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package sf.tools.reflect;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
/**
* https://www.jianshu.com/p/ce616620e720
* 使用反射实现对unsafe的调用.
*/
public final class UnsafeWrapper {
private static Class unsafeClass;
private static Object unsafeInstance;
private static Map methodMap = new ConcurrentHashMap<>();
private static UnsafeWrapper instance = new UnsafeWrapper();
private UnsafeWrapper() {
//no instance
}
public static UnsafeWrapper getInstance() {
return instance;
}
/** ==============================================*/
/** ====================内存块操作==================*/
/** ==============================================*/
/**
* Allocates a new block of native memory, of the given size in bytes. The
* contents of the memory are uninitialized; they will generally be
* garbage. The resulting native pointer will never be zero, and will be
* aligned for all value types. Dispose of this memory by calling {@link
* #freeMemory}, or resize it with {@link #reallocateMemory}.
*
* Note: It is the resposibility of the caller to make
* sure arguments are checked before the methods are called. While
* some rudimentary checks are performed on the input, the checks
* are best effort and when performance is an overriding priority,
* as when methods of this class are optimized by the runtime
* compiler, some or all checks (if any) may be elided. Hence, the
* caller must not rely on the checks and corresponding
* exceptions!
* @throws RuntimeException if the size is negative or too large
* for the native size_t type
* @throws OutOfMemoryError if the allocation is refused by the system
* @see #getByte(long)
* @see #putByte(long, byte)
*/
public static long allocateMemory(long bytes) {
long address = 0;
try {
Method allocateMemoryMethod = getMethod("allocateMemory", long.class);
address = (long) allocateMemoryMethod.invoke(unsafeInstance(), bytes);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
return address;
}
/**
* Resizes a new block of native memory, to the given size in bytes. The
* contents of the new block past the size of the old block are
* uninitialized; they will generally be garbage. The resulting native
* pointer will be zero if and only if the requested size is zero. The
* resulting native pointer will be aligned for all value types. Dispose
* of this memory by calling {@link #freeMemory}, or resize it with {@link
* #reallocateMemory}. The address passed to this method may be null, in
* which case an allocation will be performed.
*
* Note: It is the resposibility of the caller to make
* sure arguments are checked before the methods are called. While
* some rudimentary checks are performed on the input, the checks
* are best effort and when performance is an overriding priority,
* as when methods of this class are optimized by the runtime
* compiler, some or all checks (if any) may be elided. Hence, the
* caller must not rely on the checks and corresponding
* exceptions!
* @throws RuntimeException if the size is negative or too large
* for the native size_t type
* @throws OutOfMemoryError if the allocation is refused by the system
* @see #allocateMemory
*/
public static long reallocateMemory(long address, long bytes) {
long result = 0;
try {
Method allocateMemoryMethod = getMethod("reallocateMemory", long.class, long.class);
result = (long) allocateMemoryMethod.invoke(unsafeInstance(), address, bytes);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
return result;
}
/**
* Disposes of a block of native memory, as obtained from {@link
* #allocateMemory} or {@link #reallocateMemory}. The address passed to
* this method may be null, in which case no action is taken.
*
* Note: It is the resposibility of the caller to make
* sure arguments are checked before the methods are called. While
* some rudimentary checks are performed on the input, the checks
* are best effort and when performance is an overriding priority,
* as when methods of this class are optimized by the runtime
* compiler, some or all checks (if any) may be elided. Hence, the
* caller must not rely on the checks and corresponding
* exceptions!
* @throws RuntimeException if any of the arguments is invalid
* @see #allocateMemory
*/
public static void freeMemory(long address) {
try {
Method freeMemoryMethod = getMethod("freeMemory", long.class);
freeMemoryMethod.invoke(unsafeInstance(), address);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
}
/**
* Fetches a value from a given memory address. If the address is zero, or
* does not point into a block obtained from {@link #allocateMemory}, the
* results are undefined.
* @see #allocateMemory
*/
public static byte getByte(long address) {
byte result = 0;
try {
Method allocateMemoryMethod = getMethod("getByte", long.class);
result = (byte) allocateMemoryMethod.invoke(unsafeInstance(), address);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
return result;
}
/**
* Stores a value into a given memory address. If the address is zero, or
* does not point into a block obtained from {@link #allocateMemory}, the
* results are undefined.
* @see #getByte(long)
*/
public static void putByte(long address, byte x) {
try {
Method allocateMemoryMethod = getMethod("putByte", long.class, byte.class);
allocateMemoryMethod.invoke(unsafeInstance(), address, x);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
}
/**
* 从内存中读取一个数组
* @param startAddress 内存起始地址
* @param len 要读取的数组的长度
* @return 返回从内存中读取到的数组
*/
public static byte[] readByteArray(long startAddress, int len) {
byte[] bytes = new byte[len];
long currentAddress = startAddress;
long lastAddress = startAddress + len;
while (currentAddress < lastAddress) {
int currentIndex = (int) (currentAddress - startAddress);
bytes[currentIndex] = getByte(currentAddress);
currentAddress++;
}
return bytes;
}
/**
* 把一个byte[]放到指定的内存块中
* @param startAddress 内存块的起始位置
* @param bytes 要被存放的内存
*/
public static void putByteArray(long startAddress, byte[] bytes) {
long currentAddress = startAddress;
long lastAddress = startAddress + bytes.length;
while (currentAddress < lastAddress) {
int currentIndex = (int) (currentAddress - startAddress);
putByte(currentAddress, bytes[currentIndex]);
currentAddress++;
}
}
/**
* @see #getByte(long)
*/
public static short getShort(long address) {
short result = 0;
try {
Method method = getMethod("getShort", long.class);
result = (short) method.invoke(unsafeInstance(), address);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
return result;
}
/**
* @see #putByte(long, byte)
*/
public static void putShort(long address, short x) {
try {
Method method = getMethod("putShort", long.class, short.class);
method.invoke(unsafeInstance(), address, x);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
}
/**
* @see #getByte(long)
*/
public static char getChar(long address) {
char result = 0;
try {
Method method = getMethod("getChar", long.class);
result = (char) method.invoke(unsafeInstance(), address);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
return result;
}
/**
* @see #putByte(long, byte)
*/
public static void putChar(long address, char x) {
try {
Method method = getMethod("putChar", long.class, char.class);
method.invoke(unsafeInstance(), address, x);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
}
/**
* @see #getByte(long)
*/
public static int getInt(long address) {
int result = 0;
try {
Method method = getMethod("getInt", long.class);
result = (int) method.invoke(unsafeInstance(), address);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
return result;
}
/**
* @see #putByte(long, byte)
*/
public static void putInt(long address, int x) {
try {
Method method = getMethod("putInt", long.class, int.class);
method.invoke(unsafeInstance(), address, x);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
}
/**
* @see #getByte(long)
*/
public static long getLong(long address) {
long result = 0;
try {
Method method = getMethod("getLong", long.class);
result = (long) method.invoke(unsafeInstance(), address);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
return result;
}
/**
* @see #putByte(long, byte)
*/
public static void putLong(long address, long x) {
try {
Method method = getMethod("putLong", long.class, long.class);
method.invoke(unsafeInstance(), address, x);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
}
/**
* @see #getByte(long)
*/
public static float getFloat(long address) {
float result = 0;
try {
Method method = getMethod("getFloat", long.class);
result = (float) method.invoke(unsafeInstance(), address);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
return result;
}
/**
* @see #putByte(long, byte)
*/
public static void putFloat(long address, float x) {
try {
Method method = getMethod("putFloat", long.class, float.class);
method.invoke(unsafeInstance(), address, x);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
}
/**
* @see #getByte(long)
*/
public static double getDouble(long address) {
double result = 0;
try {
Method method = getMethod("getDouble", long.class);
result = (double) method.invoke(unsafeInstance(), address);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
return result;
}
/**
* @see #putByte(long, byte)
*/
public static void putDouble(long address, double x) {
try {
Method method = getMethod("putDouble", long.class, double.class);
method.invoke(unsafeInstance(), address, x);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
}
/** ==============================================*/
/** ====================对象操作====================*/
/** ==============================================*/
/**
* Allocates an instance but does not run any constructor.
* Initializes the class if it has not yet been.
*/
public static T allocateInstance(Class klass) {
T result = null;
try {
Method allocateInstanceMethod = getMethod("allocateInstance", Class.class);
result = (T) allocateInstanceMethod.invoke(unsafeInstance(), klass);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
}
return result;
}
/**
* @see #getInt(Object, long)
*/
public static byte getByte(Object o, long offset) {
byte result = 0;
try {
Method method = getMethod("getByte", Object.class, long.class);
result = (byte) method.invoke(unsafeInstance(), o, offset);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
return result;
}
/**
* @see #putInt(Object, long, int)
*/
public static void putByte(Object o, long offset, byte x) {
try {
Method method = getMethod("putByte", Object.class, long.class, byte.class);
method.invoke(unsafeInstance(), o, offset, x);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
}
/**
* Fetches a value from a given Java variable.
* More specifically, fetches a field or array element within the given
* object {@code o} at the given offset, or (if {@code o} is null)
* from the memory address whose numerical value is the given offset.
*
* The results are undefined unless one of the following cases is true:
*
* - The offset was obtained from {@link #objectFieldOffset} on
* the {@link Field} of some Java field and the object
* referred to by {@code o} is of a class compatible with that
* field's class.
*
*
- The offset and object reference {@code o} (either null or
* non-null) were both obtained via {@link #staticFieldOffset}
* and {@link #staticFieldBase} (respectively) from the
* reflective {@link Field} representation of some Java field.
*
*
- The object referred to by {@code o} is an array, and the offset
* is an integer of the form {@code B+N*S}, where {@code N} is
* a valid index into the array, and {@code B} and {@code S} are
* the values obtained by {@link #arrayBaseOffset} and {@link
* #arrayIndexScale} (respectively) from the array's class. The value
* referred to is the {@code N}th element of the array.
*
*
*
* If one of the above cases is true, the call references a specific Java
* variable (field or array element). However, the results are undefined
* if that variable is not in fact of the type returned by this method.
*
* This method refers to a variable by means of two parameters, and so
* it provides (in effect) a double-register addressing mode
* for Java variables. When the object reference is null, this method
* uses its offset as an absolute address. This is similar in operation
* to methods such as {@link #getInt(long)}, which provide (in effect) a
* single-register addressing mode for non-Java variables.
* However, because Java variables may have a different layout in memory
* from non-Java variables, programmers should not assume that these
* two addressing modes are ever equivalent. Also, programmers should
* remember that offsets from the double-register addressing mode cannot
* be portably confused with longs used in the single-register addressing
* mode.
* @param o Java heap object in which the variable resides, if any, else
* null
* @param offset indication of where the variable resides in a Java heap
* object, if any, else a memory address locating the variable
* statically
* @return the value fetched from the indicated Java variable
* @throws RuntimeException No defined exceptions are thrown, not even
* {@link NullPointerException}
*/
public static int getInt(Object o, long offset) {
int result = 0;
try {
Method method = getMethod("getInt", Object.class, long.class);
result = (int) method.invoke(unsafeInstance(), o, offset);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
return result;
}
/**
* Stores a value into a given Java variable.
*
* The first two parameters are interpreted exactly as with
* {@link #getInt(Object, long)} to refer to a specific
* Java variable (field or array element). The given value
* is stored into that variable.
*
* The variable must be of the same type as the method
* parameter {@code x}.
* @param o Java heap object in which the variable resides, if any, else
* null
* @param offset indication of where the variable resides in a Java heap
* object, if any, else a memory address locating the variable
* statically
* @param x the value to store into the indicated Java variable
* @throws RuntimeException No defined exceptions are thrown, not even
* {@link NullPointerException}
*/
public static void putInt(Object o, long offset, int x) {
try {
Method method = getMethod("putInt", Object.class, long.class, int.class);
method.invoke(unsafeInstance(), o, offset, x);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
}
/**
* Fetches a reference value from a given Java variable.
* @see #getInt(Object, long)
*/
public static Object getObject(Object o, long offset) {
Object result = null;
try {
Method method = getMethod("getObject", Object.class, long.class);
result = method.invoke(unsafeInstance(), o, offset);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
return result;
}
/**
* Stores a reference value into a given Java variable.
*
* Unless the reference {@code x} being stored is either null
* or matches the field type, the results are undefined.
* If the reference {@code o} is non-null, card marks or
* other store barriers for that object (if the VM requires them)
* are updated.
* @see #putInt(Object, long, int)
*/
public static void putObject(Object o, long offset, Object x) {
try {
Method method = getMethod("putObject", Object.class, long.class, Object.class);
method.invoke(unsafeInstance(), o, offset, x);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
}
/**
* @see #getInt(Object, long)
*/
public static boolean getBoolean(Object o, long offset) {
boolean result = false;
try {
Method method = getMethod("getBoolean", Object.class, long.class);
result = (boolean) method.invoke(unsafeInstance(), o, offset);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
return result;
}
/**
* @see #putInt(Object, long, int)
*/
public static void putBoolean(Object o, long offset, boolean x) {
try {
Method method = getMethod("putBoolean", Object.class, long.class, boolean.class);
method.invoke(unsafeInstance(), o, offset, x);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
}
/**
* @see #getInt(Object, long)
*/
public static short getShort(Object o, long offset) {
short result = 0;
try {
Method method = getMethod("getShort", Object.class, long.class);
result = (short) method.invoke(unsafeInstance(), o, offset);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
return result;
}
/**
* @see #putInt(Object, long, int)
*/
public static void putShort(Object o, long offset, short x) {
try {
Method method = getMethod("putShort", Object.class, long.class, short.class);
method.invoke(unsafeInstance(), o, offset, x);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
}
/**
* @see #getInt(Object, long)
*/
public static char getChar(Object o, long offset) {
char result = 0;
try {
Method method = getMethod("getChar", Object.class, long.class);
result = (char) method.invoke(unsafeInstance(), o, offset);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
return result;
}
/**
* @see #putInt(Object, long, int)
*/
public static void putChar(Object o, long offset, char x) {
try {
Method method = getMethod("putChar", Object.class, long.class, char.class);
method.invoke(unsafeInstance(), o, offset, x);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
}
/**
* @see #getInt(Object, long)
*/
public static long getLong(Object o, long offset) {
long result = 0;
try {
Method method = getMethod("getLong", Object.class, long.class);
result = (long) method.invoke(unsafeInstance(), o, offset);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
return result;
}
/**
* @see #putInt(Object, long, int)
*/
public static void putLong(Object o, long offset, long x) {
try {
Method method = getMethod("putLong", Object.class, long.class, long.class);
method.invoke(unsafeInstance(), o, offset, x);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
}
/**
* @see #getInt(Object, long)
*/
public static float getFloat(Object o, long offset) {
float result = 0f;
try {
Method method = getMethod("getFloat", Object.class, long.class);
result = (float) method.invoke(unsafeInstance(), o, offset);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
return result;
}
/**
* @see #putInt(Object, long, int)
*/
public static void putFloat(Object o, long offset, float x) {
try {
Method method = getMethod("putFloat", Object.class, long.class, float.class);
method.invoke(unsafeInstance(), o, offset, x);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
}
/**
* @see #getInt(Object, long)
*/
public static double getDouble(Object o, long offset) {
double result = 0;
try {
Method method = getMethod("getDouble", Object.class, long.class);
result = (double) method.invoke(unsafeInstance(), o, offset);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
return result;
}
/**
* @see #putInt(Object, long, int)
*/
public static void putDouble(Object o, long offset, double x) {
try {
Method method = getMethod("putDouble", Object.class, long.class, double.class);
method.invoke(unsafeInstance(), o, offset, x);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
}
/** ==============================================*/
/** ================偏移量操作======================*/
/** ==============================================*/
/**
* Reports the location of a given field in the storage allocation of its
* class. Do not expect to perform any sort of arithmetic on this offset;
* it is just a cookie which is passed to the unsafe heap memory accessors.
*
*
Any given field will always have the same offset and base, and no
* two distinct fields of the same class will ever have the same offset
* and base.
*
*
As of 1.4.1, offsets for fields are represented as long values,
* although the Sun JVM does not use the most significant 32 bits.
* However, JVM implementations which store static fields at absolute
* addresses can use long offsets and null base pointers to express
* the field locations in a form usable by {@link #getInt(Object, long)}.
* Therefore, code which will be ported to such JVMs on 64-bit platforms
* must preserve all bits of static field offsets.
* @see #getInt(Object, long)
*/
public static long objectFieldOffset(Field field) {
long result = 0;
try {
Method method = getMethod("objectFieldOffset", Field.class);
result = (long) method.invoke(unsafeInstance(), field);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
return result;
}
/**
* Reports the location of a given static field, in conjunction with {@link
* #staticFieldBase}.
*
Do not expect to perform any sort of arithmetic on this offset;
* it is just a cookie which is passed to the unsafe heap memory accessors.
*
*
Any given field will always have the same offset, and no two distinct
* fields of the same class will ever have the same offset.
*
*
As of 1.4.1, offsets for fields are represented as long values,
* although the Sun JVM does not use the most significant 32 bits.
* It is hard to imagine a JVM technology which needs more than
* a few bits to encode an offset within a non-array object,
* However, for consistency with other methods in this class,
* this method reports its result as a long value.
* @see #getInt(Object, long)
*/
public static long staticFieldOffset(Field field) {
long result = 0;
try {
Method method = getMethod("staticFieldOffset", Field.class);
result = (long) method.invoke(unsafeInstance(), field);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
return result;
}
/**
* Reports the location of a given static field, in conjunction with {@link
* #staticFieldOffset}.
*
Fetch the base "Object", if any, with which static fields of the
* given class can be accessed via methods like {@link #getInt(Object,
* long)}. This value may be null. This value may refer to an object
* which is a "cookie", not guaranteed to be a real Object, and it should
* not be used in any way except as argument to the get and put routines in
* this class.
*/
public static Object staticFieldBase(Field field) {
Object result = false;
try {
Method method = getMethod("staticFieldBase", Field.class);
result = method.invoke(unsafeInstance(), field);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
return result;
}
/**
* Reports the offset of the first element in the storage allocation of a
* given array class. If {@link #arrayIndexScale} returns a non-zero value
* for the same class, you may use that scale factor, together with this
* base offset, to form new offsets to access elements of arrays of the
* given class.
* @see #getInt(Object, long)
* @see #putInt(Object, long, int)
*/
public static int arrayBaseOffset(Class arrayClass) {
int result = 0;
try {
Method method = getMethod("arrayBaseOffset", Class.class);
result = (int) method.invoke(unsafeInstance(), arrayClass);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
return result;
}
/**
* Reports the scale factor for addressing elements in the storage
* allocation of a given array class. However, arrays of "narrow" types
* will generally not work properly with accessors like {@link
* #getByte(Object, long)}, so the scale factor for such classes is reported
* as zero.
* @see #arrayBaseOffset
* @see #getInt(Object, long)
* @see #putInt(Object, long, int)
*/
public static int arrayIndexScale(Class arrayClass) {
int result = 0;
try {
Method method = getMethod("arrayIndexScale", Class.class);
result = (int) method.invoke(unsafeInstance(), arrayClass);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
return result;
}
/** ==============================================*/
/** ==================CAS操作======================*/
/** ==============================================*/
/**
* Atomically updates Java variable to {@code x} if it is currently
* holding {@code expected}.
*
*
This operation has memory semantics of a {@code volatile} read
* and write. Corresponds to C11 atomic_compare_exchange_strong.
* @return {@code true} if successful
*/
public static boolean compareAndSwapObject(Object o, long offset, Object expected, Object x) {
boolean result = false;
try {
Method method = getMethod("compareAndSwapObject", Object.class, long.class, Object.class, Object.class);
result = (boolean) method.invoke(unsafeInstance(), o, offset, expected, x);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
return result;
}
/**
* Atomically updates Java variable to {@code x} if it is currently
* holding {@code expected}.
*
*
This operation has memory semantics of a {@code volatile} read
* and write. Corresponds to C11 atomic_compare_exchange_strong.
* @return {@code true} if successful
*/
public static boolean compareAndSwapInt(Object o, long offset, int expected, int x) {
boolean result = false;
try {
Method method = getMethod("compareAndSwapInt", Object.class, long.class, int.class, int.class);
result = (boolean) method.invoke(unsafeInstance(), o, offset, expected, x);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
return result;
}
/**
* Atomically updates Java variable to {@code x} if it is currently
* holding {@code expected}.
*
*
This operation has memory semantics of a {@code volatile} read
* and write. Corresponds to C11 atomic_compare_exchange_strong.
* @return {@code true} if successful
*/
public static boolean compareAndSwapLong(Object o, long offset, long expected, long x) {
boolean result = false;
try {
Method method = getMethod("compareAndSwapLong", Object.class, long.class, long.class, long.class);
result = (boolean) method.invoke(unsafeInstance(), o, offset, expected, x);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
return result;
}
/**
* Unblocks the given thread blocked on {@code park}, or, if it is
* not blocked, causes the subsequent call to {@code park} not to
* block. Note: this operation is "unsafe" solely because the
* caller must somehow ensure that the thread has not been
* destroyed. Nothing special is usually required to ensure this
* when called from Java (in which there will ordinarily be a live
* reference to the thread) but this is not nearly-automatically
* so when calling from native code.
* @param thread the thread to unpark.
*/
public void unpark(Object thread) {
try {
Method method = getMethod("park", Object.class);
method.invoke(unsafeInstance(), thread);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
}
/**
* Blocks current thread, returning when a balancing
* {@code unpark} occurs, or a balancing {@code unpark} has
* already occurred, or the thread is interrupted, or, if not
* absolute and time is not zero, the given time nanoseconds have
* elapsed, or if absolute, the given deadline in milliseconds
* since Epoch has passed, or spuriously (i.e., returning for no
* "reason"). Note: This operation is in the Unsafe class only
* because {@code unpark} is, so it would be strange to place it
* elsewhere.
*/
public void park(boolean isAbsolute, long time) {
try {
Method method = getMethod("park", boolean.class, long.class);
method.invoke(unsafeInstance(), isAbsolute, time);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
}
}
private static void init() {
try {
unsafeClass = Class.forName("sun.misc.Unsafe");
Field theUnsafeField = unsafeClass.getDeclaredField("theUnsafe");
boolean orignialAccessible = theUnsafeField.isAccessible();
theUnsafeField.setAccessible(true);
unsafeInstance = theUnsafeField.get(null);
theUnsafeField.setAccessible(orignialAccessible);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (NoSuchFieldException e) {
throw new RuntimeException(e);
} catch (ClassNotFoundException e) {
throw new RuntimeException(e);
}
}
private static Object unsafeInstance() {
if (unsafeInstance == null) init();
return unsafeInstance;
}
private static Class unsafeClass() {
if (unsafeClass == null) init();
return unsafeClass;
}
private static Method getMethod(String name, Class... parameterTypes) throws NoSuchMethodException {
StringBuilder key = new StringBuilder();
key.append(name);
if (parameterTypes != null) {
for (Class c : parameterTypes) {
key.append(c.getName());
}
}
if (methodMap.containsKey(key)) {
return methodMap.get(key);
}
Method m = unsafeClass().getDeclaredMethod(name, parameterTypes);
if (m != null) {
methodMap.putIfAbsent(key.toString(), m);
}
return m;
}
}