gr.uoa.di.madgik.grs.proxy.tcp.mirror

Class TCPWriterMirror

java.lang.Object

java.lang.Thread

gr.uoa.di.madgik.grs.proxy.tcp.mirror.TCPWriterMirror

All Implemented Interfaces:

IMirror, Runnable

public class TCPWriterMirror
extends Thread
implements IMirror

This implementation of the IMirror interface specializes the mirroring procedure that needs to be performed from the writer side of the mirroring procedure. The technology employed is communication over raw TCP sockets. The communication protocol is coupled with the one implemented by the TCPReaderMirror which is the writer side counterpart of this class

Author:

gpapanikos

Nested Class Summary

Nested classes/interfaces inherited from class java.lang.Thread

Thread.State, Thread.UncaughtExceptionHandler

Nested classes/interfaces inherited from interface gr.uoa.di.madgik.grs.proxy.mirror.IMirror

IMirror.MirroringState

Field Summary

Fields inherited from class java.lang.Thread

MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY

Constructor Summary

Constructors

Constructor and Description
TCPWriterMirror()

Method Summary

Methods

Modifier and Type	Method and Description
void	dispose() Dispose the resources employed by the mirroring implementations
void	dispose(boolean purge) This method disposes the resources that are used by the instance but does so in two phases.
IBuffer	getBuffer() Retrieves the IBuffer that is managed by the IMirror implementation.
void	handle() This invocation of this method starts a new execution thread where the mirroring procedure is executed.
boolean	pollPartial(long recordIndex, int fieldIndex)
long	requestPartial(long recordIndex, int fieldIndex, IBuffer.TransportOverride override, Object notify) This method is used by the reader side mirror to request payload that belongs to an IBuffer item that has been transfered only partially and more data is requested by the reader client
void	run()
void	setInputStream(ObjectInputStream ois)
void	setKey(String key) Sets the local GRSRegistry key associated with the IBuffer that needs to be mirrored
void	setSocket(Socket socket) Sets the socket used by the TCPReaderMirror
void	writerAcceptRequests()

Methods inherited from class java.lang.Thread

activeCount, checkAccess, clone, countStackFrames, currentThread, destroy, dumpStack, enumerate, getAllStackTraces, getContextClassLoader, getDefaultUncaughtExceptionHandler, getId, getName, getPriority, getStackTrace, getState, getThreadGroup, getUncaughtExceptionHandler, holdsLock, interrupt, interrupted, isAlive, isDaemon, isInterrupted, join, join, join, resume, setContextClassLoader, setDaemon, setDefaultUncaughtExceptionHandler, setName, setPriority, setUncaughtExceptionHandler, sleep, sleep, start, stop, stop, suspend, toString, yield

Methods inherited from class java.lang.Object

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

Constructor Detail

TCPWriterMirror

public TCPWriterMirror()

Method Detail

setInputStream

public void setInputStream(ObjectInputStream ois)

setSocket

public void setSocket(Socket socket)

Sets the socket used by the TCPReaderMirror

Parameters:

socket - the socket to use for the communication

setKey

public void setKey(String key)

Sets the local GRSRegistry key associated with the IBuffer that needs to be mirrored

Parameters:

key - the key associated with the served IBuffer

getBuffer

public IBuffer getBuffer()

Retrieves the IBuffer that is managed by the IMirror implementation. Depending on the mirror side, this instance is either the one the writer is authoring, or the one the reader is accessing.

Specified by:

getBuffer in interface IMirror

Returns:

the IBuffer that is managed by the IMirror implementation

See Also:

IMirror.getBuffer()

handle

public void handle()
            throws GRS2ProxyMirrorInvalidOperationException

This invocation of this method starts a new execution thread where the mirroring procedure is executed. The created thread of execution is executed in the background and as a daemon service.

Throws:

GRS2ProxyMirrorInvalidOperationException - if the mirroring state does not allow the operation to be executed

dispose

public void dispose()

Dispose the resources employed by the mirroring implementations

This method actually invokes the respective dispose(boolean) with an argument of false. This is because the actual disposing needs to take place when the mirroring thread is prepared to gracefully exit its execution

Specified by:

dispose in interface IMirror

See Also:

IMirror.dispose()

dispose

public void dispose(boolean purge)

This method disposes the resources that are used by the instance but does so in two phases. One can request the disposal passing an argument of false which puts the mirroring thread in a state where the needed actions are taken to gracefully exit this part of the protocol but also notify the respective TCPReaderMirror to stop the mirroring procedure gracefully. When the method in again invoked with a true argument from the protocol implementing thread, all resources are disposed.

Parameters:

purge - whether the resources need to be immediately disposed, or this need to wait until the protocol thread is ready to purge the involved resources

pollPartial

public boolean pollPartial(long recordIndex,
                  int fieldIndex)
                    throws GRS2ProxyMirrorInvalidOperationException

This method is not supported in the TCPWriterMirror

Specified by:

pollPartial in interface IMirror

Parameters:

recordIndex - The record index / id, for which the requester has requested data to be delivered

fieldIndex - The field index of the specific record for which data are requested

Returns:

false if the requester needs to wait again until data is returned false otherwise. In case true is returned, the data have either been retrieved, or no more data is expected to be send, possibly because of a closed connection

Throws:

GRS2ProxyMirrorInvalidOperationException - if the method is invoked

See Also:

IMirror.pollPartial(long, int)

requestPartial

public long requestPartial(long recordIndex,
                  int fieldIndex,
                  IBuffer.TransportOverride override,
                  Object notify)
                    throws GRS2ProxyMirrorInvalidOperationException

This method is used by the reader side mirror to request payload that belongs to an IBuffer item that has been transfered only partially and more data is requested by the reader client

This method is not supported in the TCPWriterMirror

Specified by:

requestPartial in interface IMirror

Parameters:

recordIndex - The index of the record whose payload is requested. As described in Record, this index coincides with the record id.

fieldIndex - The index of the field belonging to the defined record for which additional data is requested

override - whether or not the field's IBuffer.TransportDirective should be overridden as explained in IBuffer

notify - A synchronization object that can be used for the requester to block on until the required data is provided

Returns:

An indicative amount of time that the requester can wait before the data is available. This value is only indicative and it does not imply that after this period the data will be available. For this. the IMirror.pollPartial(long, int) should be used

Throws:

GRS2ProxyMirrorInvalidOperationException - if the method is invoked

See Also:

IMirror.requestPartial(long, int, gr.uoa.di.madgik.grs.buffer.IBuffer.TransportOverride, java.lang.Object)

writerAcceptRequests

public void writerAcceptRequests()
                          throws Exception

In the context of the mirroring procedure, the execution of this thread includes the following actions.
Initially, the local GRSRegistry is queried for the IBuffer to serve and its state is checked to make sure that it is available for mirroring.
The main protocol loop is then initialized. On every iteration, the reader request is read and the needed Records are returned limited based on the mirroring factor defined by the IBuffer and the available records. Additionally, if there are requests for partial data to be transfered, they are included in the response.
Additionally, after the request is read, the incoming events are read and emitted in the local IBuffer and after all record data is send, the available events are send. The status of the local mirroring procedure is also transmitted, while the remote state received is checked to see if the connection should be teardown.

Throws:

Exception

See Also:

Thread.run()

run

public void run()

Specified by:

run in interface Runnable

Overrides:

run in class Thread