Examples of com.google.appengine.api.memcache.MemcacheService.increment()

com.google.appengine.api.memcache.MemcacheService.increment()

Atomically fetches, increments, and stores a given integral value. "Integral" types are {@link Byte}, {@link Short}, {@link Integer}, {@link Long}, and in some cases {@link String}. The entry must already exist, and have a non-negative value.

Incrementing by positive amounts will reach signed 64-bit max ( {@code 2^63 - 1}) and then wrap-around to signed 64-bit min ( {@code -2^63}), continuing increments from that point.

To facilitate use as an atomic countdown, incrementing by a negative value (i.e. decrementing) will not go below zero: incrementing {@code 2} by{@code -5} will return {@code 0}, not {@code -3}.

Note: The actual representation of all numbers in Memcache is a string. This means if you initially stored a number as a string (e.g., "10") and then increment it, everything will work properly.

When you {@link #get(Object)} a key for a string value, wrapping occursafter exceeding the max value of an unsigned 64-bit number ( {@code 2^64 - 1}). When you {@link #get(Object)} a keyfor a numerical type, wrapping occurs after exceeding the type max value. @param key the key of the entry to manipulate @param delta the size of the increment, positive or negative @return the post-increment value, as a long. However, a{@link #get(Object)} of the key will still have the original type ({@link Byte}, {@link Short}, etc.). If there is no entry for {@code key}, returns {@code null}. @throws IllegalArgumentException if {@code key} is not{@link Serializable} and is not {@code null} @throws InvalidValueException if the object incremented is not of aintegral type or holding a negative value

        memcache.setNamespace("News");
        headlines = (List<String>) memcache.get("headlines");


        memcache.put("work_done", 0);


        Long workDone = memcache.increment("work_done", 1);


        Stats stats = memcache.getStatistics();
        int ageOfOldestItemMillis = stats.getMaxTimeWithoutAccess();


        memcache.setErrorHandler(new StrictErrorHandler());

     */
    @Test
    public void memcacheIncrement() throws Exception {
        tester.setUp();
        MemcacheService ms = MemcacheServiceFactory.getMemcacheService();
        ms.increment("aaa", 1, 1L);
        tester.tearDown();
        ApiProxy.setDelegate(AppEngineTester.apiProxyLocalImpl);
        ApiProxy.setEnvironmentForCurrentThread(new TestEnvironment());
        assertThat(ms.contains("aaa"), is(false));
    }

      memcacheKeys.add(memcacheKey);
    }
    // memcache.incrementAll(memcacheKeys, 1, 0L);
    // broken method ↑
    for (String key : memcacheKeys) {
      memcache.increment(key, 1, 0L);
    }


    return null;
  }

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