Synchronize/align periodic sync alarms based on a random per device seed value. (69d95de5) · Commits · e / os / android_frameworks_base

core/java/android/content/SyncManager.java

+45 −14

Original line number	Diff line number	Diff line
		@@ -204,6 +204,9 @@ public class SyncManager implements OnAccountsUpdateListener {

		private final PowerManager mPowerManager;

		// Use this as a random offset to seed all periodic syncs
		private int mSyncRandomOffsetMillis;

		private static final long SYNC_ALARM_TIMEOUT_MIN = 30 * 1000; // 30 seconds
		private static final long SYNC_ALARM_TIMEOUT_MAX = 2 * 60 * 60 * 1000; // two hours

		@@ -472,6 +475,9 @@ public class SyncManager implements OnAccountsUpdateListener {
		// do this synchronously to ensure we have the accounts before this call returns
		onAccountsUpdated(null);
		}

		// Pick a random second in a day to seed all periodic syncs
		mSyncRandomOffsetMillis = mSyncStorageEngine.getSyncRandomOffset() * 1000;
		}

		/**
		@@ -700,6 +706,7 @@ public class SyncManager implements OnAccountsUpdateListener {

		private void sendCheckAlarmsMessage() {
		if (Log.isLoggable(TAG, Log.VERBOSE)) Log.v(TAG, "sending MESSAGE_CHECK_ALARMS");
		mSyncHandler.removeMessages(SyncHandler.MESSAGE_CHECK_ALARMS);
		mSyncHandler.sendEmptyMessage(SyncHandler.MESSAGE_CHECK_ALARMS);
		}

		@@ -748,6 +755,8 @@ public class SyncManager implements OnAccountsUpdateListener {
		}

		private void increaseBackoffSetting(SyncOperation op) {
		// TODO: Use this function to align it to an already scheduled sync
		// operation in the specified window
		final long now = SystemClock.elapsedRealtime();

		final Pair<Long, Long> previousSettings =
		@@ -1094,6 +1103,8 @@ public class SyncManager implements OnAccountsUpdateListener {
		final long now = SystemClock.elapsedRealtime();
		pw.print("now: "); pw.print(now);
		pw.println(" (" + formatTime(System.currentTimeMillis()) + ")");
		pw.print("offset: "); pw.print(DateUtils.formatElapsedTime(mSyncRandomOffsetMillis/1000));
		pw.println(" (HH:MM:SS)");
		pw.print("uptime: "); pw.print(DateUtils.formatElapsedTime(now/1000));
		pw.println(" (HH:MM:SS)");
		pw.print("time spent syncing: ");
		@@ -1805,6 +1816,9 @@ public class SyncManager implements OnAccountsUpdateListener {
		AccountAndUser[] accounts = mAccounts;

		final long nowAbsolute = System.currentTimeMillis();
		final long shiftedNowAbsolute = (0 < nowAbsolute - mSyncRandomOffsetMillis)
		? (nowAbsolute - mSyncRandomOffsetMillis) : 0;

		ArrayList<SyncStorageEngine.AuthorityInfo> infos = mSyncStorageEngine.getAuthorities();
		for (SyncStorageEngine.AuthorityInfo info : infos) {
		// skip the sync if the account of this operation no longer exists
		@@ -1826,16 +1840,32 @@ public class SyncManager implements OnAccountsUpdateListener {
		SyncStatusInfo status = mSyncStorageEngine.getOrCreateSyncStatus(info);
		for (int i = 0, N = info.periodicSyncs.size(); i < N; i++) {
		final Bundle extras = info.periodicSyncs.get(i).first;
		final Long periodInSeconds = info.periodicSyncs.get(i).second;
		final Long periodInMillis = info.periodicSyncs.get(i).second * 1000;
		// find when this periodic sync was last scheduled to run
		final long lastPollTimeAbsolute = status.getPeriodicSyncTime(i);
		// compute when this periodic sync should next run - this can be in the future
		// for example if the user changed the time, synced and changed back.
		final long nextPollTimeAbsolute = lastPollTimeAbsolute > nowAbsolute
		? nowAbsolute
		: lastPollTimeAbsolute + periodInSeconds * 1000;
		// if it is ready to run then schedule it and mark it as having been scheduled
		if (nextPollTimeAbsolute <= nowAbsolute) {

		long remainingMillis
		= periodInMillis - (shiftedNowAbsolute % periodInMillis);

		/*
		* Sync scheduling strategy:
		* Set the next periodic sync based on a random offset (in seconds).
		*
		* Also sync right now if any of the following cases hold
		* and mark it as having been scheduled
		*
		* Case 1: This sync is ready to run now.
		* Case 2: If the lastPollTimeAbsolute is in the future,
		* sync now and reinitialize. This can happen for
		* example if the user changed the time, synced and
		* changed back.
		* Case 3: If we failed to sync at the last scheduled time
		*/
		if (remainingMillis == periodInMillis // Case 1
		\|\| lastPollTimeAbsolute > nowAbsolute // Case 2
		\|\| (nowAbsolute - lastPollTimeAbsolute
		>= periodInMillis)) { // Case 3
		// Sync now
		final Pair<Long, Long> backoff = mSyncStorageEngine.getBackoff(
		info.account, info.userId, info.authority);
		final RegisteredServicesCache.ServiceInfo<SyncAdapterType> syncAdapterInfo =
		@@ -1853,15 +1883,16 @@ public class SyncManager implements OnAccountsUpdateListener {
		info.account, info.userId, info.authority),
		syncAdapterInfo.type.allowParallelSyncs()));
		status.setPeriodicSyncTime(i, nowAbsolute);
		} else {
		// it isn't ready to run, remember this time if it is earlier than
		// earliestFuturePollTime
		}
		// Compute when this periodic sync should next run
		final long nextPollTimeAbsolute = nowAbsolute + remainingMillis;

		// remember this time if it is earlier than earliestFuturePollTime
		if (nextPollTimeAbsolute < earliestFuturePollTime) {
		earliestFuturePollTime = nextPollTimeAbsolute;
		}
		}
		}
		}

		if (earliestFuturePollTime == Long.MAX_VALUE) {
		return Long.MAX_VALUE;

core/java/android/content/SyncStorageEngine.java

+20 −0

Original line number	Diff line number	Diff line
		@@ -37,6 +37,7 @@ import android.os.Message;
		import android.os.Parcel;
		import android.os.RemoteCallbackList;
		import android.os.RemoteException;
		import android.os.SystemClock;
		import android.util.Log;
		import android.util.SparseArray;
		import android.util.Xml;
		@@ -49,6 +50,7 @@ import java.util.ArrayList;
		import java.util.Calendar;
		import java.util.HashMap;
		import java.util.Iterator;
		import java.util.Random;
		import java.util.TimeZone;
		import java.util.List;

		@@ -65,6 +67,7 @@ public class SyncStorageEngine extends Handler {

		private static final String XML_ATTR_NEXT_AUTHORITY_ID = "nextAuthorityId";
		private static final String XML_ATTR_LISTEN_FOR_TICKLES = "listen-for-tickles";
		private static final String XML_ATTR_SYNC_RANDOM_OFFSET = "offsetInSeconds";
		private static final String XML_ATTR_ENABLED = "enabled";
		private static final String XML_ATTR_USER = "user";
		private static final String XML_TAG_LISTEN_FOR_TICKLES = "listenForTickles";
		@@ -277,6 +280,8 @@ public class SyncStorageEngine extends Handler {

		private static volatile SyncStorageEngine sSyncStorageEngine = null;

		private int mSyncRandomOffset;

		/**
		* This file contains the core engine state: all accounts and the
		* settings for them. It must never be lost, and should be changed
		@@ -375,6 +380,10 @@ public class SyncStorageEngine extends Handler {
		}
		}

		public int getSyncRandomOffset() {
		return mSyncRandomOffset;
		}

		public void addStatusChangeListener(int mask, ISyncStatusObserver callback) {
		synchronized (mAuthorities) {
		mChangeListeners.register(callback, mask);
		@@ -1465,6 +1474,16 @@ public class SyncStorageEngine extends Handler {
		} catch (NumberFormatException e) {
		// don't care
		}
		String offsetString = parser.getAttributeValue(null, XML_ATTR_SYNC_RANDOM_OFFSET);
		try {
		mSyncRandomOffset = (offsetString == null) ? 0 : Integer.parseInt(offsetString);
		} catch (NumberFormatException e) {
		mSyncRandomOffset = 0;
		}
		if (mSyncRandomOffset == 0) {
		Random random = new Random(System.currentTimeMillis());
		mSyncRandomOffset = random.nextInt(86400);
		}
		mMasterSyncAutomatically.put(0, listen == null \|\| Boolean.parseBoolean(listen));
		eventType = parser.next();
		AuthorityInfo authority = null;
		@@ -1705,6 +1724,7 @@ public class SyncStorageEngine extends Handler {
		out.startTag(null, "accounts");
		out.attribute(null, "version", Integer.toString(ACCOUNTS_VERSION));
		out.attribute(null, XML_ATTR_NEXT_AUTHORITY_ID, Integer.toString(mNextAuthorityId));
		out.attribute(null, XML_ATTR_SYNC_RANDOM_OFFSET, Integer.toString(mSyncRandomOffset));

		// Write the Sync Automatically flags for each user
		final int M = mMasterSyncAutomatically.size();