Modifier and Type	Class and Description
private class	ReplicationMessageReceive.SlavePingThread Thread that sends ping messages to the master on request to check if the replication network is working

Field Summary

Modifier and Type	Field and Description
private boolean	connectionConfirmed Whether or not the connection with the master is confirmed to be working.
private static final int	DEFAULT_PING_TIMEOUT The maximum number of millis to wait before giving up waiting for a ping response
private boolean	doSendPing Whether or not the ping thread has been notified to check connection.
private boolean	killPingThread Used to terminate the ping thread.
private Thread	pingThread Thread used to send ping messages to master to check if the connection is working.
private final Object	receivePongSemaphore Used for synchronization when waiting for a ping reply message
private final Object	sendPingSemaphore Used for synchronization of the ping thread
private ServerSocket	serverSocket Contains the `ServerSocket` used to listen for connections from the replication master.
private final SlaveAddress	slaveAddress Contains the address (hostname and port number) of the slave to replicate to.
private SocketConnection	socketConn Contains the methods used to read and write to the Object streams obtained from a `Socket` connection.

Constructor Summary

Access	Constructor and Description
public	ReplicationMessageReceive(SlaveAddress the address (host name and port number) of the slave to connect to. slaveAddress, String the name of the database. dbname) Constructor initializes the slave address used in replication.

Method Summary

Modifier and Type	Method and Description
private void	checkSocketConnection() Verifies if the `SocketConnection` is valid.
private ServerSocket	Returns: an instance of the `ServerSocket` class. createServerSocket() Used to create a `ServerSocket` for listening to connections from the master.
private void	handleUnexpectedMessage(String the name of the replicated database dbname, String the expected message type expextedMsgId, String the received message type receivedMsgId) Notify other replication peer that the message type was unexpected and throw a StandardException
public void	initConnection(int 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 timeout, long 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! synchOnInstant, String the name of the replicated database 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.
public synchronized boolean	Returns: true if the pong message was received before timing out after DEFAULT_PING_TIMEOUT millis, false otherwise isConnectedToMaster() Check if the repliation network is working.
private void	parseAndAckInstant(ReplicationMessage the object containing the UID. initiatorMessage, long 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! synchOnInstant, String the name of the replicated database dbname) Used to parse the log instant initiator message from the master and check that the master and slave log files are in synch.
private void	parseAndAckVersion(ReplicationMessage the object containing the UID. initiatorMessage, String the name of the replicated database dbname) Used to parse the initiator message from the master and check if the slave is compatible with the master by comparing the UID of the `ReplicationMessage` class of the master, that is wrapped in the initiator message, with the UID of the same class in the slave.
public ReplicationMessage	Returns: a `ReplicationMessage` object that contains the reply that is sent. readMessage() Used to read a replication message sent by the master.
public void	sendMessage(ReplicationMessage a `ReplicationMessage` object that contains the message to be transmitted. message) Used to send a replication message to the master.
public void	tearDown() Used to close the `ServerSocket` and the resources associated with it.

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

Field Detail

connectionConfirmed	back to summary
private boolean connectionConfirmed Whether or not the connection with the master is confirmed to be working. Set to false by isConnectedToMaster, set to true when a pong (i.e., a response to a ping) is received. Field protected by receivePongSemephore

DEFAULT_PING_TIMEOUT	back to summary
private static final int DEFAULT_PING_TIMEOUT The maximum number of millis to wait before giving up waiting for a ping response

doSendPing	back to summary
private boolean doSendPing Whether or not the ping thread has been notified to check connection. Protected by sendPingSemaphore.

killPingThread	back to summary
private boolean killPingThread Used to terminate the ping thread.

pingThread	back to summary
private Thread pingThread Thread used to send ping messages to master to check if the connection is working. The ping message must be sent from a separate thread because failed message shipping over TCP does not timeout for two minutes (not configurable).

receivePongSemaphore	back to summary
private final Object receivePongSemaphore Used for synchronization when waiting for a ping reply message

sendPingSemaphore	back to summary
private final Object sendPingSemaphore Used for synchronization of the ping thread

serverSocket	back to summary
private ServerSocket serverSocket Contains the `ServerSocket` used to listen for connections from the replication master.

slaveAddress	back to summary
private final SlaveAddress slaveAddress Contains the address (hostname and port number) of the slave to replicate to.

socketConn	back to summary
private SocketConnection socketConn Contains the methods used to read and write to the Object streams obtained from a `Socket` connection.

Constructor Detail

ReplicationMessageReceive	back to summary
public ReplicationMessageReceive(SlaveAddress slaveAddress, 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:SlaveAddress the address (host name and port number) of the slave to connect to. dbname:String the name of the database.

ReplicationMessageReceive

back to summary

public ReplicationMessageReceive(SlaveAddress slaveAddress, 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:SlaveAddress: the address (host name and port number) of the slave to connect to.
dbname:String: the name of the database.

Method Detail

checkSocketConnection back to summary

checkSocketConnection	back to summary
private void checkSocketConnection() throws IOException Verifies if the `SocketConnection` is valid. Exceptions IOException: If the socket connection object is not valid (is null).

private void checkSocketConnection() throws IOException

Verifies if the SocketConnection is valid.

Exceptions

IOException:: If the socket connection object is not valid (is null).

createServerSocket back to summary

createServerSocket	back to summary
private ServerSocket createServerSocket() throws IOException Used to create a `ServerSocket` for listening to connections from the master. Returns:ServerSocket an instance of the `ServerSocket` class. Exceptions IOException: if an exception occurs while trying to open a connection.

private ServerSocket createServerSocket() throws IOException

Used to create a ServerSocket for listening to connections from the master.

Returns:ServerSocket

an instance of the ServerSocket class.

Exceptions

IOException:: if an exception occurs while trying to open a connection.

handleUnexpectedMessage	back to summary
private void handleUnexpectedMessage(String dbname, String expextedMsgId, String receivedMsgId) throws StandardException, IOException Notify other replication peer that the message type was unexpected and throw a StandardException Parameters dbname:String the name of the replicated database expextedMsgId:String the expected message type receivedMsgId:String the received message type Exceptions StandardException: exception describing that an unexpected message was received is always thrown IOException: thrown if an exception occurs while sending the error message

handleUnexpectedMessage

back to summary

private void handleUnexpectedMessage(String dbname, String expextedMsgId, String receivedMsgId) throws StandardException, IOException

Notify other replication peer that the message type was unexpected and throw a StandardException

Parameters

dbname:String: the name of the replicated database
expextedMsgId:String: the expected message type
receivedMsgId:String: the received message type

Exceptions

StandardException:: exception describing that an unexpected message was received is always thrown
IOException:: thrown if an exception occurs while sending the error message

initConnection back to summary

initConnection	back to summary
public void initConnection(int timeout, long synchOnInstant, String dbname) throws IOException, StandardException, 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:int 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:long 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:String the name of the replicated database Exceptions IOException: if an exception occurs while trying to create the `SocketConnection` class or while trying to open a connection. StandardException: if an incompatible database version is found. ClassNotFoundException: Class of a serialized object cannot be found.

public void initConnection(int timeout, long synchOnInstant, String dbname) throws IOException, StandardException, 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:int: 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:long: 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:String: the name of the replicated database

Exceptions

IOException:: if an exception occurs while trying to create the SocketConnection class or while trying to open a connection.
StandardException:: if an incompatible database version is found.
ClassNotFoundException:: Class of a serialized object cannot be found.

isConnectedToMaster back to summary

isConnectedToMaster	back to summary
public synchronized 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:boolean true if the pong message was received before timing out after DEFAULT_PING_TIMEOUT millis, false otherwise See Also `DEFAULT_PING_TIMEOUT`

public synchronized 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:boolean: true if the pong message was received before timing out after DEFAULT_PING_TIMEOUT millis, false otherwise
See Also: DEFAULT_PING_TIMEOUT

parseAndAckInstant	back to summary
private void parseAndAckInstant(ReplicationMessage initiatorMessage, long synchOnInstant, String dbname) throws IOException, StandardException Used to parse the log instant initiator message from the master and check that the master and slave log files are in synch. Parameters initiatorMessage:ReplicationMessage the object containing the UID. synchOnInstant:long 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:String the name of the replicated database Exceptions IOException: If an exception occurs while sending the acknowledgment. StandardException: If the log files are not in synch

parseAndAckInstant

back to summary

private void parseAndAckInstant(ReplicationMessage initiatorMessage, long synchOnInstant, String dbname) throws IOException, StandardException

Used to parse the log instant initiator message from the master and check that the master and slave log files are in synch.

Parameters

initiatorMessage:ReplicationMessage: the object containing the UID.
synchOnInstant:long: 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:String: the name of the replicated database

Exceptions

IOException:: If an exception occurs while sending the acknowledgment.
StandardException:: If the log files are not in synch

parseAndAckVersion back to summary

parseAndAckVersion	back to summary
private void parseAndAckVersion(ReplicationMessage initiatorMessage, String dbname) throws IOException, StandardException Used to parse the initiator message from the master and check if the slave is compatible with the master by comparing the UID of the `ReplicationMessage` class of the master, that is wrapped in the initiator message, with the UID of the same class in the slave. Parameters initiatorMessage:ReplicationMessage the object containing the UID. dbname:String the name of the replicated database Exceptions IOException: If an exception occurs while sending the acknowledgment. StandardException: If the UID's do not match.

private void parseAndAckVersion(ReplicationMessage initiatorMessage, String dbname) throws IOException, StandardException

Used to parse the initiator message from the master and check if the slave is compatible with the master by comparing the UID of the ReplicationMessage class of the master, that is wrapped in the initiator message, with the UID of the same class in the slave.

Parameters

initiatorMessage:ReplicationMessage: the object containing the UID.
dbname:String: the name of the replicated database

Exceptions

IOException:: If an exception occurs while sending the acknowledgment.
StandardException:: If the UID's do not match.

readMessage back to summary

readMessage	back to summary
public ReplicationMessage readMessage() throws ClassNotFoundException, 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:ReplicationMessage a `ReplicationMessage` object that contains the reply that is sent. Exceptions ClassNotFoundException: Class of a serialized object cannot be found. IOException: 1) if an exception occurs while reading from the stream, 2) if the connection handle is invalid.

public ReplicationMessage readMessage() throws ClassNotFoundException, 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:ReplicationMessage

a ReplicationMessage object that contains the reply that is sent.

Exceptions

ClassNotFoundException:: Class of a serialized object cannot be found.
IOException:: 1) if an exception occurs while reading from the stream, 2) if the connection handle is invalid.

sendMessage back to summary

sendMessage	back to summary
public void sendMessage(ReplicationMessage message) throws IOException Used to send a replication message to the master. Parameters message:ReplicationMessage a `ReplicationMessage` object that contains the message to be transmitted. Exceptions IOException: 1) if an exception occurs while transmitting the message, 2) if the connection handle is invalid.

public void sendMessage(ReplicationMessage message) throws IOException

Used to send a replication message to the master.

Parameters

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

Exceptions

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

tearDown back to summary

tearDown	back to summary
public void tearDown() throws IOException Used to close the `ServerSocket` and the resources associated with it. Exceptions IOException: If an exception occurs while trying to close the socket or the associated resources.

public void tearDown() throws IOException

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

Exceptions

IOException:: If an exception occurs while trying to close the socket or the associated resources.

org.apache.derby.impl.store.replication.net back to summary

private Class ReplicationMessageReceive.SlavePingThread

Class Inheritance

extends Thread

java.lang.Object
java.lang.Thread
org.apache.derby.impl.store.replication.net.ReplicationMessageReceive.SlavePingThread

Thread that sends ping messages to the master on request to check if the replication network is working

Field Summary

Modifier and Type	Field and Description
private final ReplicationMessage	pingMsg

Inherited from java.lang.Thread:: MAX_PRIORITY MIN_PRIORITY NORM_PRIORITY

Constructor Summary

Access	Constructor and Description
pack-priv	SlavePingThread(String dbname)

Method Summary

Modifier and Type	Method and Description
public void	run() Overrides java.lang.Thread.run. Implements java.lang.Runnable.run. This method is run by the thread when it executes.

Field Detail

pingMsg	back to summary
private final ReplicationMessage pingMsg

Constructor Detail

SlavePingThread	back to summary
pack-priv SlavePingThread(String dbname)

Method Detail

run back to summary

run	back to summary
public void run() Overrides java.lang.Thread.run. Implements java.lang.Runnable.run. Doc from java.lang.Thread.run. This method is run by the thread when it executes. Subclasses of `Thread` may override this method. This method is not intended to be invoked directly. If this thread is a platform thread created with a `Runnable` task then invoking this method will invoke the task's `run` method. If this thread is a virtual thread then invoking this method directly does nothing.

public void run()

Overrides java.lang.Thread.run.

Implements java.lang.Runnable.run.

Doc from java.lang.Thread.run.

This method is run by the thread when it executes. Subclasses of Thread may override this method.

This method is not intended to be invoked directly. If this thread is a platform thread created with a Runnable task then invoking this method will invoke the task's run method. If this thread is a virtual thread then invoking this method directly does nothing.

public Class ReplicationMessageReceive

Nested and Inner Type Summary

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail

private Class ReplicationMessageReceive.SlavePingThread

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail