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本文主要研究一下Elasticsearch的ConcurrentMapLong
ConcurrentMapLong
elasticsearch-7.0.1/server/src/main/java/org/elasticsearch/common/util/concurrent/ConcurrentMapLong.java
public interface ConcurrentMapLong<T> extends ConcurrentMap<Long, T> { T get(long key); T remove(long key); T put(long key, T value); T putIfAbsent(long key, T value);}- ConcurrentMapLong继承了ConcurrentMap接口，并指定key类型为Long
ConcurrentHashMapLong
elasticsearch-7.0.1/server/src/main/java/org/elasticsearch/common/util/concurrent/ConcurrentHashMapLong.java
public class ConcurrentHashMapLong<T> implements ConcurrentMapLong<T> { private final ConcurrentMap<Long, T> map; public ConcurrentHashMapLong(ConcurrentMap<Long, T> map) { this.map = map; } @Override public T get(long key) { return map.get(key); } @Override public T remove(long key) { return map.remove(key); } @Override public T put(long key, T value) { return map.put(key, value); } @Override public T putIfAbsent(long key, T value) { return map.putIfAbsent(key, value); } // MAP DELEGATION @Override public boolean isEmpty() { return map.isEmpty(); } @Override public int size() { return map.size(); } @Override public T get(Object key) { return map.get(key); } @Override public boolean containsKey(Object key) { return map.containsKey(key); } @Override public boolean containsValue(Object value) { return map.containsValue(value); } @Override public T put(Long key, T value) { return map.put(key, value); } @Override public T putIfAbsent(Long key, T value) { return map.putIfAbsent(key, value); } @Override public void putAll(Map<? extends Long, ? extends T> m) { map.putAll(m); } @Override public T remove(Object key) { return map.remove(key); } @Override public boolean remove(Object key, Object value) { return map.remove(key, value); } @Override public boolean replace(Long key, T oldValue, T newValue) { return map.replace(key, oldValue, newValue); } @Override public T replace(Long key, T value) { return map.replace(key, value); } @Override public void clear() { map.clear(); } @Override public Set<Long> keySet() { return map.keySet(); } @Override public Collection<T> values() { return map.values(); } @Override public Set<Entry<Long, T>> entrySet() { return map.entrySet(); } @Override public boolean equals(Object o) { return map.equals(o); } @Override public int hashCode() { return map.hashCode(); } @Override public String toString() { return map.toString(); }}- ConcurrentHashMapLong实现了ConcurrentMapLong接口，它内部使用ConcurrentMap实现
ConcurrentCollections
elasticsearch-7.0.1/server/src/main/java/org/elasticsearch/common/util/concurrent/ConcurrentCollections.java
public abstract class ConcurrentCollections { static final int aggressiveConcurrencyLevel; static { aggressiveConcurrencyLevel = Math.max(Runtime.getRuntime().availableProcessors() * 2, 16); } //...... public static <K, V> ConcurrentMap<K, V> newConcurrentMap() { return new ConcurrentHashMap<>(); } public static <V> ConcurrentMapLong<V> newConcurrentMapLong() { return new ConcurrentHashMapLong<>(ConcurrentCollections.<Long, V>newConcurrentMap()); } public static <V> ConcurrentMapLong<V> newConcurrentMapLongWithAggressiveConcurrency() { return new ConcurrentHashMapLong<>(ConcurrentCollections.<Long, V>newConcurrentMapWithAggressiveConcurrency()); } public static <K, V> ConcurrentMap<K, V> newConcurrentMapWithAggressiveConcurrency() { return newConcurrentMapWithAggressiveConcurrency(16); } public static <K, V> ConcurrentMap<K, V> newConcurrentMapWithAggressiveConcurrency(int initalCapacity) { return new ConcurrentHashMap<>(initalCapacity, 0.75f, aggressiveConcurrencyLevel); } //......}- ConcurrentCollections提供了newConcurrentMapLong及newConcurrentMapLongWithAggressiveConcurrency两个静态方法用于创建ConcurrentMapLong；其中newConcurrentMapLongWithAggressiveConcurrency方法创建initalCapacity为16，loadFactor为0.75f，concurrencyLevel为aggressiveConcurrencyLevel(
Math.max(Runtime.getRuntime().availableProcessors() * 2, 16))的ConcurrentHashMap
小结
- ConcurrentMapLong继承了ConcurrentMap接口，并指定key类型为Long
- ConcurrentHashMapLong实现了ConcurrentMapLong接口，它内部使用ConcurrentMap实现
- ConcurrentCollections提供了newConcurrentMapLong及newConcurrentMapLongWithAggressiveConcurrency两个静态方法用于创建ConcurrentMapLong；其中newConcurrentMapLongWithAggressiveConcurrency方法创建initalCapacity为16，loadFactor为0.75f，concurrencyLevel为aggressiveConcurrencyLevel(
Math.max(Runtime.getRuntime().availableProcessors() * 2, 16))的ConcurrentHashMap
doc
- ConcurrentMapLong
- ConcurrentHashMapLong
- ConcurrentCollections