Here's how you can pull them off in Java using Google's Guava. If the cache loader associated with this cache performs refresh asynchronously then this method may return before refresh completes. In this article, we've explained how a LoadingCache is used by a CacheLoader in order to calculate values on cache misses, and also on cache refreshes. Returns without doing anything if another thread is currently loading the value for key. In some cases a loading Cache can be useful even if it doesn't evict entries, due to its automatic cache loading. Iterators from the returned map are at least weakly consistent: they are safe for concurrent use, but if the cache is modified (including by eviction) after the iterator is created, it is undefined which of the changes (if any) will be reflected in that iterator. Sr.No Method & Description; 1: V apply(K key) Deprecated. The implementation of these examples can be found over on GitHub. Here’s an extract from Guava’s wiki: LoadingCache graphs = CacheBuilder.newBuilder() .build( new CacheLoader() { public Graph load(Key key) throws AnyException { return createExpensiveGraph(key); } }); Basically, … Guava cache is a simple library that provides flexible and powerful caching features. abstract V: load (K key) Computes or … The asMap().compute implementation did not take into account that the present value may be loading. Since Guava library was released, I’ve been a huge fan of MapMaker, later renamed to CacheBuilder. The decision to use a Guava Cache really comes down to the tradeoff between memory availability/usage versus increases in performance. The feature I prefer is the LoadingCache. Returns a view of the entries stored in this cache as a thread-safe map. Provided to satisfy the Function interface; use get(K) or getUnchecked(K) instead. We are encountering issue of hanging thread while accessing the cache values. Generally, guava-cacheis applicable whenever: You are willing to spend some memory to improve speed. 2: ConcurrentMap asMap() Returns a view of the entries stored in this cache as a thread-safe map. A load does not block other writes to that entry and takes into account that it may be clobbered, causing it to automatically discard itself. Using Google Guava For Cache With Timeout – Java If you need a list to keep your objects for a while and then automatically delete/expire them, you can use caches from Google Guava . We are using Loading cache which has specific eviction timeout set for entries. Modifications made to the map directly affect the cache. Lazy Loading and Caching Objects With Guava Lazy loading and caching are powerful performance tools, but they can be implemented poorly. Loading is asynchronous only if CacheLoader.reload(K, V) was overridden with an asynchronous implementation. This is a known design choice that breaks linearizability assumptions (#1881). A Cache on the other hand is generally configured to evict entries automatically, in order to constrain its memory footprint. It's also worth checking out this more in-depth article on Guava Caching. The Guava Cache presents some very compelling functionality. 6 threads were trying to access the cache . This is a Maven project, so should be easy to run as is. static CacheLoader from (Supplier supplier) Returns a cache loader based on an existing supplier instance. Returns a cache loader that uses function to load keys, without supporting either reloading or bulk loading.
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