src/com/android/phone/vvm/omtp/sync/OmtpVvmSyncService.java - platform/packages/services/Telephony - Git at Google

 /*
  * Copyright (C) 2015 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License
  */
 package com.android.phone.vvm.omtp.sync;

 import android.app.AlarmManager;
 import android.app.IntentService;
 import android.app.PendingIntent;
 import android.content.Context;
 import android.content.Intent;
 import android.net.ConnectivityManager;
 import android.net.Network;
 import android.net.ConnectivityManager.NetworkCallback;
 import android.net.NetworkCapabilities;
 import android.net.NetworkRequest;
 import android.provider.VoicemailContract;
 import android.telecom.PhoneAccountHandle;
 import android.telecom.Voicemail;
 import android.telephony.TelephonyManager;
 import android.util.Log;

 import com.android.phone.PhoneUtils;
 import com.android.phone.settings.VisualVoicemailSettingsUtil;
 import com.android.phone.vvm.omtp.LocalLogHelper;
 import com.android.phone.vvm.omtp.OmtpVvmCarrierConfigHelper;
 import com.android.phone.vvm.omtp.imap.ImapHelper;

 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;

 /**
  * Sync OMTP visual voicemail.
  */
 public class OmtpVvmSyncService extends IntentService {
     private static final String TAG = OmtpVvmSyncService.class.getSimpleName();

     /** Signifies a sync with both uploading to the server and downloading from the server. */
     public static final String SYNC_FULL_SYNC = "full_sync";
     /** Only upload to the server. */
     public static final String SYNC_UPLOAD_ONLY = "upload_only";
     /** Only download from the server. */
     public static final String SYNC_DOWNLOAD_ONLY = "download_only";
     /** The account to sync. */
     public static final String EXTRA_PHONE_ACCOUNT = "phone_account";

     // Timeout used to call ConnectivityManager.requestNetwork
     private static final int NETWORK_REQUEST_TIMEOUT_MILLIS = 60 * 1000;

     // Minimum time allowed between full syncs
     private static final int MINIMUM_FULL_SYNC_INTERVAL_MILLIS = 60 * 1000;

     // Number of retries
     private static final int NETWORK_RETRY_COUNT = 6;

     private VoicemailsQueryHelper mQueryHelper;
     private ConnectivityManager mConnectivityManager;

     public OmtpVvmSyncService() {
         super("OmtpVvmSyncService");
     }

     public static Intent getSyncIntent(Context context, String action,
             PhoneAccountHandle phoneAccount, boolean firstAttempt) {
         if (firstAttempt) {
             if (phoneAccount != null) {
                 VisualVoicemailSettingsUtil.resetVisualVoicemailRetryInterval(context,
                         phoneAccount);
             } else {
                 OmtpVvmSourceManager vvmSourceManager =
                         OmtpVvmSourceManager.getInstance(context);
                 Set<PhoneAccountHandle> sources = vvmSourceManager.getOmtpVvmSources();
                 for (PhoneAccountHandle source : sources) {
                     VisualVoicemailSettingsUtil.resetVisualVoicemailRetryInterval(context, source);
                 }
             }
         }

         Intent serviceIntent = new Intent(context, OmtpVvmSyncService.class);
         serviceIntent.setAction(action);
         if (phoneAccount != null) {
             serviceIntent.putExtra(EXTRA_PHONE_ACCOUNT, phoneAccount);
         }

         cancelRetriesForIntent(context, serviceIntent);
         return serviceIntent;
     }

     /**
      * Cancel all retry syncs for an account.
      * @param context The context the service runs in.
      * @param phoneAccount The phone account for which to cancel syncs.
      */
     public static void cancelAllRetries(Context context, PhoneAccountHandle phoneAccount) {
         cancelRetriesForIntent(context, getSyncIntent(context, SYNC_FULL_SYNC, phoneAccount,
                 false));
     }

     /**
      * A helper method to cancel all pending alarms for intents that would be identical to the given
      * intent.
      * @param context The context the service runs in.
      * @param intent The intent to search and cancel.
      */
     private static void cancelRetriesForIntent(Context context, Intent intent) {
         AlarmManager alarmManager = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
         alarmManager.cancel(PendingIntent.getService(context, 0, intent, 0));

         Intent copyIntent = new Intent(intent);
         if (SYNC_FULL_SYNC.equals(copyIntent.getAction())) {
             // A full sync action should also cancel both of the other types of syncs
             copyIntent.setAction(SYNC_DOWNLOAD_ONLY);
             alarmManager.cancel(PendingIntent.getService(context, 0, copyIntent, 0));
             copyIntent.setAction(SYNC_UPLOAD_ONLY);
             alarmManager.cancel(PendingIntent.getService(context, 0, copyIntent, 0));
         }
     }

     @Override
     public void onCreate() {
         super.onCreate();
         mQueryHelper = new VoicemailsQueryHelper(this);
     }

     @Override
     protected void onHandleIntent(Intent intent) {
         if (intent == null) {
             Log.d(TAG, "onHandleIntent: could not handle null intent");
             return;
         }

         String action = intent.getAction();

         PhoneAccountHandle phoneAccount = intent.getParcelableExtra(EXTRA_PHONE_ACCOUNT);

         LocalLogHelper.log(TAG, "Sync requested: " + action +
                 " for all accounts: " + String.valueOf(phoneAccount == null));

         if (phoneAccount != null) {
             Log.v(TAG, "Sync requested: " + action + " - for account: " + phoneAccount);
             setupAndSendRequest(phoneAccount, action);
         } else {
             Log.v(TAG, "Sync requested: " + action + " - for all accounts");
             OmtpVvmSourceManager vvmSourceManager =
                     OmtpVvmSourceManager.getInstance(this);
             Set<PhoneAccountHandle> sources = vvmSourceManager.getOmtpVvmSources();
             for (PhoneAccountHandle source : sources) {
                 setupAndSendRequest(source, action);
             }
         }
     }

     private void setupAndSendRequest(PhoneAccountHandle phoneAccount, String action) {
         if (!VisualVoicemailSettingsUtil.isVisualVoicemailEnabled(this, phoneAccount)) {
             Log.v(TAG, "Sync requested for disabled account");
             return;
         }

         if (SYNC_FULL_SYNC.equals(action)) {
             long lastSyncTime = VisualVoicemailSettingsUtil.getVisualVoicemailLastFullSyncTime(
                     this, phoneAccount);
             long currentTime = System.currentTimeMillis();
             if (currentTime - lastSyncTime < MINIMUM_FULL_SYNC_INTERVAL_MILLIS) {
                 // If it's been less than a minute since the last sync, bail.
                 Log.v(TAG, "Avoiding duplicate full sync: synced recently for "
                         + phoneAccount.getId());
                 return;
             }
             VisualVoicemailSettingsUtil.setVisualVoicemailLastFullSyncTime(
                     this, phoneAccount, currentTime);
         }

         int subId = PhoneUtils.getSubIdForPhoneAccountHandle(phoneAccount);
         OmtpVvmCarrierConfigHelper carrierConfigHelper =
                 new OmtpVvmCarrierConfigHelper(this, subId);

         if (TelephonyManager.VVM_TYPE_CVVM.equals(carrierConfigHelper.getVvmType())) {
             doSync(null, null, phoneAccount, action);
         } else {
             OmtpVvmNetworkRequestCallback networkCallback = new OmtpVvmNetworkRequestCallback(
                     phoneAccount, action);
             requestNetwork(networkCallback);
         }
     }

     private class OmtpVvmNetworkRequestCallback extends ConnectivityManager.NetworkCallback {
         PhoneAccountHandle mPhoneAccount;
         String mAction;
         NetworkRequest mNetworkRequest;

         public OmtpVvmNetworkRequestCallback(PhoneAccountHandle phoneAccount,
                 String action) {
             mPhoneAccount = phoneAccount;
             mAction = action;
             mNetworkRequest = new NetworkRequest.Builder()
                     .addTransportType(NetworkCapabilities.TRANSPORT_CELLULAR)
                     .addCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET)
                     .setNetworkSpecifier(
                             Integer.toString(
                                     PhoneUtils.getSubIdForPhoneAccountHandle(phoneAccount)))
                     .build();
         }

         public NetworkRequest getNetworkRequest() {
             return mNetworkRequest;
         }

         @Override
         public void onAvailable(final Network network) {
             doSync(network, this, mPhoneAccount, mAction);
         }

         @Override
         public void onLost(Network network) {
             releaseNetwork(this);
         }

         @Override
         public void onUnavailable() {
             releaseNetwork(this);
         }
     }

     private void doSync(Network network, OmtpVvmNetworkRequestCallback callback,
             PhoneAccountHandle phoneAccount, String action) {
         int retryCount = NETWORK_RETRY_COUNT;

         boolean uploadSuccess;
         boolean downloadSuccess;

         while (retryCount > 0) {
             uploadSuccess = true;
             downloadSuccess = true;

             ImapHelper imapHelper = new ImapHelper(this, phoneAccount, network);
             if (!imapHelper.isSuccessfullyInitialized()) {
                 Log.w(TAG, "Can't retrieve Imap credentials.");
                 releaseNetwork(callback);
                 VisualVoicemailSettingsUtil.resetVisualVoicemailRetryInterval(this,
                         phoneAccount);
                 return;
             }

             if (SYNC_FULL_SYNC.equals(action) || SYNC_UPLOAD_ONLY.equals(action)) {
                 uploadSuccess = upload(imapHelper);
             }
             if (SYNC_FULL_SYNC.equals(action) || SYNC_DOWNLOAD_ONLY.equals(action)) {
                 downloadSuccess = download(imapHelper);
             }

             Log.v(TAG, "upload succeeded: ["+  String.valueOf(uploadSuccess)
                     + "] download succeeded: [" + String.valueOf(downloadSuccess) + "]");

             // Need to check again for whether visual voicemail is enabled because it could have
             // been disabled while waiting for the response from the network.
             if (VisualVoicemailSettingsUtil.isVisualVoicemailEnabled(this, phoneAccount) &&
                     (!uploadSuccess || !downloadSuccess)) {
                 retryCount--;
                 // Re-adjust so that only the unsuccessful action needs to be retried.
                 // No need to re-adjust if both are unsuccessful. It means the full sync
                 // failed so the action remains unchanged.
                 if (uploadSuccess) {
                     action = SYNC_DOWNLOAD_ONLY;
                 } else if (downloadSuccess) {
                     action = SYNC_UPLOAD_ONLY;
                 }

                 Log.v(TAG, "Retrying " + action);
                 LocalLogHelper.log(TAG, "Immediately retrying " + action);
             } else {
                 // Nothing more to do here, just exit.
                 releaseNetwork(callback);

                 VisualVoicemailSettingsUtil.resetVisualVoicemailRetryInterval(this, phoneAccount);
                 return;
             }
         }

         releaseNetwork(callback);
         setRetryAlarm(phoneAccount, action);
     }

     private void requestNetwork(OmtpVvmNetworkRequestCallback networkCallback) {
         getConnectivityManager().requestNetwork(networkCallback.getNetworkRequest(),
                 networkCallback, NETWORK_REQUEST_TIMEOUT_MILLIS);
     }

     private void releaseNetwork(NetworkCallback networkCallback) {
         if (networkCallback != null) {
             getConnectivityManager().unregisterNetworkCallback(networkCallback);
         }
     }

     private ConnectivityManager getConnectivityManager() {
         if (mConnectivityManager == null) {
             mConnectivityManager = (ConnectivityManager) this.getSystemService(
                     Context.CONNECTIVITY_SERVICE);
         }
         return mConnectivityManager;
     }

     private void setRetryAlarm(PhoneAccountHandle phoneAccount, String action) {
         Intent serviceIntent = new Intent(this, OmtpVvmSyncService.class);
         serviceIntent.setAction(action);
         serviceIntent.putExtra(OmtpVvmSyncService.EXTRA_PHONE_ACCOUNT, phoneAccount);
         PendingIntent pendingIntent = PendingIntent.getService(this, 0, serviceIntent, 0);
         long retryInterval = VisualVoicemailSettingsUtil.getVisualVoicemailRetryInterval(this,
                 phoneAccount);

         Log.v(TAG, "Retrying "+ action + " in " + retryInterval + "ms");
         LocalLogHelper.log(TAG, "Retrying "+ action + " in " + retryInterval + "ms");

         AlarmManager alarmManager = (AlarmManager)
                 this.getSystemService(Context.ALARM_SERVICE);
         alarmManager.set(AlarmManager.RTC, System.currentTimeMillis() + retryInterval,
                 pendingIntent);

         VisualVoicemailSettingsUtil.setVisualVoicemailRetryInterval(this, phoneAccount,
                 retryInterval * 2);
     }

     private boolean upload(ImapHelper imapHelper) {
         List<Voicemail> readVoicemails = mQueryHelper.getReadVoicemails();
         List<Voicemail> deletedVoicemails = mQueryHelper.getDeletedVoicemails();

         boolean success = true;

         if (deletedVoicemails.size() > 0) {
             if (imapHelper.markMessagesAsDeleted(deletedVoicemails)) {
                 // We want to delete selectively instead of all the voicemails for this provider
                 // in case the state changed since the IMAP query was completed.
                 mQueryHelper.deleteFromDatabase(deletedVoicemails);
             } else {
                 success = false;
             }
         }

         if (readVoicemails.size() > 0) {
             if (imapHelper.markMessagesAsRead(readVoicemails)) {
                 mQueryHelper.markReadInDatabase(readVoicemails);
             } else {
                 success = false;
             }
         }

         return success;
     }

     private boolean download(ImapHelper imapHelper) {
         List<Voicemail> serverVoicemails = imapHelper.fetchAllVoicemails();
         List<Voicemail> localVoicemails = mQueryHelper.getAllVoicemails();

         if (localVoicemails == null || serverVoicemails == null) {
             // Null value means the query failed.
             return false;
         }

         Map<String, Voicemail> remoteMap = buildMap(serverVoicemails);

         // Go through all the local voicemails and check if they are on the server.
         // They may be read or deleted on the server but not locally. Perform the
         // appropriate local operation if the status differs from the server. Remove
         // the messages that exist both locally and on the server to know which server
         // messages to insert locally.
         for (int i = 0; i < localVoicemails.size(); i++) {
             Voicemail localVoicemail = localVoicemails.get(i);
             Voicemail remoteVoicemail = remoteMap.remove(localVoicemail.getSourceData());
             if (remoteVoicemail == null) {
                 mQueryHelper.deleteFromDatabase(localVoicemail);
             } else {
                 if (remoteVoicemail.isRead() != localVoicemail.isRead()) {
                     mQueryHelper.markReadInDatabase(localVoicemail);
                 }
             }
         }

         // The leftover messages are messages that exist on the server but not locally.
         for (Voicemail remoteVoicemail : remoteMap.values()) {
             VoicemailContract.Voicemails.insert(this, remoteVoicemail);
         }

         return true;
     }

     /**
      * Builds a map from provider data to message for the given collection of voicemails.
      */
     private Map<String, Voicemail> buildMap(List<Voicemail> messages) {
         Map<String, Voicemail> map = new HashMap<String, Voicemail>();
         for (Voicemail message : messages) {
             map.put(message.getSourceData(), message);
         }
         return map;
     }
 }
	/*
	* Copyright (C) 2015 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License
	*/
	package com.android.phone.vvm.omtp.sync;

	import android.app.AlarmManager;
	import android.app.IntentService;
	import android.app.PendingIntent;
	import android.content.Context;
	import android.content.Intent;
	import android.net.ConnectivityManager;
	import android.net.Network;
	import android.net.ConnectivityManager.NetworkCallback;
	import android.net.NetworkCapabilities;
	import android.net.NetworkRequest;
	import android.provider.VoicemailContract;
	import android.telecom.PhoneAccountHandle;
	import android.telecom.Voicemail;
	import android.telephony.TelephonyManager;
	import android.util.Log;

	import com.android.phone.PhoneUtils;
	import com.android.phone.settings.VisualVoicemailSettingsUtil;
	import com.android.phone.vvm.omtp.LocalLogHelper;
	import com.android.phone.vvm.omtp.OmtpVvmCarrierConfigHelper;
	import com.android.phone.vvm.omtp.imap.ImapHelper;

	import java.util.HashMap;
	import java.util.List;
	import java.util.Map;
	import java.util.Set;

	/**
	* Sync OMTP visual voicemail.
	*/
	public class OmtpVvmSyncService extends IntentService {
	private static final String TAG = OmtpVvmSyncService.class.getSimpleName();

	/** Signifies a sync with both uploading to the server and downloading from the server. */
	public static final String SYNC_FULL_SYNC = "full_sync";
	/** Only upload to the server. */
	public static final String SYNC_UPLOAD_ONLY = "upload_only";
	/** Only download from the server. */
	public static final String SYNC_DOWNLOAD_ONLY = "download_only";
	/** The account to sync. */
	public static final String EXTRA_PHONE_ACCOUNT = "phone_account";

	// Timeout used to call ConnectivityManager.requestNetwork
	private static final int NETWORK_REQUEST_TIMEOUT_MILLIS = 60 * 1000;

	// Minimum time allowed between full syncs
	private static final int MINIMUM_FULL_SYNC_INTERVAL_MILLIS = 60 * 1000;

	// Number of retries
	private static final int NETWORK_RETRY_COUNT = 6;

	private VoicemailsQueryHelper mQueryHelper;
	private ConnectivityManager mConnectivityManager;

	public OmtpVvmSyncService() {
	super("OmtpVvmSyncService");
	}

	public static Intent getSyncIntent(Context context, String action,
	PhoneAccountHandle phoneAccount, boolean firstAttempt) {
	if (firstAttempt) {
	if (phoneAccount != null) {
	VisualVoicemailSettingsUtil.resetVisualVoicemailRetryInterval(context,
	phoneAccount);
	} else {
	OmtpVvmSourceManager vvmSourceManager =
	OmtpVvmSourceManager.getInstance(context);
	Set<PhoneAccountHandle> sources = vvmSourceManager.getOmtpVvmSources();
	for (PhoneAccountHandle source : sources) {
	VisualVoicemailSettingsUtil.resetVisualVoicemailRetryInterval(context, source);
	}
	}
	}

	Intent serviceIntent = new Intent(context, OmtpVvmSyncService.class);
	serviceIntent.setAction(action);
	if (phoneAccount != null) {
	serviceIntent.putExtra(EXTRA_PHONE_ACCOUNT, phoneAccount);
	}

	cancelRetriesForIntent(context, serviceIntent);
	return serviceIntent;
	}

	/**
	* Cancel all retry syncs for an account.
	* @param context The context the service runs in.
	* @param phoneAccount The phone account for which to cancel syncs.
	*/
	public static void cancelAllRetries(Context context, PhoneAccountHandle phoneAccount) {
	cancelRetriesForIntent(context, getSyncIntent(context, SYNC_FULL_SYNC, phoneAccount,
	false));
	}

	/**
	* A helper method to cancel all pending alarms for intents that would be identical to the given
	* intent.
	* @param context The context the service runs in.
	* @param intent The intent to search and cancel.
	*/
	private static void cancelRetriesForIntent(Context context, Intent intent) {
	AlarmManager alarmManager = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
	alarmManager.cancel(PendingIntent.getService(context, 0, intent, 0));

	Intent copyIntent = new Intent(intent);
	if (SYNC_FULL_SYNC.equals(copyIntent.getAction())) {
	// A full sync action should also cancel both of the other types of syncs
	copyIntent.setAction(SYNC_DOWNLOAD_ONLY);
	alarmManager.cancel(PendingIntent.getService(context, 0, copyIntent, 0));
	copyIntent.setAction(SYNC_UPLOAD_ONLY);
	alarmManager.cancel(PendingIntent.getService(context, 0, copyIntent, 0));
	}
	}

	@Override
	public void onCreate() {
	super.onCreate();
	mQueryHelper = new VoicemailsQueryHelper(this);
	}

	@Override
	protected void onHandleIntent(Intent intent) {
	if (intent == null) {
	Log.d(TAG, "onHandleIntent: could not handle null intent");
	return;
	}

	String action = intent.getAction();

	PhoneAccountHandle phoneAccount = intent.getParcelableExtra(EXTRA_PHONE_ACCOUNT);

	LocalLogHelper.log(TAG, "Sync requested: " + action +
	" for all accounts: " + String.valueOf(phoneAccount == null));

	if (phoneAccount != null) {
	Log.v(TAG, "Sync requested: " + action + " - for account: " + phoneAccount);
	setupAndSendRequest(phoneAccount, action);
	} else {
	Log.v(TAG, "Sync requested: " + action + " - for all accounts");
	OmtpVvmSourceManager vvmSourceManager =
	OmtpVvmSourceManager.getInstance(this);
	Set<PhoneAccountHandle> sources = vvmSourceManager.getOmtpVvmSources();
	for (PhoneAccountHandle source : sources) {
	setupAndSendRequest(source, action);
	}
	}
	}

	private void setupAndSendRequest(PhoneAccountHandle phoneAccount, String action) {
	if (!VisualVoicemailSettingsUtil.isVisualVoicemailEnabled(this, phoneAccount)) {
	Log.v(TAG, "Sync requested for disabled account");
	return;
	}

	if (SYNC_FULL_SYNC.equals(action)) {
	long lastSyncTime = VisualVoicemailSettingsUtil.getVisualVoicemailLastFullSyncTime(
	this, phoneAccount);
	long currentTime = System.currentTimeMillis();
	if (currentTime - lastSyncTime < MINIMUM_FULL_SYNC_INTERVAL_MILLIS) {
	// If it's been less than a minute since the last sync, bail.
	Log.v(TAG, "Avoiding duplicate full sync: synced recently for "
	+ phoneAccount.getId());
	return;
	}
	VisualVoicemailSettingsUtil.setVisualVoicemailLastFullSyncTime(
	this, phoneAccount, currentTime);
	}

	int subId = PhoneUtils.getSubIdForPhoneAccountHandle(phoneAccount);
	OmtpVvmCarrierConfigHelper carrierConfigHelper =
	new OmtpVvmCarrierConfigHelper(this, subId);

	if (TelephonyManager.VVM_TYPE_CVVM.equals(carrierConfigHelper.getVvmType())) {
	doSync(null, null, phoneAccount, action);
	} else {
	OmtpVvmNetworkRequestCallback networkCallback = new OmtpVvmNetworkRequestCallback(
	phoneAccount, action);
	requestNetwork(networkCallback);
	}
	}

	private class OmtpVvmNetworkRequestCallback extends ConnectivityManager.NetworkCallback {
	PhoneAccountHandle mPhoneAccount;
	String mAction;
	NetworkRequest mNetworkRequest;

	public OmtpVvmNetworkRequestCallback(PhoneAccountHandle phoneAccount,
	String action) {
	mPhoneAccount = phoneAccount;
	mAction = action;
	mNetworkRequest = new NetworkRequest.Builder()
	.addTransportType(NetworkCapabilities.TRANSPORT_CELLULAR)
	.addCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET)
	.setNetworkSpecifier(
	Integer.toString(
	PhoneUtils.getSubIdForPhoneAccountHandle(phoneAccount)))
	.build();
	}

	public NetworkRequest getNetworkRequest() {
	return mNetworkRequest;
	}

	@Override
	public void onAvailable(final Network network) {
	doSync(network, this, mPhoneAccount, mAction);
	}

	@Override
	public void onLost(Network network) {
	releaseNetwork(this);
	}

	@Override
	public void onUnavailable() {
	releaseNetwork(this);
	}
	}

	private void doSync(Network network, OmtpVvmNetworkRequestCallback callback,
	PhoneAccountHandle phoneAccount, String action) {
	int retryCount = NETWORK_RETRY_COUNT;

	boolean uploadSuccess;
	boolean downloadSuccess;

	while (retryCount > 0) {
	uploadSuccess = true;
	downloadSuccess = true;

	ImapHelper imapHelper = new ImapHelper(this, phoneAccount, network);
	if (!imapHelper.isSuccessfullyInitialized()) {
	Log.w(TAG, "Can't retrieve Imap credentials.");
	releaseNetwork(callback);
	VisualVoicemailSettingsUtil.resetVisualVoicemailRetryInterval(this,
	phoneAccount);
	return;
	}

	if (SYNC_FULL_SYNC.equals(action) \|\| SYNC_UPLOAD_ONLY.equals(action)) {
	uploadSuccess = upload(imapHelper);
	}
	if (SYNC_FULL_SYNC.equals(action) \|\| SYNC_DOWNLOAD_ONLY.equals(action)) {
	downloadSuccess = download(imapHelper);
	}

	Log.v(TAG, "upload succeeded: ["+ String.valueOf(uploadSuccess)
	+ "] download succeeded: [" + String.valueOf(downloadSuccess) + "]");

	// Need to check again for whether visual voicemail is enabled because it could have
	// been disabled while waiting for the response from the network.
	if (VisualVoicemailSettingsUtil.isVisualVoicemailEnabled(this, phoneAccount) &&
	(!uploadSuccess \|\| !downloadSuccess)) {
	retryCount--;
	// Re-adjust so that only the unsuccessful action needs to be retried.
	// No need to re-adjust if both are unsuccessful. It means the full sync
	// failed so the action remains unchanged.
	if (uploadSuccess) {
	action = SYNC_DOWNLOAD_ONLY;
	} else if (downloadSuccess) {
	action = SYNC_UPLOAD_ONLY;
	}

	Log.v(TAG, "Retrying " + action);
	LocalLogHelper.log(TAG, "Immediately retrying " + action);
	} else {
	// Nothing more to do here, just exit.
	releaseNetwork(callback);

	VisualVoicemailSettingsUtil.resetVisualVoicemailRetryInterval(this, phoneAccount);
	return;
	}
	}

	releaseNetwork(callback);
	setRetryAlarm(phoneAccount, action);
	}

	private void requestNetwork(OmtpVvmNetworkRequestCallback networkCallback) {
	getConnectivityManager().requestNetwork(networkCallback.getNetworkRequest(),
	networkCallback, NETWORK_REQUEST_TIMEOUT_MILLIS);
	}

	private void releaseNetwork(NetworkCallback networkCallback) {
	if (networkCallback != null) {
	getConnectivityManager().unregisterNetworkCallback(networkCallback);
	}
	}

	private ConnectivityManager getConnectivityManager() {
	if (mConnectivityManager == null) {
	mConnectivityManager = (ConnectivityManager) this.getSystemService(
	Context.CONNECTIVITY_SERVICE);
	}
	return mConnectivityManager;
	}

	private void setRetryAlarm(PhoneAccountHandle phoneAccount, String action) {
	Intent serviceIntent = new Intent(this, OmtpVvmSyncService.class);
	serviceIntent.setAction(action);
	serviceIntent.putExtra(OmtpVvmSyncService.EXTRA_PHONE_ACCOUNT, phoneAccount);
	PendingIntent pendingIntent = PendingIntent.getService(this, 0, serviceIntent, 0);
	long retryInterval = VisualVoicemailSettingsUtil.getVisualVoicemailRetryInterval(this,
	phoneAccount);

	Log.v(TAG, "Retrying "+ action + " in " + retryInterval + "ms");
	LocalLogHelper.log(TAG, "Retrying "+ action + " in " + retryInterval + "ms");

	AlarmManager alarmManager = (AlarmManager)
	this.getSystemService(Context.ALARM_SERVICE);
	alarmManager.set(AlarmManager.RTC, System.currentTimeMillis() + retryInterval,
	pendingIntent);

	VisualVoicemailSettingsUtil.setVisualVoicemailRetryInterval(this, phoneAccount,
	retryInterval * 2);
	}

	private boolean upload(ImapHelper imapHelper) {
	List<Voicemail> readVoicemails = mQueryHelper.getReadVoicemails();
	List<Voicemail> deletedVoicemails = mQueryHelper.getDeletedVoicemails();

	boolean success = true;

	if (deletedVoicemails.size() > 0) {
	if (imapHelper.markMessagesAsDeleted(deletedVoicemails)) {
	// We want to delete selectively instead of all the voicemails for this provider
	// in case the state changed since the IMAP query was completed.
	mQueryHelper.deleteFromDatabase(deletedVoicemails);
	} else {
	success = false;
	}
	}

	if (readVoicemails.size() > 0) {
	if (imapHelper.markMessagesAsRead(readVoicemails)) {
	mQueryHelper.markReadInDatabase(readVoicemails);
	} else {
	success = false;
	}
	}

	return success;
	}

	private boolean download(ImapHelper imapHelper) {
	List<Voicemail> serverVoicemails = imapHelper.fetchAllVoicemails();
	List<Voicemail> localVoicemails = mQueryHelper.getAllVoicemails();

	if (localVoicemails == null \|\| serverVoicemails == null) {
	// Null value means the query failed.
	return false;
	}

	Map<String, Voicemail> remoteMap = buildMap(serverVoicemails);

	// Go through all the local voicemails and check if they are on the server.
	// They may be read or deleted on the server but not locally. Perform the
	// appropriate local operation if the status differs from the server. Remove
	// the messages that exist both locally and on the server to know which server
	// messages to insert locally.
	for (int i = 0; i < localVoicemails.size(); i++) {
	Voicemail localVoicemail = localVoicemails.get(i);
	Voicemail remoteVoicemail = remoteMap.remove(localVoicemail.getSourceData());
	if (remoteVoicemail == null) {
	mQueryHelper.deleteFromDatabase(localVoicemail);
	} else {
	if (remoteVoicemail.isRead() != localVoicemail.isRead()) {
	mQueryHelper.markReadInDatabase(localVoicemail);
	}
	}
	}

	// The leftover messages are messages that exist on the server but not locally.
	for (Voicemail remoteVoicemail : remoteMap.values()) {
	VoicemailContract.Voicemails.insert(this, remoteVoicemail);
	}

	return true;
	}

	/**
	* Builds a map from provider data to message for the given collection of voicemails.
	*/
	private Map<String, Voicemail> buildMap(List<Voicemail> messages) {
	Map<String, Voicemail> map = new HashMap<String, Voicemail>();
	for (Voicemail message : messages) {
	map.put(message.getSourceData(), message);
	}
	return map;
	}
	}