/**
* Creates a caching variant of the closure with automatic cache size adjustment and lower limit
* on the cache size. Whenever the closure is called, the mapping between the parameters and the
* return value is preserved in cache making subsequent calls with the same arguments fast. This
* variant allows the garbage collector to release entries from the cache and at the same time
* allows the user to specify how many entries should be protected from the eventual gc-initiated
* eviction. Cached entries exceeding the specified preservation threshold are made available for
* eviction based on the LRU (Last Recently Used) strategy. Given the non-deterministic nature of
* garbage collector, the actual cache size may grow well beyond the limits set by the user if
* memory is plentiful. The returned function can be safely used concurrently from multiple
* threads, however, the implementation values high average-scenario performance and so concurrent
* calls on the memoized function with identical argument values may not necessarily be able to
* benefit from each other's cached return value. Also the protectedCacheSize parameter might not
* be respected accurately in such scenarios for some periods of time. With this having been
* mentioned, the performance trade-off still makes concurrent use of memoized functions safe and
* highly recommended.
*
* <p>The cache gets garbage-collected together with the memoized closure.
*
* @param protectedCacheSize Number of cached return values to protect from garbage collection
* @return A new function forwarding to the original one while caching the results
*/
public Closure<V> memoizeAtLeast(final int protectedCacheSize) {
if (protectedCacheSize < 0)
throw new IllegalArgumentException(
"A non-negative number is required as the protectedCacheSize parameter for memoizeAtLeast.");
return Memoize.buildSoftReferenceMemoizeFunction(
protectedCacheSize, new UnlimitedConcurrentCache(), this);
}
/**
* Creates a caching variant of the closure with automatic cache size adjustment and lower and
* upper limits on the cache size. Whenever the closure is called, the mapping between the
* parameters and the return value is preserved in cache making subsequent calls with the same
* arguments fast. This variant allows the garbage collector to release entries from the cache and
* at the same time allows the user to specify how many entries should be protected from the
* eventual gc-initiated eviction. Cached entries exceeding the specified preservation threshold
* are made available for eviction based on the LRU (Last Recently Used) strategy. Given the
* non-deterministic nature of garbage collector, the actual cache size may grow well beyond the
* protected size limits set by the user, if memory is plentiful. Also, this variant will never
* exceed in size the upper size limit. Once the upper size limit has been reached, the values in
* the cache start rotating using the LRU (Last Recently Used) strategy. The returned function can
* be safely used concurrently from multiple threads, however, the implementation values high
* average-scenario performance and so concurrent calls on the memoized function with identical
* argument values may not necessarily be able to benefit from each other's cached return value.
* Also the protectedCacheSize parameter might not be respected accurately in such scenarios for
* some periods of time. With this having been mentioned, the performance trade-off still makes
* concurrent use of memoized functions safe and highly recommended.
*
* <p>The cache gets garbage-collected together with the memoized closure.
*
* @param protectedCacheSize Number of cached return values to protect from garbage collection
* @param maxCacheSize The maximum size the cache can grow to
* @return A new function forwarding to the original one while caching the results
*/
public Closure<V> memoizeBetween(final int protectedCacheSize, final int maxCacheSize) {
if (protectedCacheSize < 0)
throw new IllegalArgumentException(
"A non-negative number is required as the protectedCacheSize parameter for memoizeBetween.");
if (maxCacheSize < 0)
throw new IllegalArgumentException(
"A non-negative number is required as the maxCacheSize parameter for memoizeBetween.");
if (protectedCacheSize > maxCacheSize)
throw new IllegalArgumentException(
"The maxCacheSize parameter to memoizeBetween is required to be greater or equal to the protectedCacheSize parameter.");
return Memoize.buildSoftReferenceMemoizeFunction(
protectedCacheSize, new LRUCache(maxCacheSize), this);
}
