org.agrona

Class IoUtil

java.lang.Object

org.agrona.IoUtil

public class IoUtil
extends java.lang.Object

Collection of IO utilities.

Field Summary

Fields

Modifier and Type	Field and Description
static int	BLOCK_SIZE Size in bytes of a file page.

Constructor Summary

Constructors

Constructor and Description
IoUtil()

Method Summary

Modifier and Type	Method and Description
static void	checkFileExists(java.io.File file, java.lang.String name) Check that a file exists and throw an exception if not.
static java.nio.channels.FileChannel	createEmptyFile(java.io.File file, long length) Create an empty file, fill with 0s, and return the FileChannel
static void	delete(java.io.File file, boolean ignoreFailures) Recursively delete a file or directory tree.
static void	deleteIfExists(java.io.File file) Delete file only if it already exists.
static void	ensureDirectoryExists(java.io.File directory, java.lang.String descriptionLabel) Create a directory if it doesn't already exist.
static void	ensureDirectoryIsRecreated(java.io.File directory, java.lang.String descriptionLabel, java.util.function.BiConsumer<java.lang.String,java.lang.String> callback) Create a directory, removing previous directory if it already exists.
static void	fill(java.nio.channels.FileChannel fileChannel, long position, long length, byte value) Fill a region of a file with a given byte value.
static long	map(java.nio.channels.FileChannel fileChannel, java.nio.channels.FileChannel.MapMode mode, long offset, long length) Map a range of a file and return the address at which the range begins.
static java.nio.MappedByteBuffer	mapExistingFile(java.io.File location, java.lang.String descriptionLabel) Check that file exists, open file, and return MappedByteBuffer for entire file
static java.nio.MappedByteBuffer	mapExistingFile(java.io.File location, java.lang.String descriptionLabel, long offset, long size) Check that file exists, open file, and return MappedByteBuffer for only region specified
static java.nio.MappedByteBuffer	mapNewFile(java.io.File location, long size) Create a new file, fill with 0s, and return a MappedByteBuffer for the file
static java.lang.String	tmpDirName() Return the system property for java.io.tmpdir ensuring a File.separator is at the end.
static void	unmap(java.nio.ByteBuffer buffer) Unmap a ByteBuffer without waiting for the next GC cycle if its memory mapped.
static void	unmap(java.nio.channels.FileChannel fileChannel, long address, long length) Unmap a region of a file.
static void	unmap(java.nio.MappedByteBuffer buffer) Unmap a MappedByteBuffer without waiting for the next GC cycle.

Methods inherited from class java.lang.Object

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

Field Detail

BLOCK_SIZE

public static final int BLOCK_SIZE

Size in bytes of a file page.

See Also:

Constant Field Values

Constructor Detail

IoUtil

public IoUtil()

Method Detail

fill

public static void fill(java.nio.channels.FileChannel fileChannel,
                        long position,
                        long length,
                        byte value)

Fill a region of a file with a given byte value.

Parameters:

fileChannel - to fill

position - at which to start writing.

length - of the region to write.

value - to fill the region with.

delete

public static void delete(java.io.File file,
                          boolean ignoreFailures)

Recursively delete a file or directory tree.

Parameters:

file - to be deleted.

ignoreFailures - don't throw an exception if a delete fails.

ensureDirectoryExists

public static void ensureDirectoryExists(java.io.File directory,
                                         java.lang.String descriptionLabel)

Create a directory if it doesn't already exist.

Parameters:

directory - the directory which definitely exists after this method call.

descriptionLabel - to associate with the directory for any exceptions.

ensureDirectoryIsRecreated

public static void ensureDirectoryIsRecreated(java.io.File directory,
                                              java.lang.String descriptionLabel,
                                              java.util.function.BiConsumer<java.lang.String,java.lang.String> callback)

Create a directory, removing previous directory if it already exists.

Call callback if it does exist.

Parameters:

directory - the directory which definitely exists after this method call.

descriptionLabel - to associate with the directory for any exceptions and callback.

callback - to call if directory exists passing back absolute path and descriptionLabel.

deleteIfExists

public static void deleteIfExists(java.io.File file)

Delete file only if it already exists.

Parameters:

file - to delete

createEmptyFile

public static java.nio.channels.FileChannel createEmptyFile(java.io.File file,
                                                            long length)

Create an empty file, fill with 0s, and return the FileChannel

Parameters:

file - to create

length - of the file to create

Returns:

FileChannel for the file

mapExistingFile

public static java.nio.MappedByteBuffer mapExistingFile(java.io.File location,
                                                        java.lang.String descriptionLabel)

Check that file exists, open file, and return MappedByteBuffer for entire file

The file itself will be closed, but the mapping will persist.

Parameters:

location - of the file to map

descriptionLabel - to be associated for any exceptions

Returns:

MappedByteBuffer for the file

mapExistingFile

public static java.nio.MappedByteBuffer mapExistingFile(java.io.File location,
                                                        java.lang.String descriptionLabel,
                                                        long offset,
                                                        long size)

Check that file exists, open file, and return MappedByteBuffer for only region specified

The file itself will be closed, but the mapping will persist.

Parameters:

location - of the file to map

descriptionLabel - to be associated for an exceptions

offset - offset to start mapping at

size - length to map region

Returns:

MappedByteBuffer for the file

mapNewFile

public static java.nio.MappedByteBuffer mapNewFile(java.io.File location,
                                                   long size)

Create a new file, fill with 0s, and return a MappedByteBuffer for the file

The file itself will be closed, but the mapping will persist.

Parameters:

location - of the file to create and map

size - of the file to create and map

Returns:

MappedByteBuffer for the file

checkFileExists

public static void checkFileExists(java.io.File file,
                                   java.lang.String name)

Check that a file exists and throw an exception if not.

Parameters:

file - to check existence of.

name - to associate for the exception

unmap

public static void unmap(java.nio.MappedByteBuffer buffer)

Unmap a MappedByteBuffer without waiting for the next GC cycle.

Parameters:

buffer - to be unmapped.

map

public static long map(java.nio.channels.FileChannel fileChannel,
                       java.nio.channels.FileChannel.MapMode mode,
                       long offset,
                       long length)

Map a range of a file and return the address at which the range begins.

Parameters:

fileChannel - to be mapped.

mode - for the mapped region.

offset - within the file the mapped region should start.

length - of the mapped region.

Returns:

the address at which the mapping starts.

unmap

public static void unmap(java.nio.channels.FileChannel fileChannel,
                         long address,
                         long length)

Unmap a region of a file.

Parameters:

fileChannel - which has been mapped.

address - at which the mapping begins.

length - of the mapped region.

unmap

public static void unmap(java.nio.ByteBuffer buffer)

Unmap a ByteBuffer without waiting for the next GC cycle if its memory mapped.

Parameters:

buffer - to be unmapped.

tmpDirName

public static java.lang.String tmpDirName()

Return the system property for java.io.tmpdir ensuring a File.separator is at the end.

Returns:

tmp directory for the runtime