org.apache.giraph.ooc.persistence

Interface OutOfCoreDataAccessor

All Known Implementing Classes:

InMemoryDataAccessor, LocalDiskDataAccessor

public interface OutOfCoreDataAccessor

Interface representing data accessor object (DAO) used as persistence layer in out-of-core mechanism. Note: any class implementing this interface should have one and only one constructor taking one and only one argument of type ImmutableClassesGiraphConfiguration

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	OutOfCoreDataAccessor.DataInputWrapper Interface to wrap DataInput
static interface	OutOfCoreDataAccessor.DataOutputWrapper Interface to warp DataOutput

Method Summary

Modifier and Type	Method and Description
boolean	dataExist(int threadId, DataIndex index) Whether the data for the given thread and index chain exists?
int	getNumAccessorThreads()
void	initialize() Initialize the DAO
OutOfCoreDataAccessor.DataInputWrapper	prepareInput(int threadId, DataIndex index) Prepare a wrapper containing DataInput representation for a given thread involved in persistence for a given index chain for data.
OutOfCoreDataAccessor.DataOutputWrapper	prepareOutput(int threadId, DataIndex index, boolean shouldAppend) Prepare a wrapper containing DataOutput representation for a given thread involved in persistence for a given index chain for data.
void	shutdown() Shut down the DAO

Method Detail

initialize

void initialize()

Initialize the DAO

shutdown

void shutdown()

Shut down the DAO

getNumAccessorThreads

int getNumAccessorThreads()

Returns:

the number of threads involved in data persistence

prepareInput

OutOfCoreDataAccessor.DataInputWrapper prepareInput(int threadId,
                                                    DataIndex index)
                                             throws IOException

Prepare a wrapper containing DataInput representation for a given thread involved in persistence for a given index chain for data.

Parameters:

threadId - id of the thread involved in persistence

index - index chain of the data to access the serialized data form

Returns:

the wrapper for DataInput representation of data

Throws:

IOException

prepareOutput

OutOfCoreDataAccessor.DataOutputWrapper prepareOutput(int threadId,
                                                      DataIndex index,
                                                      boolean shouldAppend)
                                               throws IOException

Prepare a wrapper containing DataOutput representation for a given thread involved in persistence for a given index chain for data.

Parameters:

threadId - id of the thread involved in persistence

index - index chain of the data to access the serialized data form

shouldAppend - whether the DataOutput should be used for appending to already existing data for the given index or the DataOutput should create new instance to store serialized data

Returns:

the wrapper for DataOutput representation of data

Throws:

IOException

dataExist

boolean dataExist(int threadId,
                  DataIndex index)

Whether the data for the given thread and index chain exists?

Parameters:

threadId - id of the thread involved in persistence

index - index chain used to access the data

Returns:

True if the data exists for the given index chain for the given thread, False otherwise