oracle.toplink.essentials.descriptors.invalidation.CacheInvalidationPolicy Maven / Gradle / Ivy
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package oracle.toplink.essentials.descriptors.invalidation;
import oracle.toplink.essentials.internal.identitymaps.CacheKey;
/**
* PUBLIC:
* A CacheInvalidationPolicy is used to set objects in TopLink's identity maps to be invalid
* following given rules. CacheInvalidationPolicy is the abstract superclass for all
* policies used for cache invalidation.
* By default in TopLink, objects do not expire in the cache. Several different policies
* are available to allow objects to expire. These can be set on the Descriptor.
* @see oracle.toplink.essentials.publicinterface.Descriptor
* @see oracle.toplink.essentials.descriptors.cacheinvalidation.NoExpiryCacheInvalidationPolicy
* @see oracle.toplink.essentials.descriptors.cacheinvalidation.DailyCacheInvalidationPolicy
* @see oracle.toplink.essentials.descriptors.cacheinvalidation.TimeToLiveCacheInvalidationPolicy
*/
public abstract class CacheInvalidationPolicy implements java.io.Serializable {
public static final long NO_EXPIRY = -1;
/** this will represent objects that do not expire */
protected boolean shouldUpdateReadTimeOnUpdate = false;
/**
* INTERNAL:
* Get the next time when this object will become invalid
*/
public abstract long getExpiryTimeInMillis(CacheKey key);
/**
* INTERNAL:
* Return the remaining life of this object
*/
public long getRemainingValidTime(CacheKey key) {
long expiryTime = getExpiryTimeInMillis(key);
long remainingTime = expiryTime - System.currentTimeMillis();
if (remainingTime > 0) {
return remainingTime;
}
return 0;
}
/**
* INTERNAL:
* return true if this object is expire, false otherwise.
*/
public abstract boolean isInvalidated(CacheKey key, long currentTimeMillis);
/**
* PUBLIC:
* Set whether to update the stored time an object was read when an object is updated.
* When the read time is updated, it indicates to TopLink that the data in the object
* is up to date. This means that cache invalidation checks will occur relative to the
* new read time.
* By default, the read time will not be updated when an object is updated.
* Often it is possible to be confident that the object is up to date after an update
* because otherwise the update will fail because of the locking policies in use.
*/
public void setShouldUpdateReadTimeOnUpdate(boolean shouldUpdateReadTime) {
shouldUpdateReadTimeOnUpdate = shouldUpdateReadTime;
}
/**
* PUBLIC:
* Return whether objects affected by this CacheInvalidationPolicy should have
* the read time on their cache keys updated when an update occurs.
*/
public boolean shouldUpdateReadTimeOnUpdate() {
return shouldUpdateReadTimeOnUpdate;
}
}