guava cache RemovalListener not called

Question

I created a cache with the following parameters:

cacheTempFiles = CacheBuilder.newBuilder().maximumSize(250).expireAfterWrite(15, TimeUnit.SECONDS).removalListener(new RemovalListener<String, Path>()
        {

            @Override
            public void onRemoval(RemovalNotification<String, Path> notification)
            {
                deleteTemporaryFile(notification.getValue());

            }
        }).build();

Moreover, I'm calling every 2 minutes cacheTempFiles.cleanUp(); . However, it seems that onRemoval is never called.

What is missing in my implementation?

Answer 1

It definitely should work, see example below:

@Test
public void shouldCallRemovalListener() {
    AtomicInteger counter = new AtomicInteger();
    MutableClock clock = MutableClock.epochUTC();
    Ticker ticker = new Ticker() {
        @Override
        public long read() {
            return TimeUnit.MILLISECONDS.toNanos(clock.millis());
        }
    };
    Path tmpPath = Path.of("/tmp");

    Cache<String, Path> cacheTempFiles = CacheBuilder.newBuilder()
            .ticker(ticker)
            .maximumSize(250)
            .expireAfterWrite(15, TimeUnit.SECONDS)
            .removalListener(
                    (RemovalNotification<String, Path> notification) ->
                            System.out.println(String.format(
                                    "Delete '%s -> %s' (%d times)",
                                    notification.getKey(), notification.getValue(), counter.incrementAndGet())))
            .build();
    cacheTempFiles.put("tmp", tmpPath);

    assertThat(cacheTempFiles.asMap()).containsOnly(Assertions.entry("tmp", tmpPath));
    assertThat(counter).hasValue(0);

    clock.add(Duration.ofSeconds(20));
    cacheTempFiles.cleanUp();

    assertThat(cacheTempFiles.asMap()).isEmpty();
    assertThat(counter).hasValue(1);
}

Passes and outputs Delete 'tmp -> /tmp' (1 times) .