Package org.cyclos.impl.sql

Class BaseDbLockHandlerImpl

java.lang.Object

org.cyclos.impl.sql.BaseDbLockHandlerImpl

All Implemented Interfaces:

DbLockHandler

Direct Known Subclasses:

PostgresqlLockHandlerImpl

public abstract class BaseDbLockHandlerImpl
extends Object
implements DbLockHandler

Base implementation for DbLockHandler

Field Summary

Fields

Modifier and Type	Field	Description
protected JdbcTemplate	jdbcTemplate
protected static int	KEEPALIVE_SECONDS	Interval in seconds which nodes should update the db_lock row
protected static int	VALID_SECONDS	(seconds since the last keepalive) - this constant is the interval to sleep until the next check (when there was a valid row in db_lock)

Constructor Summary

Constructors

Constructor	Description
BaseDbLockHandlerImpl(JdbcTemplate jdbcTemplate)

Method Summary

Modifier and Type	Method	Description
protected abstract void	create(String hostId)
protected abstract DbLock	doRead()
protected abstract void	keepalive()
void	lock(String hostId, DbLock dbLock)	Locks the database, by either inserting or updating the existing row in db_lock table, and schedules a timer to update the table every few seconds
DbLock	read()	Return the current row, if any
protected void	shutdown()
void	sleepUntilTryingAgain(DbLock dbLock)	Sleeps for a few seconds before attempting to check again if the db is locked
void	throwAlreadyLocked(DbLock dbLock)	Throws an appropriate error indicating the current db is already locked
protected abstract boolean	update(String hostId, int version)

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.cyclos.impl.sql.DbLockHandler

prepare, unlock

Field Detail

KEEPALIVE_SECONDS

protected static final int KEEPALIVE_SECONDS

Interval in seconds which nodes should update the db_lock row

See Also:

Constant Field Values

VALID_SECONDS

protected static final int VALID_SECONDS

(seconds since the last keepalive) - this constant is the interval to sleep until the next check (when there was a valid row in db_lock)

See Also:

Constant Field Values

jdbcTemplate

protected JdbcTemplate jdbcTemplate

Constructor Detail

BaseDbLockHandlerImpl

public BaseDbLockHandlerImpl(JdbcTemplate jdbcTemplate)

Method Detail

lock

public final void lock(String hostId,
                       DbLock dbLock)

Description copied from interface: DbLockHandler

Locks the database, by either inserting or updating the existing row in db_lock table, and schedules a timer to update the table every few seconds

Specified by:

lock in interface DbLockHandler

read

public final DbLock read()

Description copied from interface: DbLockHandler

Return the current row, if any

Specified by:

read in interface DbLockHandler

sleepUntilTryingAgain

public final void sleepUntilTryingAgain(DbLock dbLock)

Description copied from interface: DbLockHandler

Sleeps for a few seconds before attempting to check again if the db is locked

Specified by:

sleepUntilTryingAgain in interface DbLockHandler

throwAlreadyLocked

public final void throwAlreadyLocked(DbLock dbLock)

Description copied from interface: DbLockHandler

Throws an appropriate error indicating the current db is already locked

Specified by:

throwAlreadyLocked in interface DbLockHandler

create

protected abstract void create(String hostId)

doRead

protected abstract DbLock doRead()

keepalive

protected abstract void keepalive()

shutdown

protected void shutdown()

update

protected abstract boolean update(String hostId,
                                  int version)