com.smaato.switchgear.circuitbreaker.TimeoutScheduler Maven / Gradle / Ivy

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Switchgear is a Java library that provides an API for call isolation, timeouts, and circuit breaker functionality. Our main goal is to achieve minimal performance overhead of the library, even when used in the hottest place of your application. Additionally, we've opted for zero transitive dependencies and maintaining a fluent API.

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package com.smaato.switchgear.circuitbreaker;

import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;
import java.util.function.Supplier;

import com.smaato.switchgear.circuitbreaker.state.bucket.BucketRange;

class TimeoutScheduler {

    private static final boolean DO_NOT_INTERRUPT = false;

    private final ScheduledExecutorService scheduler;

    TimeoutScheduler(final ScheduledExecutorService scheduler) {
        this.scheduler = scheduler;
    }

     Supplier> addTimeout(final Supplier> futureSupplier,
                                                  final int timeoutInMillis,
                                                  final BucketRange timeoutBucketRange) {
        return () -> scheduleTimeout(futureSupplier.get(), timeoutInMillis, timeoutBucketRange);
    }

    private  CompletableFuture scheduleTimeout(final CompletableFuture future,
                                                     final int timeoutInMillis,
                                                     final BucketRange timeoutBucketRange) {
        final ScheduledFuture timeoutCheckFuture = scheduler.schedule(() -> {
            if (!future.isDone()) {
                future.completeExceptionally(TimeoutExceptionBuilder.builder().withTimeoutRange(timeoutBucketRange).build());
            }
        }, timeoutInMillis, TimeUnit.MILLISECONDS);

        // Configure the event future to delete the timeout check immediately when it finishes.
        future.whenComplete((event, error) -> {
            if (!timeoutCheckFuture.isDone()) {
                timeoutCheckFuture.cancel(DO_NOT_INTERRUPT);
            }
        });

        return future;
    }
}