ostore.read
Class ReadStage

java.lang.Object
  |
  +--ostore.read.ReadStage

All Implemented Interfaces:

EventHandlerIF, ProfilableIF, SingleThreadedEventHandlerIF

public class ReadStage

extends Object

implements SingleThreadedEventHandlerIF, EventHandlerIF, ProfilableIF

The ReadStage performs the read satisfying a ReadReq event. The ReadStage implements the low-level bytes read or slice read satisfying the BytesReadReq or SliceReadReq, respectively. The ReadStage is a SandStorm stage that performs a read satisfying a ReadReq event.

The ReadStage implements the low-level bytes bytes read or slice read satisfying the BytesReadReq or SliceReadReq, respectively. The ReadStage performs a ReadReq by either placing the requested bytes in a BytesReadResp or the requested blocks in a SliceReadResp.

USAGE

To read bytes of an object dispatch a BytesReadReq containing the versionId of the object to read, the A-GUID (tree_id) of the object, the Selection to read, the fault_mode, and a Map of spare_blocks. The local ReadStage will receive the BytesReadReq event and return a BytesReadResp containing the bytes and any missing bytes depending on the fault mode.

To read the blocks that are contained in a slice of an object from the data to the root of an object dispatch a SliceReadReq containing the versionId of the object to read, the A-GUID (tree_id) of the object, the Selection to read, and the fault_mode The local ReadStage will receive the SliceReadReq event and return a SliceReadResp containing a Map of the blocks read, a Selection of the blocks read, and a Selection of the blocks missing.

INITIALIZATION PARAMETERS

node_id

NodeId of the local server where this stage is running.

AlarmTimeout

Period to timeout (in milliseconds)

Version:

$Id: ReadStage.java,v 1.50 2004/05/13 20:16:04 hweather Exp $

Author:

Hakim Weatherspoon

See Also:

ReadReq, ReadResp, BytesReadReq, BytesReadResp, SliceReadReq, SliceReadResp, ReplicaStage, Selection, VerifiableBlock, DataObject, Btree.InteriorNode, DataObject.DataBlock

Constructor Summary

ReadStage()

Method Summary

void	destroy()
void	handleEvent(QueueElementIF item)
void	handleEvents(QueueElementIF[] items)
void	init(ConfigDataIF config)
int	profileSize()

Methods inherited from class java.lang.Object

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

Constructor Detail

ReadStage

public ReadStage()

Method Detail

handleEvent

public void handleEvent(QueueElementIF item)
                 throws EventHandlerException

Specified by:

handleEvent in interface EventHandlerIF

EventHandlerException

handleEvents

public void handleEvents(QueueElementIF[] items)
                  throws EventHandlerException

Specified by:

handleEvents in interface EventHandlerIF

EventHandlerException

init

public void init(ConfigDataIF config)
          throws Exception

Specified by:

init in interface EventHandlerIF

Exception

destroy

public void destroy()
             throws Exception

Specified by:

destroy in interface EventHandlerIF

Exception

profileSize

public int profileSize()

Specified by:

profileSize in interface ProfilableIF