Package org.cy3sbml.cache

Class MemoryCache<K,V>

java.lang.Object

org.cy3sbml.cache.MemoryCache<K,V>

public final class MemoryCache<K,V>
extends Object

Thread-safe, size-bounded least-recently-used cache for web service lookups.

A found value is cached until evicted. A "not found" result (e.g. an HTTP 404) is cached for a short TTL, so a missing term is not re-requested on every render. A transport or parse error is never cached, so a transient outage (e.g. while offline) recovers on the next lookup.

Each key is loaded at most once at a time: concurrent requests for a key that is being loaded wait for that load and share its result. Loads of different keys run in parallel; no lock is held while the loader runs.

Field Summary

Fields

Modifier and Type	Field	Description
static final Duration	DEFAULT_NOT_FOUND_TTL	Default TTL for a cached "not found" result.

Constructor Summary

Constructors

Constructor	Description
MemoryCache(int maxEntries)
MemoryCache(int maxEntries, Duration notFoundTtl, Clock clock)	For tests: an injectable TTL and clock for the "not found" entries.

Method Summary

Modifier and Type	Method	Description
void	clear()
Optional<V>	get(K key, Function<K,FetchResult<V>> loader)	Returns the cached value or loads it with the given loader.
int	size()

Methods inherited from class java.lang.Object

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

Field Details

DEFAULT_NOT_FOUND_TTL

public static final Duration DEFAULT_NOT_FOUND_TTL

Default TTL for a cached "not found" result.

Constructor Details

MemoryCache

public MemoryCache(int maxEntries)

MemoryCache

public MemoryCache(int maxEntries,
 Duration notFoundTtl,
 Clock clock)

For tests: an injectable TTL and clock for the "not found" entries.

Method Details

get

public Optional<V> get(K key,
 Function<K,FetchResult<V>> loader)

Returns the cached value or loads it with the given loader. A found value is cached until evicted; a "not found" result is cached for a short TTL; an error is not cached, so it is retried on the next call.

size

public int size()

clear

public void clear()