Package org.apache.hadoop.util

Common utilities.

See: Description

Interface Summary

Interface	Description
GSet<K,E extends K>	A GSet is set, which supports the GSet.get(Object) operation.
IdGenerator	Generic ID generator used for generating various types of number sequences.
IndexedSortable	Interface for collections capable of being sorted by IndexedSorter algorithms.
IndexedSorter	Interface for sort algorithms accepting IndexedSortable items.
LightWeightCache.Entry	Entries of LightWeightCache.
LightWeightGSet.LinkedElement	Elements of LightWeightGSet.
Progressable	A facility for reporting progress.
ServicePlugin	Service plug-in interface.
Tool	A tool interface that supports handling of generic command-line options.

Class Summary

Class	Description
AsyncDiskService
ClassUtil
Daemon	A thread that has called Thread.setDaemon(boolean) with true.
Daemon.DaemonFactory	Provide a factory for named daemon threads, for use in ExecutorServices constructors
DataChecksum	This class provides inteface and utilities for processing checksums for DFS data transfers.
DiskChecker	Class that provides utility functions for checking disk problem
ExitUtil	Facilitates hooking process termination for tests and debugging.
GenericOptionsParser	GenericOptionsParser is a utility to parse command line arguments generic to the Hadoop framework.
GenericsUtil	Contains utility methods for dealing with Java Generics.
GSetByHashMap<K,E extends K>	A GSet implementation by HashMap.
HeapSort	An implementation of the core algorithm of HeapSort.
HostsFileReader
LightWeightCache<K,E extends K>	A low memory footprint Cache which extends LightWeightGSet.
LightWeightGSet<K,E extends K>	A low memory footprint GSet implementation, which uses an array for storing the elements and linked lists for collision resolution.
LineReader	A class that provides a line reader from an input stream.
MergeSort	An implementation of the core algorithm of MergeSort.
NativeCodeLoader	A helper to load the native hadoop code i.e.
NativeLibraryChecker
Options	This class allows generic access to variable length type-safe parameter lists.
Options.BooleanOption
Options.ClassOption
Options.FSDataInputStreamOption
Options.FSDataOutputStreamOption
Options.IntegerOption
Options.LongOption
Options.PathOption
Options.ProgressableOption
Options.StringOption
PlatformName	A helper class for getting build-info of the java-vm.
PrintJarMainClass	A micro-application that prints the main class name out of a jar file.
PriorityQueue<T>	A PriorityQueue maintains a partial ordering of its elements such that the least element can always be found in constant time.
ProgramDriver	A driver that is used to run programs added to it
Progress	Utility to assist with generation of progress reports.
ProtoUtil
PureJavaCrc32	A pure-java implementation of the CRC32 checksum that uses the same polynomial as the built-in native CRC32.
PureJavaCrc32C	A pure-java implementation of the CRC32 checksum that uses the CRC32-C polynomial, the same polynomial used by iSCSI and implemented on many Intel chipsets supporting SSE4.2.
QuickSort	An implementation of the core algorithm of QuickSort.
ReflectionUtils	General reflection utils
RunJar	Run a Hadoop job jar.
SequentialNumber	Sequential number generator.
ServletUtil
Shell	A base class for running a Unix command.
Shell.ShellCommandExecutor	A simple shell command executor.
ShutdownHookManager	The ShutdownHookManager enables running shutdownHook in a deterministic order, higher priority first.
ShutdownThreadsHelper	Helper class to shutdown Threads and ExecutorServices.
StringInterner	Provides equivalent behavior to String.intern() to optimize performance, whereby does not consume memory in the permanent generation.
StringUtils	General string utils
ThreadUtil
Time	Utility methods for getting the time and computing intervals.
ToolRunner	A utility to help run Tools.
UTF8ByteArrayUtils
VersionInfo	This class returns build information about Hadoop components.
VersionUtil
XMLUtils	General xml utilities.
ZKUtil	Utilities for working with ZooKeeper.
ZKUtil.ZKAuthInfo	An authentication token passed to ZooKeeper.addAuthInfo

Enum Summary

Enum	Description
DataChecksum.Type	The checksum types
SignalLogger	This class logs a message whenever we're about to exit on a UNIX signal.
StringUtils.TraditionalBinaryPrefix	The traditional binary prefixes, kilo, mega, ..., exa, which can be represented by a 64-bit integer.

Exception Summary

Exception	Description
DiskChecker.DiskErrorException
DiskChecker.DiskOutOfSpaceException
ExitUtil.ExitException
ExitUtil.HaltException
Shell.ExitCodeException	This is an IOException with exit code added.
ZKUtil.BadAclFormatException
ZKUtil.BadAuthFormatException

Package org.apache.hadoop.util Description

Common utilities.