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Implementation of this interface needs to register with ReplicationManager and will receive updates to be applied to its locally replicated data. If locks are used the implementation is resposible for lock acquisition and management. To do so, it probably needs to maintain a lock table (keys = resource objects, values = transactions) to associate resources with locks and possibly a transaction table (keys = transactions, values = locks) to keep track of all locks for a given transaction (to commit/release all modifications/locks for a given transaction).
Method Summary | |
void |
commit(Xid transaction)
Commit the modifications to the locally replicated data and release all locks. |
java.lang.Object |
receive(Xid transaction,
byte[] data,
byte[] lock_info,
long lock_acquisition_timeout,
long lock_lease_timeout,
boolean use_locks)
Receives data sent by a sender to all group members and applies update to locally replicated data. |
void |
rollback(Xid transaction)
Discard all modifications and release all locks. |
Method Detail |
public java.lang.Object receive(Xid transaction, byte[] data, byte[] lock_info, long lock_acquisition_timeout, long lock_lease_timeout, boolean use_locks) throws LockingException, UpdateException
ReplicationManager.send(org.jgroups.Address, byte[], boolean, long, org.jgroups.blocks.Xid, byte[], long, long, boolean)
call.
transaction
- The transaction under which all locks will be acquired. Will be null if no locks are used (e.g.
use_locks
is null).data
- The data to be modified. In case of a database, this data would have to be stored in stable storage,
and would only be applied on a commit()
. In case of a distributed replicated in-memory
data structure, the update might be applied directly and the subsequent commit() or rollback() might
be ignored. Note that this argument may contain the resource to be locked; in this case the
lock_info
parameter might be null.lock_info
- Information about the resource(s) to be locked. Will be null if no locks are used (e.g.
use_locks
is null). Can also be null even if locks are used, e.g. when the resource(s)
to be locked are an implicit part of data
.lock_acquisition_timeout
- If locks are used, the number of milliseconds to wait for a lock to be acquired.
If this time elapses, a TimeoutException will be thrown. A value of 0 means
to wait forever. If use_locks
is false, this value is ignored.lock_lease_timeout
- The number of milliseconds to hold on to the lock, once it is acquired. A value of 0
means to never release the lock until commit() or rollback() are called.use_locks
- Whether to use locking or not. If this value is false, all lock-related arguments will be
ignored, regardless of whether they are non-null.
ReplicationManager.send(org.jgroups.Address, byte[], boolean, long, org.jgroups.blocks.Xid, byte[], long, long, boolean)
and the receiver. If no special value should be returned, null can be returned. Note that in the
latter case, null is still treated as a response (in the synchronous call).
LockingException
- Thrown when a lock on a resource cannot be acquired
UpdateException
- Thrown when the update fails (application semantics)public void commit(Xid transaction)
public void rollback(Xid transaction)
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