HaHaWTH
126 lines
3.9 KiB
Java
126 lines
3.9 KiB
Java
package fr.xephi.authme.util.expiring;
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import java.util.Map;
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import java.util.concurrent.ConcurrentHashMap;
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import java.util.concurrent.TimeUnit;
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/**
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* Set whose entries expire after a configurable amount of time. Once an entry
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* has expired, the set will act as if the entry no longer exists. Time starts
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* counting after the entry has been inserted.
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* <p>
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* Internally, expired entries are not guaranteed to be cleared automatically.
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* A cleanup of all expired entries may be triggered with
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* {@link #removeExpiredEntries()}. Adding an entry that is already present
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* effectively resets its expiration.
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*
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* @param <E> the type of the entries
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*/
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public class ExpiringSet<E> {
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private Map<E, Long> entries = new ConcurrentHashMap<>();
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private long expirationMillis;
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/**
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* Constructor.
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*
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* @param duration the duration of time after which entries expire
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* @param unit the time unit in which {@code duration} is expressed
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*/
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public ExpiringSet(long duration, TimeUnit unit) {
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setExpiration(duration, unit);
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}
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/**
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* Adds an entry to the set.
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*
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* @param entry the entry to add
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*/
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public void add(E entry) {
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entries.put(entry, System.currentTimeMillis() + expirationMillis);
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}
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/**
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* Returns whether this set contains the given entry, if it hasn't expired.
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*
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* @param entry the entry to check
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* @return true if the entry is present and not expired, false otherwise
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*/
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public boolean contains(E entry) {
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Long expiration = entries.get(entry);
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if (expiration == null) {
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return false;
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} else if (expiration > System.currentTimeMillis()) {
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return true;
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} else {
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entries.remove(entry);
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return false;
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}
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}
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/**
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* Removes the given entry from the set (if present).
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*
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* @param entry the entry to remove
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*/
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public void remove(E entry) {
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entries.remove(entry);
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}
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/**
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* Removes all entries from the set.
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*/
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public void clear() {
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entries.clear();
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}
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/**
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* Removes all entries which have expired from the internal structure.
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*/
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public void removeExpiredEntries() {
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entries.entrySet().removeIf(entry -> System.currentTimeMillis() > entry.getValue());
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}
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/**
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* Returns the duration of the entry until it expires (provided it is not removed or re-added).
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* If the entry does not exist, a duration of -1 seconds is returned.
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*
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* @param entry the entry whose duration before it expires should be returned
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* @return duration the entry will remain in the set (if there are not modifications)
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*/
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public Duration getExpiration(E entry) {
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Long expiration = entries.get(entry);
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if (expiration == null) {
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return new Duration(-1, TimeUnit.SECONDS);
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}
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long stillPresentMillis = expiration - System.currentTimeMillis();
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if (stillPresentMillis < 0) {
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entries.remove(entry);
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return new Duration(-1, TimeUnit.SECONDS);
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}
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return Duration.createWithSuitableUnit(stillPresentMillis, TimeUnit.MILLISECONDS);
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}
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/**
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* Sets a new expiration duration. Note that already present entries
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* will still make use of the old expiration.
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*
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* @param duration the duration of time after which entries expire
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* @param unit the time unit in which {@code duration} is expressed
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*/
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public void setExpiration(long duration, TimeUnit unit) {
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this.expirationMillis = unit.toMillis(duration);
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}
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/**
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* Returns whether this map is empty. This reflects the state of the
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* internal map, which may contain expired entries only. The result
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* may change after running {@link #removeExpiredEntries()}.
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*
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* @return true if map is really empty, false otherwise
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*/
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public boolean isEmpty() {
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return entries.isEmpty();
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}
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}
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