. More reliable background sync by using wake lock

--> Background sync now work even when the device is asleep
(Thanks danapple0)

AndroidManifest.xml

@@ -8,6 +8,7 @@
     <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
     <uses-permission android:name="android.permission.INTERNET"/>
     <uses-permission android:name="android.permission.VIBRATE"/>
+    <uses-permission android:name="android.permission.WAKE_LOCK" />
     <permission android:name="com.android.email.permission.READ_ATTACHMENT"
                 android:permissionGroup="android.permission-group.MESSAGES"
                 android:protectionLevel="dangerous"

src/com/android/email/Email.java

@@ -100,6 +100,11 @@ public class Email extends Application {
      */
     public static final int MAX_ATTACHMENT_DOWNLOAD_SIZE = (5 * 1024 * 1024);
     
+    /**
+     * Max time (in millis) the wake lock will be held for when background sync is happening 
+     */
+    public static final int WAKE_LOCK_TIMEOUT = 30000;
+
     /**
      * Called throughout the application when the number of accounts has changed. This method
      * enables or disables the Compose activity, the boot receiver and the service based on

src/com/android/email/service/MailService.java

@@ -11,6 +11,8 @@ import android.app.Service;
 import android.content.Context;
 import android.content.Intent;
 import android.os.IBinder;
+import android.os.PowerManager;
+import android.os.PowerManager.WakeLock;
 import android.os.SystemClock;
 import android.util.Config;
 import android.util.Log;
@@ -61,6 +63,7 @@ public class MailService extends Service {
             if (Config.LOGV) {
                 Log.v(Email.LOG_TAG, "***** MailService *****: checking mail");
             }
+            mListener.wakeLockAcquire();
             MessagingController.getInstance(getApplication()).checkMail(this, null, mListener);
         }
         else if (ACTION_CANCEL.equals(intent.getAction())) {
@@ -124,6 +127,25 @@ public class MailService extends Service {
 
     class Listener extends MessagingListener {
         HashMap<Account, Integer> accountsWithNewMail = new HashMap<Account, Integer>();
+        private WakeLock wakeLock = null;
+        
+        // wakelock strategy is to be very conservative.  If there is any reason to release, then release
+        // don't want to take the chance of running wild
+        public synchronized void wakeLockAcquire() {
+        	if (wakeLock == null) {
+                PowerManager pm = (PowerManager) getSystemService(Context.POWER_SERVICE);
+                wakeLock = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "Email");
+                wakeLock.setReferenceCounted(false);
+                wakeLock.acquire(Email.WAKE_LOCK_TIMEOUT);
+        	}
+        }
+
+        public synchronized void wakeLockRelease() {
+        	if (wakeLock != null) {
+        		wakeLock.release();
+        		wakeLock = null;
+        	}
+        }
 
         @Override
         public void checkMailStarted(Context context, Account account) {
@@ -133,6 +155,7 @@ public class MailService extends Service {
         @Override
         public void checkMailFailed(Context context, Account account, String reason) {
             reschedule();
+            wakeLockRelease();
             stopSelf(mStartId);
         }
 
@@ -187,6 +210,7 @@ public class MailService extends Service {
             }
 
             reschedule();
+            wakeLockRelease();
             stopSelf(mStartId);
         }
     }