How to disable Guava caching?

guava, java

Solution

The method `newBuilder` constructs a new `CacheBuilder` instance with default settings, ignoring the call to `from`. However, you want to construct a `CacheBuilder` with a specific maximum size. So, remove the call to `newBuider`. You should use your call to `build` to get a `CacheBuilder` matching your spec rather than getting one with default settings:

underTest = CacheBuilder.from("maximumSize=0")
                .recordStats()
                .removalListener(new RemovalListener<String, Long>() {
                    @Override
                    public void onRemoval(RemovalNotification<String, Long> removalNotification) {
                        LOG.info(String.format("%s cached value %s for key %s is evicted.", removalNotification.getCause().name(), removalNotification.getValue(), removalNotification.getKey()));
                    }
                })
                .build(new CacheLoader<String, Long>() {
                    private final AtomicLong al = new AtomicLong(0);
                    @Override
                    public Long load(@NotNull final String key) throws Exception {
                        LOG.info(String.format("Cache miss for key '%s'.", key));
                        return al.incrementAndGet();
                    }
                });

Problem

JavaCachingWithGuava suggests the canonical way to turn off caching is to set maximumSize=0. However, I'd expect the test below to pass: ``` public class LoadingCacheTest { private static final Logger LOG = LoggerFactory.getLogger(LoadingCacheTest.class); LoadingCache<String, Long> underTest; @Before public void setup() throws Exception { underTest = CacheBuilder.from("maximumSize=0").newBuilder() .recordStats() .removalListener(new RemovalListener<String, Long>() { @Override public void onRemoval(RemovalNotification<String, Long> removalNotification) { LOG.info(String.format("%s cached value %s for key %s is evicted.", removalNotification.getCause().name(), removalNotification.getValue(), removalNotification.getKey())); } }) .build(new CacheLoader<String, Long>() { private final AtomicLong al = new AtomicLong(0); @Override public Long load(@NotNull final String key) throws Exception { LOG.info(String.format("Cache miss for key '%s'.", key)); return al.incrementAndGet(); } }); } @Test public void testAlwaysCacheMissIfCacheDisabled() throws Exception { String key1 = "Key1"; String key2 = "Key2"; underTest.get(key1); underTest.get(key1); underTest.get(key2); underTest.get(key2); LOG.info(underTest.stats().toString()); Assert.assertThat(underTest.stats().missCount(), is(equalTo(4L))); } } ``` That is, turning off the cache always results in a cache miss. The test fails, though. Is my interpretation incorrect?

Original source