Package io.deephaven.engine.table

Class SharedContext

java.lang.Object

io.deephaven.engine.table.SharedContext

All Implemented Interfaces:

Context, ResettableContext, SafeCloseable, AutoCloseable

public class SharedContext
extends Object
implements ResettableContext

ResettableContext used as a holder for other ResettableContexts that may be shared across components.

This serves as a place to cache re-usable computations or resources, but must be reset() for every step of an operation (usually a chunk of ordered keys).

For example, redirected data sources that share the same mappings may cache a chunk of redirections for the most recent chunk of row keys they have been handed.

It's important that "nested" usage follows the convention of creating a new instance and passing that instance to context creation methods. Said nested instance should be (or be attached to) an entry in the parent context, and reset/closed when said entry is. It should always be safe to skip nested SharedContext creation if all sources that may be using a given instance will be passed the same ordered keys.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	SharedContext.ExactReferenceSharingKey<VALUE_TYPE extends ResettableContext>	Abstract SharedContext.Key implementation for use when a simple Object reference coupled with sub-class identity can determine equality for sharing purposes.
static interface	SharedContext.Key<VALUE_TYPE extends ResettableContext>	Key marker interface.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	SharedContext()

Method Summary

Modifier and Type	Method	Description
void	close()	Close implementation which invokes SafeCloseable.close() on all values registered via getOrCreate(Key, Supplier), and then forgets all registered values.
final <V extends ResettableContext, K extends SharedContext.Key<V>> V	getOrCreate(K key, @NotNull Supplier<V> valueFactory)	Get or create the ResettableContext value for a SharedContext.Key key.
static SharedContext	makeSharedContext()	Construct a new, empty shared context.
void	reset()	Reset implementation which invokes ResettableContext.reset() on all values registered via getOrCreate(Key, Supplier).

Methods inherited from class java.lang.Object

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

Constructor Details

SharedContext

protected SharedContext()

Method Details

getOrCreate

public final <V extends ResettableContext,
K extends SharedContext.Key<V>>
V getOrCreate(K key,
 @NotNull
 @NotNull Supplier<V> valueFactory)

Get or create the ResettableContext value for a SharedContext.Key key. If the value is computed, the result value will be associated with the key until the SharedContext is close()ed.

Parameters:

key - The key

valueFactory - The value factory, to be invoked if key is not found within this SharedContext

Returns:

The value associated with key, possibly newly-created

reset

@OverridingMethodsMustInvokeSuper
public void reset()

Reset implementation which invokes ResettableContext.reset() on all values registered via getOrCreate(Key, Supplier).

Sub-classes should be sure to call super.reset().

Specified by:

reset in interface ResettableContext

close

@OverridingMethodsMustInvokeSuper
public void close()

Close implementation which invokes SafeCloseable.close() on all values registered via getOrCreate(Key, Supplier), and then forgets all registered values.

Sub-classes should be sure to call super.close().

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Context

Specified by:

close in interface SafeCloseable

makeSharedContext

public static SharedContext makeSharedContext()

Construct a new, empty shared context.