本文整理了Java中java.util.concurrent.ConcurrentHashMap.compute()方法的一些代码示例，展示了ConcurrentHashMap.compute()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.compute()方法的具体详情如下：
包路径：java.util.concurrent.ConcurrentHashMap
类名称：ConcurrentHashMap
方法名：compute

ConcurrentHashMap.compute介绍

暂无

代码示例

代码示例来源：origin: wildfly/wildfly

public V compute(final K key, final BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
  return backingMap.compute(key, remappingFunction);
}

代码示例来源：origin: GoogleContainerTools/jib

/**
 * Updates the progress for {@link Allocation} atomically relative to the {@code allocation}.
 *
 * <p>For any {@link Allocation}, this method <em>must</em> have been called on all of its parents
 * beforehand.
 *
 * @param allocation the {@link Allocation} to update progress for
 * @param units the units of progress
 * @return {@code true} if the map was updated; {@code false} if {@code allocation} was already
 *     present. Note that this may return {@code true} even if the map was not updated if called
 *     concurrently, but never {@code false} if the map was updated.
 */
boolean updateProgress(Allocation allocation, long units) {
 if (units == 0L) {
  // Puts the allocation in the map if not present, with progress initialized to 0.
  boolean alreadyPresent = completionMap.containsKey(allocation);
  completionMap.computeIfAbsent(allocation, InsertionOrderUnits::new);
  return !alreadyPresent;
 }
 completionMap.compute(
   allocation,
   (ignored, insertionOrderUnits) -> {
    if (insertionOrderUnits == null) {
     insertionOrderUnits = new InsertionOrderUnits(allocation);
    }
    updateInsertionOrderUnits(insertionOrderUnits, units);
    return insertionOrderUnits;
   });
 return true;
}

代码示例来源：origin: google/guava

/**
 * If {@code key} is not already associated with a value or if {@code key} is associated with
 * zero, associate it with {@code newValue}. Returns the previous value associated with {@code
 * key}, or zero if there was no mapping for {@code key}.
 */
long putIfAbsent(K key, long newValue) {
 AtomicBoolean noValue = new AtomicBoolean(false);
 Long result =
   map.compute(
     key,
     (k, oldValue) -> {
      if (oldValue == null || oldValue == 0) {
       noValue.set(true);
       return newValue;
      } else {
       return oldValue;
      }
     });
 return noValue.get() ? 0L : result.longValue();
}

代码示例来源：origin: google/guava

/**
 * Updates the value currently associated with {@code key} with the specified function, and
 * returns the new value. If there is not currently a value associated with {@code key}, the
 * function is applied to {@code 0L}.
 *
 * @since 21.0
 */
@CanIgnoreReturnValue
public long updateAndGet(K key, LongUnaryOperator updaterFunction) {
 checkNotNull(updaterFunction);
 return map.compute(
   key, (k, value) -> updaterFunction.applyAsLong((value == null) ? 0L : value.longValue()));
}

代码示例来源：origin: prestodb/presto

/**
 * If {@code key} is not already associated with a value or if {@code key} is associated with
 * zero, associate it with {@code newValue}. Returns the previous value associated with {@code
 * key}, or zero if there was no mapping for {@code key}.
 */
long putIfAbsent(K key, long newValue) {
 AtomicBoolean noValue = new AtomicBoolean(false);
 Long result =
   map.compute(
     key,
     (k, oldValue) -> {
      if (oldValue == null || oldValue == 0) {
       noValue.set(true);
       return newValue;
      } else {
       return oldValue;
      }
     });
 return noValue.get() ? 0L : result.longValue();
}

代码示例来源：origin: google/guava

/**
 * Updates the value currently associated with {@code key} with the specified function, and
 * returns the old value. If there is not currently a value associated with {@code key}, the
 * function is applied to {@code 0L}.
 *
 * @since 21.0
 */
@CanIgnoreReturnValue
public long getAndUpdate(K key, LongUnaryOperator updaterFunction) {
 checkNotNull(updaterFunction);
 AtomicLong holder = new AtomicLong();
 map.compute(
   key,
   (k, value) -> {
    long oldValue = (value == null) ? 0L : value.longValue();
    holder.set(oldValue);
    return updaterFunction.applyAsLong(oldValue);
   });
 return holder.get();
}

代码示例来源：origin: apache/hbase

V put(K k, Supplier<V> supplier) {
 return ((Payload<V>)map.compute(k, (k1, oldValue) -> {
  if (oldValue != null) {
   oldValue.refCount++;
   return oldValue;
  } else {
   return new Payload(supplier.get());
  }
 })).v;
}

代码示例来源：origin: wildfly/wildfly

/**
 * If {@code key} is not already associated with a value or if {@code key} is associated with
 * zero, associate it with {@code newValue}. Returns the previous value associated with {@code
 * key}, or zero if there was no mapping for {@code key}.
 */
long putIfAbsent(K key, long newValue) {
 AtomicBoolean noValue = new AtomicBoolean(false);
 Long result =
   map.compute(
     key,
     (k, oldValue) -> {
      if (oldValue == null || oldValue == 0) {
       noValue.set(true);
       return newValue;
      } else {
       return oldValue;
      }
     });
 return noValue.get() ? 0L : result.longValue();
}

代码示例来源：origin: oracle/helidon

void evict() {
  cacheMap.forEachKey(evictParallelismThreshold, key -> cacheMap.compute(key, (key1, cacheRecord) -> {
    if ((null == cacheRecord) || evictor.apply(cacheRecord.getKey(), cacheRecord.getValue())) {
      return null;
    } else {
      if (cacheRecord.isValid(cacheTimoutNanos)) {
        return cacheRecord;
      } else {
        return null;
      }
    }
  }));
}

代码示例来源：origin: apache/hbase

@Override
public void put(RegionInfo regionInfo, long size) {
 if (LOG.isTraceEnabled()) {
  LOG.trace("Setting space quota size for " + regionInfo + " to " + size);
 }
 // Atomic. Either sets the new size for the first time, or replaces the existing value.
 store.compute(regionInfo,
  (key,value) -> value == null ? new RegionSizeImpl(size) : value.setSize(size));
}

代码示例来源：origin: apache/hbase

@Override
public void incrementRegionSize(RegionInfo regionInfo, long delta) {
 if (LOG.isTraceEnabled()) {
  LOG.trace("Updating space quota size for " + regionInfo + " with a delta of " + delta);
 }
 // Atomic. Recomputes the stored value with the delta if there is one, otherwise use the delta.
 store.compute(regionInfo,
  (key,value) -> value == null ? new RegionSizeImpl(delta) : value.incrementSize(delta));
}

代码示例来源：origin: wildfly/wildfly

/**
 * Updates the value currently associated with {@code key} with the specified function, and
 * returns the new value. If there is not currently a value associated with {@code key}, the
 * function is applied to {@code 0L}.
 *
 * @since 21.0
 */
@CanIgnoreReturnValue
public long updateAndGet(K key, LongUnaryOperator updaterFunction) {
 checkNotNull(updaterFunction);
 return map.compute(
   key, (k, value) -> updaterFunction.applyAsLong((value == null) ? 0L : value.longValue()));
}

代码示例来源：origin: prestodb/presto

/**
 * Updates the value currently associated with {@code key} with the specified function, and
 * returns the old value. If there is not currently a value associated with {@code key}, the
 * function is applied to {@code 0L}.
 *
 * @since 21.0
 */
@CanIgnoreReturnValue
public long getAndUpdate(K key, LongUnaryOperator updaterFunction) {
 checkNotNull(updaterFunction);
 AtomicLong holder = new AtomicLong();
 map.compute(
   key,
   (k, value) -> {
    long oldValue = (value == null) ? 0L : value.longValue();
    holder.set(oldValue);
    return updaterFunction.applyAsLong(oldValue);
   });
 return holder.get();
}

代码示例来源：origin: prestodb/presto

/**
 * Updates the value currently associated with {@code key} with the specified function, and
 * returns the new value. If there is not currently a value associated with {@code key}, the
 * function is applied to {@code 0L}.
 *
 * @since 21.0
 */
@CanIgnoreReturnValue
public long updateAndGet(K key, LongUnaryOperator updaterFunction) {
 checkNotNull(updaterFunction);
 return map.compute(
   key, (k, value) -> updaterFunction.applyAsLong((value == null) ? 0L : value.longValue()));
}

代码示例来源：origin: ben-manes/caffeine

/**
 * A {@link Map#compute(Object, BiFunction)} that does not directly record any cache statistics.
 *
 * @param key key with which the specified value is to be associated
 * @param remappingFunction the function to compute a value
 * @return the new value associated with the specified key, or null if none
 */
V remap(K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
 // ensures that the removal notification is processed after the removal has completed
 @SuppressWarnings({"unchecked", "rawtypes"})
 V[] oldValue = (V[]) new Object[1];
 RemovalCause[] cause = new RemovalCause[1];
 V nv = data.compute(key, (K k, V value) -> {
  V newValue = remappingFunction.apply(k, value);
  if ((value == null) && (newValue == null)) {
   return null;
  }
  cause[0] = (newValue == null) ? RemovalCause.EXPLICIT : RemovalCause.REPLACED;
  if (hasRemovalListener() && (value != null) && (newValue != value)) {
   oldValue[0] = value;
  }
  return newValue;
 });
 if (oldValue[0] != null) {
  notifyRemoval(key, oldValue[0], cause[0]);
 }
 return nv;
}

代码示例来源：origin: apache/incubator-druid

public DruidServer addDataSegment(DataSegment segment)
{
 // ConcurrentHashMap.compute() ensures that all actions for specific dataSource are linearizable.
 dataSources.compute(
   segment.getDataSource(),
   (dataSourceName, dataSource) -> {
    if (dataSource == null) {
     dataSource = new DruidDataSource(dataSourceName, ImmutableMap.of("client", "side"));
    }
    if (dataSource.addSegmentIfAbsent(segment)) {
     currSize.addAndGet(segment.getSize());
     totalSegments.incrementAndGet();
    } else {
     log.warn("Asked to add data segment that already exists!? server[%s], segment[%s]", getName(), segment);
    }
    return dataSource;
   }
 );
 return this;
}

代码示例来源：origin: ben-manes/caffeine

@Override
public @Nullable V put(K key, V value, boolean notifyWriter) {
 requireNonNull(value);
 // ensures that the removal notification is processed after the removal has completed
 @SuppressWarnings({"unchecked", "rawtypes"})
 V[] oldValue = (V[]) new Object[1];
 if ((writer == CacheWriter.disabledWriter()) || !notifyWriter) {
  oldValue[0] = data.put(key, value);
 } else {
  data.compute(key, (k, v) -> {
   if (value != v) {
    writer.write(key, value);
   }
   oldValue[0] = v;
   return value;
  });
 }
 if (hasRemovalListener() && (oldValue[0] != null) && (oldValue[0] != value)) {
  notifyRemoval(key, oldValue[0], RemovalCause.REPLACED);
 }
 return oldValue[0];
}

代码示例来源：origin: apache/incubator-druid

dataSources.compute(
  segmentId.getDataSource(),
  (dataSourceName, dataSource) -> {

代码示例来源：origin: reactor/reactor-core

@Test
public void shouldPickEvenly() throws Exception {
  int n = 4;
  int m = 25;
  Scheduler scheduler = Schedulers.newParallel("test", n);
  CountDownLatch latch = new CountDownLatch(m*n);
  ConcurrentHashMap<String, Integer> map = new ConcurrentHashMap<>();
  for (int i = 0; i < m * n; i++) {
    scheduler.schedule(() -> {
      String threadName = Thread.currentThread().getName();
      map.compute(threadName, (name, val) -> Optional.ofNullable(val).map(x -> x+1).orElse(1));
      latch.countDown();
    });
  }
  latch.await();
  assertThat(map.values()).containsOnly(m);
}

代码示例来源：origin: Alluxio/alluxio

/**
 * Writes a key/value pair to the cache.
 *
 * @param key the key
 * @param value the value
 */
public void put(K key, V value) {
 mMap.compute(key, (k, entry) -> {
  onPut(key, value);
  if (entry == null && cacheIsFull()) {
   writeToBackingStore(key, value);
   return null;
  }
  if (entry == null || entry.mValue == null) {
   onCacheUpdate(key, value);
   return new Entry(key, value);
  }
  entry.mValue = value;
  entry.mReferenced = true;
  entry.mDirty = true;
  return entry;
 });
 wakeEvictionThreadIfNecessary();
}