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RedisHashMap.java
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360 lines (307 loc) · 10.2 KB
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package RedisDataBase;
import Common.RedisUtil;
import sun.misc.Unsafe;
import javax.swing.tree.TreeNode;
import java.lang.reflect.Field;
import java.util.HashMap;
import java.util.Map;
import java.util.Objects;
import java.util.Random;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;
class Node<K,V>{
final int hash;
final K key;
V value;
Node<K,V> next;
Node(int hash, K key, V value, Node<K,V> next) {
this.hash = hash;
this.key = key;
this.value = value;
this.next = next;
}
public final K getKey() { return key; }
public final V getValue() { return value; }
public final int hashCode() {
return Objects.hashCode(key) ^ Objects.hashCode(value);
}
public final boolean equals(Object o) {
if (o == this)
return true;
if (o instanceof Map.Entry) {
Map.Entry<?,?> e = (Map.Entry<?,?>)o;
if (Objects.equals(key, e.getKey()) && Objects.equals(value, e.getValue())) {
return true;
}
}
return false;
}
}
// 用来处理rehash情况
// todo 这里必须要全部重写一遍了,因为自动扩容没有办法控制,即便在rehash的时候也是线程不安全的
class RedisHashMap<K,V> {
Random rand = new Random();
transient Node<K,V>[] table;
int size = 0;
public RedisHashMap(){
this(1);
}
public RedisHashMap(int initialSize){
if(initialSize >= 1048576){
}
table = new Node[tableSizeFor(initialSize)];
}
/* 为了使用多态
* 这里需要使用对象池将原来的对象进行归还
*/
public void remove(Object key,boolean releaseNow) {
Node<K,V> e;
e = removeNode(hash(key), key, null, false);
if(e != null){
RedisUtil.doRelease(e.key,!releaseNow);
doReleaseRedisObject(e.value,false);
}
}
// 这里会进行release
// true代表移除成功, false代表没有这个数据
public Boolean remove2(Object key,boolean releaseNow){
Node<K,V> e;
e = removeNode(hash(key), key, null, false);
if(e != null){
RedisUtil.doRelease(e.key,!releaseNow);
doReleaseRedisObject(e.value,false);
}
return e != null;
}
void doReleaseRedisObject(Object ro,boolean lazy){
if(ro instanceof RedisObject){
RedisObject o = (RedisObject) ro;
RedisUtil.doRelease(o.getData(),lazy);//另外老的value也可以直接释放,因为不会再用到了
}
}
final Node<K,V> removeNode(int hash, Object key, Object value, boolean matchValue) {
Node<K,V>[] tab = table;
Node<K,V> p;
int n = table.length, index;
if ((p = tab[index = (n - 1) & hash]) == null){
return null;
}
Node<K,V> node = null, e; K k; V v;
if (p.hash == hash && ((k = p.key) == key || (key != null && key.equals(k)))){
node = p;
} else if ((e = p.next) != null) {
do {
if (e.hash == hash && ((k = e.key) == key || (key != null && key.equals(k)))) {
node = e;
break;
}
p = e;
} while ((e = e.next) != null);
}
if (node != null && (!matchValue || (v = node.value) == value || (value != null && value.equals(v)))) {
if (node == p) {
tab[index] = node.next;
}
else {
p.next = node.next;
}
--size;
return node;
}
return null;
}
public V get(Object key) {
Node<K,V> e;
return (e = getNode(hash(key), key)) == null ? null : e.value;
}
// protected方法
final Node<K,V> getNode(int hash, Object key) {
Node<K,V>[] tab; Node<K,V> first, e; int n; K k;
if ((tab = table) != null && (n = tab.length) > 0 &&
(first = tab[(n - 1) & hash]) != null) {
if (first.hash == hash && // always check first node
((k = first.key) == key || (key != null && key.equals(k))))
return first;
if ((e = first.next) != null) {
do {
if (e.hash == hash &&
((k = e.key) == key || (key != null && key.equals(k))))
return e;
} while ((e = e.next) != null);
}
}
return null;
}
// return true代表有老数据， return false代表没有老的数据
public boolean put(K key, V value,boolean releaseKeyNow) {
V ret = putVal(hash(key), key, value, false);
if(ret != null){
RedisUtil.doRelease(key,!releaseKeyNow);// 可能延迟释放这次的key,因为后面逻辑处理可能会用到这个key
doReleaseRedisObject(ret,false);
return true;
}
return false;
}
final V putVal(int hash, K key, V value, boolean onlyIfAbsent) {
Node<K,V>[] tab; Node<K,V> p;
int n = table.length;
int i;
tab = table;
if ((p = tab[i = (n - 1) & hash]) == null) {
tab[i] = newNode(hash, key, value, null);
}
else {
Node<K,V> e; K k;
if (p.hash == hash && ((k = p.key) == key || (key != null && key.equals(k)))){
e = p;
} else {
while (true){
if ((e = p.next) == null) {
p.next = newNode(hash, key, value, null);
break;
}
if (e.hash == hash && ((k = e.key) == key || (key != null && key.equals(k)))){
break;
}
p = e;
}
}
if (e != null) { // existing mapping for key
V oldValue = e.value;
if (!onlyIfAbsent || oldValue == null){
e.value = value;
}
// afterNodeAccess(e);
return oldValue;
}
}
++size;
return null;
}
public void rehash(){
if(size > table.length){
regrow();
}else if(size < table.length / 2){
retrim();
}
}
// 自动发起的rehash
// 只能针对普通map
final void regrow(){
Node<K,V>[] oldTab = table;
int oldCap = oldTab.length;
int newCap = oldCap << 1;
Node<K,V>[] newTab = (Node<K,V>[])new Node[newCap];
table = newTab;
for (int j = 0; j < oldCap; ++j) {
Node<K,V> e;
if ((e = oldTab[j]) == null){
continue;
}
oldTab[j] = null;
if (e.next == null){
newTab[e.hash & (newCap - 1)] = e;
continue;
}
// 下面是处理多元素链表的过程,一次遍历将链表分成两部分
Node<K,V> loHead = null, loTail = null;
Node<K,V> hiHead = null, hiTail = null;
Node<K,V> next;
do {
next = e.next;
if ((e.hash & oldCap) == 0) {
if (loTail == null)
loHead = e;
else
loTail.next = e;
loTail = e;
}
else {
if (hiTail == null)
hiHead = e;
else
hiTail.next = e;
hiTail = e;
}
} while ((e = next) != null);
if (loTail != null) {
loTail.next = null;
newTab[j] = loHead;
}
if (hiTail != null) {
hiTail.next = null;
newTab[j + oldCap] = hiHead;
}
}
}
// 自动发起的缩容
// 只能针对普通map
final void retrim(){
Node<K,V>[] oldTab = table;
int oldCap = oldTab.length;
int newCap = oldCap >> 1;
// todo 严重错误
@SuppressWarnings({"rawtypes","unchecked"})
Node<K,V>[] newTab = (Node<K,V>[])new Node[newCap];
table = newTab;
for (int j = 0; j < oldCap / 2; ++j) {
Node<K,V> le = oldTab[j];
Node<K,V> he = oldTab[j + newCap];
oldTab[j] = null;
oldTab[j + newCap] = null;
// 下面是处理多元素链表的过程,一次遍历将j 和 j + newCap的位置都尝试一遍
newTab[j] = mergeSlots(le,he);
}
}
final Node mergeSlots(Node first, Node second){
if(first == null && second == null) return null;
if(first == null || second == null) {return first == null ? second : first;}
// 从头部插入second的最后一个节点
Node sLast = second;
while (sLast.next != null){
sLast = sLast.next;
}
sLast.next = first;
return second;
}
public int size(){return size;}
public int length() {
return table.length;
}
// 首先随机获取一个Entry,这个随机不是真随机,是假随机
// 首先获取一个Node
// 接下来按概率往前走1-4步
public Node random(){
int len = length();
int times = 0;
Node e;
do{
int index = rand.nextInt(len);
e = table[index];
}while (e == null && times++ < 16);
if(e != null && e.next != null){
int step = rand.nextInt(4);
while (e.next != null && step-- > 0){
e = e.next;
}
}
return e;
}
protected int hash(Object key){
int h;
h = (key == null) ? 0 : (h = key.hashCode()) ^ (h >>> 16);
return h;
}
static final int tableSizeFor(int cap) {
int n = cap - 1;
n |= n >>> 1;
n |= n >>> 2;
n |= n >>> 4;
n |= n >>> 8;
n |= n >>> 16;
return (n < 0) ? 1 : n + 1;
}
Node<K,V> newNode(int hash, K key, V value, Node<K,V> next) {
return new Node<>(hash, key, value, next);
}
}
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