alluxio.client.file

Class FileSystemUtils

java.lang.Object

alluxio.client.file.FileSystemUtils

@ThreadSafe
public final class FileSystemUtils
extends Object

Collection of utility methods to handle with FileSystem related objects.

Method Summary

Modifier and Type	Method and Description
static boolean	metadataEnabled(AlluxioConfiguration conf)
static void	persistAndWait(FileSystem fs, AlluxioURI uri, long persistenceWaitTime) Convenience method for #persistAndWait(fs, uri, persistenceWaitTime, -1).
static void	persistAndWait(FileSystem fs, AlluxioURI uri, long persistenceWaitTime, int timeoutMs) Persists the given path to the under file system and returns once the persist is complete.
static boolean	waitCompleted(FileSystem fs, AlluxioURI uri) Shortcut for waitCompleted(fs, uri, -1, TimeUnit.MILLISECONDS), i.e., wait for an indefinite amount of time.
static boolean	waitCompleted(FileSystem fs, AlluxioURI uri, long timeout, TimeUnit tunit) Waits for a file to be marked as completed.
static void	waitForAlluxioPercentage(FileSystem fs, AlluxioURI uri, int expectedPercentage) Waits until the specified file has the desired percentage in Alluxio.

Methods inherited from class java.lang.Object

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

Method Detail

metadataEnabled

public static boolean metadataEnabled(AlluxioConfiguration conf)

Parameters:

conf - the configuration to get info from

Returns:

whether metadata cache is enabled in the given configuration

waitCompleted

public static boolean waitCompleted(FileSystem fs,
                                    AlluxioURI uri)
                             throws IOException,
                                    AlluxioException

Shortcut for waitCompleted(fs, uri, -1, TimeUnit.MILLISECONDS), i.e., wait for an indefinite amount of time. Note that if a file is never completed, the thread will block forever, so use with care.

Parameters:

fs - a FileSystem instance

uri - the URI of the file on which the thread should wait

Returns:

true if the file is complete when this method returns and false if the method timed out before the file was complete.

Throws:

IOException

AlluxioException

See Also:

waitCompleted(FileSystem, AlluxioURI, long, TimeUnit)

waitCompleted

public static boolean waitCompleted(FileSystem fs,
                                    AlluxioURI uri,
                                    long timeout,
                                    TimeUnit tunit)
                             throws IOException,
                                    AlluxioException

Waits for a file to be marked as completed.

The calling thread will block for at most timeout time units (as specified via tunit or until the file is reported as complete by the master. The method will return the last known completion status of the file (hence, false only if the method has timed out). A zero value on the timeout parameter will make the calling thread check once and return; a negative value will make it block indefinitely. Note that, in this last case, if a file is never completed, the thread will block forever, so use with care.

Note that the file whose uri is specified, might not exist at the moment this method this call. The method will deliberately block anyway for the specified amount of time, waiting for the file to be created and eventually completed. Note also that the file might be moved or deleted while it is waited upon. In such cases the method will throw the a AlluxioException

IMPLEMENTATION NOTES This method is implemented by periodically polling the master about the file status. The polling period is controlled by the PropertyKey.USER_FILE_WAITCOMPLETED_POLL_MS java property and defaults to a generous 1 second.

Parameters:

fs - an instance of FileSystem

uri - the URI of the file whose completion status is to be watied for

timeout - maximum time the calling thread should be blocked on this call

tunit - the @{link TimeUnit} instance describing the timeout parameter

Returns:

true if the file is complete when this method returns and false if the method timed out before the file was complete.

Throws:

IOException

AlluxioException

persistAndWait

public static void persistAndWait(FileSystem fs,
                                  AlluxioURI uri,
                                  long persistenceWaitTime)
                           throws FileDoesNotExistException,
                                  IOException,
                                  AlluxioException,
                                  TimeoutException,
                                  InterruptedException

Convenience method for #persistAndWait(fs, uri, persistenceWaitTime, -1). i.e. wait for an indefinite period of time to persist. This will block for an indefinite period of time if the path is never persisted. Use with care.

Parameters:

fs - FileSystem to carry out Alluxio operations

uri - the uri of the file to persist

persistenceWaitTime - the persistence wait time

Throws:

FileDoesNotExistException

IOException

AlluxioException

TimeoutException

InterruptedException

persistAndWait

public static void persistAndWait(FileSystem fs,
                                  AlluxioURI uri,
                                  long persistenceWaitTime,
                                  int timeoutMs)
                           throws FileDoesNotExistException,
                                  IOException,
                                  AlluxioException,
                                  TimeoutException,
                                  InterruptedException

Persists the given path to the under file system and returns once the persist is complete. Note that if this method times out, the persist may still occur after the timeout period.

Parameters:

fs - FileSystem to carry out Alluxio operations

uri - the uri of the file to persist

persistenceWaitTime - the initial persistence wait time

timeoutMs - max amount of time to wait for persist in milliseconds. -1 to wait indefinitely

Throws:

TimeoutException - if the persist takes longer than the timeout

FileDoesNotExistException

IOException

AlluxioException

InterruptedException

waitForAlluxioPercentage

public static void waitForAlluxioPercentage(FileSystem fs,
                                            AlluxioURI uri,
                                            int expectedPercentage)
                                     throws TimeoutException,
                                            InterruptedException

Waits until the specified file has the desired percentage in Alluxio.

Parameters:

fs - the file system

uri - the uri to check the percentage for

expectedPercentage - the desired percentage

Throws:

TimeoutException

InterruptedException