org.apache.hadoop.contrib.failmon
Class Environment

java.lang.Object
  org.apache.hadoop.contrib.failmon.Environment

public class Environment
extends Object

This class provides various methods for interaction with the configuration and the operating system environment. Also provides some helper methods for use by other classes in the package.

Field Summary

static int	DEFAULT_LOG_INTERVAL
static int	DEFAULT_POLL_INTERVAL
static org.apache.commons.logging.Log	LOG
static int	MAX_OUTPUT_LENGTH
static int	MIN_INTERVAL

Constructor Summary

Environment()

Method Summary

static boolean	checkExistence(String cmd) Checks whether a specific shell command is available in the system.
static int	gcd(int[] numbers) Determines the greatest common divisor (GCD) of a list of integers.
static int	gcd(int m, int n) Determines the greatest common divisor (GCD) of two integers.
static int	getInterval(ArrayList<MonitorJob> monitors) Determines the minimum interval at which the executor thread needs to wake upto execute jobs.
static ArrayList<MonitorJob>	getJobs() Scans the configuration file to determine which monitoring utilities are available in the system.
static String	getProperty(String key) Fetches the value of a property from the configuration file.
static void	logInfo(String str)
static void	prepare(String fname) Initializes structures needed by other methods.
static StringBuffer	runCommand(String cmd) Runs a shell command in the system and provides a StringBuffer with the output of the command.
static StringBuffer	runCommand(String[] cmd) Runs a shell command in the system and provides a StringBuffer with the output of the command.
static void	setProperty(String key, String value) Sets the value of a property inthe configuration file.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

DEFAULT_LOG_INTERVAL

public static final int DEFAULT_LOG_INTERVAL

See Also:

Constant Field Values

DEFAULT_POLL_INTERVAL

public static final int DEFAULT_POLL_INTERVAL

See Also:

Constant Field Values

MIN_INTERVAL

public static int MIN_INTERVAL

MAX_OUTPUT_LENGTH

public static final int MAX_OUTPUT_LENGTH

See Also:

Constant Field Values

LOG

public static org.apache.commons.logging.Log LOG

Constructor Detail

Environment

public Environment()

Method Detail

prepare

public static void prepare(String fname)

Initializes structures needed by other methods. Also determines whether the executing user has superuser privileges.

getProperty

public static String getProperty(String key)

Fetches the value of a property from the configuration file.

Parameters:

key - the name of the property

Returns:

the value of the property, if it exists and null otherwise

setProperty

public static void setProperty(String key,
                               String value)

Sets the value of a property inthe configuration file.

Parameters:

key - the name of the property

value - the new value for the property

getJobs

public static ArrayList<MonitorJob> getJobs()

Scans the configuration file to determine which monitoring utilities are available in the system. For each one of them, a job is created. All such jobs are scheduled and executed by Executor.

Returns:

an ArrayList that contains jobs to be executed by theExecutor.

getInterval

public static int getInterval(ArrayList<MonitorJob> monitors)

Determines the minimum interval at which the executor thread needs to wake upto execute jobs. Essentially, this is interval equals the GCD of intervals of all scheduled jobs.

Parameters:

monitors - the list of scheduled jobs

Returns:

the minimum interval between two scheduled jobs

checkExistence

public static boolean checkExistence(String cmd)

Checks whether a specific shell command is available in the system.

Parameters:

cmd - the command to check against

Returns:

true, if the command is availble, false otherwise

runCommand

public static StringBuffer runCommand(String[] cmd)

Runs a shell command in the system and provides a StringBuffer with the output of the command.

Parameters:

cmd - an array of string that form the command to run

Returns:

a StringBuffer that contains the output of the command

runCommand

public static StringBuffer runCommand(String cmd)

Runs a shell command in the system and provides a StringBuffer with the output of the command.

Parameters:

cmd - the command to run

Returns:

a StringBuffer that contains the output of the command

gcd

public static int gcd(int m,
                      int n)

Determines the greatest common divisor (GCD) of two integers.

Parameters:

m - the first integer

n - the second integer

Returns:

the greatest common divisor of m and n

gcd

public static int gcd(int[] numbers)

Determines the greatest common divisor (GCD) of a list of integers.

Parameters:

numbers - the list of integers to process

Returns:

the greatest common divisor of all numbers

logInfo

public static void logInfo(String str)