com.ly.mybatis.mapperservice.holder.ConcurrentReferenceHashMap Maven / Gradle / Ivy
package com.ly.mybatis.mapperservice.holder;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ObjectUtils;
import java.lang.ref.*;
import java.lang.reflect.Array;
import java.util.*;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.locks.ReentrantLock;
@SuppressWarnings("all")
public class ConcurrentReferenceHashMap extends AbstractMap implements ConcurrentMap {
private static final int DEFAULT_INITIAL_CAPACITY = 16;
private static final float DEFAULT_LOAD_FACTOR = 0.75f;
private static final int DEFAULT_CONCURRENCY_LEVEL = 16;
private static final ReferenceType DEFAULT_REFERENCE_TYPE = ReferenceType.SOFT;
private static final int MAXIMUM_CONCURRENCY_LEVEL = 1 << 16;
private static final int MAXIMUM_SEGMENT_SIZE = 1 << 30;
private final Segment[] segments;
private final float loadFactor;
private final ReferenceType referenceType;
private final int shift;
@Nullable
private volatile Set> entrySet;
public ConcurrentReferenceHashMap() {
this(DEFAULT_INITIAL_CAPACITY, DEFAULT_LOAD_FACTOR, DEFAULT_CONCURRENCY_LEVEL, DEFAULT_REFERENCE_TYPE);
}
@SuppressWarnings("unchecked")
public ConcurrentReferenceHashMap(
int initialCapacity, float loadFactor, int concurrencyLevel, ReferenceType referenceType
) {
Assert.isTrue(initialCapacity >= 0, "Initial capacity must not be negative");
Assert.isTrue(loadFactor > 0f, "Load factor must be positive");
Assert.isTrue(concurrencyLevel > 0, "Concurrency level must be positive");
Assert.notNull(referenceType, "Reference type must not be null");
this.loadFactor = loadFactor;
this.shift = calculateShift(concurrencyLevel, MAXIMUM_CONCURRENCY_LEVEL);
int size = 1 << this.shift;
this.referenceType = referenceType;
int roundedUpSegmentCapacity = (int) ((initialCapacity + size - 1L) / size);
int initialSize = 1 << calculateShift(roundedUpSegmentCapacity, MAXIMUM_SEGMENT_SIZE);
Segment[] segments = (Segment[]) Array.newInstance(Segment.class, size);
int resizeThreshold = (int) (initialSize * getLoadFactor());
for (int i = 0; i < segments.length; i++) {
segments[i] = new Segment(initialSize, resizeThreshold);
}
this.segments = segments;
}
public ConcurrentReferenceHashMap(int initialCapacity) {
this(initialCapacity, DEFAULT_LOAD_FACTOR, DEFAULT_CONCURRENCY_LEVEL, DEFAULT_REFERENCE_TYPE);
}
public ConcurrentReferenceHashMap(int initialCapacity, float loadFactor) {
this(initialCapacity, loadFactor, DEFAULT_CONCURRENCY_LEVEL, DEFAULT_REFERENCE_TYPE);
}
public ConcurrentReferenceHashMap(int initialCapacity, int concurrencyLevel) {
this(initialCapacity, DEFAULT_LOAD_FACTOR, concurrencyLevel, DEFAULT_REFERENCE_TYPE);
}
public ConcurrentReferenceHashMap(int initialCapacity, ReferenceType referenceType) {
this(initialCapacity, DEFAULT_LOAD_FACTOR, DEFAULT_CONCURRENCY_LEVEL, referenceType);
}
public ConcurrentReferenceHashMap(int initialCapacity, float loadFactor, int concurrencyLevel) {
this(initialCapacity, loadFactor, concurrencyLevel, DEFAULT_REFERENCE_TYPE);
}
protected static int calculateShift(int minimumValue, int maximumValue) {
int shift = 0;
int value = 1;
while (value < minimumValue && value < maximumValue) {
value <<= 1;
shift++;
}
return shift;
}
@Override
@Nullable
public V getOrDefault(@Nullable Object key, @Nullable V defaultValue) {
Reference ref = getReference(key, Restructure.WHEN_NECESSARY);
Entry entry = (ref != null ? ref.get() : null);
return (entry != null ? entry.getValue() : defaultValue);
}
@Override
@Nullable
public V putIfAbsent(@Nullable K key, @Nullable V value) {
return put(key, value, false);
}
@Override
public boolean remove(Object key, final Object value) {
Boolean result = doTask(key, new Task(TaskOption.RESTRUCTURE_AFTER, TaskOption.SKIP_IF_EMPTY) {
@Override
protected Boolean execute(@Nullable Reference ref, @Nullable Entry entry) {
if (entry != null && ObjectUtils.nullSafeEquals(entry.getValue(), value)) {
if (ref != null) {
ref.release();
}
return true;
}
return false;
}
});
return (Boolean.TRUE.equals(result));
}
@Override
public boolean replace(K key, final V oldValue, final V newValue) {
Boolean result = doTask(key, new Task(TaskOption.RESTRUCTURE_BEFORE, TaskOption.SKIP_IF_EMPTY) {
@Override
protected Boolean execute(@Nullable Reference ref, @Nullable Entry entry) {
if (entry != null && ObjectUtils.nullSafeEquals(entry.getValue(), oldValue)) {
entry.setValue(newValue);
return true;
}
return false;
}
});
return (Boolean.TRUE.equals(result));
}
@Override
@Nullable
public V replace(K key, final V value) {
return doTask(key, new Task(TaskOption.RESTRUCTURE_BEFORE, TaskOption.SKIP_IF_EMPTY) {
@Override
@Nullable
protected V execute(@Nullable Reference ref, @Nullable Entry entry) {
if (entry != null) {
V oldValue = entry.getValue();
entry.setValue(value);
return oldValue;
}
return null;
}
});
}
public void purgeUnreferencedEntries() {
for (Segment segment : this.segments) {
segment.restructureIfNecessary(false);
}
}
@Override
public int size() {
int size = 0;
for (Segment segment : this.segments) {
size += segment.getCount();
}
return size;
}
@Override
public boolean isEmpty() {
for (Segment segment : this.segments) {
if (segment.getCount() > 0) {
return false;
}
}
return true;
}
@Override
public boolean containsKey(@Nullable Object key) {
Reference ref = getReference(key, Restructure.WHEN_NECESSARY);
Entry entry = (ref != null ? ref.get() : null);
return (entry != null && ObjectUtils.nullSafeEquals(entry.getKey(), key));
}
@Override
@Nullable
public V get(@Nullable Object key) {
Reference ref = getReference(key, Restructure.WHEN_NECESSARY);
Entry entry = (ref != null ? ref.get() : null);
return (entry != null ? entry.getValue() : null);
}
@Override
@Nullable
public V put(@Nullable K key, @Nullable V value) {
return put(key, value, true);
}
@Override
@Nullable
public V remove(Object key) {
return doTask(key, new Task(TaskOption.RESTRUCTURE_AFTER, TaskOption.SKIP_IF_EMPTY) {
@Override
@Nullable
protected V execute(@Nullable Reference ref, @Nullable Entry entry) {
if (entry != null) {
if (ref != null) {
ref.release();
}
return entry.value;
}
return null;
}
});
}
@Override
public void clear() {
for (Segment segment : this.segments) {
segment.clear();
}
}
@Override
public Set> entrySet() {
Set> entrySet = this.entrySet;
if (entrySet == null) {
entrySet = new EntrySet();
this.entrySet = entrySet;
}
return entrySet;
}
protected final float getLoadFactor() {
return this.loadFactor;
}
@Nullable
protected final Reference getReference(@Nullable Object key, Restructure restructure) {
int hash = getHash(key);
return getSegmentForHash(hash).getReference(key, hash, restructure);
}
protected int getHash(@Nullable Object o) {
int hash = (o != null ? o.hashCode() : 0);
hash += (hash << 15) ^ 0xffffcd7d;
hash ^= (hash >>> 10);
hash += (hash << 3);
hash ^= (hash >>> 6);
hash += (hash << 2) + (hash << 14);
hash ^= (hash >>> 16);
return hash;
}
protected final int getSegmentsSize() {
return this.segments.length;
}
protected final Segment getSegment(int index) {
return this.segments[index];
}
protected ReferenceManager createReferenceManager() {
return new ReferenceManager();
}
@Nullable
private V put(@Nullable final K key, @Nullable final V value, final boolean overwriteExisting) {
return doTask(key, new Task(TaskOption.RESTRUCTURE_BEFORE, TaskOption.RESIZE) {
@Override
@Nullable
protected V execute(
@Nullable Reference ref,
@Nullable Entry entry,
@Nullable Entries entries
) {
if (entry != null) {
V oldValue = entry.getValue();
if (overwriteExisting) {
entry.setValue(value);
}
return oldValue;
}
Assert.state(entries != null, "No entries segment");
entries.add(value);
return null;
}
});
}
@Nullable
private T doTask(@Nullable Object key, Task task) {
int hash = getHash(key);
return getSegmentForHash(hash).doTask(hash, key, task);
}
private Segment getSegmentForHash(int hash) {
return this.segments[(hash >>> (32 - this.shift)) & (this.segments.length - 1)];
}
public enum ReferenceType {
SOFT,
WEAK
}
private enum TaskOption {
RESTRUCTURE_BEFORE, RESTRUCTURE_AFTER, SKIP_IF_EMPTY, RESIZE
}
protected enum Restructure {
WHEN_NECESSARY, NEVER
}
protected interface Reference {
@Nullable
Entry get();
int getHash();
@Nullable
Reference getNext();
void release();
}
private interface Entries {
void add(@Nullable V value);
}
protected static final class Entry implements Map.Entry {
@Nullable
private final K key;
@Nullable
private volatile V value;
public Entry(@Nullable K key, @Nullable V value) {
this.key = key;
this.value = value;
}
@Override
public final int hashCode() {
return (ObjectUtils.nullSafeHashCode(this.key) ^ ObjectUtils.nullSafeHashCode(this.value));
}
@Override
@SuppressWarnings("rawtypes")
public final boolean equals(@Nullable Object other) {
if (this == other) {
return true;
}
if (!(other instanceof Map.Entry)) {
return false;
}
Map.Entry otherEntry = (Map.Entry) other;
return (
ObjectUtils.nullSafeEquals(getKey(), otherEntry.getKey()) &&
ObjectUtils.nullSafeEquals(getValue(), otherEntry.getValue())
);
}
@Override
public String toString() {
return (this.key + "=" + this.value);
}
@Override
@Nullable
public K getKey() {
return this.key;
}
@Override
@Nullable
public V getValue() {
return this.value;
}
@Override
@Nullable
public V setValue(@Nullable V value) {
V previous = this.value;
this.value = value;
return previous;
}
}
private static final class SoftEntryReference extends SoftReference> implements Reference {
private final int hash;
@Nullable
private final Reference nextReference;
public SoftEntryReference(
Entry entry, int hash, @Nullable Reference next,
ReferenceQueue> queue
) {
super(entry, queue);
this.hash = hash;
this.nextReference = next;
}
@Override
public int getHash() {
return this.hash;
}
@Override
@Nullable
public Reference getNext() {
return this.nextReference;
}
@Override
public void release() {
enqueue();
clear();
}
}
private static final class WeakEntryReference extends WeakReference> implements Reference {
private final int hash;
@Nullable
private final Reference nextReference;
public WeakEntryReference(
Entry entry, int hash, @Nullable Reference next,
ReferenceQueue> queue
) {
super(entry, queue);
this.hash = hash;
this.nextReference = next;
}
@Override
public int getHash() {
return this.hash;
}
@Override
@Nullable
public Reference getNext() {
return this.nextReference;
}
@Override
public void release() {
enqueue();
clear();
}
}
@SuppressWarnings("serial")
protected final class Segment extends ReentrantLock {
private final ReferenceManager referenceManager;
private final int initialSize;
private final AtomicInteger count = new AtomicInteger(0);
private volatile Reference[] references;
private int resizeThreshold;
public Segment(int initialSize, int resizeThreshold) {
this.referenceManager = createReferenceManager();
this.initialSize = initialSize;
this.references = createReferenceArray(initialSize);
this.resizeThreshold = resizeThreshold;
}
@Nullable
public Reference getReference(@Nullable Object key, int hash, Restructure restructure) {
if (restructure == Restructure.WHEN_NECESSARY) {
restructureIfNecessary(false);
}
if (this.count.get() == 0) {
return null;
}
Reference[] references = this.references;
int index = getIndex(hash, references);
Reference head = references[index];
return findInChain(head, key, hash);
}
@Nullable
public T doTask(final int hash, @Nullable final Object key, final Task task) {
boolean resize = task.hasOption(TaskOption.RESIZE);
if (task.hasOption(TaskOption.RESTRUCTURE_BEFORE)) {
restructureIfNecessary(resize);
}
if (task.hasOption(TaskOption.SKIP_IF_EMPTY) && this.count.get() == 0) {
return task.execute(null, null, null);
}
lock();
try {
final int index = getIndex(hash, this.references);
final Reference head = this.references[index];
Reference ref = findInChain(head, key, hash);
Entry entry = (ref != null ? ref.get() : null);
Entries entries = value -> {
@SuppressWarnings("unchecked")
Entry newEntry = new Entry<>((K) key, value);
Reference newReference = Segment.this.referenceManager.createReference(newEntry, hash, head);
Segment.this.references[index] = newReference;
Segment.this.count.incrementAndGet();
};
return task.execute(ref, entry, entries);
} finally {
unlock();
if (task.hasOption(TaskOption.RESTRUCTURE_AFTER)) {
restructureIfNecessary(resize);
}
}
}
public void clear() {
if (this.count.get() == 0) {
return;
}
lock();
try {
this.references = createReferenceArray(this.initialSize);
this.resizeThreshold = (int) (this.references.length * getLoadFactor());
this.count.set(0);
} finally {
unlock();
}
}
public final int getSize() {
return this.references.length;
}
public final int getCount() {
return this.count.get();
}
protected final void restructureIfNecessary(boolean allowResize) {
int currCount = this.count.get();
boolean needsResize = allowResize && (currCount > 0 && currCount >= this.resizeThreshold);
Reference ref = this.referenceManager.pollForPurge();
if (ref != null || (needsResize)) {
restructure(allowResize, ref);
}
}
@SuppressWarnings({"rawtypes", "unchecked"})
private Reference[] createReferenceArray(int size) {
return new Reference[size];
}
private int getIndex(int hash, Reference[] references) {
return (hash & (references.length - 1));
}
@Nullable
private Reference findInChain(Reference ref, @Nullable Object key, int hash) {
Reference currRef = ref;
while (currRef != null) {
if (currRef.getHash() == hash) {
Entry entry = currRef.get();
if (entry != null) {
K entryKey = entry.getKey();
if (ObjectUtils.nullSafeEquals(entryKey, key)) {
return currRef;
}
}
}
currRef = currRef.getNext();
}
return null;
}
private void restructure(boolean allowResize, @Nullable Reference ref) {
boolean needsResize;
lock();
try {
int countAfterRestructure = this.count.get();
Set> toPurge = Collections.emptySet();
if (ref != null) {
toPurge = new HashSet<>();
while (ref != null) {
toPurge.add(ref);
ref = this.referenceManager.pollForPurge();
}
}
countAfterRestructure -= toPurge.size();
needsResize = (countAfterRestructure > 0 && countAfterRestructure >= this.resizeThreshold);
boolean resizing = false;
int restructureSize = this.references.length;
if (allowResize && needsResize && restructureSize < MAXIMUM_SEGMENT_SIZE) {
restructureSize <<= 1;
resizing = true;
}
Reference[] restructured =
(resizing ? createReferenceArray(restructureSize) : this.references);
for (int i = 0; i < this.references.length; i++) {
ref = this.references[i];
if (!resizing) {
restructured[i] = null;
}
while (ref != null) {
if (!toPurge.contains(ref)) {
Entry entry = ref.get();
if (entry != null) {
int index = getIndex(ref.getHash(), restructured);
restructured[index] = this.referenceManager.createReference(
entry, ref.getHash(), restructured[index]);
}
}
ref = ref.getNext();
}
}
if (resizing) {
this.references = restructured;
this.resizeThreshold = (int) (this.references.length * getLoadFactor());
}
this.count.set(Math.max(countAfterRestructure, 0));
} finally {
unlock();
}
}
}
private abstract class Task {
private final EnumSet options;
public Task(TaskOption... options) {
this.options = (options.length == 0 ? EnumSet.noneOf(TaskOption.class) : EnumSet.of(options[0], options));
}
public boolean hasOption(TaskOption option) {
return this.options.contains(option);
}
@Nullable
protected T execute(@Nullable Reference ref, @Nullable Entry entry, @Nullable Entries entries) {
return execute(ref, entry);
}
@Nullable
protected T execute(@Nullable Reference ref, @Nullable Entry entry) {
return null;
}
}
private class EntrySet extends AbstractSet> {
@Override
public Iterator> iterator() {
return new EntryIterator();
}
@Override
public int size() {
return ConcurrentReferenceHashMap.this.size();
}
@Override
public boolean contains(@Nullable Object o) {
if (o instanceof Map.Entry) {
Map.Entry entry = (Map.Entry) o;
Reference ref = ConcurrentReferenceHashMap.this.getReference(
entry.getKey(),
Restructure.NEVER
);
Entry otherEntry = (ref != null ? ref.get() : null);
if (otherEntry != null) {
return ObjectUtils.nullSafeEquals(otherEntry.getValue(), otherEntry.getValue());
}
}
return false;
}
@Override
public boolean remove(Object o) {
if (o instanceof Map.Entry) {
Map.Entry entry = (Map.Entry) o;
return ConcurrentReferenceHashMap.this.remove(
entry.getKey(),
entry.getValue()
);
}
return false;
}
@Override
public void clear() {
ConcurrentReferenceHashMap.this.clear();
}
}
private class EntryIterator implements Iterator> {
private int segmentIndex;
private int referenceIndex;
@Nullable
private Reference[] references;
@Nullable
private Reference reference;
@Nullable
private Entry next;
@Nullable
private Entry last;
public EntryIterator() {
moveToNextSegment();
}
@Override
public boolean hasNext() {
getNextIfNecessary();
return (this.next != null);
}
@Override
public Entry next() {
getNextIfNecessary();
if (this.next == null) {
throw new NoSuchElementException();
}
this.last = this.next;
this.next = null;
return this.last;
}
@Override
public void remove() {
Assert.state(this.last != null, "No element to remove");
ConcurrentReferenceHashMap.this.remove(this.last.getKey());
}
private void moveToNextSegment() {
this.reference = null;
this.references = null;
if (this.segmentIndex < ConcurrentReferenceHashMap.this.segments.length) {
this.references = ConcurrentReferenceHashMap.this.segments[this.segmentIndex].references;
this.segmentIndex++;
}
}
private void getNextIfNecessary() {
while (this.next == null) {
moveToNextReference();
if (this.reference == null) {
return;
}
this.next = this.reference.get();
}
}
private void moveToNextReference() {
if (this.reference != null) {
this.reference = this.reference.getNext();
}
while (this.reference == null && this.references != null) {
if (this.referenceIndex >= this.references.length) {
moveToNextSegment();
this.referenceIndex = 0;
} else {
this.reference = this.references[this.referenceIndex];
this.referenceIndex++;
}
}
}
}
protected class ReferenceManager {
private final ReferenceQueue> queue = new ReferenceQueue<>();
public Reference createReference(Entry entry, int hash, @Nullable Reference next) {
if (ConcurrentReferenceHashMap.this.referenceType == ReferenceType.WEAK) {
return new WeakEntryReference<>(entry, hash, next, this.queue);
}
return new SoftEntryReference<>(entry, hash, next, this.queue);
}
@SuppressWarnings("unchecked")
@Nullable
public Reference pollForPurge() {
return (Reference) this.queue.poll();
}
}
}
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