org.aredis.io

Class ClassDescriptorStorage

java.lang.Object

org.aredis.io.ClassDescriptorStorage

Direct Known Subclasses:

RedisClassDescriptorStorage

public abstract class ClassDescriptorStorage
extends Object

Defines a persistent ClassDescriptor Store for OptiObjectInputStream and OptiObjectOutputStream. The store should be accessible to retrieve the class descriptors and also update it in case the OptiObjectOutputStream encounters a new class.

Author:

Suresh

Constructor Summary

Constructors

Constructor and Description
ClassDescriptorStorage() Creates a Class Descriptor Storage.

Method Summary

Methods

Modifier and Type	Method and Description
int	getCleanupAgeDays() Getter for cleanupAgeDays.
abstract ClassDescriptors	getMasterClassDescriptors(boolean refreshFromStore) Gets the class descriptors from the store.
long	getUseTimeUpdateInterval() Getter for useTimeUpdateInterval.
void	setCleanupAgeDays(int pcleanupAgeDays) Setter for cleanupAgeDays.
void	setUseTimeUpdateInterval(long puseTimeUpdateInterval) Setter for useTimeUpdateInterval.
abstract boolean	updateClassDescriptors(ClassDescriptors updatedDescriptors) Updates the class descriptors based on optimistic locking (Dirty write check) similar to WATCH-MULTI-EXEC or in redis or CAS in memcached.
boolean	updateTimingsAndCleanup(long updateInterval, long lastUseTimeForCleanup) Updates the last use times of the descriptors and removes old descriptors not used since the passed lastUseTimeForCleanup.

Methods inherited from class java.lang.Object

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

Constructor Detail

ClassDescriptorStorage

public ClassDescriptorStorage()

Creates a Class Descriptor Storage.

Method Detail

getMasterClassDescriptors

public abstract ClassDescriptors getMasterClassDescriptors(boolean refreshFromStore)
                                                    throws IOException

Gets the class descriptors from the store. If refreshFromStore is false then a local copy if available is returned. If refreshFromStore is true or a local copy is not available then it is fetched from the store. If the class descriptors are not yet stored then a new instance is created and returned.

Parameters:

refreshFromStore - Whether to fetch the Class Descriptors from store even if a local copy is available

Returns:

Non null ClassDescriptors

Throws:

IOException - In case of error fetching the ClassDescriptors

updateClassDescriptors

public abstract boolean updateClassDescriptors(ClassDescriptors updatedDescriptors)
                                        throws IOException

Updates the class descriptors based on optimistic locking (Dirty write check) similar to WATCH-MULTI-EXEC or in redis or CAS in memcached. The passed Class Descriptors should be saved if the versionNo of the passed descriptors is 1 greater than that in the store. If the descriptors have not yet been created then the incoming versionNo should be 1. If the update fails then the local ClassDescriptors copy should be replaced with the latest copy from the store. The caller will then retry the operation by using the new ClassDescriptors.

Parameters:

updatedDescriptors - Updated Class Descriptors

Returns:

true if the operation succeeds, false if it fails because it has already been updated since the local copy was fetched.

Throws:

IOException - In case there is an error updating the ClassDescriptors

updateTimingsAndCleanup

public boolean updateTimingsAndCleanup(long updateInterval,
                              long lastUseTimeForCleanup)
                                throws IOException

Updates the last use times of the descriptors and removes old descriptors not used since the passed lastUseTimeForCleanup. It uses the requiresTimingUpdate and removeOldDescriptors methods of ClassDescriptors. This method is invoked via a periodic task initialized in the constructor. The cleanup feature has not been tested, so 100 years ago is the default lastUseTimeForCleanup used.

Parameters:

updateInterval - Specifies the time interval required between the current lastUseTime and lastUseTime when the descriptors were fetched from the store so that the descriptors are updated to update lastUseTime

lastUseTimeForCleanup - Last Use Time in milliseconds time. Descriptors not used since this time are removed from the store by setting the corresponding entry in the array to null

Returns:

true if the update was successful, false otherwise

Throws:

IOException

getUseTimeUpdateInterval

public long getUseTimeUpdateInterval()

Getter for useTimeUpdateInterval. This is used in the periodic task which calls updateTimingsAndClenaup. The default is 1 day (Milliseconds in a day).

Returns:

the useTimeUpdateInterval

setUseTimeUpdateInterval

public void setUseTimeUpdateInterval(long puseTimeUpdateInterval)

Setter for useTimeUpdateInterval.

Parameters:

puseTimeUpdateInterval - the useTimeUpdateInterval to set

getCleanupAgeDays

public int getCleanupAgeDays()

Getter for cleanupAgeDays. This is used to calculate the lastUseTimeForCleanup in the periodic task which calls updateTimingsAndClenaup. The default for this is 36500 (100 years).

Returns:

the cleanupAgeDays

setCleanupAgeDays

public void setCleanupAgeDays(int pcleanupAgeDays)

Setter for cleanupAgeDays.

Parameters:

pcleanupAgeDays - the cleanupAgeDays to set