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scouter.util.CacheTable Maven / Gradle / Ivy
/*
* Copyright 2015 the original author or authors.
* @https://github.com/scouter-project/scouter
*
* Licensed 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.
*
*
* The initial idea for this class is from "org.apache.commons.lang.IntHashMap";
* http://commons.apache.org/commons-lang-2.6-src.zip
*
*/
package scouter.util;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.NoSuchElementException;
/**
* HashTable with entry expiration.
* - it use only active expiration : delete entry when access expired data
* @param Key type
* @param Value type
*/
public class CacheTable {
private static final int DEFAULT_CAPACITY = 101;
private static final float DEFAULT_LOAD_FACTOR = 0.75f;
private ENTRY table[];
private ENTRY header;
private int count;
private int threshold;
private float loadFactor;
private long defaultKeepTime = 0;
public CacheTable() {
this(DEFAULT_CAPACITY, DEFAULT_LOAD_FACTOR);
}
public CacheTable(int initCapacity, float loadFactor) {
if (initCapacity < 0)
throw new RuntimeException("Capacity Error: " + initCapacity);
if (loadFactor <= 0)
throw new RuntimeException("Load Count Error: " + loadFactor);
if (initCapacity == 0)
initCapacity = 1;
this.loadFactor = loadFactor;
this.table = new ENTRY[initCapacity];
this.header = new ENTRY(null, null, 0, null);
this.header.link_next = header.link_prev = header;
threshold = (int) (initCapacity * loadFactor);
}
public int size() {
return count;
}
public synchronized Enumeration keys() {
return new Enumer(TYPE.KEYS);
}
public synchronized Enumeration values() {
return new Enumer(TYPE.VALUES);
}
public synchronized Enumeration> entries() {
return new Enumer(TYPE.ENTRIES);
}
public synchronized boolean containsKey(K key) {
return getEntry(key) != null;
}
public synchronized V get(K key) {
ENTRY e = getEntry(key);
return e == null ? null : e.getValue();
}
public synchronized V getKeepAlive(K key, long keepAlive) {
ENTRY e = getEntry(key);
if (e == null)
return null;
e.keepAlive(keepAlive);
return e.getValue();
}
public synchronized V getKeepAlive(K key) {
ENTRY e = getEntry(key);
if (e == null)
return null;
e.keepAlive(defaultKeepTime);
return e.getValue();
}
private ENTRY getEntry(K key) {
if (key == null)
return null;
ENTRY tab[] = table;
int index = hash(key) % tab.length;
for (ENTRY e = tab[index]; e != null; e = e.next) {
if (CompareUtil.equals(e.key, key)) {
if (e.isExpired()) {
remove(e.getKey());
return null;
} else {
return e;
}
}
}
return null;
}
private V getValue(ENTRY e) {
if (e == null)
return null;
if (e.isExpired()) {
remove(e.key);
return null;
}
return e.value;
}
public synchronized V getFirstValue() {
if (isEmpty())
return null;
return getValue(this.header.link_next);
}
public synchronized V getLastValue() {
if (isEmpty())
return null;
return getValue(this.header.link_prev);
}
public synchronized int getRemindTime(K key) {
ENTRY entry = getEntry(key);
if (entry != null) {
if (entry.timeOfExpiration == 0)
return Integer.MAX_VALUE;
return (int) (entry.timeOfExpiration - System.currentTimeMillis());
} else {
return 0;
}
}
public void clearExpiredItems() {
try {
ArrayList delete = new ArrayList();
Enumeration> en = this.entries();
while (en.hasMoreElements()) {
ENTRY e = en.nextElement();
if (e.isExpired()) {
delete.add((K) e.getKey());
}
}
for (int i = 0; i < delete.size(); i++) {
remove(delete.get(i));
}
} catch (Throwable t) {
t.printStackTrace();
}
}
private int hash(Object key) {
return (int) (key.hashCode()) & Integer.MAX_VALUE;
}
protected void rehash() {
int oldCapacity = table.length;
ENTRY oldMap[] = table;
int newCapacity = oldCapacity * 2 + 1;
ENTRY newMap[] = new ENTRY[newCapacity];
threshold = (int) (newCapacity * loadFactor);
table = newMap;
for (int i = oldCapacity; i-- > 0;) {
for (ENTRY old = oldMap[i]; old != null;) {
ENTRY e = old;
old = old.next;
K key = e.key;
int index = hash(key) % newCapacity;
e.next = newMap[index];
newMap[index] = e;
}
}
}
private int max;
public CacheTable setMaxRow(int max) {
this.max = max;
return this;
}
public CacheTable setDefaultKeepTime(long time) {
this.defaultKeepTime = time;
return this;
}
private static enum MODE {
FORCE_FIRST, FORCE_LAST, FIRST, LAST
};
public V put(K key, V value, long keepTime) {
return _put(key, value, keepTime, MODE.LAST);
}
public V putLast(K key, V value, long keepTime) {
return _put(key, value, keepTime, MODE.FORCE_LAST);
}
public V putFirst(K key, V value, long keepTime) {
return _put(key, value, keepTime, MODE.FORCE_FIRST);
}
public V put(K key, V value) {
return _put(key, value, defaultKeepTime, MODE.LAST);
}
public V putLast(K key, V value) {
return _put(key, value, defaultKeepTime, MODE.FORCE_LAST);
}
public V putFirst(K key, V value) {
return _put(key, value, defaultKeepTime, MODE.FORCE_FIRST);
}
private synchronized V _put(K key, V value, long keepTime, MODE m) {
ENTRY tab[] = table;
int index = hash(key) % tab.length;
for (ENTRY e = tab[index]; e != null; e = e.next) {
if (CompareUtil.equals(e.key, key)) {
V old = e.value;
e.value = value;
e.keepAlive(keepTime);
switch (m) {
case FORCE_FIRST:
if (header.link_next != e) {
unchain(e);
chain(header, header.link_next, e);
}
break;
case FORCE_LAST:
if (header.link_prev != e) {
unchain(e);
chain(header.link_prev, header, e);
}
break;
}
return old;
}
}
if (max > 0) {
switch (m) {
case FORCE_FIRST:
case FIRST:
while (count >= max) {
removeLast();
}
break;
case FORCE_LAST:
case LAST:
while (count >= max) {
removeFirst();
}
break;
}
}
if (count >= threshold) {
rehash();
tab = table;
index = hash(key) % tab.length;
}
ENTRY e = new ENTRY(key, value, keepTime, tab[index]);
tab[index] = e;
switch (m) {
case FORCE_FIRST:
case FIRST:
chain(header, header.link_next, e);
break;
case FORCE_LAST:
case LAST:
chain(header.link_prev, header, e);
break;
}
count++;
return null;
}
public synchronized V remove(Object key) {
if (key == null)
return null;
ENTRY tab[] = table;
int index = hash(key) % tab.length;
for (ENTRY e = tab[index], prev = null; e != null; prev = e, e = e.next) {
if (CompareUtil.equals(e.key, key)) {
if (prev != null) {
prev.next = e.next;
} else {
tab[index] = e.next;
}
count--;
V oldValue = e.value;
e.value = null;
//
unchain(e);
return oldValue;
}
}
return null;
}
public synchronized V removeFirst() {
if (isEmpty())
return null;
return remove(header.link_next.key);
}
public synchronized V removeLast() {
if (isEmpty())
return null;
return remove(header.link_prev.key);
}
public boolean isEmpty() {
return size() == 0;
}
public synchronized void clear() {
ENTRY tab[] = table;
for (int index = tab.length; --index >= 0;)
tab[index] = null;
this.header.link_next = header.link_prev = header;
count = 0;
}
public String toString() {
StringBuffer buf = new StringBuffer();
Enumeration it = entries();
buf.append("{");
for (int i = 0; it.hasMoreElements(); i++) {
ENTRY e = (ENTRY) (it.nextElement());
if (i > 0)
buf.append(", ");
buf.append(e.getKey() + "=" + e.getValue());
}
buf.append("}");
return buf.toString();
}
public String toKeyString() {
StringBuffer buf = new StringBuffer();
Enumeration it = keys();
buf.append("{");
for (int i = 0; it.hasMoreElements(); i++) {
K key = it.nextElement();
if (i > 0)
buf.append(", ");
buf.append(key);
}
buf.append("}");
return buf.toString();
}
public String toFormatString() {
StringBuffer buf = new StringBuffer();
Enumeration it = entries();
buf.append("{\n");
while (it.hasMoreElements()) {
ENTRY e = (ENTRY) it.nextElement();
buf.append("\t").append(e.getKey() + "=" + e.getValue()).append("\n");
}
buf.append("}");
return buf.toString();
}
public static class ENTRY {
private K key;
private V value;
private long timeOfExpiration;
private long keepTime = 0;
ENTRY next;
ENTRY link_next, link_prev;
protected ENTRY(K key, V value, long keepTime, ENTRY next) {
this.key = key;
this.value = value;
this.keepAlive(keepTime);
this.next = next;
}
protected Object clone() {
return new ENTRY(key, value, keepTime, (next == null ? null : (ENTRY) next.clone()));
}
public K getKey() {
return key;
}
public V getValue() {
return value;
}
public V setValue(V value) {
V oldValue = this.value;
this.value = value;
return oldValue;
}
public boolean isExpired() {
if (timeOfExpiration > 0) {
if (timeOfExpiration < System.currentTimeMillis())
return true;
else
return false;
} else {
return false;
}
}
public void keepAlive(long keepTime) {
if (keepTime > 0) {
this.keepTime = keepTime;
this.timeOfExpiration = System.currentTimeMillis() + keepTime;
} else {
this.keepTime = 0;
this.timeOfExpiration = 0;
}
}
public void keep() {
if (this.keepTime > 0) {
this.timeOfExpiration = System.currentTimeMillis() + this.keepTime;
}
}
public boolean equals(Object o) {
if (!(o instanceof ENTRY))
return false;
ENTRY e = (ENTRY) o;
return CompareUtil.equals(key, e.key) && CompareUtil.equals(value, e.value);
}
public int hashCode() {
return key.hashCode() ^ (value == null ? 0 : value.hashCode());
}
public String toString() {
return key + "=" + value;
}
}
private enum TYPE {
KEYS, VALUES, ENTRIES
}
private class Enumer implements Enumeration {
TYPE type;
ENTRY entry = CacheTable.this.header.link_next;
ENTRY lastEnt;
Enumer(TYPE type) {
this.type = type;
}
public boolean hasMoreElements() {
return header != entry && entry != null;
}
public V nextElement() {
if (hasMoreElements()) {
ENTRY e = lastEnt = entry;
entry = e.link_next;
switch (type) {
case KEYS:
return (V) e.key;
case VALUES:
return (V) e.value;
default:
return (V) e;
}
}
throw new NoSuchElementException("no more next");
}
}
private void chain(ENTRY link_prev, ENTRY link_next, ENTRY e) {
e.link_prev = link_prev;
e.link_next = link_next;
link_prev.link_next = e;
link_next.link_prev = e;
}
private void unchain(ENTRY e) {
e.link_prev.link_next = e.link_next;
e.link_next.link_prev = e.link_prev;
e.link_prev = null;
e.link_next = null;
}
public static void main(String[] args) throws Exception {
CacheTable t = new CacheTable().setDefaultKeepTime(1000).setMaxRow(100);
for (int i = 0; i < 100; i++) {
// if (i % 5 == 0) {
// t.put(i, i, 10000);
// } else {
t.put(i, i);
// }
}
Enumeration e = t.keys();
System.out.println(t.get(0));
System.out.println(t.get(10));
System.out.println(t.get(99));
Thread.sleep(2000);
// t.clearExpiredItems();
System.out.println("----->" + t.size());
System.out.println(t.getFirstValue());
}
}
