com.cloudera.sqoop.util.Executor.java Source code

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Here is the source code for com.cloudera.sqoop.util.Executor.java

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/**
 * Licensed to Cloudera, Inc. under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  Cloudera, Inc. licenses this file
 * to you 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 com.cloudera.sqoop.util;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * Runs a process via Runtime.exec() and allows handling of stdout/stderr to be
 * deferred to other threads.
 *
 */
public final class Executor {

    public static final Log LOG = LogFactory.getLog(Executor.class.getName());

    private Executor() {
    }

    /**
     * Execute a program defined by the args array with default stream sinks
     * that consume the program's output (to prevent it from blocking on buffers)
     * and then ignore said output.
     */
    public static int exec(String[] args) throws IOException {
        NullAsyncSink s = new NullAsyncSink();
        return exec(args, s, s);
    }

    /**
     * Run a command via Runtime.exec(), with its stdout and stderr streams
     * directed to be handled by threads generated by AsyncSinks.
     * Block until the child process terminates. 
     *
     * @return the exit status of the ran program
     */
    public static int exec(String[] args, AsyncSink outSink, AsyncSink errSink) throws IOException {
        return exec(args, null, outSink, errSink);
    }

    /**
     * Run a command via Runtime.exec(), with its stdout and stderr streams
     * directed to be handled by threads generated by AsyncSinks.
     * Block until the child process terminates. Allows the programmer to
     * specify an environment for the child program.
     *
     * @return the exit status of the ran program
     */
    public static int exec(String[] args, String[] envp, AsyncSink outSink, AsyncSink errSink) throws IOException {

        // launch the process.
        Process p = Runtime.getRuntime().exec(args, envp);

        // dispatch its stdout and stderr to stream sinks if available.
        if (null != outSink) {
            outSink.processStream(p.getInputStream());
        }

        if (null != errSink) {
            errSink.processStream(p.getErrorStream());
        }

        // wait for the return value.
        while (true) {
            try {
                int ret = p.waitFor();
                return ret;
            } catch (InterruptedException ie) {
                continue;
            }
        }
    }

    /**
     * @return An array formatted correctly for use as an envp based on the
     * current environment for this program.
     */
    public static List<String> getCurEnvpStrings() {
        Map<String, String> curEnv = System.getenv();
        ArrayList<String> array = new ArrayList<String>();

        if (null == curEnv) {
            return null;
        }

        for (Map.Entry<String, String> entry : curEnv.entrySet()) {
            array.add(entry.getKey() + "=" + entry.getValue());
        }

        return array;
    }
}