michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: package org.mozilla.gecko.sync;
michael@0: 
michael@0: import android.content.SharedPreferences;
michael@0: import android.content.SharedPreferences.Editor;
michael@0: 
michael@0: public class PrefsBackoffHandler implements BackoffHandler {
michael@0:   public static final String PREF_EARLIEST_NEXT = "earliestnext";
michael@0: 
michael@0:   private final SharedPreferences prefs;
michael@0:   private final String prefEarliest;
michael@0: 
michael@0:   public PrefsBackoffHandler(final SharedPreferences prefs, final String prefSuffix) {
michael@0:     if (prefs == null) {
michael@0:       throw new IllegalArgumentException("prefs must not be null.");
michael@0:     }
michael@0:     this.prefs = prefs;
michael@0:     this.prefEarliest = PREF_EARLIEST_NEXT + "." + prefSuffix;
michael@0:   }
michael@0: 
michael@0:   @Override
michael@0:   public synchronized long getEarliestNextRequest() {
michael@0:     return prefs.getLong(prefEarliest, 0);
michael@0:   }
michael@0: 
michael@0:   @Override
michael@0:   public synchronized void setEarliestNextRequest(final long next) {
michael@0:     final Editor edit = prefs.edit();
michael@0:     edit.putLong(prefEarliest, next);
michael@0:     edit.commit();
michael@0:   }
michael@0: 
michael@0:   @Override
michael@0:   public synchronized void extendEarliestNextRequest(final long next) {
michael@0:     if (prefs.getLong(prefEarliest, 0) >= next) {
michael@0:       return;
michael@0:     }
michael@0:     final Editor edit = prefs.edit();
michael@0:     edit.putLong(prefEarliest, next);
michael@0:     edit.commit();
michael@0:   }
michael@0: 
michael@0:   /**
michael@0:    * Return the number of milliseconds until we're allowed to touch the server again,
michael@0:    * or 0 if now is fine.
michael@0:    */
michael@0:   @Override
michael@0:   public long delayMilliseconds() {
michael@0:     long earliestNextRequest = getEarliestNextRequest();
michael@0:     if (earliestNextRequest <= 0) {
michael@0:       return 0;
michael@0:     }
michael@0:     long now = System.currentTimeMillis();
michael@0:     return Math.max(0, earliestNextRequest - now);
michael@0:   }
michael@0: }