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org.apache.kafka.streams.state.internals.NamedCache Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.kafka.streams.state.internals;
import java.util.NavigableMap;
import java.util.TreeMap;
import java.util.TreeSet;
import org.apache.kafka.common.metrics.Sensor;
import org.apache.kafka.common.utils.Bytes;
import org.apache.kafka.streams.KeyValue;
import org.apache.kafka.streams.processor.internals.metrics.StreamsMetricsImpl;
import org.apache.kafka.streams.state.internals.metrics.NamedCacheMetrics;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Set;
class NamedCache {
private static final Logger log = LoggerFactory.getLogger(NamedCache.class);
private final String name;
private final String storeName;
private final String taskName;
private final NavigableMap cache = new TreeMap<>();
private final Set dirtyKeys = new LinkedHashSet<>();
private ThreadCache.DirtyEntryFlushListener listener;
private LRUNode tail;
private LRUNode head;
private long currentSizeBytes;
private final StreamsMetricsImpl streamsMetrics;
private final Sensor hitRatioSensor;
// internal stats
private long numReadHits = 0;
private long numReadMisses = 0;
private long numOverwrites = 0;
private long numFlushes = 0;
NamedCache(final String name, final StreamsMetricsImpl streamsMetrics) {
this.name = name;
this.streamsMetrics = streamsMetrics;
storeName = ThreadCache.underlyingStoreNamefromCacheName(name);
taskName = ThreadCache.taskIDfromCacheName(name);
hitRatioSensor = NamedCacheMetrics.hitRatioSensor(
streamsMetrics,
Thread.currentThread().getName(),
taskName,
storeName
);
}
synchronized final String name() {
return name;
}
synchronized long hits() {
return numReadHits;
}
synchronized long misses() {
return numReadMisses;
}
synchronized long overwrites() {
return numOverwrites;
}
synchronized long flushes() {
return numFlushes;
}
synchronized LRUCacheEntry get(final Bytes key) {
if (key == null) {
return null;
}
final LRUNode node = getInternal(key);
if (node == null) {
return null;
}
updateLRU(node);
return node.entry;
}
synchronized void setListener(final ThreadCache.DirtyEntryFlushListener listener) {
this.listener = listener;
}
synchronized void flush() {
flush(null);
}
private void flush(final LRUNode evicted) {
numFlushes++;
if (log.isTraceEnabled()) {
log.trace("Named cache {} stats on flush: #hits={}, #misses={}, #overwrites={}, #flushes={}",
name, hits(), misses(), overwrites(), flushes());
}
if (listener == null) {
throw new IllegalArgumentException("No listener for namespace " + name + " registered with cache");
}
if (dirtyKeys.isEmpty()) {
return;
}
final List entries = new ArrayList<>();
final List deleted = new ArrayList<>();
// evicted already been removed from the cache so add it to the list of
// flushed entries and remove from dirtyKeys.
if (evicted != null) {
entries.add(new ThreadCache.DirtyEntry(evicted.key, evicted.entry.value(), evicted.entry));
dirtyKeys.remove(evicted.key);
}
for (final Bytes key : dirtyKeys) {
final LRUNode node = getInternal(key);
if (node == null) {
throw new IllegalStateException("Key = " + key + " found in dirty key set, but entry is null");
}
entries.add(new ThreadCache.DirtyEntry(key, node.entry.value(), node.entry));
node.entry.markClean();
if (node.entry.value() == null) {
deleted.add(node.key);
}
}
// clear dirtyKeys before the listener is applied as it may be re-entrant.
dirtyKeys.clear();
listener.apply(entries);
for (final Bytes key : deleted) {
delete(key);
}
}
synchronized void put(final Bytes key, final LRUCacheEntry value) {
if (!value.isDirty() && dirtyKeys.contains(key)) {
throw new IllegalStateException(
String.format(
"Attempting to put a clean entry for key [%s] into NamedCache [%s] when it already contains a dirty entry for the same key",
key, name
)
);
}
LRUNode node = cache.get(key);
if (node != null) {
numOverwrites++;
currentSizeBytes -= node.size();
node.update(value);
updateLRU(node);
} else {
node = new LRUNode(key, value);
// put element
putHead(node);
cache.put(key, node);
}
if (value.isDirty()) {
// first remove and then add so we can maintain ordering as the arrival order of the records.
dirtyKeys.remove(key);
dirtyKeys.add(key);
}
currentSizeBytes += node.size();
}
synchronized long sizeInBytes() {
return currentSizeBytes;
}
private LRUNode getInternal(final Bytes key) {
final LRUNode node = cache.get(key);
if (node == null) {
numReadMisses++;
return null;
} else {
numReadHits++;
hitRatioSensor.record((double) numReadHits / (double) (numReadHits + numReadMisses));
}
return node;
}
private void updateLRU(final LRUNode node) {
remove(node);
putHead(node);
}
private void remove(final LRUNode node) {
if (node.previous != null) {
node.previous.next = node.next;
} else {
head = node.next;
}
if (node.next != null) {
node.next.previous = node.previous;
} else {
tail = node.previous;
}
}
private void putHead(final LRUNode node) {
node.next = head;
node.previous = null;
if (head != null) {
head.previous = node;
}
head = node;
if (tail == null) {
tail = head;
}
}
synchronized void evict() {
if (tail == null) {
return;
}
final LRUNode eldest = tail;
currentSizeBytes -= eldest.size();
remove(eldest);
cache.remove(eldest.key);
if (eldest.entry.isDirty()) {
flush(eldest);
}
}
synchronized LRUCacheEntry putIfAbsent(final Bytes key, final LRUCacheEntry value) {
final LRUCacheEntry originalValue = get(key);
if (originalValue == null) {
put(key, value);
}
return originalValue;
}
synchronized void putAll(final List> entries) {
for (final KeyValue entry : entries) {
put(Bytes.wrap(entry.key), entry.value);
}
}
synchronized LRUCacheEntry delete(final Bytes key) {
final LRUNode node = cache.remove(key);
if (node == null) {
return null;
}
remove(node);
dirtyKeys.remove(key);
currentSizeBytes -= node.size();
return node.entry();
}
public long size() {
return cache.size();
}
public boolean isEmpty() {
return cache.isEmpty();
}
synchronized Iterator keyRange(final Bytes from, final Bytes to, final boolean toInclusive) {
return keySetIterator(cache.navigableKeySet().subSet(from, true, to, toInclusive), true);
}
synchronized Iterator reverseKeyRange(final Bytes from, final Bytes to) {
return keySetIterator(cache.navigableKeySet().subSet(from, true, to, true), false);
}
private Iterator keySetIterator(final Set keySet, final boolean forward) {
if (forward) {
return new TreeSet<>(keySet).iterator();
} else {
return new TreeSet<>(keySet).descendingIterator();
}
}
synchronized Iterator allKeys() {
return keySetIterator(cache.navigableKeySet(), true);
}
synchronized Iterator reverseAllKeys() {
return keySetIterator(cache.navigableKeySet(), false);
}
synchronized LRUCacheEntry first() {
if (head == null) {
return null;
}
return head.entry;
}
synchronized LRUCacheEntry last() {
if (tail == null) {
return null;
}
return tail.entry;
}
synchronized LRUNode head() {
return head;
}
synchronized LRUNode tail() {
return tail;
}
synchronized void close() {
head = tail = null;
listener = null;
currentSizeBytes = 0;
dirtyKeys.clear();
cache.clear();
streamsMetrics.removeAllCacheLevelSensors(Thread.currentThread().getName(), taskName, storeName);
}
/**
* A simple wrapper class to implement a doubly-linked list around MemoryLRUCacheBytesEntry
*/
static class LRUNode {
private final Bytes key;
private LRUCacheEntry entry;
private LRUNode previous;
private LRUNode next;
LRUNode(final Bytes key, final LRUCacheEntry entry) {
this.key = key;
this.entry = entry;
}
LRUCacheEntry entry() {
return entry;
}
Bytes key() {
return key;
}
long size() {
return key.get().length +
8 + // entry
8 + // previous
8 + // next
entry.size();
}
LRUNode next() {
return next;
}
LRUNode previous() {
return previous;
}
private void update(final LRUCacheEntry entry) {
this.entry = entry;
}
}
}
