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Favor ConcurrentHashMap over lock guarded map #32

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Favor ConcurrentHashMap over lock guarded map #32

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118 changes: 25 additions & 93 deletions common-lib/src/main/java/com/codekutter/common/utils/MapThreadCache.java
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Original file line number Diff line number Diff line change
Expand Up @@ -18,102 +18,57 @@
package com.codekutter.common.utils;

import com.codekutter.common.ICloseDelegate;
import com.google.common.base.Preconditions;

import java.util.Collections;
import java.util.concurrent.ConcurrentHashMap;
import javax.annotation.Nonnull;
import java.io.Closeable;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.locks.ReentrantLock;

public class MapThreadCache<K, V> implements Closeable {
private Map<Long, Map<K, V>> cache = new HashMap<>();
private ReentrantLock cacheLock = new ReentrantLock();
private final Map<Long, Map<K, V>> cache = new ConcurrentHashMap<>();

public V put(@Nonnull K key, @Nonnull V value) {
long threadId = Thread.currentThread().getId();
if (!cache.containsKey(threadId)) {
cacheLock.lock();
try {
if (!cache.containsKey(threadId)) {
Map<K, V> values = new HashMap<>();
cache.put(threadId, values);
}
} finally {
cacheLock.unlock();
}
}
Map<K, V> values = cache.get(threadId);
values.put(key, value);
cache.computeIfAbsent(threadId, k -> new ConcurrentHashMap<>()).put(key, value);
return value;
}

public Map<K, V> get() {
long threadId = Thread.currentThread().getId();
if (cache.containsKey(threadId)) {
return new HashMap<>(cache.get(threadId));
}
return null;
return Collections.unmodifiableMap(cache.getOrDefault(threadId, Collections.emptyMap()));
}

public V get(K key) {
Map<K, V> values = get();
if (values != null && !values.isEmpty()) {
return values.get(key);
}
return null;
return get().get(key);
}

public boolean containsKey(K key) {
if (containsThread()) {
return get().containsKey(key);
}
return false;
return get().containsKey(key);
}

public boolean remove(K key) {
long threadId = Thread.currentThread().getId();
cacheLock.lock();
try {
Map<K, V> values = cache.get(threadId);
if (values != null && !values.isEmpty()) {
if (values.containsKey(key)) {
V value = values.remove(key);
return value != null;
}
Preconditions.checkState(get(key) == null);
}
return false;
} finally {
cacheLock.unlock();
}

Map<K, V> values = cache.getOrDefault(threadId, Collections.emptyMap());
return values.remove(key) != null;
}

public void clear() {
Map<K, V> values = get();
if (values != null) {
values.clear();
cacheLock.lock();
try {
cache.remove(Thread.currentThread().getId());
} finally {
cacheLock.unlock();
}
cache.remove(Thread.currentThread().getId());
}
}

public int size() {
Map<K, V> values = get();
if (values != null) return values.size();
return 0;
return get().size();
}

public void dispose() {
for (long id : cache.keySet()) {
Map<K, V> map = cache.get(id);
map.clear();
}
cache.values().forEach(Map::clear);
cache.clear();
}

Expand All @@ -123,49 +78,26 @@ public boolean containsThread() {

@Override
public void close() throws IOException {
cacheLock.lock();
try {
if (!cache.isEmpty()) {
for (long id : cache.keySet()) {
Map<K, V> map = cache.get(id);
if (!map.isEmpty()) {
for (K key : map.keySet()) {
V value = map.get(key);
if (value instanceof Closeable) {
((Closeable) value).close();
;
}
}
map.clear();
}
for (Map<K, V> eachMap : cache.values()) {
for (V value : eachMap.values()) {
if (value instanceof Closeable) {
((Closeable) value).close();
}
cache.clear();
}
} finally {
cacheLock.unlock();
}
cache.clear();
}

public void close(ICloseDelegate<V> delegate) throws IOException {
cacheLock.lock();
try {
if (!cache.isEmpty()) {
for (long id : cache.keySet()) {
Map<K, V> map = cache.get(id);
if (!map.isEmpty()) {
for (K key : map.keySet()) {
V value = map.get(key);
delegate.close(value);
}
map.clear();
}
for (Map<K, V> eachMap : cache.values()) {
for (V value : eachMap.values()) {
try {
delegate.close(value);
} catch (Exception ex) {
throw new IOException(ex);
}
cache.clear();
}
} catch (Exception ex) {
throw new IOException(ex);
} finally {
cacheLock.unlock();
eachMap.clear();
}
}
}