org.libj.util

Class TieredRangeFetcher<A extends Comparable<A>,B>

java.lang.Object

org.libj.util.TieredRangeFetcher<A,B>

Type Parameters:

A - Type parameter of the "range" data.

B - Type parameter of the data.

public abstract class TieredRangeFetcher<A extends Comparable<A>,B>
extends Object

A "data fetcher" that facilitates the retrieval of data representing information pertaining to a dimension that can be denoted as a "range" (such as time or distance). The TieredRangeFetcher abstracts the concept of tiered data sources. When data is fetched (via the fetch(Comparable,Comparable) method), the TieredRangeFetcher attempts to retrieve the requested range from the "top" tier of the stack. If all or a part of the range is not present in the tier, the TieredRangeFetcher attempts to fetch the missing portion of the range from the next tier. Upon successfully fetching the data, the TieredRangeFetcher thereafter inserts the fetched data into the top tier, thus resembling a caching mechanism. The TieredRangeFetcher is intended to provide an abstraction for the caching of range data belonging to a data source that is expensive to call, such as a remote database.

Constructor Summary

Constructors

Constructor and Description
TieredRangeFetcher(TieredRangeFetcher<A,B> next) Creates a TieredRangeFetcher with the specified next TieredRangeFetcher that represents the next tier.

Method Summary

Modifier and Type	Method and Description
SortedMap<A,B>	fetch(A from, A to) Returns a SortedMap of data from from (inclusive) to to (exclusive).
SortedMap<A,B>	fetch(A from, A to, TieredRangeFetcher<A,B> last) Returns a SortedMap of data from from (inclusive) to to (exclusive).
protected abstract void	insert(A from, A to, SortedMap<A,B> data) Inserts a SortedMap of data into this TieredRangeFetcher for the range between from and to.
protected abstract A[]	range() Returns the range of the keys present in this TieredFetcher, as an array of length 2.
protected abstract SortedMap<A,B>	select(A from, A to) Returns a SortedMap of data in this TieredRangeFetcher for the range between from and to.

Methods inherited from class java.lang.Object

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

Constructor Detail

TieredRangeFetcher

public TieredRangeFetcher(TieredRangeFetcher<A,B> next)

Creates a TieredRangeFetcher with the specified next TieredRangeFetcher that represents the next tier.

Parameters:

next - The TieredRangeFetcher that represents the next tier.

Method Detail

fetch

public SortedMap<A,B> fetch(A from,
                            A to)

Returns a SortedMap of data from from (inclusive) to to (exclusive).

Parameters:

from - The lower bound of the range, inclusive.

to - The upper bound of the range, exclusive.

Returns:

A SortedMap of data from from (inclusive) to to (exclusive).

fetch

public SortedMap<A,B> fetch(A from,
                            A to,
                            TieredRangeFetcher<A,B> last)

Returns a SortedMap of data from from (inclusive) to to (exclusive).

Parameters:

from - The lower bound of the range, inclusive.

to - The upper bound of the range, exclusive.

last - The TieredRangeFetcher representing the previous tier.

Returns:

A SortedMap of data from from (inclusive) to to (exclusive).

range

protected abstract A[] range()

Returns the range of the keys present in this TieredFetcher, as an array of length 2. Must not be null, and must be of length 2.

Returns:

The not-null range of the keys present in this TieredFetcher, as an array of length 2.

select

protected abstract SortedMap<A,B> select(A from,
                                         A to)

Returns a SortedMap of data in this TieredRangeFetcher for the range between from and to.

Parameters:

from - The start of the range, inclusive.

to - The end of the range, exclusive.

Returns:

A SortedMap of data in this TieredRangeFetcher for the range between from and to.

insert

protected abstract void insert(A from,
                               A to,
                               SortedMap<A,B> data)

Inserts a SortedMap of data into this TieredRangeFetcher for the range between from and to.

Parameters:

from - The start of the range, inclusive.

to - The end of the range, exclusive.

data - The SortedMap.