graphql.execution.instrumentation.threadpools

Class ExecutorInstrumentation

java.lang.Object

graphql.execution.instrumentation.SimpleInstrumentation

graphql.execution.instrumentation.threadpools.ExecutorInstrumentation

All Implemented Interfaces:

Instrumentation

@Beta
public class ExecutorInstrumentation
extends SimpleInstrumentation

This instrumentation can be used to control on what thread calls to DataFetchers happen on.

If your data fetching is inherently IO bound then you could use a IO oriented thread pool for your fetches and transfer control back to a CPU oriented thread pool and allow graphql-java code to run the post processing of results there.

An IO oriented thread pool is typically a multiple of Runtime.availableProcessors() while a CPU oriented thread pool is typically no more than Runtime.availableProcessors().

The instrumentation will use the Instrumentation.instrumentDataFetcher(DataFetcher, InstrumentationFieldFetchParameters) method to change your data fetchers so they are executed on a thread pool dedicated to fetching (if you provide one).

Once the data fetcher value is returns it will transfer control back to a processing thread pool (if you provide one).

This code uses CompletableFuture.supplyAsync(Supplier, Executor) and CompletableFuture.thenApplyAsync(Function, Executor) to transfer control between thread pools.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	ExecutorInstrumentation.Builder

Field Summary

Fields inherited from class graphql.execution.instrumentation.SimpleInstrumentation

INSTANCE

Method Summary

Modifier and Type	Method and Description
java.util.concurrent.Executor	getFetchExecutor()
java.util.concurrent.Executor	getProcessingExecutor()
DataFetcher<?>	instrumentDataFetcher(DataFetcher<?> originalDataFetcher, InstrumentationFieldFetchParameters parameters) This is called to instrument a DataFetcher just before it is used to fetch a field, allowing you to adjust what information is passed back or record information about specific data fetches.
static ExecutorInstrumentation.Builder	newThreadPoolExecutionInstrumentation()

Methods inherited from class graphql.execution.instrumentation.SimpleInstrumentation

beginExecuteOperation, beginExecution, beginExecutionStrategy, beginField, beginFieldFetch, beginParse, beginValidation

Methods inherited from class java.lang.Object

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

Methods inherited from interface graphql.execution.instrumentation.Instrumentation

beginFieldComplete, beginFieldListComplete, beginSubscribedFieldEvent, createState, createState, instrumentDocumentAndVariables, instrumentExecutionContext, instrumentExecutionInput, instrumentExecutionResult, instrumentSchema

Method Detail

getFetchExecutor

public java.util.concurrent.Executor getFetchExecutor()

getProcessingExecutor

public java.util.concurrent.Executor getProcessingExecutor()

newThreadPoolExecutionInstrumentation

public static ExecutorInstrumentation.Builder newThreadPoolExecutionInstrumentation()

instrumentDataFetcher

public DataFetcher<?> instrumentDataFetcher(DataFetcher<?> originalDataFetcher,
                                            InstrumentationFieldFetchParameters parameters)

Description copied from interface: Instrumentation

This is called to instrument a DataFetcher just before it is used to fetch a field, allowing you to adjust what information is passed back or record information about specific data fetches. Note the same data fetcher instance maybe presented to you many times and that data fetcher implementations widely vary.

Parameters:

originalDataFetcher - the data fetcher about to be used

parameters - the parameters describing the field to be fetched

Returns:

a non null instrumented DataFetcher, the default is to return to the same object