| org.apache.derby.iapi.services.cache.CacheManager
All known Subclasses: org.apache.derby.impl.services.cache.Clock,
| CacheManager | | public interface CacheManager (Code) | | |
| Method Summary | |
| public void | ageOut()
Age as many objects as possible out of the cache. | | public void | clean(Matchable partialKey)
Clean all objects that match the partialKey (or exact key).
Any cached object that results in the partialKey.equals(Object)
method returning true when passed the cached object will be cleaned. | | public void | cleanAll()
Place all objects in their clean state by calling their clean method
if they are dirty. | | public boolean | containsKey(Object key)
Determine whether a key is in the cache. | | public Cacheable | create(Object key, Object createParameter)
Create an object in the cache. | | public boolean | discard(Matchable partialKey)
Discard all objects that match the partialKey (or exact key).
Any cached object that results in the partialKey.equals(Object)
method returning true when passed the cached object will be thrown out of the cache
if and only if it is not in use. | | public Cacheable | find(Object key)
Find an object in the cache.
Find an object in the cache that matches the key provided using the equals()
method, i.e. | | public Cacheable | findCached(Object key)
Find an object in the cache.
Find an object in the cache that matches the key provided using the equals()
method, i.e. | | public long[] | getCacheStats()
Return statistics about cache that may be implemented. | | public long | getMaximumSize()
| | public int | getNumberInUse()
Report the number of items in use (with Identity) in this cache. | | public void | release(Cacheable entry)
Release a Cacheable object previously found with find() or findCached(). | | public void | remove(Cacheable entry)
Delete and remove an object from the cache. | | public void | resetCacheStats()
reset the cache statistics to 0. | | public void | resize(long newSize)
Change the maximum size of the cache. | | public void | scan(Matchable filter, Operator operator)
Perform an operation on (approximately) all entries that matches the filter,
or all entries if the filter is null. | | public void | setUsed(Object[] keys)
Mark a set of entries as having been used. | | public void | shutdown()
Shutdown the cache. | | public void | useDaemonService(DaemonService daemon)
|
| ageOut | | public void ageOut()(Code) | | Age as many objects as possible out of the cache.
This call is guaranteed not to block.
It is not guaranteed to leave the cache empty.
It is guaranteed that all unkept, clean objects will be
removed from the cache.
See Also: Cacheable.clean
See Also: Cacheable.clearIdentity |
| clean | | public void clean(Matchable partialKey) throws StandardException(Code) | | Clean all objects that match the partialKey (or exact key).
Any cached object that results in the partialKey.equals(Object)
method returning true when passed the cached object will be cleaned.
In order to clean more than one object the Cacheable equals method must
be able to handle a partial key, e.g. a page has PageKey but a clean
may pass a ContainerKey which will discard all pages in that container.
exception:
StandardException - Standard Cloudscape error policy. |
| cleanAll | | public void cleanAll() throws StandardException(Code) | | Place all objects in their clean state by calling their clean method
if they are dirty. This method guarantees that all objects that existed
in the cache at the time of the call are placed in the clean state
sometime during this call. Objects that are added to the cache during
this call or objects that are dirtied during this call (by other
callers) are not guaranteed to be clean once this call returns.
See Also: Cacheable.clean
See Also: Cacheable.isDirty
exception:
StandardException - Standard Cloudscape error policy. |
| containsKey | | public boolean containsKey(Object key)(Code) | | Determine whether a key is in the cache.
WARNING: This method does not keep a lock on the entry or the cache, so
the return value could be made incorrect by the time that this method returns.
Therefore this method should only be used for statistical purposes.
|
| create | | public Cacheable create(Object key, Object createParameter) throws StandardException(Code) | | Create an object in the cache. The resulting object will match the key provided using the equals()
method, i.e. the return Cacheable will have getIdentifier.equals(key) true.
If an object that matches the key already exists in the cache then
an exception is thrown.
The object will be added by one of:
- creating a new holder object and calling its initParameter() method and then its
createIdentity() method with key as the parameter.
- Calling clearIdentity() on an holder object in the clean state and then calling its
createIdentity() method with key as the parameter.
- Calling clean() on a dirty holder object and then calling clearIdentity() on an
holder object in the clean state and then calling its createIdentity() method with key
as the parameter.
In all cases the setIdentity() method is called with the createParameter as the second
argument.
If the object cannot be created then an exception is thrown by createIdentity.
The returned object is kept, i.e. its identity will not change, until the release()
method is called. The release() method must be called after the caller is finished
with the object and throw away the reference to it, e.g.
Page p = (Page) pageCache.create(pageKey, createType);
// do stuff with p
// release p
pageCache.release(p);
p = null;
A reference to an object in the cache.
exception:
StandardException - Standard Cloudscape error policy.
See Also: Cacheable.createIdentity |
| discard | | public boolean discard(Matchable partialKey)(Code) | | Discard all objects that match the partialKey (or exact key).
Any cached object that results in the partialKey.equals(Object)
method returning true when passed the cached object will be thrown out of the cache
if and only if it is not in use. The Cacheable
will be discarded without its clean method being called.
If partialKey is null, it matches all objects. This is a way to
discard all objects from the cache in case of emergency shutdown.
In order to discard more than one object the Cacheable equals method must be able to handle
a partial key, e.g. a page has PageKey but a discard may pass a ContainerKey which will discard
all pages in that container.
true if discard has successful gotten rid of all objects thatmatch the partial or exact key. False if some objects that matcheswere not gotten rid of because it was kept. |
| find | | public Cacheable find(Object key) throws StandardException(Code) | | Find an object in the cache.
Find an object in the cache that matches the key provided using the equals()
method, i.e. the return Cacheable will have getIdentifier.equals(key) true.
If the object does not exist in the cache it will be added by one of:
- creating a new holder object and calling its initParameter() method and then its
setIdentity() method with key as the parameter.
- Calling clearIdentity() on an holder object in the clean state and then calling its
setIdentity() method with key as the parameter.
- Calling clean() on a dirty holder object and then calling clearIdentity() on an
holder object in the clean state and then calling its setIdentity() method with key
as the parameter.
In all cases the setIdentity() method is called with forCreate set to false.
The returned object is kept, i.e. its identity will not change, until the release()
method is called. The release() method must be called after the caller is finished
with the object and throw away the reference to it, e.g.
Page p = (Page) pageCache.find(pageKey);
// do stuff with p
// release p
pageCache.release(p);
p = null;
A reference to an object in the cache, or null if the object cannot be found.
exception:
StandardException - Standard Cloudscape error policy.
See Also: Cacheable.setIdentity |
| findCached | | public Cacheable findCached(Object key) throws StandardException(Code) | | Find an object in the cache.
Find an object in the cache that matches the key provided using the equals()
method, i.e. the return Cacheable will have getIdentifier.equals(key) true.
If a matching object does not exist in the cache, null is returned.
The returned object is kept, i.e. its identity will not change, until the release()
method is called. The release() method must be called after the caller is finished
with the object and throw away the reference to it, e.g.
Page p = (Page) pageCache.findCached(pageKey);
if (p != null) {
// do stuff with p
// release p
pageCache.release(p);
p = null;
}
exception:
StandardException - Standard Cloudscape error policy. |
| getCacheStats | | public long[] getCacheStats()(Code) | | Return statistics about cache that may be implemented.
|
| getMaximumSize | | public long getMaximumSize()(Code) | | the current maximum size of the cache. |
| getNumberInUse | | public int getNumberInUse()(Code) | | Report the number of items in use (with Identity) in this cache.
|
| release | | public void release(Cacheable entry)(Code) | | Release a Cacheable object previously found with find() or findCached().
After this call the caller must throw away the reference to item.
|
| remove | | public void remove(Cacheable entry) throws StandardException(Code) | | Delete and remove an object from the cache. It is up to the user of the cache
to provide synchronization of some form that ensures that only one caller
executes remove() on a cached object.
The object must have previously been found with find() or findCached().
The item will be placed into the NoIdentity
state through clean(true) (if required) and clearIdentity(). The removal of the
object will be delayed until it is not kept by anyone. Objects that are in the
to be removed state can still be found through find() and findCached()
until their keep count drops to zero. This call waits until the object
has been removed.
After this call the caller must throw away the reference to item.
exception:
StandardException - Standard Cloudscape error policy. |
| resetCacheStats | | public void resetCacheStats()(Code) | | reset the cache statistics to 0.
|
| resize | | public void resize(long newSize) throws StandardException(Code) | | Change the maximum size of the cache. If the size is decreased then cache entries
will be thrown out.
Parameters:
newSize - the new maximum cache size
exception:
StandardException - Cloudscape Standard error policy |
| scan | | public void scan(Matchable filter, Operator operator)(Code) | | Perform an operation on (approximately) all entries that matches the filter,
or all entries if the filter is null. Entries that are added while the
cache is being scanned might or might not be missed.
Parameters:
filter -
Parameters:
operator - |
| setUsed | | public void setUsed(Object[] keys)(Code) | | Mark a set of entries as having been used. Normally this is done as a side effect
of find() or findCached. If the entry has been replaced then this method
does nothing.
Parameters:
keys - the key of the used entry. |
| shutdown | | public void shutdown() throws StandardException(Code) | | Shutdown the cache. This call stops the cache returning
any more valid references on a find() or findCached() call,
and then cleanAll() and ageOut() are called. The cache remains
in existence until the last kept object has been unkept.
exception:
StandardException - Standard Cloudscape error policy. |
| useDaemonService | | public void useDaemonService(DaemonService daemon)(Code) | | This cache can use this DaemonService if it needs some work to be done
int he background
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