io.netty.util.internal

类 PlatformDependent

java.lang.Object

io.netty.util.internal.PlatformDependent

public final class PlatformDependent
extends java.lang.Object

Utility that detects various properties specific to the current runtime environment, such as Java version and the availability of the sun.misc.Unsafe object.

You can disable the use of sun.misc.Unsafe if you specify the system property io.netty.noUnsafe.

字段概要

字段

限定符和类型	字段和说明
static boolean	BIG_ENDIAN_NATIVE_ORDER

方法概要

限定符和类型	方法和说明
static int	addressSize() Return the address size of the OS. 4 (for 32 bits systems ) and 8 (for 64 bits systems).
static long	align(long value, int alignment)
static java.nio.ByteBuffer	alignDirectBuffer(java.nio.ByteBuffer buffer, int alignment)
static java.nio.ByteBuffer	allocateDirectNoCleaner(int capacity) Allocate a new ByteBuffer with the given capacity.
static long	allocateMemory(long size)
static byte[]	allocateUninitializedArray(int size)
static int	bitMode() Returns the bit mode of the current VM (usually 32 or 64.)
static long	byteArrayBaseOffset()
static boolean	canEnableTcpNoDelayByDefault() Returns true if and only if it is fine to enable TCP_NODELAY socket option by default.
static void	copyMemory(byte[] src, int srcIndex, byte[] dst, int dstIndex, long length)
static void	copyMemory(byte[] src, int srcIndex, long dstAddr, long length)
static void	copyMemory(long srcAddr, byte[] dst, int dstIndex, long length)
static void	copyMemory(long srcAddr, long dstAddr, long length)
static java.io.File	createTempFile(java.lang.String prefix, java.lang.String suffix, java.io.File directory)
static java.nio.ByteBuffer	directBuffer(long memoryAddress, int size)
static long	directBufferAddress(java.nio.ByteBuffer buffer)
static boolean	directBufferPreferred() Returns true if the platform has reliable low-level direct buffer access API and a user has not specified -Dio.netty.noPreferDirect option.
static boolean	equals(byte[] bytes1, int startPos1, byte[] bytes2, int startPos2, int length) Compare two byte arrays for equality.
static int	equalsConstantTime(byte[] bytes1, int startPos1, byte[] bytes2, int startPos2, int length) Compare two byte arrays for equality without leaking timing information.
static long	estimateMaxDirectMemory() Compute an estimate of the maximum amount of direct memory available to this JVM.
static void	freeDirectBuffer(java.nio.ByteBuffer buffer) Try to deallocate the specified direct ByteBuffer.
static void	freeDirectNoCleaner(java.nio.ByteBuffer buffer) This method MUST only be called for ByteBuffers that were allocated via allocateDirectNoCleaner(int).
static void	freeMemory(long address)
static byte	getByte(byte[] data, int index)
static byte	getByte(byte[] data, long index)
static byte	getByte(long address)
static java.lang.ClassLoader	getClassLoader(java.lang.Class<?> clazz) Return the ClassLoader for the given Class.
static java.lang.ClassLoader	getContextClassLoader() Return the context ClassLoader for the current Thread.
static int	getInt(byte[] data, int index)
static int	getInt(int[] data, long index)
static int	getInt(long address)
static int	getInt(java.lang.Object object, long fieldOffset)
static int	getIntVolatile(long address)
static long	getLong(byte[] data, int index)
static long	getLong(long address)
static long	getLong(long[] data, long index)
static java.lang.Object	getObject(java.lang.Object object, long fieldOffset)
static short	getShort(byte[] data, int index)
static short	getShort(long address)
static java.lang.ClassLoader	getSystemClassLoader() Return the system ClassLoader.
static java.lang.Throwable	getUnsafeUnavailabilityCause() Return the reason (if any) why sun.misc.Unsafe was not available.
static boolean	hasAlignDirectByteBuffer()
static boolean	hasDirectBufferNoCleanerConstructor()
static int	hashCodeAscii(byte[] bytes, int startPos, int length) Calculate a hash code of a byte array assuming ASCII character encoding.
static int	hashCodeAscii(java.lang.CharSequence bytes) Calculate a hash code of a byte array assuming ASCII character encoding.
static boolean	hasUnsafe() Return true if sun.misc.Unsafe was found on the classpath and can be used for accelerated direct memory access.
static boolean	isAndroid() Returns true if and only if the current platform is Android
static boolean	isIkvmDotNet() Returns true if the running JVM is IKVM.NET, false otherwise.
static boolean	isJ9Jvm() Returns true if the running JVM is either IBM J9 or Eclipse OpenJ9, false otherwise.
static boolean	isOsx() Return true if the JVM is running on OSX / MacOS
static boolean	isUnaligned() true if and only if the platform supports unaligned access.
static boolean	isWindows() Return true if the JVM is running on Windows
static boolean	isZero(byte[] bytes, int startPos, int length) Determine if a subsection of an array is zero.
static int	javaVersion() Return the version of Java under which this library is used.
static long	maxDirectMemory() Returns the maximum memory reserved for direct buffer allocation.
static boolean	maybeSuperUser() Return true if the current user may be a super-user.
static <C> java.util.Deque<C>	newConcurrentDeque() Returns a new concurrent Deque.
static <K,V> java.util.concurrent.ConcurrentMap<K,V>	newConcurrentHashMap() Creates a new fastest ConcurrentMap implementation for the current platform.
static <K,V> java.util.concurrent.ConcurrentMap<K,V>	newConcurrentHashMap(int initialCapacity) Creates a new fastest ConcurrentMap implementation for the current platform.
static <K,V> java.util.concurrent.ConcurrentMap<K,V>	newConcurrentHashMap(int initialCapacity, float loadFactor) Creates a new fastest ConcurrentMap implementation for the current platform.
static <K,V> java.util.concurrent.ConcurrentMap<K,V>	newConcurrentHashMap(int initialCapacity, float loadFactor, int concurrencyLevel) Creates a new fastest ConcurrentMap implementation for the current platform.
static <K,V> java.util.concurrent.ConcurrentMap<K,V>	newConcurrentHashMap(java.util.Map<? extends K,? extends V> map) Creates a new fastest ConcurrentMap implementation for the current platform.
static <T> java.util.Queue<T>	newFixedMpscQueue(int capacity) Create a new Queue which is safe to use for multiple producers (different threads) and a single consumer (one thread!)
static LongCounter	newLongCounter() Creates a new fastest LongCounter implementation for the current platform.
static <T> java.util.Queue<T>	newMpscQueue() Create a new Queue which is safe to use for multiple producers (different threads) and a single consumer (one thread!).
static <T> java.util.Queue<T>	newMpscQueue(int maxCapacity) Create a new Queue which is safe to use for multiple producers (different threads) and a single consumer (one thread!).
static <T> java.util.Queue<T>	newMpscQueue(int chunkSize, int maxCapacity) Create a new Queue which is safe to use for multiple producers (different threads) and a single consumer (one thread!).
static <T> java.util.Queue<T>	newSpscQueue() Create a new Queue which is safe to use for single producer (one thread!)
static java.lang.String	normalizedArch()
static java.util.Set<java.lang.String>	normalizedLinuxClassifiers()
static java.lang.String	normalizedOs()
static long	objectFieldOffset(java.lang.reflect.Field field)
static void	putByte(byte[] data, int index, byte value)
static void	putByte(long address, byte value)
static void	putByte(java.lang.Object data, long offset, byte value)
static void	putInt(byte[] data, int index, int value)
static void	putInt(long address, int value)
static void	putIntOrdered(long adddress, int newValue)
static void	putLong(byte[] data, int index, long value)
static void	putLong(long address, long value)
static void	putObject(java.lang.Object o, long offset, java.lang.Object x)
static void	putShort(byte[] data, int index, short value)
static void	putShort(long address, short value)
static java.nio.ByteBuffer	reallocateDirectNoCleaner(java.nio.ByteBuffer buffer, int capacity) Reallocate a new ByteBuffer with the given capacity.
static long	reallocateMemory(long address, long newSize)
static void	setMemory(byte[] dst, int dstIndex, long bytes, byte value)
static void	setMemory(long address, long bytes, byte value)
static java.util.Random	threadLocalRandom() Return a Random which is not-threadsafe and so can only be used from the same thread.
static void	throwException(java.lang.Throwable t) Raises an exception bypassing compiler checks for checked exceptions.
static java.io.File	tmpdir() Returns the temporary directory.
static long	usedDirectMemory() Returns the current memory reserved for direct buffer allocation.
static boolean	useDirectBufferNoCleaner()

从类继承的方法 java.lang.Object

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

字段详细资料

BIG_ENDIAN_NATIVE_ORDER

public static final boolean BIG_ENDIAN_NATIVE_ORDER

方法详细资料

byteArrayBaseOffset

public static long byteArrayBaseOffset()

hasDirectBufferNoCleanerConstructor

public static boolean hasDirectBufferNoCleanerConstructor()

allocateUninitializedArray

public static byte[] allocateUninitializedArray(int size)

isAndroid

public static boolean isAndroid()

Returns true if and only if the current platform is Android

isWindows

public static boolean isWindows()

Return true if the JVM is running on Windows

isOsx

public static boolean isOsx()

Return true if the JVM is running on OSX / MacOS

maybeSuperUser

public static boolean maybeSuperUser()

Return true if the current user may be a super-user. Be aware that this is just an hint and so it may return false-positives.

javaVersion

public static int javaVersion()

Return the version of Java under which this library is used.

canEnableTcpNoDelayByDefault

public static boolean canEnableTcpNoDelayByDefault()

Returns true if and only if it is fine to enable TCP_NODELAY socket option by default.

hasUnsafe

public static boolean hasUnsafe()

Return true if sun.misc.Unsafe was found on the classpath and can be used for accelerated direct memory access.

getUnsafeUnavailabilityCause

public static java.lang.Throwable getUnsafeUnavailabilityCause()

Return the reason (if any) why sun.misc.Unsafe was not available.

isUnaligned

public static boolean isUnaligned()

true if and only if the platform supports unaligned access.

另请参阅:

Wikipedia on segfault

directBufferPreferred

public static boolean directBufferPreferred()

Returns true if the platform has reliable low-level direct buffer access API and a user has not specified -Dio.netty.noPreferDirect option.

maxDirectMemory

public static long maxDirectMemory()

Returns the maximum memory reserved for direct buffer allocation.

usedDirectMemory

public static long usedDirectMemory()

Returns the current memory reserved for direct buffer allocation. This method returns -1 in case that a value is not available.

另请参阅:

maxDirectMemory()

tmpdir

public static java.io.File tmpdir()

Returns the temporary directory.

bitMode

public static int bitMode()

Returns the bit mode of the current VM (usually 32 or 64.)

addressSize

public static int addressSize()

Return the address size of the OS. 4 (for 32 bits systems ) and 8 (for 64 bits systems).

allocateMemory

public static long allocateMemory(long size)

freeMemory

public static void freeMemory(long address)

reallocateMemory

public static long reallocateMemory(long address,
                                    long newSize)

throwException

public static void throwException(java.lang.Throwable t)

Raises an exception bypassing compiler checks for checked exceptions.

newConcurrentHashMap

public static <K,V> java.util.concurrent.ConcurrentMap<K,V> newConcurrentHashMap()

Creates a new fastest ConcurrentMap implementation for the current platform.

newLongCounter

public static LongCounter newLongCounter()

Creates a new fastest LongCounter implementation for the current platform.

newConcurrentHashMap

public static <K,V> java.util.concurrent.ConcurrentMap<K,V> newConcurrentHashMap(int initialCapacity)

Creates a new fastest ConcurrentMap implementation for the current platform.

newConcurrentHashMap

public static <K,V> java.util.concurrent.ConcurrentMap<K,V> newConcurrentHashMap(int initialCapacity,
                                                                                 float loadFactor)

Creates a new fastest ConcurrentMap implementation for the current platform.

newConcurrentHashMap

public static <K,V> java.util.concurrent.ConcurrentMap<K,V> newConcurrentHashMap(int initialCapacity,
                                                                                 float loadFactor,
                                                                                 int concurrencyLevel)

Creates a new fastest ConcurrentMap implementation for the current platform.

newConcurrentHashMap

public static <K,V> java.util.concurrent.ConcurrentMap<K,V> newConcurrentHashMap(java.util.Map<? extends K,? extends V> map)

Creates a new fastest ConcurrentMap implementation for the current platform.

freeDirectBuffer

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

Try to deallocate the specified direct ByteBuffer. Please note this method does nothing if the current platform does not support this operation or the specified buffer is not a direct buffer.

directBufferAddress

public static long directBufferAddress(java.nio.ByteBuffer buffer)

directBuffer

public static java.nio.ByteBuffer directBuffer(long memoryAddress,
                                               int size)

getObject

public static java.lang.Object getObject(java.lang.Object object,
                                         long fieldOffset)

getInt

public static int getInt(java.lang.Object object,
                         long fieldOffset)

getIntVolatile

public static int getIntVolatile(long address)

putIntOrdered

public static void putIntOrdered(long adddress,
                                 int newValue)

getByte

public static byte getByte(long address)

getShort

public static short getShort(long address)

getInt

public static int getInt(long address)

getLong

public static long getLong(long address)

getByte

public static byte getByte(byte[] data,
                           int index)

getByte

public static byte getByte(byte[] data,
                           long index)

getShort

public static short getShort(byte[] data,
                             int index)

getInt

public static int getInt(byte[] data,
                         int index)

getInt

public static int getInt(int[] data,
                         long index)

getLong

public static long getLong(byte[] data,
                           int index)

getLong

public static long getLong(long[] data,
                           long index)

putByte

public static void putByte(long address,
                           byte value)

putShort

public static void putShort(long address,
                            short value)

putInt

public static void putInt(long address,
                          int value)

putLong

public static void putLong(long address,
                           long value)

putByte

public static void putByte(byte[] data,
                           int index,
                           byte value)

putByte

public static void putByte(java.lang.Object data,
                           long offset,
                           byte value)

putShort

public static void putShort(byte[] data,
                            int index,
                            short value)

putInt

public static void putInt(byte[] data,
                          int index,
                          int value)

putLong

public static void putLong(byte[] data,
                           int index,
                           long value)

putObject

public static void putObject(java.lang.Object o,
                             long offset,
                             java.lang.Object x)

objectFieldOffset

public static long objectFieldOffset(java.lang.reflect.Field field)

copyMemory

public static void copyMemory(long srcAddr,
                              long dstAddr,
                              long length)

copyMemory

public static void copyMemory(byte[] src,
                              int srcIndex,
                              long dstAddr,
                              long length)

copyMemory

public static void copyMemory(byte[] src,
                              int srcIndex,
                              byte[] dst,
                              int dstIndex,
                              long length)

copyMemory

public static void copyMemory(long srcAddr,
                              byte[] dst,
                              int dstIndex,
                              long length)

setMemory

public static void setMemory(byte[] dst,
                             int dstIndex,
                             long bytes,
                             byte value)

setMemory

public static void setMemory(long address,
                             long bytes,
                             byte value)

allocateDirectNoCleaner

public static java.nio.ByteBuffer allocateDirectNoCleaner(int capacity)

Allocate a new ByteBuffer with the given capacity. ByteBuffers allocated with this method MUST be deallocated via freeDirectNoCleaner(ByteBuffer).

reallocateDirectNoCleaner

public static java.nio.ByteBuffer reallocateDirectNoCleaner(java.nio.ByteBuffer buffer,
                                                            int capacity)

Reallocate a new ByteBuffer with the given capacity. ByteBuffers reallocated with this method MUST be deallocated via freeDirectNoCleaner(ByteBuffer).

freeDirectNoCleaner

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

This method MUST only be called for ByteBuffers that were allocated via allocateDirectNoCleaner(int).

hasAlignDirectByteBuffer

public static boolean hasAlignDirectByteBuffer()

alignDirectBuffer

public static java.nio.ByteBuffer alignDirectBuffer(java.nio.ByteBuffer buffer,
                                                    int alignment)

align

public static long align(long value,
                         int alignment)

useDirectBufferNoCleaner

public static boolean useDirectBufferNoCleaner()

equals

public static boolean equals(byte[] bytes1,
                             int startPos1,
                             byte[] bytes2,
                             int startPos2,
                             int length)

Compare two byte arrays for equality. For performance reasons no bounds checking on the parameters is performed.

参数:

bytes1 - the first byte array.

startPos1 - the position (inclusive) to start comparing in bytes1.

bytes2 - the second byte array.

startPos2 - the position (inclusive) to start comparing in bytes2.

length - the amount of bytes to compare. This is assumed to be validated as not going out of bounds by the caller.

isZero

public static boolean isZero(byte[] bytes,
                             int startPos,
                             int length)

Determine if a subsection of an array is zero.

参数:

bytes - The byte array.

startPos - The starting index (inclusive) in bytes.

length - The amount of bytes to check for zero.

返回:

false if bytes[startPos:startsPos+length) contains a value other than zero.

equalsConstantTime

public static int equalsConstantTime(byte[] bytes1,
                                     int startPos1,
                                     byte[] bytes2,
                                     int startPos2,
                                     int length)

Compare two byte arrays for equality without leaking timing information. For performance reasons no bounds checking on the parameters is performed.

The int return type is intentional and is designed to allow cascading of constant time operations:

     byte[] s1 = new {1, 2, 3};
     byte[] s2 = new {1, 2, 3};
     byte[] s3 = new {1, 2, 3};
     byte[] s4 = new {4, 5, 6};
     boolean equals = (equalsConstantTime(s1, 0, s2, 0, s1.length) &
                       equalsConstantTime(s3, 0, s4, 0, s3.length)) != 0;
 

参数:

bytes1 - the first byte array.

startPos1 - the position (inclusive) to start comparing in bytes1.

bytes2 - the second byte array.

startPos2 - the position (inclusive) to start comparing in bytes2.

length - the amount of bytes to compare. This is assumed to be validated as not going out of bounds by the caller.

返回:

0 if not equal. 1 if equal.

hashCodeAscii

public static int hashCodeAscii(byte[] bytes,
                                int startPos,
                                int length)

Calculate a hash code of a byte array assuming ASCII character encoding. The resulting hash code will be case insensitive.

参数:

bytes - The array which contains the data to hash.

startPos - What index to start generating a hash code in bytes

length - The amount of bytes that should be accounted for in the computation.

返回:

The hash code of bytes assuming ASCII character encoding. The resulting hash code will be case insensitive.

hashCodeAscii

public static int hashCodeAscii(java.lang.CharSequence bytes)

Calculate a hash code of a byte array assuming ASCII character encoding. The resulting hash code will be case insensitive.

This method assumes that bytes is equivalent to a byte[] but just using CharSequence for storage. The upper most byte of each char from bytes is ignored.

参数:

bytes - The array which contains the data to hash (assumed to be equivalent to a byte[]).

返回:

The hash code of bytes assuming ASCII character encoding. The resulting hash code will be case insensitive.

newMpscQueue

public static <T> java.util.Queue<T> newMpscQueue()

Create a new Queue which is safe to use for multiple producers (different threads) and a single consumer (one thread!).

返回:

A MPSC queue which may be unbounded.

newMpscQueue

public static <T> java.util.Queue<T> newMpscQueue(int maxCapacity)

Create a new Queue which is safe to use for multiple producers (different threads) and a single consumer (one thread!).

newMpscQueue

public static <T> java.util.Queue<T> newMpscQueue(int chunkSize,
                                                  int maxCapacity)

Create a new Queue which is safe to use for multiple producers (different threads) and a single consumer (one thread!). The queue will grow and shrink its capacity in units of the given chunk size.

newSpscQueue

public static <T> java.util.Queue<T> newSpscQueue()

Create a new Queue which is safe to use for single producer (one thread!) and a single consumer (one thread!).

newFixedMpscQueue

public static <T> java.util.Queue<T> newFixedMpscQueue(int capacity)

Create a new Queue which is safe to use for multiple producers (different threads) and a single consumer (one thread!) with the given fixes capacity.

getClassLoader

public static java.lang.ClassLoader getClassLoader(java.lang.Class<?> clazz)

Return the ClassLoader for the given Class.

getContextClassLoader

public static java.lang.ClassLoader getContextClassLoader()

Return the context ClassLoader for the current Thread.

getSystemClassLoader

public static java.lang.ClassLoader getSystemClassLoader()

Return the system ClassLoader.

newConcurrentDeque

public static <C> java.util.Deque<C> newConcurrentDeque()

Returns a new concurrent Deque.

threadLocalRandom

public static java.util.Random threadLocalRandom()

Return a Random which is not-threadsafe and so can only be used from the same thread.

isJ9Jvm

public static boolean isJ9Jvm()

Returns true if the running JVM is either IBM J9 or Eclipse OpenJ9, false otherwise.

isIkvmDotNet

public static boolean isIkvmDotNet()

Returns true if the running JVM is IKVM.NET, false otherwise.

estimateMaxDirectMemory

public static long estimateMaxDirectMemory()

Compute an estimate of the maximum amount of direct memory available to this JVM.

The computation is not cached, so you probably want to use maxDirectMemory() instead.

This will produce debug log output when called.

返回:

The estimated max direct memory, in bytes.

normalizedArch

public static java.lang.String normalizedArch()

normalizedOs

public static java.lang.String normalizedOs()

normalizedLinuxClassifiers

public static java.util.Set<java.lang.String> normalizedLinuxClassifiers()

createTempFile

public static java.io.File createTempFile(java.lang.String prefix,
                                          java.lang.String suffix,
                                          java.io.File directory)
                                   throws java.io.IOException

抛出:

java.io.IOException