Package org.ehcache.spi.loaderwriter

Interface CacheLoaderWriter<K,V>

Type Parameters:

K - the key type processed by this loader-writer

V - the value type processed by this loader-writer

public interface CacheLoaderWriter<K,V>

A CacheLoaderWriter is used to keep a Cache in sync with another system.

Instances of this class should be thread safe.

Any Exception thrown by the loading methods of this interface will be wrapped into a CacheLoadingException by the Cache and will need to be handled by the user. Any java.lang.Exception thrown by the writing methods will be wrapped into a CacheWritingException.

A similar thing will happen for the bulk version of the loading and writing methods and create the bulk version of the related exceptions.

See Also:

CacheLoadingException, CacheWritingException, BulkCacheLoadingException, BulkCacheWritingException

Method Summary

Modifier and Type	Method	Description
void	delete(K key)	Deletes a single mapping.
default void	deleteAll(Iterable<? extends K> keys)	Deletes multiple mappings.
V	load(K key)	Loads a single value.
default Map<K,V>	loadAll(Iterable<? extends K> keys)	Loads multiple values.
void	write(K key, V value)	Writes a single mapping.
default void	writeAll(Iterable<? extends Map.Entry<? extends K,? extends V>> entries)	Writes multiple mappings.

Method Detail

load

V load(K key)
throws Exception

Loads a single value.

When used with a cache any exception thrown by this method will be thrown back to the user as a CacheLoadingException.

Parameters:

key - the key for which to load the value

Returns:

the loaded value

Throws:

Exception - if the value cannot be loaded

loadAll

default Map<K,V> loadAll(Iterable<? extends K> keys)
                        throws BulkCacheLoadingException,
                               Exception

Loads multiple values.

The returned Map should contain null values for the keys that could not be found.

When used with a cache the mappings that will be installed are the keys as found in keys mapped to the results of loadAllResult.get(key). Any other mappings will be ignored.

By using a BulkCacheLoadingException implementors can report partial success. Any other exceptions will be thrown back to the Cache user through a BulkCacheLoadingException indicating a complete failure.

Parameters:

keys - the keys to load //Which null or not present?

Returns:

the Map of values for each key passed in, where no mapping means no value to map.

Throws:

BulkCacheLoadingException - in case of partial success

Exception - in case no values could be loaded

write

void write(K key,
           V value)
    throws Exception

Writes a single mapping.

The write may represent a brand new value or an update to an existing value.

When used with a Cache any exception thrown by this method will be thrown back to the user through a CacheWritingException.

Parameters:

key - the key to write

value - the value to write

Throws:

Exception - if the write operation failed

writeAll

default void writeAll(Iterable<? extends Map.Entry<? extends K,? extends V>> entries)
               throws BulkCacheWritingException,
                      Exception

Writes multiple mappings.

The writes may represent a mix of brand new values and updates to existing values.

By using a BulkCacheWritingException implementors can report partial success. Any other exception will be thrown back to the Cache user through a BulkCacheWritingException indicating a complete failure.

Parameters:

entries - the mappings to write

Throws:

BulkCacheWritingException - in case of partial success

Exception - in case no values could be written

delete

void delete(K key)
     throws Exception

Deletes a single mapping.

Parameters:

key - the key to delete

Throws:

Exception - if the write operation failed

deleteAll

default void deleteAll(Iterable<? extends K> keys)
                throws BulkCacheWritingException,
                       Exception

Deletes multiple mappings.

By using a BulkCacheWritingException implementors can report partial success. Any other exception will be thrown back to the Cache user through a BulkCacheWritingException indicating all deletes failed.

Parameters:

keys - the keys to delete

Throws:

BulkCacheWritingException - in case of partial success

Exception - in case no values can be loaded