本文整理了Java中java.util.concurrent.ConcurrentHashMap.putIfAbsent()方法的一些代码示例，展示了ConcurrentHashMap.putIfAbsent()的具体用法。这些代码示例主要来源于Github/Stackoverflow/Maven等平台，是从一些精选项目中提取出来的代码，具有较强的参考意义，能在一定程度帮忙到你。ConcurrentHashMap.putIfAbsent()方法的具体详情如下：
包路径：java.util.concurrent.ConcurrentHashMap
类名称：ConcurrentHashMap
方法名：putIfAbsent

ConcurrentHashMap.putIfAbsent介绍

暂无

代码示例

代码示例来源：origin: Netflix/zuul

protected Deque<PooledConnection> getPoolForEventLoop(EventLoop eventLoop)
{
  // We don't want to block under any circumstances, so can't use CHM.computeIfAbsent().
  // Instead we accept the slight inefficiency of an unnecessary instantiation of a ConcurrentLinkedDeque.
  Deque<PooledConnection> pool = connectionsPerEventLoop.get(eventLoop);
  if (pool == null) {
    pool = new ConcurrentLinkedDeque<>();
    connectionsPerEventLoop.putIfAbsent(eventLoop, pool);
  }
  return pool;
}

代码示例来源：origin: alibaba/jstorm

public MemoryMapStateBacking(String id) {
  this.db = (Map<List<Object>, T>) _dbs.get(id);
  if (db == null) {
    db = new HashMap<List<Object>, T>();
    Map<List<Object>, T> tmp = (Map<List<Object>, T>)
        _dbs.putIfAbsent(id, (Map<List<Object>, Object>)db);
    if (tmp != null) {
      db = tmp;
    }
  }
}

代码示例来源：origin: alibaba/jstorm

protected ConcurrentLinkedQueue<DRPCRequest> acquireQueue(String function) {
  ConcurrentLinkedQueue<DRPCRequest> reqQueue = requestQueues.get(function);
  if (reqQueue == null) {
    reqQueue = new ConcurrentLinkedQueue<>();
    ConcurrentLinkedQueue<DRPCRequest> tmp = requestQueues.putIfAbsent(function, reqQueue);
    if (tmp != null) {
      reqQueue = tmp;
    }
  }
  return reqQueue;
}

代码示例来源：origin: alibaba/jstorm

public Map<Integer, TkHbCacheTime> getTaskHeartbeatsCache(String topologyId, boolean createIfNotExist) {
  Map<Integer, TkHbCacheTime> ret;
  ret = taskHeartbeatsCache.get(topologyId);
  if (ret == null && createIfNotExist) {
    ret = new ConcurrentHashMap<>();
    Map<Integer, TkHbCacheTime> tmp = taskHeartbeatsCache.putIfAbsent(topologyId, ret);
    if (tmp != null) {
      ret = tmp;
    }
  }
  return ret;
}

代码示例来源：origin: apache/storm

private ConcurrentLinkedQueue<OutstandingRequest> getQueue(String function) {
  if (function == null) {
    throw new IllegalArgumentException("The function for a request cannot be null");
  }
  ConcurrentLinkedQueue<OutstandingRequest> queue = _queues.get(function);
  if (queue == null) {
    _queues.putIfAbsent(function, new ConcurrentLinkedQueue<>());
    queue = _queues.get(function);
  }
  return queue;
}

代码示例来源：origin: thinkaurelius/titan

@Override
public Locker getLocker(String lockerName) {
  Preconditions.checkNotNull(lockerName);
  Locker l = lockers.get(lockerName);
  if (null == l) {
    l = lockerCreator.apply(lockerName);
    final Locker x = lockers.putIfAbsent(lockerName, l);
    if (null != x) {
      l = x;
    }
  }
  return l;
}

代码示例来源：origin: apache/incubator-dubbo

public static <T> ProviderInvokerWrapper<T> registerProvider(Invoker<T> invoker, URL registryUrl, URL providerUrl) {
  ProviderInvokerWrapper<T> wrapperInvoker = new ProviderInvokerWrapper<>(invoker, registryUrl, providerUrl);
  String serviceUniqueName = providerUrl.getServiceKey();
  ConcurrentMap<Invoker, ProviderInvokerWrapper> invokers = providerInvokers.get(serviceUniqueName);
  if (invokers == null) {
    providerInvokers.putIfAbsent(serviceUniqueName, new ConcurrentHashMap<>());
    invokers = providerInvokers.get(serviceUniqueName);
  }
  invokers.put(invoker, wrapperInvoker);
  return wrapperInvoker;
}

代码示例来源：origin: apache/incubator-dubbo

public static <T> ProviderInvokerWrapper<T> registerProvider(Invoker<T> invoker, URL registryUrl, URL providerUrl) {
  ProviderInvokerWrapper<T> wrapperInvoker = new ProviderInvokerWrapper<>(invoker, registryUrl, providerUrl);
  String serviceUniqueName = providerUrl.getServiceKey();
  ConcurrentMap<Invoker, ProviderInvokerWrapper> invokers = providerInvokers.get(serviceUniqueName);
  if (invokers == null) {
    providerInvokers.putIfAbsent(serviceUniqueName, new ConcurrentHashMap<>());
    invokers = providerInvokers.get(serviceUniqueName);
  }
  invokers.put(invoker, wrapperInvoker);
  return wrapperInvoker;
}

代码示例来源：origin: apache/incubator-shardingsphere

@Override
  public String getDataSource(final String name, final String masterDataSourceName, final List<String> slaveDataSourceNames) {
    AtomicInteger count = COUNT_MAP.containsKey(name) ? COUNT_MAP.get(name) : new AtomicInteger(0);
    COUNT_MAP.putIfAbsent(name, count);
    count.compareAndSet(slaveDataSourceNames.size(), 0);
    return slaveDataSourceNames.get(Math.abs(count.getAndIncrement()) % slaveDataSourceNames.size());
  }
}

代码示例来源：origin: apache/zookeeper

private AvgMinMaxPercentileCounter getCounterForKey(String key) {
  AvgMinMaxPercentileCounter counter = counters.get(key);
  if (counter == null) {
    counters.putIfAbsent(key, new AvgMinMaxPercentileCounter(key + "_" + name));
    counter = counters.get(key);
  }
  return counter;
}

代码示例来源：origin: apache/zookeeper

private AvgMinMaxCounter getCounterForKey(String key) {
  AvgMinMaxCounter counter = counters.get(key);
  if (counter == null) {
    counters.putIfAbsent(key, new AvgMinMaxCounter(key + "_" + name));
    counter = counters.get(key);
  }
  return counter;
}

代码示例来源：origin: apache/storm

private static LocalServer getLocalServer(String nodeId, int port) {
  String key = nodeId + "-" + port;
  LocalServer ret = _registry.get(key);
  if (ret == null) {
    ret = new LocalServer(port);
    LocalServer tmp = _registry.putIfAbsent(key, ret);
    if (tmp != null) {
      ret = tmp;
    }
  }
  return ret;
}

代码示例来源：origin: weibocom/motan

private void addServiceListener(URL url, ServiceListener serviceListener) {
  String service = ConsulUtils.getUrlClusterInfo(url);
  ConcurrentHashMap<URL, ServiceListener> map = serviceListeners.get(service);
  if (map == null) {
    serviceListeners.putIfAbsent(service, new ConcurrentHashMap<URL, ServiceListener>());
    map = serviceListeners.get(service);
  }
  synchronized (map) {
    map.put(url, serviceListener);
  }
}

代码示例来源：origin: weibocom/motan

private void addCommandListener(URL url, CommandListener commandListener) {
  String group = url.getGroup();
  ConcurrentHashMap<URL, CommandListener> map = commandListeners.get(group);
  if (map == null) {
    commandListeners.putIfAbsent(group, new ConcurrentHashMap<URL, CommandListener>());
    map = commandListeners.get(group);
  }
  synchronized (map) {
    map.put(url, commandListener);
  }
}

代码示例来源：origin: thinkaurelius/titan

@Override
public KeyColumnValueStore openDatabase(final String name, StoreMetaData.Container metaData) throws BackendException {
  if (!stores.containsKey(name)) {
    stores.putIfAbsent(name, new InMemoryKeyColumnValueStore(name));
  }
  KeyColumnValueStore store = stores.get(name);
  Preconditions.checkNotNull(store);
  return store;
}

代码示例来源：origin: weibocom/motan

private void addToFailedMap(ConcurrentHashMap<URL, ConcurrentHashSet<NotifyListener>> failedMap, URL url, NotifyListener listener) {
  Set<NotifyListener> listeners = failedMap.get(url);
  if (listeners == null) {
    failedMap.putIfAbsent(url, new ConcurrentHashSet<NotifyListener>());
    listeners = failedMap.get(url);
  }
  listeners.add(listener);
}

代码示例来源：origin: weibocom/motan

private static StatInfo getServiceStat(String uri) {
  StatInfo stat = serviceStat.get(uri);
  if (stat == null) {
    stat = new StatInfo();
    serviceStat.putIfAbsent(uri, stat);
    stat = serviceStat.get(uri);
  }
  return stat;
}

代码示例来源：origin: apache/incubator-dubbo

public static void registerConsumer(Invoker invoker, URL registryUrl, URL consumerUrl, RegistryDirectory registryDirectory) {
  ConsumerInvokerWrapper wrapperInvoker = new ConsumerInvokerWrapper(invoker, registryUrl, consumerUrl, registryDirectory);
  String serviceUniqueName = consumerUrl.getServiceKey();
  Set<ConsumerInvokerWrapper> invokers = consumerInvokers.get(serviceUniqueName);
  if (invokers == null) {
    consumerInvokers.putIfAbsent(serviceUniqueName, new ConcurrentHashSet<ConsumerInvokerWrapper>());
    invokers = consumerInvokers.get(serviceUniqueName);
  }
  invokers.add(wrapperInvoker);
}

代码示例来源：origin: apache/incubator-dubbo

public static void registerConsumer(Invoker invoker, URL registryUrl, URL consumerUrl, RegistryDirectory registryDirectory) {
  ConsumerInvokerWrapper wrapperInvoker = new ConsumerInvokerWrapper(invoker, registryUrl, consumerUrl, registryDirectory);
  String serviceUniqueName = consumerUrl.getServiceKey();
  Set<ConsumerInvokerWrapper> invokers = consumerInvokers.get(serviceUniqueName);
  if (invokers == null) {
    consumerInvokers.putIfAbsent(serviceUniqueName, new ConcurrentHashSet<ConsumerInvokerWrapper>());
    invokers = consumerInvokers.get(serviceUniqueName);
  }
  invokers.add(wrapperInvoker);
}

代码示例来源：origin: lets-blade/blade

public static ClassDefine create(Class<?> clazz) {
  ClassDefine classDefine = pool.get(clazz);
  if (classDefine == null) {
    classDefine = new ClassDefine(clazz);
    ClassDefine old = pool.putIfAbsent(clazz, classDefine);
    if (old != null) {
      classDefine = old;
    }
  }
  return classDefine;
}