org.corfudb.runtime

Class CheckpointWriter<T extends Map>

java.lang.Object

org.corfudb.runtime.CheckpointWriter<T>

public class CheckpointWriter<T extends Map>
extends Object

Checkpoint writer for SMRMaps: take a snapshot of the object via TXBegin(), then dump the frozen object's state into CheckpointEntry records into the object's stream. TODO: Generalize to all SMR objects.

Constructor Summary

Constructors

Constructor and Description
CheckpointWriter(CorfuRuntime rt, UUID streamId, String author, T map) Constructor for Checkpoint Writer for Corfu Maps.

Method Summary

Modifier and Type	Method and Description
Token	appendCheckpoint()
void	appendObjectState(Set<Map.Entry> entries) Append zero or more CONTINUATION records to this object's stream.
void	finishCheckpoint() Append a checkpoint END record to this object's stream.
void	startCheckpoint(Token txnSnapshot, long vloVersion) Append a checkpoint START record to this object's stream.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

CheckpointWriter

public CheckpointWriter(CorfuRuntime rt,
                        UUID streamId,
                        String author,
                        T map)

Constructor for Checkpoint Writer for Corfu Maps.

Parameters:

rt - object's runtime

streamId - unique identifier of stream to checkpoint

author - checkpoint initiator

map - local reference of the map to checkpoint

Method Detail

appendCheckpoint

public Token appendCheckpoint()

Returns:

Token at which the snapshot for this checkpoint was taken.

startCheckpoint

public void startCheckpoint(Token txnSnapshot,
                            long vloVersion)

Append a checkpoint START record to this object's stream.

Corfu client transaction management, if desired, is the caller's responsibility.

appendObjectState

public void appendObjectState(Set<Map.Entry> entries)

Append zero or more CONTINUATION records to this object's stream. Each will contain a fraction of the state of the object that we're checkpointing (up to batchSize items at a time).

Corfu client transaction management, if desired, is the caller's responsibility.

The Iterators class appears to preserve the laziness of Stream processing; we don't wish to use more memory than strictly necessary to generate the checkpoint. NOTE: It would be even more useful if the map had a lazy iterator: the eagerness of map.keySet().stream() is not ideal, but at least it should be much smaller than the entire map.

NOTE: The postAppendFunc lambda is executed in the current thread context, i.e., inside of a Corfu transaction, and that transaction will be *aborted* at the end of this function. Any Corfu data modifying ops will be undone by the TXAbort().

finishCheckpoint

public void finishCheckpoint()

Append a checkpoint END record to this object's stream.

Corfu client transaction management, if desired, is the caller's responsibility.