DeltaAwareExpiringSession

DeltaAwareExpiringSession.java

public class DeltaAwareExpiringSession implements ExpiringSession {

	private final Queue<Map.Entry<String, Object>> deltas = new LinkedList<Map.Entry<String, Object>>();

	@Id
	private String id                  = UUID.randomUUID().toString();
	private long   creationTime        = System.currentTimeMillis();
	private long   lastAccessedTime    = creationTime;
	private int    maxInactiveInterval = DEFAULT_MAX_INACTIVE_INTERVAL_SECONDS;

	private volatile Map<String, Object> sessionAttrs;

	public DeltaAwareExpiringSession(Map<String, Object> sessionAttrs) {
		this.sessionAttrs = sessionAttrs;
	}

	@Override
	public String getId() {
		return id;
	}

	public void setId(String id) {
		this.id = id;
	}

	@Override
	public long getCreationTime() {
		return creationTime;
	}

	public void setCreationTime(long creationTime) {
		this.creationTime = creationTime;
	}

	@Override
	public long getLastAccessedTime() {
		return lastAccessedTime;
	}

	public void setLastAccessedTime(long lastAccessedTime) {
		this.lastAccessedTime = lastAccessedTime;
	}

	@Override
	public int getMaxInactiveIntervalInSeconds() {
		return maxInactiveInterval;
	}

	@Override
	public void setMaxInactiveIntervalInSeconds(int interval) {
		this.maxInactiveInterval = interval;
	}

	@Override
	public boolean isExpired() {
		return isExpired(System.currentTimeMillis());
	}

	@Override
	public Set<String> getAttributeNames() {
		applyDeltas();
		return sessionAttrs.keySet();
	}

	@SuppressWarnings("unchecked")
	@Override
	public <T> T getAttribute(String attributeName) {
		applyDeltas();
		return (T) sessionAttrs.get(attributeName);
	}

	@Override
	public void setAttribute(String attributeName, Object attributeValue) {
		addDelta(new AbstractMap.SimpleImmutableEntry<String, Object>(attributeName, attributeValue));
	}

	@Override
	public void removeAttribute(String attributeName) {
		setAttribute(attributeName, null);
	}

	public void applyDeltas() {
		if (deltas.isEmpty()) {
			return;
		}
		synchronized (deltas) {
			if (deltas.isEmpty()) {
				return;
			}
			Map<String, Object> sessionAttrs = new HashMap<String, Object>(this.sessionAttrs);
			Map.Entry<String, Object> attr;
			while (null != (attr = deltas.poll())) {
				if (null == attr.getValue()) {
					sessionAttrs.remove(attr.getKey());
				} else {
					sessionAttrs.put(attr.getKey(), attr.getValue());
				}
			}

			this.sessionAttrs = sessionAttrs;
		}
	}

	protected void addDelta(Map.Entry attribute) {
		deltas.add(attribute);
	}

	protected boolean isExpired(long now) {
		if (maxInactiveInterval < 0) {
			return false;
		}
		return now - TimeUnit.SECONDS.toMillis(maxInactiveInterval) >= lastAccessedTime;
	}

	@Override
	public boolean equals(Object o) {
		if (this == o) {
			return true;
		}
		if (!(o instanceof Session)) {
			return false;
		}

		Session that = (Session) o;
		if (!id.equals(that.getId())) {
			return false;
		}

		return true;
	}

	@Override
	public int hashCode() {
		return id.hashCode();
	}

}