content: /*
   * Copyright (C) 2020 ActiveJ LLC.
   *
   * 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 io.activej.async.file;
  
  import io.activej.common.Checks;
  import io.activej.promise.Promise;
  import io.activej.reactor.AbstractReactive;
  import io.activej.reactor.Reactor;
  
  import java.nio.ByteBuffer;
  import java.nio.channels.FileChannel;
  import java.util.concurrent.Executor;
  
  import static io.activej.promise.Promise.ofBlocking;
  import static io.activej.reactor.Reactive.checkInReactorThread;
  
  public final class ExecutorFileService extends AbstractReactive
  	implements IFileService {
  	private static final boolean CHECKS = Checks.isEnabled(ExecutorFileService.class);
  
  	private final Executor executor;
  
  	public ExecutorFileService(Reactor reactor, Executor executor) {
  		super(reactor);
  		this.executor = executor;
  	}
  
  	@Override
  	public Promise<Integer> read(FileChannel channel, long position, byte[] array, int offset, int size) {
  		if (CHECKS) checkInReactorThread(this);
  		return ofBlocking(executor, () -> {
  			ByteBuffer buffer = ByteBuffer.wrap(array, offset, size);
  			long pos = position;
  
  			do {
  				int readBytes = channel.read(buffer, pos);
  				if (readBytes == -1) {
  					break;
  				}
  				pos += readBytes;
  			} while (buffer.position() < buffer.limit());
  			return Math.toIntExact(pos - position);
  		});
  	}
  
  	@Override
  	public Promise<Integer> write(FileChannel channel, long position, byte[] array, int offset, int size) {
  		if (CHECKS) checkInReactorThread(this);
  		return ofBlocking(executor, () -> {
  			ByteBuffer buffer = ByteBuffer.wrap(array, offset, size);
  			long pos = position;
  
  			do {
  				pos += channel.write(buffer, pos);
  			} while (buffer.position() < buffer.limit());
  			return Math.toIntExact(pos - position);
  		});
  	}
  }
  