org.dataloader.scheduler

Interface BatchLoaderScheduler

public interface BatchLoaderScheduler

By default, when DataLoader.dispatch() is called, the BatchLoader / MappedBatchLoader function will be invoked immediately. However, you can provide your own BatchLoaderScheduler that allows this call to be done some time into the future. You will be passed a callback (BatchLoaderScheduler.ScheduledBatchLoaderCall / BatchLoaderScheduler.ScheduledMappedBatchLoaderCall and you are expected to eventually call this callback method to make the batch loading happen.

Note: Because there is a DataLoaderOptions.maxBatchSize() it is possible for this scheduling to happen N times for a given DataLoader.dispatch() call. The total set of keys will be sliced into batches themselves and then the BatchLoaderScheduler will be called for each batch of keys. Do not assume that a single call to DataLoader.dispatch() results in a single call to BatchLoaderScheduler.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	BatchLoaderScheduler.ScheduledBatchLoaderCall<V> This represents a callback that will invoke a BatchLoader function under the covers
static interface	BatchLoaderScheduler.ScheduledMappedBatchLoaderCall<K,V> This represents a callback that will invoke a MappedBatchLoader function under the covers

Method Summary

Modifier and Type	Method and Description
<K,V> java.util.concurrent.CompletionStage<java.util.List<V>>	scheduleBatchLoader(BatchLoaderScheduler.ScheduledBatchLoaderCall<V> scheduledCall, java.util.List<K> keys, BatchLoaderEnvironment environment) This is called to schedule a BatchLoader call.
<K,V> java.util.concurrent.CompletionStage<java.util.Map<K,V>>	scheduleMappedBatchLoader(BatchLoaderScheduler.ScheduledMappedBatchLoaderCall<K,V> scheduledCall, java.util.List<K> keys, BatchLoaderEnvironment environment) This is called to schedule a MappedBatchLoader call.

Method Detail

scheduleBatchLoader

<K,V> java.util.concurrent.CompletionStage<java.util.List<V>> scheduleBatchLoader(BatchLoaderScheduler.ScheduledBatchLoaderCall<V> scheduledCall,
                                                                                  java.util.List<K> keys,
                                                                                  BatchLoaderEnvironment environment)

This is called to schedule a BatchLoader call.

Type Parameters:

K - the key type

V - the value type

Parameters:

scheduledCall - the callback that needs to be invoked to allow the BatchLoader to proceed.

keys - this is the list of keys that will be passed to the BatchLoader. This is provided only for informative reasons, and you can't change the keys that are used

environment - this is the BatchLoaderEnvironment in place, which can be null if it's a simple BatchLoader call

Returns:

a promise to the values that come from the BatchLoader

scheduleMappedBatchLoader

<K,V> java.util.concurrent.CompletionStage<java.util.Map<K,V>> scheduleMappedBatchLoader(BatchLoaderScheduler.ScheduledMappedBatchLoaderCall<K,V> scheduledCall,
                                                                                         java.util.List<K> keys,
                                                                                         BatchLoaderEnvironment environment)

This is called to schedule a MappedBatchLoader call.

Type Parameters:

K - the key type

V - the value type

Parameters:

scheduledCall - the callback that needs to be invoked to allow the MappedBatchLoader to proceed.

keys - this is the list of keys that will be passed to the MappedBatchLoader. This is provided only for informative reasons and, you can't change the keys that are used

environment - this is the BatchLoaderEnvironment in place, which can be null if it's a simple MappedBatchLoader call

Returns:

a promise to the values that come from the BatchLoader