MutableKeyBuffer (Blazegraph Database Platform 2.1.5 API)

java.lang.Object
- com.bigdata.btree.raba.AbstractKeyBuffer
- - com.bigdata.btree.raba.MutableKeyBuffer

All Implemented Interfaces:

IRaba, Iterable<byte[]>
```
public class MutableKeyBuffer
extends AbstractKeyBuffer
```
A flyweight mutable implementation exposing the backing byte[][] and supporting search.

Version:

$Id$

Author:

Bryan Thompson

Field Summary

Fields
Modifier and Type Field and Description

byte[][] keys
An array containing the keys.

int nkeys
The #of defined keys.

Fields
Modifier and Type	Field and Description
`byte[][]`	`keys` An array containing the keys.
`int`	`nkeys` The #of defined keys.

Constructor Summary

Constructors
Constructor and Description
`MutableKeyBuffer(int capacity)` Allocate a mutable key buffer capable of storing capacity keys.
`MutableKeyBuffer(int nkeys, byte[][] keys)` Constructor wraps an existing byte[][].
`MutableKeyBuffer(int capacity, IRaba src)` Builds a mutable key buffer.
`MutableKeyBuffer(MutableKeyBuffer src)` Creates a new instance using a new array of keys but sharing the key references with the provided `MutableKeyBuffer`.

Method Summary

Methods
Modifier and Type	Method and Description
`protected int`	`_binarySearch(int searchKeyOffset, byte[] searchKey)` Binary search.
`protected int`	`_linearSearch(int searchKeyOffset, byte[] searchKey)` Linear search.
`protected int`	`_prefixMatchLength(int prefixLength, byte[] searchKey)` Test the search key against the leading prefix shared by all bytes in the key buffer.
`int`	`add(byte[] key)` Append a byte[] value to the end of the logical byte[][] (optional operation).
`int`	`add(byte[] key, int off, int len)` Append a byte[] value to the end of the logical byte[][] (optional operation).
`int`	`add(DataInput in, int len)` Append a byte[] value to the end of the logical byte[][] (optional operation).
`void`	`assertKeysMonotonic()` Verifies that the keys are in sort order and that undefined keys are [null].
`int`	`capacity()` The maximum #of keys that may be held in the buffer (its capacity).
`int`	`copy(int index, OutputStream out)` Copy the value at the specified index onto the output stream.
`byte[]`	`get(int index)` Returns a reference to the key at that index.
`byte[]`	`getPrefix()` Computes the #of leading bytes shared by all keys and returns a new byte[] containing those bytes.
`int`	`getPrefixLength()` Computes the length of the prefix by computed by counting the #of leading bytes that match for the first and last key in the buffer.
`int`	`insert(int index, byte[] key)` Insert a key into the buffer at the specified index, incrementing the #of keys in the buffer by one and moving down all keys from that index on down by one (towards the end of the array).
`boolean`	`isEmpty()` True iff the logical byte[][] is empty.
`boolean`	`isFull()` True iff the key buffer can not contain another key.
`boolean`	`isKeys()` Instances are searchable and do not allow `null`s.
`boolean`	`isNull(int index)` Return `true` iff the byte[] at that index is `null`.
`boolean`	`isReadOnly()` Mutable.
`int`	`length(int index)` The length of the byte[] at that index.
`int`	`remove(int index)` Remove a key in the buffer at the specified index, decrementing the #of keys in the buffer by one and moving up all keys from that index on down by one (towards the start of the array).
`int`	`search(byte[] searchKey)` Search for the given searchKey in the key buffer (optional operation).
`void`	`set(int index, byte[] key)` Set the key at the specified index.
`int`	`size()` The #of entries in the logical byte[][].
`String`	`toString()`

Methods inherited from class com.bigdata.btree.raba.AbstractKeyBuffer
iterator

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Field Detail
  - nkeys
```
public int nkeys
```
    The #of defined keys.
  - keys
```
public final byte[][] keys
```
    An array containing the keys. The size of the array is the maximum capacity of the key buffer.
- Constructor Detail
  - MutableKeyBuffer
```
public MutableKeyBuffer(int capacity)
```
    Allocate a mutable key buffer capable of storing capacity keys.
    
    Parameters:
    capacity - The capacity of the key buffer.
  - MutableKeyBuffer
```
public MutableKeyBuffer(int nkeys,
                byte[][] keys)
```
    Constructor wraps an existing byte[][].
    
    Parameters:
    nkeys - The #of defined keys in the array.
    keys - The array of keys.
  - MutableKeyBuffer
```
public MutableKeyBuffer(MutableKeyBuffer src)
```
    Creates a new instance using a new array of keys but sharing the key references with the provided MutableKeyBuffer.
    
    Parameters:
    src - An existing instance.
  - MutableKeyBuffer
```
public MutableKeyBuffer(int capacity,
                IRaba src)
```
    Builds a mutable key buffer.
    
    Parameters:
    capacity - The capacity of the new instance (this is based on the branching factor for the B+Tree).
    src - The source data.
    
    Throws:
    
    IllegalArgumentException - if the capacity is LT the IRaba.size() of the src.
    
    IllegalArgumentException - if the source is null.
- Method Detail
  - get
```
public final byte[] get(int index)
```
    Returns a reference to the key at that index.
    
    Parameters:
    index - The index in [0:IRaba.size()-1].
    
    Returns:
    The byte[] value at that index and null if a null value was stored at that index.
  - length
```
public final int length(int index)
```
    Description copied from interface: IRaba
    
    The length of the byte[] at that index.
    
    Parameters:
    index - The index in [0:IRaba.size()-1].
    
    Returns:
    The length of the byte[] at that index.
  - copy
```
public final int copy(int index,
       OutputStream out)
```
    Description copied from interface: IRaba
    
    Copy the value at the specified index onto the output stream. This is often used with an ByteArrayBuffer so that the same backing byte[] can be overwritten by each visited key.
    
    Parameters:
    index - The index in [0:IRaba.size()-1].
    
    Returns:
    The #of bytes copied.
  - isNull
```
public final boolean isNull(int index)
```
    Description copied from interface: IRaba
    
    Return true iff the byte[] at that index is null. If IRaba.isKeys() would return true then this method MUST return false since nulls are not permitted for B+Tree keys.
    
    Parameters:
    index - The index in [0:IRaba.size()-1].
  - isEmpty
```
public final boolean isEmpty()
```
    Description copied from interface: IRaba
    
    True iff the logical byte[][] is empty.
  - size
```
public final int size()
```
    Description copied from interface: IRaba
    
    The #of entries in the logical byte[][].
  - capacity
```
public final int capacity()
```
    The maximum #of keys that may be held in the buffer (its capacity).
  - isFull
```
public final boolean isFull()
```
    True iff the key buffer can not contain another key.
  - isReadOnly
```
public final boolean isReadOnly()
```
    Mutable.
  - isKeys
```
public final boolean isKeys()
```
    Instances are searchable and do not allow nulls.
    
    Returns:
    true if the IRaba represents B+Tree keys and false if it represents B+Tree values.
  - set
```
public final void set(int index,
       byte[] key)
```
    Set the key at the specified index.
    
    Parameters:
    index - The index in [0:nkeys-1].
    key - The key (non-null).
  - add
```
public final int add(byte[] key)
```
    Description copied from interface: IRaba
    
    Append a byte[] value to the end of the logical byte[][] (optional operation).
    
    Parameters:
    key - A value.
    
    Returns:
    The #of values in the logical byte[][] (postcondition).
  - add
```
public final int add(byte[] key,
      int off,
      int len)
```
    Description copied from interface: IRaba
    
    Append a byte[] value to the end of the logical byte[][] (optional operation).
    
    Parameters:
    key - A value
    off - The offset of the first byte to be copied.
    len - The #of bytes to be copied.
    
    Returns:
    The #of values in the logical byte[][] (postcondition).
  - add
```
public int add(DataInput in,
      int len)
        throws IOException
```
    Description copied from interface: IRaba
    
    Append a byte[] value to the end of the logical byte[][] (optional operation).
    
    Parameters:
    in - The input stream from which the byte[] will be read.
    len - The #of bytes to be read.
    
    Returns:
    The #of values in the logical byte[][] (postcondition).
    
    Throws:
    
    IOException
  - insert
```
public final int insert(int index,
         byte[] key)
```
    Insert a key into the buffer at the specified index, incrementing the #of keys in the buffer by one and moving down all keys from that index on down by one (towards the end of the array).
    
    Parameters:
    index - The index in [0:nkeys] (you are allowed to append using this method).
    key - The key.
    
    Returns:
    The #of keys in the buffer.
  - remove
```
public final int remove(int index)
```
    Remove a key in the buffer at the specified index, decrementing the #of keys in the buffer by one and moving up all keys from that index on down by one (towards the start of the array).
    
    Parameters:
    index - The index in [0:nkeys-1].
    key - The key.
    
    Returns:
    The #of keys in the buffer.
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object
  - search
```
public final int search(byte[] searchKey)
```
    Description copied from interface: IRaba
    Search for the given searchKey in the key buffer (optional operation). Whether or not search is supported depends on whether the logical byte[][] is ordered. However, the efficiency of search, where supported, depends on the implementation. Some implementations support binary search of the coded byte[] values. Others may require a mixture of binary and linear search, etc.
```
 entryIndex = -entryIndex - 1
 
```
    or just
```
 entryIndex = -entryIndex
 
```
    if you are looking for the first key after the searchKey.
    Parameters:
    searchKey - The search key.
    
    Returns:
    index of the search key, if it is found; otherwise, (-(insertion point) - 1). The insertion point is defined as the point at which the key would be inserted. Note that this guarantees that the return value will be >= 0 if and only if the key is found.
  - _prefixMatchLength
```
protected final int _prefixMatchLength(int prefixLength,
                     byte[] searchKey)
```
    Description copied from class: AbstractKeyBuffer
    
    Test the search key against the leading prefix shared by all bytes in the key buffer.
    
    Specified by:
    
    _prefixMatchLength in class AbstractKeyBuffer
    
    Parameters:
    prefixLength - The length of the prefix shared by all keys in the buffer.
    searchKey - The search key.
    
    Returns:
    Zero iff all bytes match and otherwise the insert position for the search key in the buffer. The insert position will be before the first key iff the search key is less than the prefix (-1) and will be after the last key iff the search key is greater than the prefix (-(nkeys)-1).
  - _linearSearch
```
protected final int _linearSearch(int searchKeyOffset,
                byte[] searchKey)
```
    Description copied from class: AbstractKeyBuffer
    
    Linear search.
    
    Specified by:
    
    _linearSearch in class AbstractKeyBuffer
  - _binarySearch
```
protected final int _binarySearch(int searchKeyOffset,
                byte[] searchKey)
```
    Description copied from class: AbstractKeyBuffer
    
    Binary search.
    
    Specified by:
    
    _binarySearch in class AbstractKeyBuffer
  - assertKeysMonotonic
```
public final void assertKeysMonotonic()
```
    Verifies that the keys are in sort order and that undefined keys are [null].
  - getPrefixLength
```
public int getPrefixLength()
```
    Computes the length of the prefix by computed by counting the #of leading bytes that match for the first and last key in the buffer.
    
    Specified by:
    
    getPrefixLength in class AbstractKeyBuffer
  - getPrefix
```
public byte[] getPrefix()
```
    Computes the #of leading bytes shared by all keys and returns a new byte[] containing those bytes.
    
    Specified by:
    
    getPrefix in class AbstractKeyBuffer

Class MutableKeyBuffer

Field Summary

Constructor Summary

Method Summary

Methods inherited from class com.bigdata.btree.raba.AbstractKeyBuffer

Methods inherited from class java.lang.Object

Field Detail

nkeys

keys

Constructor Detail

MutableKeyBuffer

MutableKeyBuffer

MutableKeyBuffer

MutableKeyBuffer

Method Detail

get

length

copy

isNull

isEmpty

size

capacity

isFull

isReadOnly

isKeys

set

add

add

add

insert

remove

toString

search

_prefixMatchLength

_linearSearch

_binarySearch

assertKeysMonotonic

getPrefixLength

getPrefix