Interface MasterFactory
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- All Known Implementing Classes:
MasterController
public interface MasterFactory
This is the interface for the replication master controller service. The master controller service is booted when this instance of Derby will have the replication master role for this database.
The replication master service is responsible for managing all replication related functionality on the master side of replication. This includes connecting to the slave, setting up a log buffer to temporarily store log records from the LogFactory, and to ship these log records to the slave.
The master controller currently only supports asynchronous replication. This means that there are no guarantees that transactions that have committed here (the master side) are also reflected on the slave side. However, the slave version of the database IS guaranteed to be transaction consistent. This implies that:
- A transaction t that is committed on the master will either be fully reflected or not be reflected at all on the slave when the slave database is turned into a non-replicated database (that is, at failover time)
- Slave execution of operations is in the same serial order as on the master because replication is based on redoing log records to the slave. By definition, log records are in serial order. This implies that if transaction t1 commits before t2 on the master, and t2 has been committed on the slave, t1 is also guaranteed to have committed on the slave.
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Field Summary
Fields Modifier and Type Field Description static java.lang.String
ASYNCHRONOUS_MODE
Property value used to indicate that the service should be booted in asynchronous replication mode.static java.lang.String
MODULE
The name of the Master Factory, used to boot the service.static java.lang.String
REPLICATION_MODE
Property key to specify replication mode
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method Description void
appendLog(long greatestInstant, byte[] log, int logOffset, int logLength)
Append a chunk of log records to the log buffer.void
flushedTo(long instant)
Used by the LogFactory to notify the replication master controller that the log records up to this instant have been flushed to disk.void
startFailover()
Will perform all work needed to failovervoid
startMaster(RawStoreFactory rawStore, DataFactory dataFac, LogFactory logFac, java.lang.String slavehost, int slaveport, java.lang.String dbname)
Will perform all the work that is needed to set up replicationvoid
stopMaster()
Will perform all work that is needed to shut down replication.void
workToDo()
Used to notify the log shipper that a log buffer element is full.
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Field Detail
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MODULE
static final java.lang.String MODULE
The name of the Master Factory, used to boot the service.- See Also:
- Constant Field Values
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REPLICATION_MODE
static final java.lang.String REPLICATION_MODE
Property key to specify replication mode- See Also:
- Constant Field Values
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ASYNCHRONOUS_MODE
static final java.lang.String ASYNCHRONOUS_MODE
Property value used to indicate that the service should be booted in asynchronous replication mode.- See Also:
- Constant Field Values
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Method Detail
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startMaster
void startMaster(RawStoreFactory rawStore, DataFactory dataFac, LogFactory logFac, java.lang.String slavehost, int slaveport, java.lang.String dbname) throws StandardException
Will perform all the work that is needed to set up replication- Parameters:
rawStore
- The RawStoreFactory for the databasedataFac
- The DataFactory for this databaselogFac
- The LogFactory ensuring recoverability for this databaseslavehost
- The hostname for the slaveslaveport
- The port the slave is listening ondbname
- The master database that is being replicated.- Throws:
StandardException
- Standard Derby exception policy, thrown on replication startup error.
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stopMaster
void stopMaster() throws StandardException
Will perform all work that is needed to shut down replication.- Throws:
StandardException
- If the replication master has been stopped already.
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startFailover
void startFailover() throws StandardException
Will perform all work needed to failover- Throws:
StandardException
- 1) If the failover succeeds, an exception is thrown to indicate that the master database was shutdown after a successful failover 2) If a failure occurs during network communication with slave.
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appendLog
void appendLog(long greatestInstant, byte[] log, int logOffset, int logLength)
Append a chunk of log records to the log buffer.- Parameters:
greatestInstant
- the instant of the log record that was added last to this chunk of loglog
- the chunk of log recordslogOffset
- offset in log to start copy fromlogLength
- number of bytes to copy, starting from logOffset
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flushedTo
void flushedTo(long instant)
Used by the LogFactory to notify the replication master controller that the log records up to this instant have been flushed to disk. The master controller takes action according to the current replication strategy when this method is called. When the asynchronous replication strategy is used, the method does not force log shipping to the slave; the log records may be shipped now or later at the MasterFactory's discretion. However, if another strategy like 2-safe replication is implemented in the future, a call to this method may force log shipment before returning control to the caller. Currently, only asynchronous replication is supported.- Parameters:
instant
- The highest log instant that has been flushed to disk- See Also:
LogFactory.flush(org.apache.derby.iapi.store.raw.log.LogInstant)
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workToDo
void workToDo()
Used to notify the log shipper that a log buffer element is full.
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