Class ReplicationMessageTransmit
- java.lang.Object
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- org.apache.derby.impl.store.replication.net.ReplicationMessageTransmit
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public class ReplicationMessageTransmit extends java.lang.Object
Used to send replication messages to the slave. Called by the Master controller to transmit replication messages wrapped in aReplicationMessage
object to a receiver. The receiver is implemented by theReplicationMessageReceive
class.
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Nested Class Summary
Nested Classes Modifier and Type Class Description private class
ReplicationMessageTransmit.MasterReceiverThread
Thread that listens for messages from the slave.
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Field Summary
Fields Modifier and Type Field Description private java.lang.String
dbname
The name of the replicated databaseprivate int
DEFAULT_MESSAGE_RESPONSE_TIMEOUT
Number of millis to wait for a response message before timing outprivate ReplicationMessage
receivedMsg
The message received from the slave as a response to sending a message.private java.lang.Object
receiveSemaphore
Used to synchronize when waiting for a response message from the slaveprivate SlaveAddress
slaveAddress
Contains the address (hostname and port number) of the slave to replicate to.private SocketConnection
socketConn
Used to write/read message objects to/from a connection.private boolean
stopMessageReceiver
Whether or not to keep the message receiver thread alive.
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Constructor Summary
Constructors Constructor Description ReplicationMessageTransmit(SlaveAddress slaveAddress)
Constructor initializes the slave address used in replication.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description private void
brokerConnection(long synchOnInstant)
Used to send initiator messages to the slave and receive information about the compatibility of the slave with the master.private void
checkSocketConnection()
Verifies if theSocketConnection
is valid.void
initConnection(int timeout, long synchOnInstant)
Used to create aSocket
connection to the slave and establish compatibility with the database version of the slave by comparing the UID's of theReplicationMessage
classes of the master and the slave.void
sendMessage(ReplicationMessage message)
Used to send a replication message to the slave.ReplicationMessage
sendMessageWaitForReply(ReplicationMessage message)
Send a replication message to the slave and return the message received as a response.private void
startMessageReceiverThread(java.lang.String dbname)
void
tearDown()
Tear down the network connection established with the other replication peerprivate boolean
verifyMessageType(ReplicationMessage message, int expectedType)
Used to parse a message received from the slave.
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Field Detail
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DEFAULT_MESSAGE_RESPONSE_TIMEOUT
private final int DEFAULT_MESSAGE_RESPONSE_TIMEOUT
Number of millis to wait for a response message before timing out- See Also:
- Constant Field Values
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receiveSemaphore
private final java.lang.Object receiveSemaphore
Used to synchronize when waiting for a response message from the slave
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receivedMsg
private ReplicationMessage receivedMsg
The message received from the slave as a response to sending a message.
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stopMessageReceiver
private volatile boolean stopMessageReceiver
Whether or not to keep the message receiver thread alive. Set to true to terminate the thread
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slaveAddress
private final SlaveAddress slaveAddress
Contains the address (hostname and port number) of the slave to replicate to.
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socketConn
private SocketConnection socketConn
Used to write/read message objects to/from a connection.
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dbname
private java.lang.String dbname
The name of the replicated database
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Constructor Detail
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ReplicationMessageTransmit
public ReplicationMessageTransmit(SlaveAddress slaveAddress)
Constructor initializes the slave address used in replication.- Parameters:
slaveAddress
- contains the address (host name and port number) of the slave to connect to.
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Method Detail
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initConnection
public void initConnection(int timeout, long synchOnInstant) throws java.io.IOException, StandardException, java.lang.ClassNotFoundException
Used to create aSocket
connection to the slave and establish compatibility with the database version of the slave by comparing the UID's of theReplicationMessage
classes of the master and the slave.- Parameters:
timeout
- the amount of time for which the connection should block before being established.synchOnInstant
- the master log instant, used to check that the master and slave log files are in synch. If no chunks of log records have been shipped to the slave yet, this is the end position in the current log file. If a chunk of log has been shipped, this is the instant of the log record shipped last. Note that there is a difference!- Throws:
java.io.IOException
- if an exception occurs while trying to create theSocketConnection
class or open a connection.StandardException
- If an error message is received from the server indicating incompatible software versions of master and slave.java.lang.ClassNotFoundException
- Class of a serialized object cannot be found.
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tearDown
public void tearDown() throws java.io.IOException
Tear down the network connection established with the other replication peer- Throws:
java.io.IOException
- if an exception occurs while trying to tear down the network connection
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sendMessage
public void sendMessage(ReplicationMessage message) throws java.io.IOException
Used to send a replication message to the slave.- Parameters:
message
- aReplicationMessage
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.
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sendMessageWaitForReply
public ReplicationMessage sendMessageWaitForReply(ReplicationMessage message) throws java.io.IOException, StandardException
Send a replication message to the slave and return the message received as a response. Will only wait DEFAULT_MESSAGE_RESPONSE_TIMEOUT millis for the response message. If not received when the wait times out, no message is returned. The method is synchronized to guarantee that only one thread will be waiting for a response message at any time.- Parameters:
message
- a ReplicationMessage object that contains the message to be transmitted.- Returns:
- the response message
- Throws:
java.io.IOException
- 1) if an exception occurs while sending or receiving a message. 2) if the connection handle is invalid.StandardException
- if the response message has not been received after DEFAULT_MESSAGE_RESPONSE_TIMEOUT millis
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brokerConnection
private void brokerConnection(long synchOnInstant) throws java.io.IOException, StandardException, java.lang.ClassNotFoundException
Used to send initiator messages to the slave and receive information about the compatibility of the slave with the master. One message is used to check that the slave and master have the same software versions. A second message is used to check that the master and slave log files are in synch.- Parameters:
synchOnInstant
- the master log instant, used to check that the master and slave log files are in synch. If no chunks of log records have been shipped to the slave yet, this is the end position in the current log file. If a chunk of log has been shipped, this is the instant of the log record shipped last. Note that there is a difference!- Throws:
java.io.IOException
- if an exception occurs during the sending or reading of the message.StandardException
- If an error message is received from the server indicating a mis-match in serialVersionUID or log files out of synch.java.lang.ClassNotFoundException
- Class of a serialized object cannot be found.
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verifyMessageType
private boolean verifyMessageType(ReplicationMessage message, int expectedType) throws StandardException
Used to parse a message received from the slave. If the message is an ack of the last shipped message, this method terminates quietly. Otherwise, it throws the exception received in the message from the slave describing why the last message could not be acked.- Throws:
StandardException
- If an error message is received from the serverjava.lang.ClassNotFoundException
- Class of a serialized object cannot be found.
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checkSocketConnection
private void checkSocketConnection() throws java.io.IOException
Verifies if theSocketConnection
is valid.- Throws:
java.io.IOException
- If the socket connection object is not valid (is null).
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startMessageReceiverThread
private void startMessageReceiverThread(java.lang.String dbname)
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