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/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF 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 org.apache.hadoop.util;
import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Map;
import java.util.Timer;
import java.util.TimerTask;
import java.util.concurrent.atomic.AtomicBoolean;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.conf.Configuration;
/**
* A base class for running a Unix command.
*
* Shell can be used to run unix commands like du or
* df. It also offers facilities to gate commands by
* time-intervals.
*/
@InterfaceAudience.LimitedPrivate({"HDFS", "MapReduce"})
@InterfaceStability.Unstable
abstract public class Shell {
public static final Log LOG = LogFactory.getLog(Shell.class);
/** a Unix command to get the current user's name */
public final static String USER_NAME_COMMAND = "whoami";
/** a Unix command to get the current user's groups list */
public static String[] getGroupsCommand() {
return new String[]{"bash", "-c", "groups"};
}
/** a Unix command to get a given user's groups list */
public static String[] getGroupsForUserCommand(final String user) {
//'groups username' command return is non-consistent across different unixes
return new String [] {"bash", "-c", "id -Gn " + user};
}
/** a Unix command to set permission */
public static final String SET_PERMISSION_COMMAND = "chmod";
/** a Unix command to set owner */
public static final String SET_OWNER_COMMAND = "chown";
public static final String SET_GROUP_COMMAND = "chgrp";
/** a Unix command to create a link */
public static final String LINK_COMMAND = "ln";
/** a Unix command to get a link target */
public static final String READ_LINK_COMMAND = "readlink";
/** Return a Unix command to get permission information. */
public static String[] getGET_PERMISSION_COMMAND() {
//force /bin/ls, except on windows.
return new String[] {(WINDOWS ? "ls" : "/bin/ls"), "-ld"};
}
/**Time after which the executing script would be timedout*/
protected long timeOutInterval = 0L;
/** If or not script timed out*/
private AtomicBoolean timedOut;
/** a Unix command to get ulimit of a process. */
public static final String ULIMIT_COMMAND = "ulimit";
/**
* Get the Unix command for setting the maximum virtual memory available
* to a given child process. This is only relevant when we are forking a
* process from within the Mapper or the Reducer implementations.
* Also see Hadoop Pipes and Hadoop Streaming.
*
* It also checks to ensure that we are running on a *nix platform else
* (e.g. in Cygwin/Windows) it returns null.
* @param memoryLimit virtual memory limit
* @return a String[] with the ulimit command arguments or
* null if we are running on a non *nix platform or
* if the limit is unspecified.
*/
public static String[] getUlimitMemoryCommand(int memoryLimit) {
// ulimit isn't supported on Windows
if (WINDOWS) {
return null;
}
return new String[] {ULIMIT_COMMAND, "-v", String.valueOf(memoryLimit)};
}
/**
* Get the Unix command for setting the maximum virtual memory available
* to a given child process. This is only relevant when we are forking a
* process from within the Mapper or the Reducer implementations.
* see also Hadoop Pipes and Streaming.
*
* It also checks to ensure that we are running on a *nix platform else
* (e.g. in Cygwin/Windows) it returns null.
* @param conf configuration
* @return a String[] with the ulimit command arguments or
* null if we are running on a non *nix platform or
* if the limit is unspecified.
* @deprecated Use {@link #getUlimitMemoryCommand(int)}
*/
@Deprecated
public static String[] getUlimitMemoryCommand(Configuration conf) {
// ulimit isn't supported on Windows
if (WINDOWS) {
return null;
}
// get the memory limit from the configuration
String ulimit = conf.get("mapred.child.ulimit");
if (ulimit == null) {
return null;
}
// Parse it to ensure it is legal/sane
int memoryLimit = Integer.valueOf(ulimit);
return getUlimitMemoryCommand(memoryLimit);
}
/** Set to true on Windows platforms */
public static final boolean WINDOWS /* borrowed from Path.WINDOWS */
= System.getProperty("os.name").startsWith("Windows");
private long interval; // refresh interval in msec
private long lastTime; // last time the command was performed
private Map environment; // env for the command execution
private File dir;
private Process process; // sub process used to execute the command
private int exitCode;
/**If or not script finished executing*/
private volatile AtomicBoolean completed;
public Shell() {
this(0L);
}
/**
* @param interval the minimum duration to wait before re-executing the
* command.
*/
public Shell( long interval ) {
this.interval = interval;
this.lastTime = (interval<0) ? 0 : -interval;
}
/** set the environment for the command
* @param env Mapping of environment variables
*/
protected void setEnvironment(Map env) {
this.environment = env;
}
/** set the working directory
* @param dir The directory where the command would be executed
*/
protected void setWorkingDirectory(File dir) {
this.dir = dir;
}
/** check to see if a command needs to be executed and execute if needed */
protected void run() throws IOException {
if (lastTime + interval > System.currentTimeMillis())
return;
exitCode = 0; // reset for next run
runCommand();
}
/** Run a command */
private void runCommand() throws IOException {
ProcessBuilder builder = new ProcessBuilder(getExecString());
Timer timeOutTimer = null;
ShellTimeoutTimerTask timeoutTimerTask = null;
timedOut = new AtomicBoolean(false);
completed = new AtomicBoolean(false);
if (environment != null) {
builder.environment().putAll(this.environment);
}
if (dir != null) {
builder.directory(this.dir);
}
process = builder.start();
if (timeOutInterval > 0) {
timeOutTimer = new Timer("Shell command timeout");
timeoutTimerTask = new ShellTimeoutTimerTask(
this);
//One time scheduling.
timeOutTimer.schedule(timeoutTimerTask, timeOutInterval);
}
final BufferedReader errReader =
new BufferedReader(new InputStreamReader(process
.getErrorStream()));
BufferedReader inReader =
new BufferedReader(new InputStreamReader(process
.getInputStream()));
final StringBuffer errMsg = new StringBuffer();
// read error and input streams as this would free up the buffers
// free the error stream buffer
Thread errThread = new Thread() {
@Override
public void run() {
try {
String line = errReader.readLine();
while((line != null) && !isInterrupted()) {
errMsg.append(line);
errMsg.append(System.getProperty("line.separator"));
line = errReader.readLine();
}
} catch(IOException ioe) {
LOG.warn("Error reading the error stream", ioe);
}
}
};
try {
errThread.start();
} catch (IllegalStateException ise) { }
try {
parseExecResult(inReader); // parse the output
// clear the input stream buffer
String line = inReader.readLine();
while(line != null) {
line = inReader.readLine();
}
// wait for the process to finish and check the exit code
exitCode = process.waitFor();
try {
// make sure that the error thread exits
errThread.join();
} catch (InterruptedException ie) {
LOG.warn("Interrupted while reading the error stream", ie);
}
completed.set(true);
//the timeout thread handling
//taken care in finally block
if (exitCode != 0) {
throw new ExitCodeException(exitCode, errMsg.toString());
}
} catch (InterruptedException ie) {
throw new IOException(ie.toString());
} finally {
if (timeOutTimer != null) {
timeOutTimer.cancel();
}
// close the input stream
try {
inReader.close();
} catch (IOException ioe) {
LOG.warn("Error while closing the input stream", ioe);
}
if (!completed.get()) {
errThread.interrupt();
}
try {
errReader.close();
} catch (IOException ioe) {
LOG.warn("Error while closing the error stream", ioe);
}
process.destroy();
lastTime = System.currentTimeMillis();
}
}
/** return an array containing the command name & its parameters */
protected abstract String[] getExecString();
/** Parse the execution result */
protected abstract void parseExecResult(BufferedReader lines)
throws IOException;
/** get the current sub-process executing the given command
* @return process executing the command
*/
public Process getProcess() {
return process;
}
/** get the exit code
* @return the exit code of the process
*/
public int getExitCode() {
return exitCode;
}
/**
* This is an IOException with exit code added.
*/
public static class ExitCodeException extends IOException {
int exitCode;
public ExitCodeException(int exitCode, String message) {
super(message);
this.exitCode = exitCode;
}
public int getExitCode() {
return exitCode;
}
}
/**
* A simple shell command executor.
*
* ShellCommandExecutorshould be used in cases where the output
* of the command needs no explicit parsing and where the command, working
* directory and the environment remains unchanged. The output of the command
* is stored as-is and is expected to be small.
*/
public static class ShellCommandExecutor extends Shell {
private String[] command;
private StringBuffer output;
public ShellCommandExecutor(String[] execString) {
this(execString, null);
}
public ShellCommandExecutor(String[] execString, File dir) {
this(execString, dir, null);
}
public ShellCommandExecutor(String[] execString, File dir,
Map env) {
this(execString, dir, env , 0L);
}
/**
* Create a new instance of the ShellCommandExecutor to execute a command.
*
* @param execString The command to execute with arguments
* @param dir If not-null, specifies the directory which should be set
* as the current working directory for the command.
* If null, the current working directory is not modified.
* @param env If not-null, environment of the command will include the
* key-value pairs specified in the map. If null, the current
* environment is not modified.
* @param timeout Specifies the time in milliseconds, after which the
* command will be killed and the status marked as timedout.
* If 0, the command will not be timed out.
*/
public ShellCommandExecutor(String[] execString, File dir,
Map env, long timeout) {
command = execString.clone();
if (dir != null) {
setWorkingDirectory(dir);
}
if (env != null) {
setEnvironment(env);
}
timeOutInterval = timeout;
}
/** Execute the shell command. */
public void execute() throws IOException {
this.run();
}
public String[] getExecString() {
return command;
}
protected void parseExecResult(BufferedReader lines) throws IOException {
output = new StringBuffer();
char[] buf = new char[512];
int nRead;
while ( (nRead = lines.read(buf, 0, buf.length)) > 0 ) {
output.append(buf, 0, nRead);
}
}
/** Get the output of the shell command.*/
public String getOutput() {
return (output == null) ? "" : output.toString();
}
/**
* Returns the commands of this instance.
* Arguments with spaces in are presented with quotes round; other
* arguments are presented raw
*
* @return a string representation of the object.
*/
public String toString() {
StringBuilder builder = new StringBuilder();
String[] args = getExecString();
for (String s : args) {
if (s.indexOf(' ') >= 0) {
builder.append('"').append(s).append('"');
} else {
builder.append(s);
}
builder.append(' ');
}
return builder.toString();
}
}
/**
* To check if the passed script to shell command executor timed out or
* not.
*
* @return if the script timed out.
*/
public boolean isTimedOut() {
return timedOut.get();
}
/**
* Set if the command has timed out.
*
*/
private void setTimedOut() {
this.timedOut.set(true);
}
/**
* Static method to execute a shell command.
* Covers most of the simple cases without requiring the user to implement
* the Shell interface.
* @param cmd shell command to execute.
* @return the output of the executed command.
*/
public static String execCommand(String ... cmd) throws IOException {
return execCommand(null, cmd, 0L);
}
/**
* Static method to execute a shell command.
* Covers most of the simple cases without requiring the user to implement
* the Shell interface.
* @param env the map of environment key=value
* @param cmd shell command to execute.
* @param timeout time in milliseconds after which script should be marked timeout
* @return the output of the executed command.o
*/
public static String execCommand(Map env, String[] cmd,
long timeout) throws IOException {
ShellCommandExecutor exec = new ShellCommandExecutor(cmd, null, env,
timeout);
exec.execute();
return exec.getOutput();
}
/**
* Static method to execute a shell command.
* Covers most of the simple cases without requiring the user to implement
* the Shell interface.
* @param env the map of environment key=value
* @param cmd shell command to execute.
* @return the output of the executed command.
*/
public static String execCommand(Map env, String ... cmd)
throws IOException {
return execCommand(env, cmd, 0L);
}
/**
* Timer which is used to timeout scripts spawned off by shell.
*/
private static class ShellTimeoutTimerTask extends TimerTask {
private Shell shell;
public ShellTimeoutTimerTask(Shell shell) {
this.shell = shell;
}
@Override
public void run() {
Process p = shell.getProcess();
try {
p.exitValue();
} catch (Exception e) {
//Process has not terminated.
//So check if it has completed
//if not just destroy it.
if (p != null && !shell.completed.get()) {
shell.setTimedOut();
p.destroy();
}
}
}
}
}