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.fxa.sync;
michael@0: 
michael@0: import org.mozilla.gecko.background.common.log.Logger;
michael@0: import org.mozilla.gecko.db.BrowserContract;
michael@0: import org.mozilla.gecko.fxa.authenticator.AndroidFxAccount;
michael@0: import org.mozilla.gecko.fxa.login.State.Action;
michael@0: import org.mozilla.gecko.sync.BackoffHandler;
michael@0: 
michael@0: import android.accounts.Account;
michael@0: import android.content.ContentResolver;
michael@0: import android.content.Context;
michael@0: import android.os.Bundle;
michael@0: 
michael@0: public class FxAccountSchedulePolicy implements SchedulePolicy {
michael@0:   private static final String LOG_TAG = "FxAccountSchedulePolicy";
michael@0: 
michael@0:   // Our poll intervals are used to trigger automatic background syncs
michael@0:   // in the absence of user activity.
michael@0:   //
michael@0:   // We also receive sync requests as a result of network tickles, so
michael@0:   // these intervals are long, with the exception of the rapid polling
michael@0:   // while we wait for verification: if we're waiting for the user to
michael@0:   // click on a verification link, we sync very often in order to detect
michael@0:   // a change in state.
michael@0:   //
michael@0:   // In the case of unverified -> unverified (no transition), this should be
michael@0:   // very close to a single HTTP request (with the SyncAdapter overhead, of
michael@0:   // course, but that's not wildly different from alarm manager overhead).
michael@0:   //
michael@0:   // The /account/status endpoint is HAWK authed by sessionToken, so we still
michael@0:   // have to do some crypto no matter what.
michael@0: 
michael@0:   // TODO: only do this for a while...
michael@0:   public static final long POLL_INTERVAL_PENDING_VERIFICATION = 60;         // 1 minute.
michael@0: 
michael@0:   // If we're in some kind of error state, there's no point trying often.
michael@0:   // This is not the same as a server-imposed backoff, which will be
michael@0:   // reflected dynamically.
michael@0:   public static final long POLL_INTERVAL_ERROR_STATE_SEC = 24 * 60 * 60;    // 24 hours.
michael@0: 
michael@0:   // If we're the only device, just sync once or twice a day in case that
michael@0:   // changes.
michael@0:   public static final long POLL_INTERVAL_SINGLE_DEVICE_SEC = 18 * 60 * 60;  // 18 hours.
michael@0: 
michael@0:   // And if we know there are other devices, let's sync often enough that
michael@0:   // we'll be more likely to be caught up (even if not completely) by the
michael@0:   // time you next use this device. This is also achieved via Android's
michael@0:   // network tickles.
michael@0:   public static final long POLL_INTERVAL_MULTI_DEVICE_SEC = 12 * 60 * 60;   // 12 hours.
michael@0: 
michael@0:   // This is used solely as an optimization for backoff handling, so it's not
michael@0:   // persisted.
michael@0:   private static volatile long POLL_INTERVAL_CURRENT_SEC = POLL_INTERVAL_SINGLE_DEVICE_SEC;
michael@0: 
michael@0:   // Never sync more frequently than this, unless forced.
michael@0:   // This is to avoid overly-frequent syncs during active browsing.
michael@0:   public static final long RATE_LIMIT_FUNDAMENTAL_SEC = 90;                 // 90 seconds.
michael@0: 
michael@0:   /**
michael@0:    * We are prompted to sync by several inputs:
michael@0:    * * Periodic syncs that we schedule at long intervals. See the POLL constants.
michael@0:    * * Network-tickle-based syncs that Android starts.
michael@0:    * * Upload-only syncs that are caused by local database writes.
michael@0:    *
michael@0:    * We rate-limit periodic and network-sourced events with this constant.
michael@0:    * We rate limit <b>both</b> with {@link FxAccountSchedulePolicy#RATE_LIMIT_FUNDAMENTAL_SEC}.
michael@0:    */
michael@0:   public static final long RATE_LIMIT_BACKGROUND_SEC = 60 * 60;             // 1 hour.
michael@0: 
michael@0:   private final AndroidFxAccount account;
michael@0:   private final Context context;
michael@0: 
michael@0:   public FxAccountSchedulePolicy(Context context, AndroidFxAccount account) {
michael@0:     this.account = account;
michael@0:     this.context = context;
michael@0:   }
michael@0: 
michael@0:   /**
michael@0:    * Return a millisecond timestamp in the future, offset from the current
michael@0:    * time by the provided amount.
michael@0:    * @param millis the duration by which to delay
michael@0:    * @return a timestamp.
michael@0:    */
michael@0:   private static long delay(long millis) {
michael@0:     return System.currentTimeMillis() + millis;
michael@0:   }
michael@0: 
michael@0:   /**
michael@0:    * Updates the existing system periodic sync interval to the specified duration.
michael@0:    *
michael@0:    * @param intervalSeconds the requested period, which Android will vary by up to 4%.
michael@0:    */
michael@0:   protected void requestPeriodicSync(final long intervalSeconds) {
michael@0:     final String authority = BrowserContract.AUTHORITY;
michael@0:     final Account account = this.account.getAndroidAccount();
michael@0:     this.context.getContentResolver();
michael@0:     Logger.info(LOG_TAG, "Scheduling periodic sync for " + intervalSeconds + ".");
michael@0:     ContentResolver.addPeriodicSync(account, authority, Bundle.EMPTY, intervalSeconds);
michael@0:     POLL_INTERVAL_CURRENT_SEC = intervalSeconds;
michael@0:   }
michael@0: 
michael@0:   @Override
michael@0:   public void onSuccessfulSync(int otherClientsCount) {
michael@0:     // This undoes the change made in observeBackoffMillis -- once we hit backoff we'll
michael@0:     // periodically sync at the backoff duration, but as soon as we succeed we'll switch
michael@0:     // into the client-count-dependent interval.
michael@0:     long interval = (otherClientsCount > 0) ? POLL_INTERVAL_MULTI_DEVICE_SEC : POLL_INTERVAL_SINGLE_DEVICE_SEC;
michael@0:     requestPeriodicSync(interval);
michael@0:   }
michael@0: 
michael@0:   @Override
michael@0:   public void onHandleFinal(Action needed) {
michael@0:     switch (needed) {
michael@0:     case NeedsPassword:
michael@0:     case NeedsUpgrade:
michael@0:       requestPeriodicSync(POLL_INTERVAL_ERROR_STATE_SEC);
michael@0:       break;
michael@0:     case NeedsVerification:
michael@0:       requestPeriodicSync(POLL_INTERVAL_PENDING_VERIFICATION);
michael@0:       break;
michael@0:     case None:
michael@0:       // No action needed: we'll set the periodic sync interval
michael@0:       // when the sync finishes, via the SessionCallback.
michael@0:       break;
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   @Override
michael@0:   public void onUpgradeRequired() {
michael@0:     // TODO: this shouldn't occur in FxA, but when we upgrade we
michael@0:     // need to reduce the interval again.
michael@0:     requestPeriodicSync(POLL_INTERVAL_ERROR_STATE_SEC);
michael@0:   }
michael@0: 
michael@0:   @Override
michael@0:   public void onUnauthorized() {
michael@0:     // TODO: this shouldn't occur in FxA, but when we fix our credentials
michael@0:     // we need to reduce the interval again.
michael@0:     requestPeriodicSync(POLL_INTERVAL_ERROR_STATE_SEC);
michael@0:   }
michael@0: 
michael@0:   @Override
michael@0:   public void configureBackoffMillisOnBackoff(BackoffHandler backoffHandler, long backoffMillis, boolean onlyExtend) {
michael@0:     if (onlyExtend) {
michael@0:       backoffHandler.extendEarliestNextRequest(delay(backoffMillis));
michael@0:     } else {
michael@0:       backoffHandler.setEarliestNextRequest(delay(backoffMillis));
michael@0:     }
michael@0: 
michael@0:     // Yes, we might be part-way through the interval, in which case the backoff
michael@0:     // code will do its job. But we certainly don't want to reduce the interval
michael@0:     // if we're given a small backoff instruction.
michael@0:     // We'll reset the poll interval next time we sync without a backoff instruction.
michael@0:     if (backoffMillis > (POLL_INTERVAL_CURRENT_SEC * 1000)) {
michael@0:       // Slightly inflate the backoff duration to ensure that a fuzzed
michael@0:       // periodic sync doesn't occur before our backoff has passed. Android
michael@0:       // 19+ default to a 4% fuzz factor.
michael@0:       requestPeriodicSync((long) Math.ceil((1.05 * backoffMillis) / 1000));
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   /**
michael@0:    * Accepts two {@link BackoffHandler} instances as input. These are used
michael@0:    * respectively to track fundamental rate limiting, and to separately
michael@0:    * rate-limit periodic and network-tickled syncs.
michael@0:    */
michael@0:   @Override
michael@0:   public void configureBackoffMillisBeforeSyncing(BackoffHandler fundamentalRateHandler, BackoffHandler backgroundRateHandler) {
michael@0:     fundamentalRateHandler.setEarliestNextRequest(delay(RATE_LIMIT_FUNDAMENTAL_SEC * 1000));
michael@0:     backgroundRateHandler.setEarliestNextRequest(delay(RATE_LIMIT_BACKGROUND_SEC * 1000));
michael@0:   }
michael@0: }