com.sleepycat.je.tree

Class INArrayRep<ARRAY_BASE_TYPE,REP_ENUM_TYPE,ELEMENT_TYPE>

java.lang.Object

com.sleepycat.je.tree.INArrayRep<ARRAY_BASE_TYPE,REP_ENUM_TYPE,ELEMENT_TYPE>

Direct Known Subclasses:

INKeyRep, INTargetRep

public abstract class INArrayRep<ARRAY_BASE_TYPE,REP_ENUM_TYPE,ELEMENT_TYPE>
extends Object

The base class for the various array representations used by fields associated with an IN node. Storage efficiency, especially when JE is operating in a "cache full" environment is the prime motivation for the various representations.

Each representation assumes that all read operations are done under a shared latch and all updates (set, copy and compact) are done under an exclusive latch. As a result, the representations themselves do not make any provisions for synchronization.

The callers of all the potentially representation mutating methods:

1. set(int, Object, IN)
2. copy(int, int, int, IN)
3. compact(IN)

must be careful to save the result value and use it for subsequent operations, since it could represent the new mutated object.

Constructor Summary

Constructors

Constructor and Description
INArrayRep()

Method Summary

Modifier and Type	Method and Description
abstract long	calculateMemorySize() Returns the current memory size of the underlying representation in bytes.
abstract ARRAY_BASE_TYPE	compact(IN parent) Chooses a more compact representation, if that's possible, otherwise does nothing.
abstract ARRAY_BASE_TYPE	copy(int from, int to, int n, IN parent) Copies n elements at index denoted by "from" to the index denoted by "to".
abstract ELEMENT_TYPE	get(int idx) Returns the element at idx.
abstract REP_ENUM_TYPE	getType()
abstract ARRAY_BASE_TYPE	resize(int capacity) Changes the capacity, either truncating existing elements at the end if the capacity is reduced, or adding empty elements at the end if the capacity is enlarged.
abstract ARRAY_BASE_TYPE	set(int idx, ELEMENT_TYPE e, IN parent) Sets the array element at idx to the node.

Methods inherited from class java.lang.Object

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

Constructor Detail

INArrayRep

public INArrayRep()

Method Detail

getType

public abstract REP_ENUM_TYPE getType()

set

public abstract ARRAY_BASE_TYPE set(int idx,
                                    ELEMENT_TYPE e,
                                    IN parent)

Sets the array element at idx to the node. The underlying representation can change as a result of the set operation.

Parameters:

idx - the index to be set

e - the array elelement at the idx

Returns:

either this, or the new representation if there was a mutation.

get

public abstract ELEMENT_TYPE get(int idx)

Returns the element at idx.

copy

public abstract ARRAY_BASE_TYPE copy(int from,
                                     int to,
                                     int n,
                                     IN parent)

Copies n elements at index denoted by "from" to the index denoted by "to". Overlapping copies are supported. It's possible that the representation may mutate as a result of the copy.

Parameters:

from - the source (inclusive) of the copy

to - the target (inclusive) of the copy

n - the number of elements to be copied.

Returns:

either this, or the new representation if there was a mutation.

compact

public abstract ARRAY_BASE_TYPE compact(IN parent)

Chooses a more compact representation, if that's possible, otherwise does nothing.

WARNING: This method must not change the memory size of the current representation and return 'this', without explicitly adjusting memory usage (via noteRepChange) before returning. Returning a new instance is the trigger for adjusting memory usage in the parent.

Returns:

this or a more compact representation.

resize

public abstract ARRAY_BASE_TYPE resize(int capacity)

Changes the capacity, either truncating existing elements at the end if the capacity is reduced, or adding empty elements at the end if the capacity is enlarged. The caller guarantees that all truncated elements are unused.

calculateMemorySize

public abstract long calculateMemorySize()

Returns the current memory size of the underlying representation in bytes. It returns the size of the representation, excluding the size of the elements contained in it.

Returns:

the memory size of the representation in bytes