net.openhft.chronicle.hash.hashing

Interface Access<T>

Type Parameters:

T - the type of the object to access

public interface Access<T>

Strategy of reading bytes, defines the abstraction of T class instances as ordered byte sequence. All getXXX(input, offset) should be consistent to each other in terms of ordered byte sequence each T instance represents. For example, if some Access implementation returns ByteOrder.LITTLE_ENDIAN on byteOrder(input) call, the following expressions should always have the same value:

• getLong(input, 0)
• getUnsignedInt(input, 0) | (getUnsignedInt(input, 4) << 32)

• getUnsignedInt(input, 0) |
      ((long) getUnsignedShort(input, 4) << 32) |
      ((long) getUnsignedByte(input, 6) << 48) |
      ((long) getUnsignedByte(input, 7) << 56)

• And so on

getXXX(input, offset) methods could throw unchecked exceptions when requested bytes range is outside of the bounds of the byte sequence, represented by the given input. However, they could omit checks for better performance.

Access API is designed for inputs, that actually represent byte sequences that lay continuously in memory. Theoretically Access strategy could be implemented for non-continuous byte sequences, or abstractions which aren't actually present in memory as they are accessed, but this should be awkward, and hashing using such Access is expected to be slow.

Method Summary

Methods

Modifier and Type	Method and Description
ByteOrder	byteOrder(T input) The byte order in which all multi-byte getXXX() reads from the given input are performed.
int	getByte(T input, long offset) Reads a single byte at the given offset in the byte sequence represented by the given input, returned widened to int.
int	getInt(T input, long offset) Reads [offset, offset + 3] bytes of the byte sequence represented by the given input as a single int value.
long	getLong(T input, long offset) Reads [offset, offset + 7] bytes of the byte sequence represented by the given input as a single long value.
int	getShort(T input, long offset) Reads [offset, offset + 1] bytes of the byte sequence represented by the given input as a single short value, returned widened to int.
int	getUnsignedByte(T input, long offset) Shortcut for getByte(input, offset) & 0xFF.
long	getUnsignedInt(T input, long offset) Shortcut for getInt(input, offset) & 0xFFFFFFFFL.
int	getUnsignedShort(T input, long offset) Shortcut for getShort(input, offset) & 0xFFFF.

Method Detail

getLong

long getLong(T input,
           long offset)

Reads [offset, offset + 7] bytes of the byte sequence represented by the given input as a single long value.

Parameters:

input - the object to access

offset - offset to the first byte to read within the byte sequence represented by the given object

Returns:

eight bytes as a long value, in the expected order

getUnsignedInt

long getUnsignedInt(T input,
                  long offset)

Shortcut for getInt(input, offset) & 0xFFFFFFFFL. Could be implemented more efficiently.

Parameters:

input - the object to access

offset - offset to the first byte to read within the byte sequence represented by the given object

Returns:

four bytes as an unsigned int value, in the expected order

getInt

int getInt(T input,
         long offset)

Reads [offset, offset + 3] bytes of the byte sequence represented by the given input as a single int value.

Parameters:

input - the object to access

offset - offset to the first byte to read within the byte sequence represented by the given object

Returns:

four bytes as an int value, in the expected order

getUnsignedShort

int getUnsignedShort(T input,
                   long offset)

Shortcut for getShort(input, offset) & 0xFFFF. Could be implemented more efficiently.

Parameters:

input - the object to access

offset - offset to the first byte to read within the byte sequence represented by the given object

Returns:

two bytes as an unsigned short value, in the expected order

getShort

int getShort(T input,
           long offset)

Reads [offset, offset + 1] bytes of the byte sequence represented by the given input as a single short value, returned widened to int.

Parameters:

input - the object to access

offset - offset to the first byte to read within the byte sequence represented by the given object

Returns:

two bytes as a short value, in the expected order, widened to int

getUnsignedByte

int getUnsignedByte(T input,
                  long offset)

Shortcut for getByte(input, offset) & 0xFF. Could be implemented more efficiently.

Parameters:

input - the object to access

offset - offset to the byte to read within the byte sequence represented by the given object

Returns:

a byte by the given offset, interpreted as unsigned

getByte

int getByte(T input,
          long offset)

Reads a single byte at the given offset in the byte sequence represented by the given input, returned widened to int.

Parameters:

input - the object to access

offset - offset to the byte to read within the byte sequence represented by the given object

Returns:

a byte by the given offset, widened to int

byteOrder

ByteOrder byteOrder(T input)

The byte order in which all multi-byte getXXX() reads from the given input are performed.

Parameters:

input - the accessed object

Returns:

the byte order of all multi-byte reads from the given input