Package org.rocksdb

Class AbstractSlice<T>

java.lang.Object

org.rocksdb.AbstractNativeReference

org.rocksdb.RocksMutableObject

org.rocksdb.AbstractSlice<T>

All Implemented Interfaces:

java.lang.AutoCloseable

Direct Known Subclasses:

DirectSlice, Slice

public abstract class AbstractSlice<T>
extends RocksMutableObject

Slices are used by RocksDB to provide efficient access to keys and values. This class is package private, implementers should extend either of the public abstract classes:

See Also:

Slice, Regards the lifecycle of Java Slices in RocksDB: At present when you configure a Comparator from Java, it creates an instance of a C++ BaseComparatorJniCallback subclass and passes that to RocksDB as the comparator. That subclass of BaseComparatorJniCallback creates the Java, subclass Objects. When you dispose the Java @see org.rocksdb.AbstractComparator subclass, it disposes the C++ BaseComparatorJniCallback subclass, which in turn destroys the Java @see org.rocksdb.AbstractSlice subclass Objects.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	AbstractSlice()
protected	AbstractSlice(long nativeHandle)

Method Summary

Modifier and Type	Method	Description
abstract void	clear()	Clears the backing slice
int	compare(AbstractSlice<?> other)	Three-way key comparison
protected static long	createNewSliceFromString(java.lang.String str)
T	data()	Returns the data of the slice.
protected abstract T	data0(long handle)	Access to the data is provided by the subtype as it needs to handle the generic typing.
protected void	disposeInternal(long handle)	Deletes underlying C++ slice pointer.
boolean	empty()	Return true if the length of the data is zero.
boolean	equals(java.lang.Object other)	If other is a slice object, then we defer to compare to check equality, otherwise we return false.
int	hashCode()
abstract void	removePrefix(int n)	Drops the specified n number of bytes from the start of the backing slice
int	size()	Return the length (in bytes) of the data.
boolean	startsWith(AbstractSlice<?> prefix)	Determines whether this slice starts with another slice
java.lang.String	toString()
java.lang.String	toString(boolean hex)	Creates a string representation of the data

Methods inherited from class org.rocksdb.RocksMutableObject

close, disposeInternal, getNativeHandle, isOwningHandle, resetNativeHandle, setNativeHandle

Methods inherited from class org.rocksdb.AbstractNativeReference

dispose, finalize

Methods inherited from class java.lang.Object

clone, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

AbstractSlice

protected AbstractSlice()

AbstractSlice

protected AbstractSlice(long nativeHandle)

Method Detail

data

public T data()

Returns the data of the slice.

Returns:

The slice data. Note, the type of access is determined by the subclass

See Also:

data0(long)

data0

protected abstract T data0(long handle)

Access to the data is provided by the subtype as it needs to handle the generic typing.

Parameters:

handle - The address of the underlying native object.

Returns:

Java typed access to the data.

removePrefix

public abstract void removePrefix(int n)

Drops the specified n number of bytes from the start of the backing slice

Parameters:

n - The number of bytes to drop

clear

public abstract void clear()

Clears the backing slice

size

public int size()

Return the length (in bytes) of the data.

Returns:

The length in bytes.

empty

public boolean empty()

Return true if the length of the data is zero.

Returns:

true if there is no data, false otherwise.

toString

public java.lang.String toString(boolean hex)

Creates a string representation of the data

Parameters:

hex - When true, the representation will be encoded in hexadecimal.

Returns:

The string representation of the data.

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

compare

public int compare(AbstractSlice<?> other)

Three-way key comparison

Parameters:

other - A slice to compare against

Returns:

Should return either: 1) < 0 if this < other 2) == 0 if this == other 3) > 0 if this > other

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

equals

public boolean equals(java.lang.Object other)

If other is a slice object, then we defer to compare to check equality, otherwise we return false.

Overrides:

equals in class java.lang.Object

Parameters:

other - Object to test for equality

Returns:

true when this.compare(other) == 0, false otherwise.

startsWith

public boolean startsWith(AbstractSlice<?> prefix)

Determines whether this slice starts with another slice

Parameters:

prefix - Another slice which may of may not be a prefix of this slice.

Returns:

true when this slice starts with the prefix slice

createNewSliceFromString

protected static long createNewSliceFromString(java.lang.String str)

disposeInternal

protected final void disposeInternal(long handle)

Deletes underlying C++ slice pointer. Note that this function should be called only after all RocksDB instances referencing the slice are closed. Otherwise an undefined behavior will occur.

Specified by:

disposeInternal in class RocksMutableObject