ratpack.file.internal.FileWritingSubscriber.java Source code

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Here is the source code for ratpack.file.internal.FileWritingSubscriber.java

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/*
 * Copyright 2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package ratpack.file.internal;

import io.netty.buffer.ByteBuf;
import org.reactivestreams.Subscriber;
import org.reactivestreams.Subscription;
import ratpack.exec.Downstream;
import ratpack.exec.Promise;

import java.nio.channels.AsynchronousFileChannel;
import java.nio.channels.CompletionHandler;

public class FileWritingSubscriber implements Subscriber<ByteBuf> {

    private final AsynchronousFileChannel out;
    private final Downstream<? super Long> downstream;

    private final long startAt;
    private long position;
    private Subscription s;

    private boolean cancelled;

    public FileWritingSubscriber(AsynchronousFileChannel out, long position, Downstream<? super Long> downstream) {
        this.position = position;
        this.startAt = position;
        this.downstream = downstream;
        this.out = out;

        if (position < 0) {
            throw new IllegalArgumentException("position must be >= 0");
        }
    }

    @Override
    public void onSubscribe(Subscription s) {
        this.s = s;
        s.request(1);
    }

    @Override
    public void onNext(ByteBuf byteBuf) {
        int toWrite = byteBuf.readableBytes();
        if (cancelled || toWrite < 1) {
            byteBuf.release();
            if (!cancelled) {
                s.request(1);
            }
            return;
        }

        Promise.<Integer>async(
                down -> out.write(byteBuf.nioBuffer(), position, null, new CompletionHandler<Integer, Void>() {
                    @Override
                    public void completed(Integer result, Void attachment) {
                        byteBuf.release();
                        down.success(result);
                    }

                    @Override
                    public void failed(Throwable exc, Void attachment) {
                        byteBuf.release();
                        down.error(exc);
                    }
                })).onError(e -> {
                    cancelled = true;
                    s.cancel();
                    downstream.error(e);
                }).then(i -> {
                    position += i;
                    s.request(1);
                });
    }

    @Override
    public void onError(Throwable t) {
        if (!cancelled) {
            downstream.error(t);
        }
    }

    @Override
    public void onComplete() {
        downstream.success(position - startAt);
    }
}