io.airlift.command.OutputProcessor.java Source code

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Here is the source code for io.airlift.command.OutputProcessor.java

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/*
 * 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.airlift.command;

import com.google.common.io.CharStreams;

import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executor;
import java.util.concurrent.Future;

import static com.google.common.base.Preconditions.checkNotNull;
import static io.airlift.command.Command.submit;
import static java.nio.charset.StandardCharsets.UTF_8;

class OutputProcessor {
    private final InputStream inputStream;
    private final Executor executor;
    private Future<String> outputFuture;

    public OutputProcessor(Process process, Executor executor) {
        this.inputStream = checkNotNull(process, "process is null").getInputStream();
        this.executor = checkNotNull(executor, "executor is null");
    }

    public void start() {
        outputFuture = submit(executor, new Callable<String>() {
            @SuppressWarnings("IOResourceOpenedButNotSafelyClosed")
            @Override
            public String call() throws IOException {
                return CharStreams.toString(new InputStreamReader(inputStream, UTF_8));
            }
        });
    }

    public String getOutput() {
        if ((outputFuture != null) && !outputFuture.isCancelled()) {
            try {
                return outputFuture.get();
            } catch (InterruptedException e) {
                Thread.currentThread().interrupt();
            } catch (ExecutionException ignored) {
            }
        }
        return null;
    }

    public void destroy() {
        // close input stream which will normally interrupt the reader
        try {
            inputStream.close();
        } catch (IOException ignored) {
        }

        if (outputFuture != null) {
            outputFuture.cancel(true);
        }
    }
}