Synchronize/align periodic sync alarms based on a random per device seed value.
Removes duplicates SyncHandler.MESSAGE_CHECK_ALARM messages from the queue.
Change-Id: Ib29a06da904cebdd45ee05c9d9a6bf00b72100eb
diff --git a/core/java/android/content/SyncManager.java b/core/java/android/content/SyncManager.java
index 06dfe90..cb3d9cf 100644
--- a/core/java/android/content/SyncManager.java
+++ b/core/java/android/content/SyncManager.java
@@ -204,6 +204,9 @@
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 @@
// 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 @@
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 @@
}
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 @@
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 @@
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 @@
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 =
@@ -1853,12 +1883,13 @@
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
- if (nextPollTimeAbsolute < earliestFuturePollTime) {
- earliestFuturePollTime = nextPollTimeAbsolute;
- }
+ }
+ // 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;
}
}
}
diff --git a/core/java/android/content/SyncStorageEngine.java b/core/java/android/content/SyncStorageEngine.java
index 9c81c9e..5ab9e5a 100644
--- a/core/java/android/content/SyncStorageEngine.java
+++ b/core/java/android/content/SyncStorageEngine.java
@@ -37,6 +37,7 @@
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.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 @@
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 @@
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 int getSyncRandomOffset() {
+ return mSyncRandomOffset;
+ }
+
public void addStatusChangeListener(int mask, ISyncStatusObserver callback) {
synchronized (mAuthorities) {
mChangeListeners.register(callback, mask);
@@ -1465,6 +1474,16 @@
} 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 @@
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();