org.apache.derby.impl.store.replication.net

Class ReplicationMessageReceive

java.lang.Object

org.apache.derby.impl.store.replication.net.ReplicationMessageReceive

public class ReplicationMessageReceive
extends java.lang.Object

This class is the Receiver (viz. Socket server or listener) part of the network communication. It receives the message from the master and performs appropriate action depending on the type of the message.

Constructor Summary

Constructors

Constructor and Description
ReplicationMessageReceive(SlaveAddress slaveAddress, java.lang.String dbname) Constructor initializes the slave address used in replication.

Method Summary

Modifier and Type	Method and Description
void	initConnection(int timeout, long synchOnInstant, java.lang.String dbname) Used to create the server socket, listen on the socket for connections from the master and verify compatibility with the database version of the master.
boolean	isConnectedToMaster() Check if the repliation network is working.
ReplicationMessage	readMessage() Used to read a replication message sent by the master.
void	sendMessage(ReplicationMessage message) Used to send a replication message to the master.
void	tearDown() Used to close the ServerSocket and the resources associated with it.

Methods inherited from class java.lang.Object

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

Constructor Detail

ReplicationMessageReceive

public ReplicationMessageReceive(SlaveAddress slaveAddress,
                                 java.lang.String dbname)

Constructor initializes the slave address used in replication. Accepts the host name and port number that constitute the slave address as parameters.

Parameters:

slaveAddress - the address (host name and port number) of the slave to connect to.

dbname - the name of the database.

Method Detail

initConnection

public void initConnection(int timeout,
                           long synchOnInstant,
                           java.lang.String dbname)
                    throws java.io.IOException,
                           StandardException,
                           java.lang.ClassNotFoundException

Used to create the server socket, listen on the socket for connections from the master and verify compatibility with the database version of the master.

Parameters:

timeout - The amount of time, in milliseconds, this method will wait for a connection to be established. If no connection has been established before the timeout, a IOException is raised with cause java.net.SocketTimeoutException

synchOnInstant - the slave log instant, used to check that the master and slave log files are in synch. If no chunks of log records have been received from the master yet, this is the end position in the current log file. If a chunk of log has been received, this is the instant of the log record received last. Note that there is a difference!

dbname - the name of the replicated database

Throws:

java.io.IOException - if an exception occurs while trying to create the SocketConnection class or while trying to open a connection.

java.lang.ClassNotFoundException - Class of a serialized object cannot be found.

StandardException - if an incompatible database version is found.

tearDown

public void tearDown()
              throws java.io.IOException

Used to close the ServerSocket and the resources associated with it.

Throws:

java.io.IOException - If an exception occurs while trying to close the socket or the associated resources.

sendMessage

public void sendMessage(ReplicationMessage message)
                 throws java.io.IOException

Used to send a replication message to the master.

Parameters:

message - a ReplicationMessage object that contains the message to be transmitted.

Throws:

java.io.IOException - 1) if an exception occurs while transmitting the message, 2) if the connection handle is invalid.

readMessage

public ReplicationMessage readMessage()
                               throws java.lang.ClassNotFoundException,
                                      java.io.IOException

Used to read a replication message sent by the master. This method would wait on the connection from the master until a message is received or a connection failure occurs. Replication network layer specific messages (i.e. ping/pong messages) are handled internally and are not returned.

Returns:

a ReplicationMessage object that contains the reply that is sent.

Throws:

java.lang.ClassNotFoundException - Class of a serialized object cannot be found.

java.io.IOException - 1) if an exception occurs while reading from the stream, 2) if the connection handle is invalid.

isConnectedToMaster

public boolean isConnectedToMaster()

Check if the repliation network is working. Tries to send a ping message to the master and returns the network status based on the success or failure of sending this message and receiving a pong reply. MT: Currently, only one thread is allowed to check the network status at any time to keep the code complexity down.

Returns:

true if the pong message was received before timing out after DEFAULT_PING_TIMEOUT millis, false otherwise

See Also:

DEFAULT_PING_TIMEOUT