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本文主要研究一下 flink 的 InternalTimeServiceManager
InternalTimeServiceManager
flink-streaming-java_2.11-1.7.0-sources.jar!/org/apache/flink/streaming/api/operators/InternalTimeServiceManager.java
@Internal
public class InternalTimeServiceManager<K> {
@VisibleForTesting
static final String TIMER_STATE_PREFIX = “_timer_state”;
@VisibleForTesting
static final String PROCESSING_TIMER_PREFIX = TIMER_STATE_PREFIX + “/processing_”;
@VisibleForTesting
static final String EVENT_TIMER_PREFIX = TIMER_STATE_PREFIX + “/event_”;
private final KeyGroupRange localKeyGroupRange;
private final KeyContext keyContext;
private final PriorityQueueSetFactory priorityQueueSetFactory;
private final ProcessingTimeService processingTimeService;
private final Map<String, InternalTimerServiceImpl<K, ?>> timerServices;
private final boolean useLegacySynchronousSnapshots;
InternalTimeServiceManager(
KeyGroupRange localKeyGroupRange,
KeyContext keyContext,
PriorityQueueSetFactory priorityQueueSetFactory,
ProcessingTimeService processingTimeService, boolean useLegacySynchronousSnapshots) {
this.localKeyGroupRange = Preconditions.checkNotNull(localKeyGroupRange);
this.priorityQueueSetFactory = Preconditions.checkNotNull(priorityQueueSetFactory);
this.keyContext = Preconditions.checkNotNull(keyContext);
this.processingTimeService = Preconditions.checkNotNull(processingTimeService);
this.useLegacySynchronousSnapshots = useLegacySynchronousSnapshots;
this.timerServices = new HashMap<>();
}
@SuppressWarnings(“unchecked”)
public <N> InternalTimerService<N> getInternalTimerService(
String name,
TimerSerializer<K, N> timerSerializer,
Triggerable<K, N> triggerable) {
InternalTimerServiceImpl<K, N> timerService = registerOrGetTimerService(name, timerSerializer);
timerService.startTimerService(
timerSerializer.getKeySerializer(),
timerSerializer.getNamespaceSerializer(),
triggerable);
return timerService;
}
@SuppressWarnings(“unchecked”)
<N> InternalTimerServiceImpl<K, N> registerOrGetTimerService(String name, TimerSerializer<K, N> timerSerializer) {
InternalTimerServiceImpl<K, N> timerService = (InternalTimerServiceImpl<K, N>) timerServices.get(name);
if (timerService == null) {
timerService = new InternalTimerServiceImpl<>(
localKeyGroupRange,
keyContext,
processingTimeService,
createTimerPriorityQueue(PROCESSING_TIMER_PREFIX + name, timerSerializer),
createTimerPriorityQueue(EVENT_TIMER_PREFIX + name, timerSerializer));
timerServices.put(name, timerService);
}
return timerService;
}
Map<String, InternalTimerServiceImpl<K, ?>> getRegisteredTimerServices() {
return Collections.unmodifiableMap(timerServices);
}
private <N> KeyGroupedInternalPriorityQueue<TimerHeapInternalTimer<K, N>> createTimerPriorityQueue(
String name,
TimerSerializer<K, N> timerSerializer) {
return priorityQueueSetFactory.create(
name,
timerSerializer);
}
public void advanceWatermark(Watermark watermark) throws Exception {
for (InternalTimerServiceImpl<?, ?> service : timerServices.values()) {
service.advanceWatermark(watermark.getTimestamp());
}
}
////////////////// Fault Tolerance Methods ///////////////////
public void snapshotStateForKeyGroup(DataOutputView stream, int keyGroupIdx) throws IOException {
Preconditions.checkState(useLegacySynchronousSnapshots);
InternalTimerServiceSerializationProxy<K> serializationProxy =
new InternalTimerServiceSerializationProxy<>(this, keyGroupIdx);
serializationProxy.write(stream);
}
public void restoreStateForKeyGroup(
InputStream stream,
int keyGroupIdx,
ClassLoader userCodeClassLoader) throws IOException {
InternalTimerServiceSerializationProxy<K> serializationProxy =
new InternalTimerServiceSerializationProxy<>(
this,
userCodeClassLoader,
keyGroupIdx);
serializationProxy.read(stream);
}
//////////////////// Methods used ONLY IN TESTS ////////////////////
@VisibleForTesting
public int numProcessingTimeTimers() {
int count = 0;
for (InternalTimerServiceImpl<?, ?> timerService : timerServices.values()) {
count += timerService.numProcessingTimeTimers();
}
return count;
}
@VisibleForTesting
public int numEventTimeTimers() {
int count = 0;
for (InternalTimerServiceImpl<?, ?> timerService : timerServices.values()) {
count += timerService.numEventTimeTimers();
}
return count;
}
}
InternalTimeServiceManager 用于管理所有 keyed operators 要使用的 timerService，它在内存使用 map 维护了 timerService 的名称与 InternalTimerServiceImpl 的映射
getInternalTimerService 方法首先调用 registerOrGetTimerService 方法获取或创建指定 name 的 InternalTimerServiceImpl，之后调用 timerService.startTimerService 进行初始化然后返回
registerOrGetTimerService 方法先从名为 timerServices 的 map 中查找指定 name 的 InternalTimerServiceImpl，没有就创建一个，然后放入到名为 timerServices 的 map 中；创建 InternalTimerServiceImpl 的时候，这里使用 createTimerPriorityQueue 来创建 KeyGroupedInternalPriorityQueue 类型的 processingTimeTimersQueue 及 eventTimeTimersQueue；createTimerPriorityQueue 是通过 priorityQueueSetFactory 来创建的
PriorityQueueSetFactory
flink-runtime_2.11-1.7.0-sources.jar!/org/apache/flink/runtime/state/PriorityQueueSetFactory.java
public interface PriorityQueueSetFactory {
@Nonnull
<T extends HeapPriorityQueueElement & PriorityComparable & Keyed> KeyGroupedInternalPriorityQueue<T> create(
@Nonnull String stateName,
@Nonnull TypeSerializer<T> byteOrderedElementSerializer);
}
PriorityQueueSetFactory 定义了 create 方法，创建的是 KeyGroupedInternalPriorityQueue，其中 T 的泛型要求是同时继承或实现 HeapPriorityQueueElement、PriorityComparable、Keyed 这三个接口
HeapPriorityQueueElement
flink-runtime_2.11-1.7.0-sources.jar!/org/apache/flink/runtime/state/heap/HeapPriorityQueueElement.java
@Internal
public interface HeapPriorityQueueElement {
/**
* The index that indicates that a {@link HeapPriorityQueueElement} object is not contained in and managed by any
* {@link HeapPriorityQueue}. We do not strictly enforce that internal indexes must be reset to this value when
* elements are removed from a {@link HeapPriorityQueue}.
*/
int NOT_CONTAINED = Integer.MIN_VALUE;
/**
* Returns the current index of this object in the internal array of {@link HeapPriorityQueue}.
*/
int getInternalIndex();
/**
* Sets the current index of this object in the {@link HeapPriorityQueue} and should only be called by the owning
* {@link HeapPriorityQueue}.
*
* @param newIndex the new index in the timer heap.
*/
void setInternalIndex(int newIndex);
}
HeapPriorityQueueElement 接口定义了 HeapPriorityQueue 所要求的元素类型，它定义了 getInternalIndex、setInternalIndex 方法
PriorityComparable
flink-runtime_2.11-1.7.0-sources.jar!/org/apache/flink/runtime/state/PriorityComparable.java
public interface PriorityComparable<T> {
int comparePriorityTo(@Nonnull T other);
}
PriorityComparable 定义了 comparePriorityTo 方法，用于根据 priority 来进行比对
Keyed
flink-runtime_2.11-1.7.0-sources.jar!/org/apache/flink/runtime/state/Keyed.java
public interface Keyed<K> {
K getKey();
}
Keyed 接口定义了 getKey 方法，用于返回该对象的 key
InternalTimer
flink-streaming-java_2.11-1.7.0-sources.jar!/org/apache/flink/streaming/api/operators/InternalTimer.java
@Internal
public interface InternalTimer<K, N> extends PriorityComparable<InternalTimer<?, ?>>, Keyed<K> {
/** Function to extract the key from a {@link InternalTimer}. */
KeyExtractorFunction<InternalTimer<?, ?>> KEY_EXTRACTOR_FUNCTION = InternalTimer::getKey;
/** Function to compare instances of {@link InternalTimer}. */
PriorityComparator<InternalTimer<?, ?>> TIMER_COMPARATOR =
(left, right) -> Long.compare(left.getTimestamp(), right.getTimestamp());
/**
* Returns the timestamp of the timer. This value determines the point in time when the timer will fire.
*/
long getTimestamp();
/**
* Returns the key that is bound to this timer.
*/
@Nonnull
@Override
K getKey();
/**
* Returns the namespace that is bound to this timer.
*/
@Nonnull
N getNamespace();
}
InternalTimer 继承了 PriorityComparable、Keyed 接口，它定义了 getTimestamp、getKey、getNamespace 方法，同时内置了 KEY_EXTRACTOR_FUNCTION、TIMER_COMPARATOR
TimerHeapInternalTimer
flink-streaming-java_2.11-1.7.0-sources.jar!/org/apache/flink/streaming/api/operators/TimerHeapInternalTimer.java
@Internal
public final class TimerHeapInternalTimer<K, N> implements InternalTimer<K, N>, HeapPriorityQueueElement {
/** The key for which the timer is scoped. */
@Nonnull
private final K key;
/** The namespace for which the timer is scoped. */
@Nonnull
private final N namespace;
/** The expiration timestamp. */
private final long timestamp;
private transient int timerHeapIndex;
TimerHeapInternalTimer(long timestamp, @Nonnull K key, @Nonnull N namespace) {
this.timestamp = timestamp;
this.key = key;
this.namespace = namespace;
this.timerHeapIndex = NOT_CONTAINED;
}
@Override
public long getTimestamp() {
return timestamp;
}
@Nonnull
@Override
public K getKey() {
return key;
}
@Nonnull
@Override
public N getNamespace() {
return namespace;
}
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (o instanceof InternalTimer) {
InternalTimer<?, ?> timer = (InternalTimer<?, ?>) o;
return timestamp == timer.getTimestamp()
&& key.equals(timer.getKey())
&& namespace.equals(timer.getNamespace());
}
return false;
}
@Override
public int getInternalIndex() {
return timerHeapIndex;
}
@Override
public void setInternalIndex(int newIndex) {
this.timerHeapIndex = newIndex;
}
void removedFromTimerQueue() {
setInternalIndex(NOT_CONTAINED);
}
@Override
public int hashCode() {
int result = (int) (timestamp ^ (timestamp >>> 32));
result = 31 * result + key.hashCode();
result = 31 * result + namespace.hashCode();
return result;
}
@Override
public String toString() {
return “Timer{” +
“timestamp=” + timestamp +
“, key=” + key +
“, namespace=” + namespace +
‘}’;
}
@Override
public int comparePriorityTo(@Nonnull InternalTimer<?, ?> other) {
return Long.compare(timestamp, other.getTimestamp());
}
}
TimerHeapInternalTimer 实现了 InternalTimer 及 HeapPriorityQueueElement 接口；这里 removedFromTimerQueue 接口是调用 setInternalIndex(NOT_CONTAINED)，即改动其 index 为 NOT_CONTAINED，逻辑删除
HeapPriorityQueueSetFactory
flink-runtime_2.11-1.7.0-sources.jar!/org/apache/flink/runtime/state/heap/HeapPriorityQueueSetFactory.java
public class HeapPriorityQueueSetFactory implements PriorityQueueSetFactory {
@Nonnull
private final KeyGroupRange keyGroupRange;
@Nonnegative
private final int totalKeyGroups;
@Nonnegative
private final int minimumCapacity;
public HeapPriorityQueueSetFactory(
@Nonnull KeyGroupRange keyGroupRange,
@Nonnegative int totalKeyGroups,
@Nonnegative int minimumCapacity) {
this.keyGroupRange = keyGroupRange;
this.totalKeyGroups = totalKeyGroups;
this.minimumCapacity = minimumCapacity;
}
@Nonnull
@Override
public <T extends HeapPriorityQueueElement & PriorityComparable & Keyed> HeapPriorityQueueSet<T> create(
@Nonnull String stateName,
@Nonnull TypeSerializer<T> byteOrderedElementSerializer) {
return new HeapPriorityQueueSet<>(
PriorityComparator.forPriorityComparableObjects(),
KeyExtractorFunction.forKeyedObjects(),
minimumCapacity,
keyGroupRange,
totalKeyGroups);
}
}
HeapPriorityQueueSetFactory 实现了 PriorityQueueSetFactory 接口，其 create 方法创建的是 HeapPriorityQueueSet
小结
InternalTimeServiceManager 用于管理所有 keyed operators 要使用的 timerService，它在内存使用 map 维护了 timerService 的名称与 InternalTimerServiceImpl 的映射；getInternalTimerService 方法首先调用 registerOrGetTimerService 方法获取或创建指定 name 的 InternalTimerServiceImpl，之后调用 timerService.startTimerService 进行初始化然后返回
registerOrGetTimerService 方法先从名为 timerServices 的 map 中查找指定 name 的 InternalTimerServiceImpl，没有就创建一个，然后放入到名为 timerServices 的 map 中；创建 InternalTimerServiceImpl 的时候，这里使用 createTimerPriorityQueue 来创建 KeyGroupedInternalPriorityQueue 类型的 processingTimeTimersQueue 及 eventTimeTimersQueue；createTimerPriorityQueue 是通过 priorityQueueSetFactory 来创建的
PriorityQueueSetFactory 定义了 create 方法，创建的是 KeyGroupedInternalPriorityQueue，其中 T 的泛型要求是同时继承或实现 HeapPriorityQueueElement、PriorityComparable、Keyed 这三个接口 (InternalTimer 继承了 PriorityComparable、Keyed 接口，TimerHeapInternalTimer 实现了 InternalTimer 及 HeapPriorityQueueElement 接口)；HeapPriorityQueueSetFactory 实现了 PriorityQueueSetFactory 接口，其 create 方法创建的是 HeapPriorityQueueSet
doc
InternalTimeServiceManager
