java.util.concurrent.atomic.AtomicInteger#getAndSet()源码实例Demo

@Test
public void testFileScan() throws Exception {
    File file = new File("build");
    FileScanner fileScanner = new FileScanner(file,10);
    AtomicInteger counter = new AtomicInteger();
    counter.getAndSet(0);
    Listener listener = event -> counter.getAndIncrement();
    fileScanner.registerListener(listener);
    Thread f = new Thread(fileScanner);
    f.start();
    TimeUnit.MILLISECONDS.sleep(50);
    FileWriter myWriter = new FileWriter("build/test.txt");
    myWriter.write("test");
    myWriter.close();
    TimeUnit.MILLISECONDS.sleep(50);
    FileUtils.deleteDir(new File("build/test.txt"));
    TimeUnit.MILLISECONDS.sleep(50);
    assertEquals(2,counter.get());
}
 

public static void main(String[] args) {
    int temValue = 0;
    AtomicInteger value = new AtomicInteger(0);
    temValue = value.getAndSet(3);
    // 首先get，获取到当前value的值为0，并赋值给temValue，之后设置新值3，此时value为3
    System.out.println("temValue = " + temValue + " value = " + value);

    temValue = value.getAndIncrement();
    System.out.println("temValue = " + temValue + " value = " + value);

    temValue = value.getAndDecrement();
    System.out.println("temValue = " + temValue + " value = " + value);

    temValue = value.getAndAdd(10);
    System.out.println("temValue = " + temValue + " value = " + value);
}
 

public static <T> T invoke(Callable<T> method, DomainNames domain) throws Exception {
    if (!initialized) {
        throw new IllegalStateException("RetryPolicyAdapter should be initialized before invoking api calls");
    }
    AtomicInteger retryCountForDomain = getRetryCountForDomain(domain);
    while (retryCountForDomain.get() < DEFAULT_MAX_RETRIES) {
        try {
            sleepIfLimitIsExceeded(domain);
            T result = method.call();
            retryCountForDomain.getAndSet(0);
            return result;
        } catch (ApiException e) {
            if (isRateLimited(e) || isInternalServerError(e)) {
                sleepAndIncrementCounter(domain);
                logger.info("Retrying, # of retries: " + retryCountForDomain + "  error code:" + e.getCode());
            } else {
                throw e;
            }
        }
    }
    throw new Exception("Max number of api call tries exceeded");
}
 

private static AtomicInteger createTextureHandle() {
	int newHandle = -1;
	if (HANDLE_CACHE.size() >= MAX_TEXTURES) {
		AtomicInteger reusedHandle = HANDLE_CACHE.poll();
		newHandle = reusedHandle.getAndSet(-1);
	}

	if (newHandle == -1) {
		int[] textures = new int[1];
		GLES20.glGenTextures(1, textures, 0);
		newHandle = textures[0];
	}
	AtomicInteger result = new AtomicInteger(newHandle);
	HANDLE_CACHE.add(result);

	return result;
}
 

@Test
public void forwardsCalls() {
  AutoConfiguredLoadBalancer lb =
      (AutoConfiguredLoadBalancer) lbf.newLoadBalancer(new TestHelper());

  final AtomicInteger calls = new AtomicInteger();
  TestLoadBalancer testlb = new TestLoadBalancer() {

    @Override
    public void handleNameResolutionError(Status error) {
      calls.getAndSet(1);
    }

    @Override
    public void handleSubchannelState(Subchannel subchannel, ConnectivityStateInfo stateInfo) {
      calls.getAndSet(2);
    }

    @Override
    public void shutdown() {
      calls.getAndSet(3);
    }
  };

  lb.setDelegate(testlb);

  lb.handleNameResolutionError(Status.RESOURCE_EXHAUSTED);
  assertThat(calls.getAndSet(0)).isEqualTo(1);

  lb.handleSubchannelState(null, null);
  assertThat(calls.getAndSet(0)).isEqualTo(2);

  lb.shutdown();
  assertThat(calls.getAndSet(0)).isEqualTo(3);
}
 

/**
 * Updates the number of threads that can be simultaneously used for
 * executing processors.
 *
 * @param maxThreadCount This method must be called while holding the write
 * lock!
 */
private void setMaxThreadCount(final int maxThreadCount, final FlowEngine engine, final AtomicInteger maxThreads) {
    if (maxThreadCount < 1) {
        throw new IllegalArgumentException();
    }

    maxThreads.getAndSet(maxThreadCount);
    if (null != engine && engine.getCorePoolSize() < maxThreadCount) {
        engine.setCorePoolSize(maxThreads.intValue());
    }
}
 

@Test
public void testClear() {
    AsyncLoadingCache<String, Integer> cachedResult = new AsyncLoadingCache<>(30000);
    AtomicInteger value = new AtomicInteger(111);
    Supplier<CompletableFuture<Integer>> supplier = () -> CompletableFuture.supplyAsync(value::get);

    consistently("we get the original value", () -> cachedResult.orElseGet("a-key", supplier).join(), is(111), 10, 2);
    value.getAndSet(222);
    consistently("we still see the cached value", () -> cachedResult.orElseGet("a-key", supplier).join(), is(111), 10, 2);
    cachedResult.clear();
    consistently("we see the new value", () -> cachedResult.orElseGet("a-key", supplier).join(), is(222), 10, 2);
}
 

public static void main(final String[] args) throws Exception
    {
        // * base-7.0.2.2
        //   pipeline= 2 (ack every 1):    OK, > 60000 updates/sec
        //   pipeline= 4 (ack every 2):    OK, >100000 updates/sec
        //   pipeline=10 (ack every 5):    Stops after 4 updates
        int pipeline = 4;
        if (args.length == 1)
            pipeline = Integer.parseInt(args[0]);

        final PVAClient pva = new PVAClient();
        final PVAChannel channel = pva.getChannel("spam");
        channel.connect().get(5, TimeUnit.SECONDS);

        AtomicInteger updates = new AtomicInteger();
        final AutoCloseable subscription = channel.subscribe("", pipeline, (ch, changes, overruns, data) ->
        {
            updates.incrementAndGet();
            // System.out.println(data);
        });

        while (true)
        {
            TimeUnit.SECONDS.sleep(10);
            final int got = updates.getAndSet(0);
            System.err.println("pipeline=" + pipeline + " got " + got + " updates in 10 seconds, " + got/10 + " per sec");
        }

//        subscription.close();
//        channel.close();
//        pva.close();
    }
 

private static void sleepIfLimitIsExceeded(DomainNames domain) throws InterruptedException {
    AtomicInteger apiCallCount = getCounterForDomain(domain);
    if ((apiCallCount.get()) >= (getLimitForDomain(domain))) {
        long current = System.currentTimeMillis();
        int sleepTime = 60000 - (int) (current - startTime);
        startTime = current;
        apiCallCount.getAndSet(0);
        logger.warn("thread will sleep for :" + sleepTime + " milliseconds.");
        Thread.sleep(sleepTime);
    }
}
 

@SuppressWarnings("deprecation")
@Test
public void forwardsCalls() {
  AutoConfiguredLoadBalancer lb = lbf.newLoadBalancer(new TestHelper());

  final AtomicInteger calls = new AtomicInteger();
  TestLoadBalancer testlb = new TestLoadBalancer() {

    @Override
    public void handleNameResolutionError(Status error) {
      calls.getAndSet(1);
    }

    @Override
    public void handleSubchannelState(Subchannel subchannel, ConnectivityStateInfo stateInfo) {
      calls.getAndSet(2);
    }

    @Override
    public void shutdown() {
      calls.getAndSet(3);
    }
  };

  lb.setDelegate(testlb);

  lb.handleNameResolutionError(Status.RESOURCE_EXHAUSTED);
  assertThat(calls.getAndSet(0)).isEqualTo(1);

  lb.handleSubchannelState(null, null);
  assertThat(calls.getAndSet(0)).isEqualTo(2);

  lb.shutdown();
  assertThat(calls.getAndSet(0)).isEqualTo(3);
}
 

/**
 * Updates the number of threads that can be simultaneously used for executing processors.
 * This method must be called while holding the write lock!
 *
 * @param maxThreadCount max number of threads
 */
private void setMaxThreadCount(final int maxThreadCount, final FlowEngine engine, final AtomicInteger maxThreads) {
    if (maxThreadCount < 1) {
        throw new IllegalArgumentException("Cannot set max number of threads to less than 2");
    }

    maxThreads.getAndSet(maxThreadCount);
    if (null != engine && engine.getCorePoolSize() < maxThreadCount) {
        engine.setCorePoolSize(maxThreads.intValue());
    }
}
 

@OpenCLMapping(atomic32 = true, mapTo = "atomic_xchg")
protected final int atomicXchg(AtomicInteger p, int newVal) {
 return p.getAndSet(newVal);
}