org.dataloader.impl

Class NoOpValueCache<K,V>

java.lang.Object

org.dataloader.impl.NoOpValueCache<K,V>

Type Parameters:

K - the type of cache keys

V - the type of cache values

All Implemented Interfaces:

ValueCache<K,V>

public class NoOpValueCache<K,V>
extends java.lang.Object
implements ValueCache<K,V>

Implementation of ValueCache that does nothing.

We don't want to store values in memory twice, so when using the default store we just say we never have the key and complete the other methods by doing nothing.

Nested Class Summary

Nested classes/interfaces inherited from interface org.dataloader.ValueCache

ValueCache.ValueCachingNotSupported

Field Summary

Fields

Modifier and Type	Field and Description
static NoOpValueCache<?,?>	NOOP a no op value cache instance

Constructor Summary

Constructors

Constructor and Description
NoOpValueCache()

Method Summary

Modifier and Type	Method and Description
java.util.concurrent.CompletableFuture<java.lang.Void>	clear() Clears all entries from the value cache.
java.util.concurrent.CompletableFuture<java.lang.Void>	delete(K key) Deletes the entry with the specified key from the value cache, if it exists.
java.util.concurrent.CompletableFuture<V>	get(K key) Gets the specified key from the value cache.
java.util.concurrent.CompletableFuture<java.util.List<Try<V>>>	getValues(java.util.List<K> keys) Gets the specified keys from the value cache, in a batch call.
java.util.concurrent.CompletableFuture<V>	set(K key, V value) Stores the value with the specified key, or updates it if the key already exists.
java.util.concurrent.CompletableFuture<java.util.List<V>>	setValues(java.util.List<K> keys, java.util.List<V> values) Stores the value with the specified keys, or updates it if the keys if they already exist.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.dataloader.ValueCache

defaultValueCache

Field Detail

NOOP

public static final NoOpValueCache<?,?> NOOP

a no op value cache instance

Constructor Detail

NoOpValueCache

public NoOpValueCache()

Method Detail

get

public java.util.concurrent.CompletableFuture<V> get(K key)

Gets the specified key from the value cache. If the key is not present, then the implementation MUST return an exceptionally completed future and not null because null is a valid cacheable value. An exceptionally completed future will cause DataLoader to load the key via batch loading instead.

Specified by:

get in interface ValueCache<K,V>

Parameters:

key - the key to retrieve

Returns:

a future containing the cached value (which maybe null) or exceptionally completed future if the key does not exist in the cache.

getValues

public java.util.concurrent.CompletableFuture<java.util.List<Try<V>>> getValues(java.util.List<K> keys)
                                                                         throws ValueCache.ValueCachingNotSupported

Description copied from interface: ValueCache

Gets the specified keys from the value cache, in a batch call. If your underlying cache cant do batch caching retrieval then do not implement this method and it will delegate back to ValueCache.get(Object) for you

Each item in the returned list of values is a Try. If the key could not be found then a failed Try just be returned otherwise a successful Try contain the cached value is returned.

You MUST return a List that is the same size as the keys passed in. The code will assert if you do not.

If your cache does not have anything in it at all, and you want to quickly short-circuit this method and avoid any object allocation then throw ValueCache.ValueCachingNotSupported and the code will know there is nothing in cache at this time.

Specified by:

getValues in interface ValueCache<K,V>

Parameters:

keys - the list of keys to get cached values for.

Returns:

a future containing a list of Try cached values for each key passed in.

Throws:

ValueCache.ValueCachingNotSupported - if this cache wants to short-circuit this method completely

set

public java.util.concurrent.CompletableFuture<V> set(K key,
                                                     V value)

Stores the value with the specified key, or updates it if the key already exists.

Specified by:

set in interface ValueCache<K,V>

Parameters:

key - the key to store

value - the value to store

Returns:

a future containing the stored value for fluent composition

setValues

public java.util.concurrent.CompletableFuture<java.util.List<V>> setValues(java.util.List<K> keys,
                                                                           java.util.List<V> values)
                                                                    throws ValueCache.ValueCachingNotSupported

Description copied from interface: ValueCache

Stores the value with the specified keys, or updates it if the keys if they already exist. If your underlying cache cant do batch caching setting then do not implement this method and it will delegate back to ValueCache.set(Object, Object) for you

Specified by:

setValues in interface ValueCache<K,V>

Parameters:

keys - the keys to store

values - the values to store

Returns:

a future containing the stored values for fluent composition

Throws:

ValueCache.ValueCachingNotSupported - if this cache wants to short-circuit this method completely

delete

public java.util.concurrent.CompletableFuture<java.lang.Void> delete(K key)

Deletes the entry with the specified key from the value cache, if it exists.

NOTE: Your implementation MUST not throw exceptions, rather it should return a CompletableFuture that has completed exceptionally. Failure to do this may cause the DataLoader code to not run properly.

Specified by:

delete in interface ValueCache<K,V>

Parameters:

key - the key to delete

Returns:

a void future for error handling and fluent composition

clear

public java.util.concurrent.CompletableFuture<java.lang.Void> clear()

Clears all entries from the value cache.

NOTE: Your implementation MUST not throw exceptions, rather it should return a CompletableFuture that has completed exceptionally. Failure to do this may cause the DataLoader code to not run properly.

Specified by:

clear in interface ValueCache<K,V>

Returns:

a void future for error handling and fluent composition