimeUnit.SECONDS;

     // Fixed parameters for the app.
     private static final String TAG = "PingPong"; // Debug tag for Log.d
     private static final String TEST_ID = "AndroidPingPongTest";
     private static final int NUM_TIMES = 100;
     // Log success/failure once blessings are received.
     private static final FutureCallback<Blessings> ON_BLESSINGS = new FutureCallback<Blessings>() {
         @Override
         public void onSuccess(Blessings b) {
             Log.d(TAG, "Got blessings!");
         }

         @Override
         public void onFailure(Throwable t) {
             Log.d(TAG, "Failure to get blessings, nothing will work.", t);
         }
     };

     // The V context tracked by the app.
     VContext mBaseContext;
     // Values that can be changed by the app.
     private int mPeerID = 0;
     private Thread mTestThread;
     private boolean mUsingProxy = false;

     public static Permissions openPermissions() {
         AccessList acl = new AccessList(
                 ImmutableList.of(new BlessingPattern("...")), ImmutableList.<String>of());
         return new Permissions(ImmutableMap.of(
                 Constants.RESOLVE.getValue(), acl,
                 Constants.DEBUG.getValue(), acl,
                 Constants.READ.getValue(), acl,
                 Constants.WRITE.getValue(), acl,
                 Constants.ADMIN.getValue(), acl));
     }

     private String getMountPoint(String testID, int peerID) {
         return MT_PREFIX + testID + "/s" + peerID;
     }

     private String getSyncgroupName(String testID) {
         return testID + SG_SUFFIX;
     }

     // Helper to show default text before the test starts.
     private void setPreTestText() {
         String suffix = mUsingProxy ? " with proxy" : " w/o proxy";
         String prefix = mPeerID == 0 ? "Pinger: Hello World!" : "Ponger: Hello World!";
         updateText(prefix + suffix);
     }

     // Helper to change the text shown by the debug TextView.
     private void updateText(String data) {
         TextView tv = (TextView) findViewById(R.id.debug_text);
         tv.setText(data);
     }

     // Callback (from button press). Changes the text color between pinger and ponger.
     public void pingpongToggle(View view) {
         if (mTestThread == null) {
             Log.d(TAG, "Toggling peer ID!");
             mPeerID = 1 - mPeerID;
             setPreTestText();
             TextView tv = (TextView) findViewById(R.id.debug_text);
             tv.setTextColor(mPeerID == 0 ? Color.BLACK : Color.BLUE);
         }
     }

     // Callback (from button press). If not pressed yet, the proxy will be added to the listen spec.
     public void useProxy(View view) {
         // If we don't proxy, we can't communicate across networks.
         if (!mUsingProxy) {
             Log.d(TAG, "Using the proxy!");
             try {
                 mBaseContext = V.withListenSpec(mBaseContext,
                         V.getListenSpec(mBaseContext).withProxy("proxy"));
                 mUsingProxy = true;
                 setPreTestText();
                 ((Button) findViewById(R.id.useproxybutton)).setText(R.string.using_proxy);

             } catch (final VException e) {
                 Log.e(TAG, "Use proxy failed", e);
             }
         }
     }

     // Prepares an asynchronous fetch of blessings using the user account.
     // On some Android versions, this will open an account picker.
     private void setUpBlessings() {
         Log.d(TAG, "Attempting to get blessings.");

         Futures.addCallback(BlessingsManager.getBlessings(mBaseContext, this, "BlessingsKey", true),
                 ON_BLESSINGS);
     }

     // Folder where Syncbase will store its data.
     private String getDataDir() {
         return getApplicationContext().getApplicationInfo().dataDir + "/" + TEST_ID;
     }

     /**
      * Callback (from button press). If the test hasn't run yet, starts the test.
      * The protocol is:
      * 1. Create app hierarchy.
      * 2. Create syncgroup if pinger, else as ponger, join the syncgroup.
      * 3. If pinger, write some data to the store.
      * 4. Watch from the beginning of time. This watch loop will have the pinger write on odd watch
      * changes. and the ponger write when it sees even watch changes.
      * 5. After enough watches have been seen, the watch loop ends, and the statistics are printed.
      * The start time and end time are set during the watch loop.
      * We allow 1 round of free sync in order to initialize before the start time is recorded.
      *
      * @param view
      */
     public void startTestPingPong(final View view) {
         if (mTestThread == null) {
             ((Button) findViewById(R.id.pingpongbutton)).setText(R.string.running_ping_pong);

             Log.d(TAG, "Starting Syncbase Ping Pong Test!");
             mTestThread = new Thread() {
                 long startTime;
                 long endTime;

                 // Count starts at -2. (The first ping and first pong are not counted in the test.)
                 int count = -2;

                 @Override
                 public void run() {
                     try {
                         testPingPong();
                     } catch (ExecutionException | InterruptedException | TimeoutException |
                             VException e) {
                         Log.e(TAG, "Ping pong test failed", e);
                         mBaseContext.cancel();
                     }
                 }

                 public void testPingPong() throws InterruptedException, ExecutionException,
                         TimeoutException, VException {

                     Log.d(TAG, "Preparing Syncbase Server");
                     helpUpdateText("Preparing Syncbase Server");

                     // Create the syncbase server...
                     try {
                         mBaseContext = SyncbaseServer.withNewServer(mBaseContext,
                                 new SyncbaseServer.Params()
                                         .withPermissions(openPermissions())
                                         .withStorageRootDir(getDataDir())
                                         .withName(getMountPoint(TEST_ID, mPeerID)));
                     } catch (SyncbaseServer.StartException e) {
                         Log.d(TAG, e.toString());
                     }

                     Server syncbaseServer = io.v.v23.V.getServer(mBaseContext);


                     Log.d(TAG, "Preparing Syncbase Client");
                     helpUpdateText("Preparing Syncbase Client");

                     Log.d(TAG, Arrays.toString(syncbaseServer.getStatus().getEndpoints()));

                     // And the syncbase client, app, db, and table...
                     SyncbaseService service = Syncbase.newService(
                             "/" + syncbaseServer.getStatus().getEndpoints()[0]);

                     // Note: In order for the two apps to find each other, the collection and
                     // syncgroup both use "..." as the blessing portion of the id. This must match
                     // or else watch and syncgroup join will not work, and "..." is the simplest
                     // string they can have in common.
                     final Database db = service.getDatabase(mBaseContext, DB_NAME, null);
                     final Collection cx = db.getCollection(new Id("...", CX_NAME));
                     Log.d(TAG, "db exists?");
                     if (!syncWithTimeout(db.exists(mBaseContext))) {
                         Log.d(TAG, "db create");
                         syncWithTimeout(db.create(mBaseContext,
                                 Util.filterPermissionsByTags(openPermissions(),
                                         io.v.v23.services.syncbase.Constants.ALL_DATABASE_TAGS)));
                     }
                     Log.d(TAG, "cx exists?");
                     if (!syncWithTimeout(cx.exists(mBaseContext))) {
                         Log.d(TAG, "cx create");
                         syncWithTimeout(cx.create(mBaseContext,
                                 Util.filterPermissionsByTags(openPermissions(),
                                         io.v.v23.services.syncbase.Constants.ALL_COLLECTION_TAGS)));
                     }

                     Log.d(TAG, "I am peer " + mPeerID);
                     helpUpdateText("I am peer " + mPeerID);

                     // If you're peer 0, you should create the syncgroup. Otherwise, join it.
                     String sgName = getSyncgroupName(TEST_ID);
                     String mtPointName = MT_PREFIX + "/" + TEST_ID;
                     Syncgroup group = db.getSyncgroup(new Id("...", sgName));

                     SyncgroupMemberInfo memberInfo = new SyncgroupMemberInfo();
                     memberInfo.setSyncPriority((byte) 3);
                     if (mPeerID == 0) {
                         Log.d(TAG, "Creating Syncgroup" + sgName);
                         helpUpdateText("Creating Syncgroup");

                         Permissions sgPerms = Util.filterPermissionsByTags(openPermissions(),
                                 io.v.v23.services.syncbase.Constants.ALL_SYNCGROUP_TAGS);

                         SyncgroupSpec spec = new SyncgroupSpec(
                                 TEST_ID, null, sgPerms,
                                 ImmutableList.of(cx.id()),
                                 ImmutableList.of(mtPointName), false);
                         syncWithTimeout(group.create(mBaseContext, spec, memberInfo));
                     } else {
                         Log.d(TAG, "Joining Syncgroup" + sgName);
                         helpUpdateText("Joining Syncgroup");
                         // Join at s0 or via the neighborhood.
                         syncWithTimeout(group.join(mBaseContext, getMountPoint(TEST_ID, 0),
                                 null, memberInfo));
                     }

                     // Now that we've all joined the syncgroup...
                     // We should synchronize our times.
                     Log.d(TAG, "We are now ready to time sync!");
                     helpUpdateText("We are now ready to time sync!");

                     // 0 will send to 1, and 1 responds via watch.
                     if (mPeerID == 0) {
                         writeData(cx);
                     }

                     watchForChanges(db, cx);

                     Log.d(TAG, "We finished!");
                     double delta = (endTime - startTime) / (NUM_TIMES * 1000000.);
                     Log.d(TAG, "Average Time: " + delta + " ms per ping pong iteration\n");
                     helpUpdateText("Average Time: " + delta + "ms per ping pong iteration!");
                 }

                 // Posts an action through the view to be run on the main thread.
                 // This is the only way we're allowed to change the UI from this Thread.
                 private void helpUpdateText(final String t) {
                     view.post(new Runnable() {
                         @Override
                         public void run() {
                             updateText(t);
                         }
                     });
                 }

                 private void watchForChanges(Database db, Collection cx) {
                     try {
                         VIterable<WatchChange> watchStream = InputChannels.asIterable(
                                 db.watch(mBaseContext, ImmutableList.of(
                                         Util.rowPrefixPattern(cx.id(), "")))
                         );

                         Log.d(TAG, "Starting watch");
                         // 0 will send to 1, and vice versa.
                         for (final WatchChange wc : watchStream) {
                             String key = wc.getRowName();
                             Integer value = (Integer)wc.getValue();
                             Log.d(TAG, "Watch: " + key + " " + value);
                             helpUpdateText("Watch: " + key + " " + value);
                             count++;

                             if (count == 0) {
                                 startTime = System.nanoTime();
                             }
                             if (count == NUM_TIMES * 2) {
                                 endTime = System.nanoTime();
                                 break;
                             }
                             if ((count + 2) % 2 == mPeerID) {
                                 writeData(cx);
                             }
                         }
                         Log.d(TAG, "Exiting watch");
                     } catch (TimeoutException | VException ve) {
                         Log.e(TAG, ve.toString());
                     }
                 }

                 private void writeData(Collection cx) throws VException, TimeoutException {
                     String actualKey = "" + count;
                     Log.d(TAG, "I write " + count);
                     syncWithTimeout(cx.put(mBaseContext, actualKey, count));
                 }
             };
             mTestThread.start();
         }
     }

     private <T> T syncWithTimeout(Future<T> f) throws TimeoutException, VException {
         return sync(f, TEST_TIMEOUT, TEST_TIMEUNIT);
     }

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.content_main);

         // Initialize Vanadium as soon as we can.
         mBaseContext = V.init(getApplicationContext(), new Options()
                 .set(OptionDefs.LOG_VLEVEL, 0)
                 .set(OptionDefs.LOG_VMODULE, "vsync*=2"));

         // We also need (trusted) blessings in order to be able to communicate with others.
         setUpBlessings();
     }
 }
	// Copyright 2016 The Vanadium 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 io.v.pingpongapp;

	import android.graphics.Color;
	import android.os.Bundle;
	import android.support.v7.app.AppCompatActivity;
	import android.util.Log;
	import android.view.View;
	import android.widget.Button;
	import android.widget.TextView;

	import com.google.common.collect.ImmutableList;
	import com.google.common.collect.ImmutableMap;
	import com.google.common.util.concurrent.FutureCallback;
	import com.google.common.util.concurrent.Futures;

	import java.util.Arrays;
	import java.util.concurrent.ExecutionException;
	import java.util.concurrent.Future;
	import java.util.concurrent.TimeUnit;
	import java.util.concurrent.TimeoutException;

	import io.v.android.security.BlessingsManager;
	import io.v.android.v23.V;
	import io.v.impl.google.services.syncbase.SyncbaseServer;
	import io.v.v23.InputChannels;
	import io.v.v23.OptionDefs;
	import io.v.v23.Options;
	import io.v.v23.VIterable;
	import io.v.v23.context.VContext;
	import io.v.v23.rpc.Server;
	import io.v.v23.security.BlessingPattern;
	import io.v.v23.security.Blessings;
	import io.v.v23.security.access.AccessList;
	import io.v.v23.security.access.Constants;
	import io.v.v23.security.access.Permissions;
	import io.v.v23.services.syncbase.Id;
	import io.v.v23.services.syncbase.SyncgroupMemberInfo;
	import io.v.v23.services.syncbase.SyncgroupSpec;
	import io.v.v23.syncbase.Syncbase;
	import io.v.v23.syncbase.SyncbaseService;
	import io.v.v23.syncbase.Database;
	import io.v.v23.syncbase.Syncgroup;
	import io.v.v23.syncbase.Collection;
	import io.v.v23.syncbase.WatchChange;
	import io.v.v23.syncbase.util.Util;
	import io.v.v23.verror.VException;

	import static io.v.v23.VFutures.sync;

	public class MainActivity extends AppCompatActivity {
	// Syncgroup-related names for where the mounttable is and the syncgroup name's suffix.
	public static final String MT_PREFIX = "/ns.dev.v.io:8101/tmp/benchmark/pingpong/";
	public static final String SG_SUFFIX = "_sg";

	// Syncbase-related names for the db/cx hierarchy and where to write data.
	public static final String DB_NAME = "db";
	public static final String CX_NAME = "cx";

	// Allow each asynchronous operation to take at most this amount of time.
	private static final long TEST_TIMEOUT = 5;
	private static final TimeUnit TEST_TIMEUNIT = TimeUnit.SECONDS;

	// Fixed parameters for the app.
	private static final String TAG = "PingPong"; // Debug tag for Log.d
	private static final String TEST_ID = "AndroidPingPongTest";
	private static final int NUM_TIMES = 100;
	// Log success/failure once blessings are received.
	private static final FutureCallback<Blessings> ON_BLESSINGS = new FutureCallback<Blessings>() {
	@Override
	public void onSuccess(Blessings b) {
	Log.d(TAG, "Got blessings!");
	}

	@Override
	public void onFailure(Throwable t) {
	Log.d(TAG, "Failure to get blessings, nothing will work.", t);
	}
	};

	// The V context tracked by the app.
	VContext mBaseContext;
	// Values that can be changed by the app.
	private int mPeerID = 0;
	private Thread mTestThread;
	private boolean mUsingProxy = false;

	public static Permissions openPermissions() {
	AccessList acl = new AccessList(
	ImmutableList.of(new BlessingPattern("...")), ImmutableList.<String>of());
	return new Permissions(ImmutableMap.of(
	Constants.RESOLVE.getValue(), acl,
	Constants.DEBUG.getValue(), acl,
	Constants.READ.getValue(), acl,
	Constants.WRITE.getValue(), acl,
	Constants.ADMIN.getValue(), acl));
	}

	private String getMountPoint(String testID, int peerID) {
	return MT_PREFIX + testID + "/s" + peerID;
	}

	private String getSyncgroupName(String testID) {
	return testID + SG_SUFFIX;
	}

	// Helper to show default text before the test starts.
	private void setPreTestText() {
	String suffix = mUsingProxy ? " with proxy" : " w/o proxy";
	String prefix = mPeerID == 0 ? "Pinger: Hello World!" : "Ponger: Hello World!";
	updateText(prefix + suffix);
	}

	// Helper to change the text shown by the debug TextView.
	private void updateText(String data) {
	TextView tv = (TextView) findViewById(R.id.debug_text);
	tv.setText(data);
	}

	// Callback (from button press). Changes the text color between pinger and ponger.
	public void pingpongToggle(View view) {
	if (mTestThread == null) {
	Log.d(TAG, "Toggling peer ID!");
	mPeerID = 1 - mPeerID;
	setPreTestText();
	TextView tv = (TextView) findViewById(R.id.debug_text);
	tv.setTextColor(mPeerID == 0 ? Color.BLACK : Color.BLUE);
	}
	}

	// Callback (from button press). If not pressed yet, the proxy will be added to the listen spec.
	public void useProxy(View view) {
	// If we don't proxy, we can't communicate across networks.
	if (!mUsingProxy) {
	Log.d(TAG, "Using the proxy!");
	try {
	mBaseContext = V.withListenSpec(mBaseContext,
	V.getListenSpec(mBaseContext).withProxy("proxy"));
	mUsingProxy = true;
	setPreTestText();
	((Button) findViewById(R.id.useproxybutton)).setText(R.string.using_proxy);

	} catch (final VException e) {
	Log.e(TAG, "Use proxy failed", e);
	}
	}
	}

	// Prepares an asynchronous fetch of blessings using the user account.
	// On some Android versions, this will open an account picker.
	private void setUpBlessings() {
	Log.d(TAG, "Attempting to get blessings.");

	Futures.addCallback(BlessingsManager.getBlessings(mBaseContext, this, "BlessingsKey", true),
	ON_BLESSINGS);
	}

	// Folder where Syncbase will store its data.
	private String getDataDir() {
	return getApplicationContext().getApplicationInfo().dataDir + "/" + TEST_ID;
	}

	/**
	* Callback (from button press). If the test hasn't run yet, starts the test.
	* The protocol is:
	* 1. Create app hierarchy.
	* 2. Create syncgroup if pinger, else as ponger, join the syncgroup.
	* 3. If pinger, write some data to the store.
	* 4. Watch from the beginning of time. This watch loop will have the pinger write on odd watch
	* changes. and the ponger write when it sees even watch changes.
	* 5. After enough watches have been seen, the watch loop ends, and the statistics are printed.
	* The start time and end time are set during the watch loop.
	* We allow 1 round of free sync in order to initialize before the start time is recorded.
	*
	* @param view
	*/
	public void startTestPingPong(final View view) {
	if (mTestThread == null) {
	((Button) findViewById(R.id.pingpongbutton)).setText(R.string.running_ping_pong);

	Log.d(TAG, "Starting Syncbase Ping Pong Test!");
	mTestThread = new Thread() {
	long startTime;
	long endTime;

	// Count starts at -2. (The first ping and first pong are not counted in the test.)
	int count = -2;

	@Override
	public void run() {
	try {
	testPingPong();
	} catch (ExecutionException \| InterruptedException \| TimeoutException \|
	VException e) {
	Log.e(TAG, "Ping pong test failed", e);
	mBaseContext.cancel();
	}
	}

	public void testPingPong() throws InterruptedException, ExecutionException,
	TimeoutException, VException {

	Log.d(TAG, "Preparing Syncbase Server");
	helpUpdateText("Preparing Syncbase Server");

	// Create the syncbase server...
	try {
	mBaseContext = SyncbaseServer.withNewServer(mBaseContext,
	new SyncbaseServer.Params()
	.withPermissions(openPermissions())
	.withStorageRootDir(getDataDir())
	.withName(getMountPoint(TEST_ID, mPeerID)));
	} catch (SyncbaseServer.StartException e) {
	Log.d(TAG, e.toString());
	}

	Server syncbaseServer = io.v.v23.V.getServer(mBaseContext);


	Log.d(TAG, "Preparing Syncbase Client");
	helpUpdateText("Preparing Syncbase Client");

	Log.d(TAG, Arrays.toString(syncbaseServer.getStatus().getEndpoints()));

	// And the syncbase client, app, db, and table...
	SyncbaseService service = Syncbase.newService(
	"/" + syncbaseServer.getStatus().getEndpoints()[0]);

	// Note: In order for the two apps to find each other, the collection and
	// syncgroup both use "..." as the blessing portion of the id. This must match
	// or else watch and syncgroup join will not work, and "..." is the simplest
	// string they can have in common.
	final Database db = service.getDatabase(mBaseContext, DB_NAME, null);
	final Collection cx = db.getCollection(new Id("...", CX_NAME));
	Log.d(TAG, "db exists?");
	if (!syncWithTimeout(db.exists(mBaseContext))) {
	Log.d(TAG, "db create");
	syncWithTimeout(db.create(mBaseContext,
	Util.filterPermissionsByTags(openPermissions(),
	io.v.v23.services.syncbase.Constants.ALL_DATABASE_TAGS)));
	}
	Log.d(TAG, "cx exists?");
	if (!syncWithTimeout(cx.exists(mBaseContext))) {
	Log.d(TAG, "cx create");
	syncWithTimeout(cx.create(mBaseContext,
	Util.filterPermissionsByTags(openPermissions(),
	io.v.v23.services.syncbase.Constants.ALL_COLLECTION_TAGS)));
	}

	Log.d(TAG, "I am peer " + mPeerID);
	helpUpdateText("I am peer " + mPeerID);

	// If you're peer 0, you should create the syncgroup. Otherwise, join it.
	String sgName = getSyncgroupName(TEST_ID);
	String mtPointName = MT_PREFIX + "/" + TEST_ID;
	Syncgroup group = db.getSyncgroup(new Id("...", sgName));

	SyncgroupMemberInfo memberInfo = new SyncgroupMemberInfo();
	memberInfo.setSyncPriority((byte) 3);
	if (mPeerID == 0) {
	Log.d(TAG, "Creating Syncgroup" + sgName);
	helpUpdateText("Creating Syncgroup");

	Permissions sgPerms = Util.filterPermissionsByTags(openPermissions(),
	io.v.v23.services.syncbase.Constants.ALL_SYNCGROUP_TAGS);

	SyncgroupSpec spec = new SyncgroupSpec(
	TEST_ID, null, sgPerms,
	ImmutableList.of(cx.id()),
	ImmutableList.of(mtPointName), false);
	syncWithTimeout(group.create(mBaseContext, spec, memberInfo));
	} else {
	Log.d(TAG, "Joining Syncgroup" + sgName);
	helpUpdateText("Joining Syncgroup");
	// Join at s0 or via the neighborhood.
	syncWithTimeout(group.join(mBaseContext, getMountPoint(TEST_ID, 0),
	null, memberInfo));
	}

	// Now that we've all joined the syncgroup...
	// We should synchronize our times.
	Log.d(TAG, "We are now ready to time sync!");
	helpUpdateText("We are now ready to time sync!");

	// 0 will send to 1, and 1 responds via watch.
	if (mPeerID == 0) {
	writeData(cx);
	}

	watchForChanges(db, cx);

	Log.d(TAG, "We finished!");
	double delta = (endTime - startTime) / (NUM_TIMES * 1000000.);
	Log.d(TAG, "Average Time: " + delta + " ms per ping pong iteration\n");
	helpUpdateText("Average Time: " + delta + "ms per ping pong iteration!");
	}

	// Posts an action through the view to be run on the main thread.
	// This is the only way we're allowed to change the UI from this Thread.
	private void helpUpdateText(final String t) {
	view.post(new Runnable() {
	@Override
	public void run() {
	updateText(t);
	}
	});
	}

	private void watchForChanges(Database db, Collection cx) {
	try {
	VIterable<WatchChange> watchStream = InputChannels.asIterable(
	db.watch(mBaseContext, ImmutableList.of(
	Util.rowPrefixPattern(cx.id(), "")))
	);

	Log.d(TAG, "Starting watch");
	// 0 will send to 1, and vice versa.
	for (final WatchChange wc : watchStream) {
	String key = wc.getRowName();
	Integer value = (Integer)wc.getValue();
	Log.d(TAG, "Watch: " + key + " " + value);
	helpUpdateText("Watch: " + key + " " + value);
	count++;

	if (count == 0) {
	startTime = System.nanoTime();
	}
	if (count == NUM_TIMES * 2) {
	endTime = System.nanoTime();
	break;
	}
	if ((count + 2) % 2 == mPeerID) {
	writeData(cx);
	}
	}
	Log.d(TAG, "Exiting watch");
	} catch (TimeoutException \| VException ve) {
	Log.e(TAG, ve.toString());
	}
	}

	private void writeData(Collection cx) throws VException, TimeoutException {
	String actualKey = "" + count;
	Log.d(TAG, "I write " + count);
	syncWithTimeout(cx.put(mBaseContext, actualKey, count));
	}
	};
	mTestThread.start();
	}
	}

	private <T> T syncWithTimeout(Future<T> f) throws TimeoutException, VException {
	return sync(f, TEST_TIMEOUT, TEST_TIMEUNIT);
	}

	@Override
	protected void onCreate(Bundle savedInstanceState) {
	super.onCreate(savedInstanceState);
	setContentView(R.layout.content_main);

	// Initialize Vanadium as soon as we can.
	mBaseContext = V.init(getApplicationContext(), new Options()
	.set(OptionDefs.LOG_VLEVEL, 0)
	.set(OptionDefs.LOG_VMODULE, "vsync*=2"));

	// We also need (trusted) blessings in order to be able to communicate with others.
	setUpBlessings();
	}
	}