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Source file | Conditionals | Statements | Methods | TOTAL | |||||||||||||||
CacheEntry.java | 58.3% | 68% | 81.2% | 67.8% |
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/*
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* Copyright (c) 2002-2003 by OpenSymphony
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* All rights reserved.
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*/
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package com.opensymphony.oscache.base;
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import com.opensymphony.oscache.web.filter.ResponseContent;
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import java.io.Serializable;
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import java.util.Collection;
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import java.util.HashSet;
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import java.util.Set;
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/**
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* A CacheEntry instance represents one entry in the cache. It holds the object that
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* is being cached, along with a host of information about that entry such as the
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* cache key, the time it was cached, whether the entry has been flushed or not and
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* the groups it belongs to.
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*
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* @version $Revision: 1.1 $
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* @author <a href="mailto:mike@atlassian.com">Mike Cannon-Brookes</a>
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* @author <a href="mailto:tgochenour@peregrine.com">Todd Gochenour</a>
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* @author <a href="mailto:fbeauregard@pyxis-tech.com">Francois Beauregard</a>
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*/
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public class CacheEntry implements Serializable { |
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/**
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* Default initialization value for the creation time and the last
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* update time. This is a placeholder that indicates the value has
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* not been set yet.
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*/
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private static final byte NOT_YET = -1; |
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/**
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* Specifying this as the refresh period for the
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* {@link #needsRefresh(int)} method will ensure
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* an entry does not become stale until it is
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* either explicitly flushed or a custom refresh
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* policy causes the entry to expire.
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*/
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public static final int INDEFINITE_EXPIRY = -1; |
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/**
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* The entry refresh policy object to use for this cache entry. This is optional.
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*/
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private EntryRefreshPolicy policy = null; |
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/**
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* The actual content that is being cached. Wherever possible this object
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* should be serializable. This allows <code>PersistenceListener</code>s
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* to serialize the cache entries to disk or database.
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*/
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private Object content = null; |
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/**
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* The set of cache groups that this cache entry belongs to, if any.
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*/
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private Set groups = null; |
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/**
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* The unique cache key for this entry
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*/
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private String key;
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/**
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* <code>true</code> if this entry was flushed
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*/
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private boolean wasFlushed = false; |
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/**
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* The time this entry was created.
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*/
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private long created = NOT_YET; |
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/**
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* The time this emtry was last updated.
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*/
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private long lastUpdate = NOT_YET; |
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/**
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* Construct a new CacheEntry using the key provided.
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*
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* @param key The key of this CacheEntry
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*/
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public CacheEntry(String key) {
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this(key, null); |
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} |
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/**
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* Construct a CacheEntry.
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*
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* @param key The unique key for this <code>CacheEntry</code>.
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* @param policy Object that implements refresh policy logic. This parameter
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* is optional.
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*/
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public CacheEntry(String key, EntryRefreshPolicy policy) {
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this(key, policy, null); |
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} |
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/**
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* Construct a CacheEntry.
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*
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* @param key The unique key for this <code>CacheEntry</code>.
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* @param policy The object that implements the refresh policy logic. This
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* parameter is optional.
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* @param groups The groups that this <code>CacheEntry</code> belongs to. This
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* parameter is optional.
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*/
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public CacheEntry(String key, EntryRefreshPolicy policy, String[] groups) {
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this.key = key;
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if (groups != null) { |
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this.groups = new HashSet(groups.length); |
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for (int i = 0; i < groups.length; i++) { |
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this.groups.add(groups[i]);
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} |
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} |
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this.policy = policy;
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this.created = System.currentTimeMillis();
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} |
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/**
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* Sets the actual content that is being cached. Wherever possible this
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* object should be <code>Serializable</code>, however it is not an
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* absolute requirement when using a memory-only cache. Being <code>Serializable</code>
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* allows <code>PersistenceListener</code>s to serialize the cache entries to disk
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* or database.
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*
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* @param value The content to store in this CacheEntry.
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*/
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public synchronized void setContent(Object value) { |
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content = value; |
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lastUpdate = System.currentTimeMillis(); |
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wasFlushed = false;
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} |
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/**
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* Get the cached content from this CacheEntry.
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*
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* @return The content of this CacheEntry.
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*/
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public Object getContent() {
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return content;
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} |
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/**
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* Get the date this CacheEntry was created.
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*
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* @return The date this CacheEntry was created.
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*/
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public long getCreated() { |
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return created;
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} |
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/**
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* Sets the cache groups for this entry.
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*
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* @param groups A string array containing all the group names
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*/
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public synchronized void setGroups(String[] groups) { |
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if (groups != null) { |
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this.groups = new HashSet(groups.length); |
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for (int i = 0; i < groups.length; i++) { |
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this.groups.add(groups[i]);
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} |
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} else {
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this.groups = null; |
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} |
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lastUpdate = System.currentTimeMillis(); |
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} |
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/**
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* Sets the cache groups for this entry
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*
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* @param groups A collection containing all the group names
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*/
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public void setGroups(Collection groups) { |
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if (groups != null) { |
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this.groups = new HashSet(groups); |
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} else {
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this.groups = null; |
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} |
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lastUpdate = System.currentTimeMillis(); |
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} |
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/**
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* Gets the cache groups that this cache entry belongs to.
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* These returned groups should be treated as immuatable.
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*
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* @return A set containing the names of all the groups that
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* this cache entry belongs to.
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*/
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public Set getGroups() {
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return groups;
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} |
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/**
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* Get the key of this CacheEntry
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*
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* @return The key of this CacheEntry
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*/
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public String getKey() {
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return key;
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} |
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/**
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* Set the date this CacheEntry was last updated.
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*
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* @param update The time (in milliseconds) this CacheEntry was last updated.
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*/
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public void setLastUpdate(long update) { |
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lastUpdate = update; |
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} |
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/**
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* Get the date this CacheEntry was last updated.
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*
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* @return The date this CacheEntry was last updated.
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*/
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public long getLastUpdate() { |
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return lastUpdate;
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} |
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/**
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* Indicates whether this CacheEntry is a freshly created one and
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* has not yet been assigned content or placed in a cache.
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*
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* @return <code>true</code> if this entry is newly created
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*/
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public boolean isNew() { |
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return lastUpdate == NOT_YET;
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} |
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/**
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* Get the size of the cache entry in bytes (roughly).<p>
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*
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* Currently this method only handles <code>String<code>s and
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* {@link ResponseContent} objects.
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*
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* @return The approximate size of the entry in bytes, or -1 if the
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* size could not be estimated.
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*/
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public int getSize() { |
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// a char is two bytes
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int size = (key.length() * 2) + 4;
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if (content.getClass() == String.class) { |
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size += ((content.toString().length() * 2) + 4); |
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} else if (content instanceof ResponseContent) { |
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size += ((ResponseContent) content).getSize(); |
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} else {
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return -1;
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} |
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//add created, lastUpdate, and wasFlushed field sizes (1, 8, and 8)
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return size + 17;
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} |
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/**
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* Flush the entry from cache.
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* note that flushing the cache doesn't actually remove the cache contents
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* it just tells the CacheEntry that it needs a refresh next time it is asked
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* this is so that the content is still there for a <usecached />.
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*/
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public void flush() { |
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wasFlushed = true;
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} |
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/**
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* Check if this CacheEntry needs to be refreshed.
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*
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* @param refreshPeriod The period of refresh (in seconds). Passing in
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* {@link #INDEFINITE_EXPIRY} will result in the content never becoming
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* stale unless it is explicitly flushed, or expired by a custom
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* {@link EntryRefreshPolicy}. Passing in 0 will always result in a
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* refresh being required.
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*
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* @return Whether or not this CacheEntry needs refreshing.
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*/
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public boolean needsRefresh(int refreshPeriod) { |
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boolean needsRefresh;
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// needs a refresh if it has never been updated
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if (lastUpdate == NOT_YET) {
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needsRefresh = true;
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} |
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// Was it flushed from cache?
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else if (wasFlushed) { |
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needsRefresh = true;
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} else if (refreshPeriod == 0) { |
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needsRefresh = true;
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} |
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// check what the policy has to say if there is one
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else if (policy != null) { |
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needsRefresh = policy.needsRefresh(this);
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} |
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// check if the last update + update period is in the past
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else if ((refreshPeriod >= 0) && (System.currentTimeMillis() >= (lastUpdate + (refreshPeriod * 1000L)))) { |
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needsRefresh = true;
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} else {
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needsRefresh = false;
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} |
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return needsRefresh;
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} |
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} |
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