org.apache.commons.cache.MemoryStash.java Source code

Introduction

Here is the source code for org.apache.commons.cache.MemoryStash.java

Source

/*
 * Copyright 2001-2004 The Apache Software Foundation
 *
 * 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.
 */
package org.apache.commons.cache;

import java.util.HashMap;
import java.io.Serializable;

/**
 * tk.
 * @version $Id: MemoryStash.java 155435 2005-02-26 13:17:27Z dirkv $
 * @author Rodney Waldhoff
 */
public class MemoryStash extends BaseStash implements Stash {
    protected HashMap _hash = null;
    protected int _maxObjs = 1000;
    protected Cache _cache = null;

    public MemoryStash(int maxobjs) {
        _maxObjs = maxobjs;
        _hash = new HashMap();
    }

    public synchronized int canStore(Serializable key, Serializable val, Long expiresAt, Long cost,
            Serializable group, byte[] serialized) {
        if (_hash.size() < _maxObjs) {
            return Stash.YES;
        } else {
            return Stash.NO_FULL;
        }
    }

    public synchronized boolean store(Serializable key, Serializable val, Long expiresAt, Long cost,
            Serializable group, byte[] serialized) {
        try {
            _hash.put(key, new CachedObjectInfoImpl(val, expiresAt, cost));
        } catch (Exception e) {
            return false;
        }
        return true;
    }

    public Serializable retrieve(Serializable key) {
        // grab a lock on the cache first, since it may try to grab a lock on me
        synchronized (_cache) {
            synchronized (this) {
                CachedObjectInfo info = (CachedObjectInfo) (_hash.get(key));
                if (null != info) {
                    Long expiry = info.getExpirationTs();
                    if (null != expiry) {
                        if (expiry.longValue() < System.currentTimeMillis()) {
                            _cache.clear(key);
                            return null;
                        } else {
                            return info.getKey();
                        }
                    } else {
                        return info.getKey();
                    }
                } else {
                    return null;
                }
            }
        }
    }

    public boolean contains(Serializable key) {
        return _hash.containsKey(key);
    }

    public synchronized float capacity() {
        return (((float) _hash.size()) / ((float) _maxObjs));
    }

    public void clear(Serializable key) {
        _hash.remove(key);
    }

    public synchronized void clear() {
        _hash.clear();
    }

    public void setCache(Cache c) {
        if (null != _cache) {
            Object mutex = _cache;
            synchronized (mutex) {
                synchronized (this) {
                    unsetCache();
                    _cache = c;
                }
            }
        } else {
            _cache = c;
        }
    }

    public void unsetCache() {
        if (null != _cache) {
            Object mutex = _cache;
            synchronized (mutex) {
                clear();
                _cache = null;
            }
        }
    }
}