fiftyone.mobile.detection.entities.stream

Class StreamCacheList<T extends BaseEntity>

java.lang.Object

fiftyone.mobile.detection.entities.stream.StreamBaseList<T>

fiftyone.mobile.detection.entities.stream.StreamCacheList<T>

Type Parameters:

T - The type of BaseEntity the list will contain

All Implemented Interfaces:

ICacheLoader<Integer,T>, ICacheList

Direct Known Subclasses:

StreamVariableList

public abstract class StreamCacheList<T extends BaseEntity>
extends StreamBaseList<T>
implements ICacheLoader<Integer,T>, ICacheList

Lists can be stored as a set of related objects entirely within memory, or the relevant objects loaded as required from a file or other permanent store as required.

This class provides core functions needed for lists which load objects as required. It implements the Cache{T} to store frequently requested objects and improve memory usage and performance.

Delegate methods are used to create new instances of items to add to the list in order to avoid creating many inherited list classes for each BaseEntity type.

Objects of this class should not be created directly as they are part of the internal logic.

Field Summary

Fields inherited from class fiftyone.mobile.detection.entities.stream.StreamBaseList

dataSet, header

Constructor Summary

Constructors

Constructor and Description
StreamCacheList(Dataset dataSet, BinaryReader reader, BaseEntityFactory<T> entityFactory, int cacheSize) Constructs a new instance of StreamBaseList{T} ready to read entities from the source.

Method Summary

Modifier and Type	Method and Description
T	fetch(Integer key) Used to retrieve items from the underlying list.
T	get(int key) Retrieves the entity at the offset or index requested.
double	getPercentageMisses() Returns Percentage of request that were not already held in the cache.
long	getSwitches() Deprecated.
void	resetCache() Resets the cache.

Methods inherited from class fiftyone.mobile.detection.entities.stream.StreamBaseList

createEntity, size

Methods inherited from class java.lang.Object

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

Constructor Detail

StreamCacheList

public StreamCacheList(Dataset dataSet,
                       BinaryReader reader,
                       BaseEntityFactory<T> entityFactory,
                       int cacheSize)

Constructs a new instance of StreamBaseList{T} ready to read entities from the source.

Parameters:

dataSet - Dataset being created.

reader - Reader used to initialise the header only.

entityFactory - Used to create new instances of the entity.

cacheSize - Number of items in list to have capacity to cache.

Method Detail

getPercentageMisses

public double getPercentageMisses()

Returns Percentage of request that were not already held in the cache.

Specified by:

getPercentageMisses in interface ICacheList

Returns:

Percentage of request that were not already held in the cache.

getSwitches

@Deprecated
public long getSwitches()

Deprecated.

Returns The number of times the cache has been switched.

Specified by:

getSwitches in interface ICacheList

Returns:

The number of times the cache has been switched.

resetCache

public void resetCache()

Resets the cache.

Specified by:

resetCache in interface ICacheList

get

public T get(int key)
      throws IOException

Retrieves the entity at the offset or index requested.

Overrides:

get in class StreamBaseList<T extends BaseEntity>

Parameters:

key - Index or offset of the entity required.

Returns:

A new instance of the entity at the offset or index.

Throws:

IOException - if there was a problem accessing data file.

fetch

public T fetch(Integer key)
        throws IOException

Used to retrieve items from the underlying list. Called by Cache{T} when a cache miss occurs.

Specified by:

fetch in interface ICacheLoader<Integer,T extends BaseEntity>

Parameters:

key - index or offset of the entity required

Returns:

he base lists item for the key provided

Throws:

IOException - if there was a problem accessing data file.