eu.fthevenet.binjr.data.adapters

Class SimpleCachingDataAdapter<T,A extends Decoder<T>>

java.lang.Object

eu.fthevenet.binjr.data.adapters.DataAdapter<T,A>

eu.fthevenet.binjr.data.adapters.SimpleCachingDataAdapter<T,A>

All Implemented Interfaces:

java.lang.AutoCloseable

Direct Known Subclasses:

HttpDataAdapterBase

public abstract class SimpleCachingDataAdapter<T,A extends Decoder<T>>
extends DataAdapter<T,A>

An abstract implementation of DataAdapter that manages a cache in between the adapter and the data source.

This is an on-heap memory cache with a finite capacity and an LRU eviction policy

Furthermore, values uses SoftReference to give the GC a chance to collect the cached elements if the memory pressure becomes too high.

Author:

Frederic Thevenet

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEFAULT_CACHE_SIZE

Fields inherited from class eu.fthevenet.binjr.data.adapters.DataAdapter

closed

Constructor Summary

Constructors

Constructor and Description
SimpleCachingDataAdapter() Initializes a new instance of the SimpleCachingDataAdapter class
SimpleCachingDataAdapter(int maxCacheEntries) Initializes a new instance of the SimpleCachingDataAdapter class with the specified maximum number of entries

Method Summary

Modifier and Type	Method and Description
void	close()
java.io.InputStream	fetchRawData(java.lang.String path, java.time.Instant begin, java.time.Instant end, boolean bypassCache) Gets raw data from the source as an output stream, for the time interval specified.
abstract byte[]	onCacheMiss(java.lang.String path, java.time.Instant begin, java.time.Instant end) Gets raw data from the source as an output stream, for the time interval specified.

Methods inherited from class eu.fthevenet.binjr.data.adapters.DataAdapter

fetchDecodedData, getBindingTree, getDecoder, getEncoding, getId, getParams, getSourceName, getTimeZoneId, isClosed, loadParams, onStart, ping, setId, toString, validateParameter, validateParameterNullity

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_CACHE_SIZE

public static final int DEFAULT_CACHE_SIZE

See Also:

Constant Field Values

Constructor Detail

SimpleCachingDataAdapter

public SimpleCachingDataAdapter()

Initializes a new instance of the SimpleCachingDataAdapter class

SimpleCachingDataAdapter

public SimpleCachingDataAdapter(int maxCacheEntries)

Initializes a new instance of the SimpleCachingDataAdapter class with the specified maximum number of entries

Parameters:

maxCacheEntries - the maximum number of entries in the cache

Method Detail

fetchRawData

public java.io.InputStream fetchRawData(java.lang.String path,
                                        java.time.Instant begin,
                                        java.time.Instant end,
                                        boolean bypassCache)
                                 throws DataAdapterException

Description copied from class: DataAdapter

Gets raw data from the source as an output stream, for the time interval specified.

Specified by:

fetchRawData in class DataAdapter<T,A extends Decoder<T>>

Parameters:

path - the path of the data in the source

begin - the start of the time interval.

end - the end of the time interval.*

bypassCache - true if adapter cache should be bypassed, false otherwise. This parameter is ignored if adapter does not support caching

Returns:

the output stream in which to return data.

Throws:

DataAdapterException - if an error occurs while retrieving data from the source.

onCacheMiss

public abstract byte[] onCacheMiss(java.lang.String path,
                                   java.time.Instant begin,
                                   java.time.Instant end)
                            throws DataAdapterException

Gets raw data from the source as an output stream, for the time interval specified.

Parameters:

path - the path of the data in the source

begin - the start of the time interval.

end - the end of the time interval.

Returns:

the data to store in the cache.

Throws:

DataAdapterException - if an error occurs while retrieving data from the source.

close

public void close()

Specified by:

close in interface java.lang.AutoCloseable

Overrides:

close in class DataAdapter<T,A extends Decoder<T>>