Package io.realm.mongodb.sync

Interface RecoverOrDiscardUnsyncedChangesStrategy

All Superinterfaces:

AutomaticClientResetStrategy, SyncClientResetStrategy

public interface RecoverOrDiscardUnsyncedChangesStrategy
extends AutomaticClientResetStrategy

Strategy that attempts to automatically recover any unsynced changes during a Client Reset, if the recovery fails the changes would be discarded.

A synced Realm may need to be reset because the MongoDB Realm Server encountered an error and had to be restored from a backup or because it has been too long since the client connected to the server so the server has rotated the logs.

The Client Reset thus occurs because the server does not have the full information required to bring the Client fully up to date.

The recover or discard unsynced changes process is as follows: when a client reset is received by the client the onBeforeReset(Realm) callback is invoked, then the client would be reset. Once the reset has concluded the callback onAfterRecovery(Realm, Realm) (Realm, Realm)} would be invoked if the changes have been recovered successfully, otherwise the changes would be discarded and onAfterDiscard(Realm, Realm) (Realm, Realm)} (Realm, Realm)} would be invoked.

In the event that the client reset could not discard the unsynced data the onManualResetFallback(SyncSession, ClientResetRequiredError) would be invoked. It allows to manually resolve the reset as it would have been done in ManuallyRecoverUnsyncedChangesStrategy.onClientReset(SyncSession, ClientResetRequiredError).

Method Summary

Modifier and Type	Method	Description
void	onAfterDiscard(Realm before, Realm after)	Callback invoked before the Client Reset discards any unsynced changes because the recovery failed.
void	onAfterRecovery(Realm before, Realm after)	Callback invoked once the Client Reset has recovered the unsynced changes successfully.
void	onBeforeReset(Realm realm)	Callback that indicates a Client Reset is about to happen.
void	onManualResetFallback(SyncSession session, ClientResetRequiredError error)	Callback that indicates the Client reset failed to complete.

Method Detail

onBeforeReset

void onBeforeReset(Realm realm)

Callback that indicates a Client Reset is about to happen. It provides a handle to the local realm before the reset.

Specified by:

onBeforeReset in interface AutomaticClientResetStrategy

Parameters:

realm - frozen Realm in its state before the reset.

onAfterRecovery

void onAfterRecovery(Realm before,
                     Realm after)

Callback invoked once the Client Reset has recovered the unsynced changes successfully. It provides two Realm instances, a frozen one displaying the state before the reset and a regular Realm with the current state.

Parameters:

before - Realm frozen Realm in the state before the reset.

after - Realm Realm after the reset.

onAfterDiscard

void onAfterDiscard(Realm before,
                    Realm after)

Callback invoked before the Client Reset discards any unsynced changes because the recovery failed. It provides two Realm instances, a frozen one displaying the state before the reset and a regular Realm displaying the current state that can be used to recover objects from the reset.

Parameters:

before - Realm frozen Realm in the state before the reset.

after - Realm Realm after the reset.

onManualResetFallback

void onManualResetFallback(SyncSession session,
                           ClientResetRequiredError error)

Callback that indicates the Client reset failed to complete. It should be handled as ManuallyRecoverUnsyncedChangesStrategy.onClientReset(SyncSession, ClientResetRequiredError).

Specified by:

onManualResetFallback in interface AutomaticClientResetStrategy

Parameters:

session - SyncSession this error happened on.

error - ClientResetRequiredError the specific Client Reset error.