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
暂无
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();
}内容来源于网络，如有侵权，请联系作者删除！