public interface MutableCacheEntry<K,V> extends CacheEntry<K,V>
EntryProcessor to perform
updates and retrieve information from a cache entry.
A mutation is only done if a method for mutation is called, e.g.
setValue or remove. If multiple mutate methods
are called in sequence only the last method will have an effect.
One instance is only usable by a single thread and for
one call of EntryProcessor.process(MutableCacheEntry).
EntryProcessor| Modifier and Type | Method and Description |
|---|---|
boolean |
exists()
True if a mapping exists in the cache, never invokes the loader / cache source.
|
long |
getCurrentTime()
Current time as provided by the internal time source (usually
System.currentTimeMillis(). |
V |
getOldValue()
The current value in the cache.
|
long |
getRefreshedTime()
Timestamp of the last refresh of the cached value.
|
V |
getValue()
Returns the value to which the cache associated the key,
or
null if the cache contains no mapping for this key. |
MutableCacheEntry<K,V> |
remove()
Removes an entry from the cache.
|
MutableCacheEntry<K,V> |
setException(Throwable ex)
Insert or update the entry and sets an exception.
|
MutableCacheEntry<K,V> |
setExpiryTime(long t)
Set a new expiry time for the entry.
|
MutableCacheEntry<K,V> |
setRefreshedTime(long t)
If
setValue(Object) is used, this sets an alternative refreshed time for
expiry calculations. |
MutableCacheEntry<K,V> |
setValue(V v)
Insert or updates the cache value assigned to this key.
|
boolean |
wasExisting()
True if a mapping exists in the cache, never invokes the loader / cache source.
|
getException, getKey, getLastModificationV getValue()
Returns the value to which the cache associated the key,
or null if the cache contains no mapping for this key.
null is also returned if this entry contains an exception.
If the cache does permit null values, then a return value of
null does not necessarily indicate that the cache
contained no mapping for the key. It is also possible that the cache
explicitly associated the key to the value null. Use exists()
to check whether an entry is existing instead of a null check.
If read through operation is enabled and the entry is not yet existing in the cache, the call to this method triggers a call to the cache loader.
In contrast to the main cache interface there is no no peekValue method,
since the same effect can be achieved by the combination of exists()
and getValue().
getValue in interface CacheEntry<K,V>RestartException - If the information is not yet available and the cache
needs to do an asynchronous operation to supply it.
After completion, the entry processor will be
executed again.CacheLoaderboolean exists()
After this method returns true, a call to getValue will always
return the cached value and never invoke the loader. The potential expiry
of the value is only checked once and the return values of this method and
getValue will be consistent.
RestartException - If the information is not yet available and the cache
needs to do an asynchronous operation to supply it.
After completion, the entry processor will be
executed again.V getOldValue()
getValue(), but not modified
after a mutation method is called. Intended for fluent operation.
If read through operation is enabled and the entry is not yet existing in the cache, the call to this method triggers a call to the cache loader.
RestartException - If the information is not yet available and the cache
needs to do an asynchronous operation to supply it.
After completion, the entry processor will be
executed again.boolean wasExisting()
exists(), but not modified
after a mutation method is called. Intended for fluent operation.RestartException - If the information is not yet available and the cache
needs to do an asynchronous operation to supply it.
After completion, the entry processor will be
executed again.long getCurrentTime()
System.currentTimeMillis().
The time is retrieved once when the entry processor is invoked and will not change afterwards.
If a load is triggered this value will be identical to
AdvancedCacheLoader.load(Object, long, CacheEntry) and
ExceptionInformation.getLoadTime()MutableCacheEntry<K,V> setValue(V v)
exists will return true and getValue will return the set value.
If a writer is registered, the CacheWriter.write(Object, Object)
is called.
MutableCacheEntry<K,V> remove()
In case a writer is registered, CacheWriter.delete(K)
is called. If a remove is performed on a not existing cache entry the writer
method will also be called.
MutableCacheEntry<K,V> setException(Throwable ex)
CacheLoaderException.
Identical to setValue an expiry of the exception will be determined
according to the resilience settings. Hint: If no expiry is configured the
default behavior will be that the set exception expires immediately, so
the effect will be similar to remove in this case.
MutableCacheEntry<K,V> setExpiryTime(long t)
setValue(V) the entry
will be updated or inserted with this expiry time, otherwise just the expiry time
will be updated.
Special time values are defined and described at ExpiryTimeValues
t - Time in millis since epoch.long getRefreshedTime()
Cache.put(K, V) or other sorts
of mutation.
Rationale: We call it "refreshed" time since we don't know whether the value actually changed. If a load produces the same value as before the entry is refreshed but effectively not updated or modified. The past tense means its the time of the last refresh and is not the upcoming refresh.
MutableCacheEntry<K,V> setRefreshedTime(long t)
setValue(Object) is used, this sets an alternative refreshed time for
expiry calculations. The entry refreshed time is not updated, if the entry is
not mutated.
If refresh ahead is enabled via Cache2kBuilder.refreshAhead(boolean),
the next refresh time is controlled by the expiry time.
cache2k API documentation. Copyright © 2000–2019 headissue GmbH, Munich.