SyncAdapter & SyncResult

Question

I want to know what is the default behavior of SyncManager when we use the object SyncResult during the operation onPerformSync()

For instance, when sync is in error due to IOException, we set

syncResult.stats.numIoExceptions++

Then SyncManager must manage the re-send sync until a delay specify by the system.

But how many times the sync is re-call if IOException accurs at each sync? What is the default delay set between each sync? Is that possible to define its own behaviors? Where can I find documentation about that?

Answer 1

The SyncResult object has a delayUntil field that you can set from your sync adapter which will delay each following sync by the specified number of seconds. Maybe this is the field you're looking for.

Otherwise, the sync will be rescheduled if

SyncResult.madeSomeProgress() returns true - i.e. some work was successfully accomplished by the sync (corresponding to stats.numDeletes, stats.numInserts > 0, stats.numUpdates > 0)

SyncResult.hasSoftError() returns true - i.e. it failed due to an IOException or because SyncResult.syncAlreadyInProgress was true.

So to answer your question, if IOExceptions occur at EVERY sync, the SyncManager will retry ad infinitum - with exponential backoff.

The caveat to this is that the sync adapter can set SyncResult.tooManyRetries = true which will indicate to the SyncManager that the sync is not to rescheduled.

Answer 2

The initial retry time:

/**
 * When retrying a sync for the first time use this delay. After that
 * the retry time will double until it reached MAX_SYNC_RETRY_TIME.
 * In milliseconds.
 */
private static final long INITIAL_SYNC_RETRY_TIME_IN_MS = 30 * 1000; // 30 seconds

You can tell the framework to stop retrying the sync by setting SyncResult#tooManyRetries to true.

Source: SyncManager.java