Package org.apache.catalina.tribes.tipis

Interface ReplicatedMapEntry

All Superinterfaces:

Serializable

All Known Implementing Classes:

DeltaSession

public interface ReplicatedMapEntry
extends Serializable

For smarter replication, an object can implement this interface to replicate diffs
The replication logic will call the methods in the following order:
1. if ( entry.isDirty() )
try { 2. entry.lock();
3. byte[] diff = entry.getDiff();
4. entry.reset();
} finally {
5. entry.unlock();
}
}


When the data is deserialized the logic is called in the following order
1. ReplicatedMapEntry entry = (ReplicatedMapEntry)objectIn.readObject();
2. if ( isBackup(entry)||isPrimary(entry) ) entry.setOwner(owner);


Method Summary

Modifier and Type	Method	Description
void	accessEntry()	Access to an existing object.
void	applyDiff(byte[] diff, int offset, int length)	Applies a diff to an existing object.
byte[]	getDiff()	Returns a diff and sets the dirty map to false
long	getLastTimeReplicated()
long	getVersion()	For accuracy checking, a serialized attribute can contain a version number This number increases as modifications are made to the data.
boolean	isAccessReplicate()	If this returns true, to replicate that an object has been accessed
boolean	isDiffable()	If this returns true, the map will extract the diff using getDiff() Otherwise it will serialize the entire object.
boolean	isDirty()	Has the object changed since last replication and is not in a locked state
void	lock()	Lock during serialization
void	resetDiff()	Resets the current diff state and resets the dirty flag
void	setLastTimeReplicated(long lastTimeReplicated)	Set the last replicate time.
void	setOwner(Object owner)	This method is called after the object has been created on a remote map.
void	setVersion(long version)	Forces a certain version to a replicated map entry
void	unlock()	Unlock after serialization

Method Details

isDirty

boolean isDirty()

Has the object changed since last replication and is not in a locked state

Returns:

boolean

isDiffable

boolean isDiffable()

If this returns true, the map will extract the diff using getDiff() Otherwise it will serialize the entire object.

Returns:

boolean

getDiff

byte[] getDiff()
        throws IOException

Returns a diff and sets the dirty map to false

Returns:

Serialized diff data

Throws:

IOException - IO error serializing

applyDiff

void applyDiff(byte[] diff,
 int offset,
 int length)
        throws IOException,
ClassNotFoundException

Applies a diff to an existing object.

Parameters:

diff - Serialized diff data

offset - Array offset

length - Array length

Throws:

IOException - IO error deserializing

ClassNotFoundException - Serialization error

resetDiff

void resetDiff()

Resets the current diff state and resets the dirty flag

lock

void lock()

Lock during serialization

unlock

void unlock()

Unlock after serialization

setOwner

void setOwner(Object owner)

This method is called after the object has been created on a remote map. On this method, the object can initialize itself for any data that wasn't

Parameters:

owner - Object

getVersion

long getVersion()

For accuracy checking, a serialized attribute can contain a version number This number increases as modifications are made to the data. The replicated map can use this to ensure accuracy on a periodic basis

Returns:

long - the version number or -1 if the data is not versioned

setVersion

void setVersion(long version)

Forces a certain version to a replicated map entry

Parameters:

version - long

getLastTimeReplicated

long getLastTimeReplicated()

Returns:

the last replicate time.

setLastTimeReplicated

void setLastTimeReplicated(long lastTimeReplicated)

Set the last replicate time.

Parameters:

lastTimeReplicated - New timestamp

isAccessReplicate

boolean isAccessReplicate()

If this returns true, to replicate that an object has been accessed

Returns:

boolean

accessEntry

void accessEntry()

Access to an existing object.