Package com.inductiveautomation.perspective.gateway.assets

Class AbstractAssetManager<K,V>

java.lang.Object

com.inductiveautomation.ignition.common.lifecycle.AbstractLifecycle

com.inductiveautomation.perspective.gateway.assets.AbstractAssetManager<K,V>

Type Parameters:

K - The type of key for the asset cache

V - The type of value for the asset cache

Direct Known Subclasses:

FontManagerImpl, IconManagerImpl, ThemeManagerImpl

public abstract class AbstractAssetManager<K,V>
extends AbstractLifecycle

Base class for managing static assets. During setup() files from the injected asset's defaults will be moved to the respective assets directory in the system home directory even if they do exist. Uses a FileWatcher to react to changes to the injected asset directory under the perspective modules directory of the system home directory. Changes in the watched asset directory will cause the in memory cache to be updated. Extensions of this class must override generateKey(Path) and parseValue(Path) so that this class may update its cache with the appropriate entry.

Field Summary

Fields

Modifier and Type	Field	Description
protected final Path	assetPath
protected final Object	cacheLock
protected final PerspectiveContext	perspectiveContext

Constructor Summary

Constructors

Constructor	Description
AbstractAssetManager(PerspectiveContext perspectiveContext, String asset)
AbstractAssetManager(PerspectiveContext perspectiveContext, String asset, FileFilter fileFilter)

Method Summary

Modifier and Type	Method	Description
protected void	copyInputStreamToPath(InputStream is, Path pathTo)
protected void	copyInputStreamToPath(String name, byte[] defaultAssetData, byte[] defaultAssetDigest, byte[] existingAssetDigest)
protected CopyOption[]	copyOptions(byte[] existingAssetDigest, byte[] currentExistingAssetDigest)
protected abstract Optional<K>	generateKey(Path path)	Generate a cache key for the given Path
protected Map<K,V>	getCache()	Fetch a copy of the cache
protected Optional<V>	getCachedValue(K key)	Fetch the cached value associated with a key
Optional<com.inductiveautomation.ignition.common.gson.JsonObject>	getDigestCopy()
protected Optional<String>	getDigestFor(K assetKey)	If the assetKey exists in the cache and it's been hashed, the digest may be retrieved for the asset name
protected void	onCacheChanged()	Invoked within a synchronized block, that holds onto the cache lock, when there is a create, modify, or delete watch event.
protected void	onShutdown()
protected void	onStartup()
protected abstract Optional<V>	parseValue(Path path)	Parse the cache value for the given Path
void	setup()	Setup the Asset Manager.

Methods inherited from class com.inductiveautomation.ignition.common.lifecycle.AbstractLifecycle

isRunning, shutdown, startup

Methods inherited from class java.lang.Object

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

Field Details

perspectiveContext

protected final PerspectiveContext perspectiveContext

assetPath

protected final Path assetPath

cacheLock

protected final Object cacheLock

Constructor Details

AbstractAssetManager

public AbstractAssetManager(@Nonnull
 PerspectiveContext perspectiveContext,
 @Nonnull
 String asset)

AbstractAssetManager

public AbstractAssetManager(@Nonnull
 PerspectiveContext perspectiveContext,
 @Nonnull
 String asset,
 @Nonnull
 FileFilter fileFilter)

Method Details

getCache

protected Map<K,V> getCache()

Fetch a copy of the cache

Returns:

A copy of the cache

getCachedValue

protected Optional<V> getCachedValue(K key)

Fetch the cached value associated with a key

Parameters:

key - The cache key

Returns:

An Optional containing the cached value associated with the given key, or an empty Optional of there is no such cached value associated with the given key

copyInputStreamToPath

protected void copyInputStreamToPath(@Nonnull
 InputStream is,
 @Nonnull
 Path pathTo)
                              throws IOException

Throws:

IOException

copyOptions

protected CopyOption[] copyOptions(@Nonnull
 byte[] existingAssetDigest,
 @Nonnull
 byte[] currentExistingAssetDigest)

copyInputStreamToPath

protected void copyInputStreamToPath(@Nonnull
 String name,
 @Nonnull
 byte[] defaultAssetData,
 @Nonnull
 byte[] defaultAssetDigest,
 @Nullable
 byte[] existingAssetDigest)
                              throws IOException

Throws:

IOException

getDigestCopy

public Optional<com.inductiveautomation.ignition.common.gson.JsonObject> getDigestCopy()

Returns:

a copy of the digests object, if present, otherwise empty optional

getDigestFor

protected Optional<String> getDigestFor(@Nullable
 K assetKey)

If the assetKey exists in the cache and it's been hashed, the digest may be retrieved for the asset name

Parameters:

assetKey - the name of the asset being cached, generally the filename of the asset

Returns:

optional containing the digest for the named asset

setup

public void setup()

Setup the Asset Manager. Copies any defaults into the asset home directory. Should be run before AbstractLifecycle.startup()

onStartup

protected void onStartup()

Specified by:

onStartup in class AbstractLifecycle

onShutdown

protected void onShutdown()

Specified by:

onShutdown in class AbstractLifecycle

generateKey

@Nonnull
protected abstract Optional<K> generateKey(@Nonnull
 Path path)

Generate a cache key for the given Path

Parameters:

path - The Path for which we want to generate a cache key

Returns:

An Optional containing the cache key or an empty Optional if the cache key could not be generated

parseValue

@Nonnull
protected abstract Optional<V> parseValue(@Nonnull
 Path path)

Parse the cache value for the given Path

Parameters:

path - The Path for which we want to generate a cache value

Returns:

An Optional containing the cache value or an empty Optional if the cache value could not be generated

onCacheChanged

protected void onCacheChanged()

Invoked within a synchronized block, that holds onto the cache lock, when there is a create, modify, or delete watch event. Invoked immediately following modification of the cache, the cache values and digest will be updated prior to being called. Override this method to update any cache local to the subclass.