net.openhft.chronicle.core

Class OS

java.lang.Object

net.openhft.chronicle.core.OS

public final class OS
extends Object

Low level access to OS class.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	OS.Unmapper

Field Summary

Fields

Modifier and Type	Field and Description
static int	SAFE_PAGE_SIZE
static String	TARGET Deprecated.
static Exception	TIME_LIMIT
static String	TMP
static String	USER_DIR
static String	USER_HOME

Method Summary

Modifier and Type	Method and Description
static @NotNull String	findDir(@NotNull String suffix)
static @NotNull File	findFile(String... path) Search a list of directories to find a path which is the last element.
static String	getHostName()
static long	getPidMax()
static int	getProcessId()
static String	getTarget()
static String	getUserName()
static boolean	is64Bit()
static boolean	isLinux()
static boolean	isMacOSX()
static boolean	isWindows() This may or may not be the OS thread id, but should be unique across processes
static long	map(@NotNull FileChannel fileChannel, FileChannel.MapMode mode, long start, long size) Map a region of a file into memory.
static long	mapAlign(long offset) Align an offset of a memory mapping in file based on OS.
static long	mapAlignment() Returns the alignment of offsets in file, from which memory mapping could start, based on OS.
static @NotNull Memory	memory()
static long	memoryMapped()
static long	pageAlign(long size) Align the size to page boundary
static int	pageSize()
static int	read0(FileDescriptor fd, long address, int len)
static long	spaceUsed(@NotNull String filename) Get the space actually used by a file.
static void	unmap(long address, long size) Unmap a region of memory.
static String	userDir()
static int	write0(FileDescriptor fd, long address, int len)

Methods inherited from class java.lang.Object

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

Field Detail

TMP

public static final String TMP

USER_DIR

public static final String USER_DIR

USER_HOME

public static final String USER_HOME

TIME_LIMIT

public static final Exception TIME_LIMIT

TARGET

@Deprecated
public static final String TARGET

Deprecated.

SAFE_PAGE_SIZE

public static final int SAFE_PAGE_SIZE

See Also:

Constant Field Values

Method Detail

findDir

@NotNull
public static @NotNull String findDir(@NotNull
                                               @NotNull String suffix)
                                        throws FileNotFoundException

Throws:

FileNotFoundException

findFile

@NotNull
public static @NotNull File findFile(@NotNull
                                              String... path)

Search a list of directories to find a path which is the last element.

Parameters:

path - of directories to use if found, the last path is always appended.

Returns:

the resulting File path.

getHostName

public static String getHostName()

getUserName

public static String getUserName()

getTarget

public static String getTarget()

memory

@NotNull
public static @NotNull Memory memory()

Returns:

native memory accessor class

pageAlign

public static long pageAlign(long size)

Align the size to page boundary

Parameters:

size - the size to align

Returns:

aligned size

See Also:

pageSize()

pageSize

public static int pageSize()

Returns:

size of pages

See Also:

pageAlign(long)

mapAlign

public static long mapAlign(long offset)

Align an offset of a memory mapping in file based on OS.

Parameters:

offset - to align

Returns:

offset aligned

See Also:

mapAlignment()

mapAlignment

public static long mapAlignment()

Returns the alignment of offsets in file, from which memory mapping could start, based on OS.

Returns:

granularity of an offset in a file

See Also:

mapAlign(long)

is64Bit

public static boolean is64Bit()

Returns:

is the JVM 64-bit

getProcessId

public static int getProcessId()

isWindows

public static boolean isWindows()

This may or may not be the OS thread id, but should be unique across processes

Returns:

a unique tid of up to 48 bits.

isMacOSX

public static boolean isMacOSX()

isLinux

public static boolean isLinux()

getPidMax

public static long getPidMax()

Returns:

the maximum PID.

Throws:

NumberFormatException - if ?

AssertionError - if ?

map

public static long map(@NotNull
                       @NotNull FileChannel fileChannel,
                       FileChannel.MapMode mode,
                       long start,
                       long size)
                throws IOException,
                       IllegalArgumentException

Map a region of a file into memory.

Parameters:

fileChannel - to map

mode - of access

start - offset within a file

size - of region to map.

Returns:

the address of the memory mapping.

Throws:

IOException - if the mapping fails

IllegalArgumentException - if the arguments are not valid

unmap

public static void unmap(long address,
                         long size)
                  throws IOException

Unmap a region of memory.

Parameters:

address - of the start of the mapping.

size - of the region mapped.

Throws:

IOException - if the unmap fails.

memoryMapped

public static long memoryMapped()

spaceUsed

public static long spaceUsed(@NotNull
                             @NotNull String filename)

Get the space actually used by a file.

Parameters:

filename - to get the actual size of

Returns:

size in bytes.

userDir

public static String userDir()

read0

public static int read0(FileDescriptor fd,
                        long address,
                        int len)
                 throws IOException

Throws:

IOException

write0

public static int write0(FileDescriptor fd,
                         long address,
                         int len)
                  throws IOException

Throws:

IOException