com.almende.eve.state.memory.MemoryState.java Source code

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Here is the source code for com.almende.eve.state.memory.MemoryState.java

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/*
 * Copyright: Almende B.V. (2014), Rotterdam, The Netherlands
 * License: The Apache Software License, Version 2.0
 */
package com.almende.eve.state.memory;

import java.io.Serializable;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.logging.Level;
import java.util.logging.Logger;

import com.almende.eve.state.AbstractState;
import com.almende.eve.state.State;
import com.almende.eve.state.StateService;
import com.fasterxml.jackson.databind.node.ObjectNode;

/**
 * The Class MemoryState.
 * 
 * @author jos
 * @class MemoryState
 * 
 *        A state for an Eve Agent, which stores the data in memory.
 *        (After a restart of the application, the data will be gone!)
 * 
 *        The state provides general information for the agent (about itself,
 *        the environment, and the system configuration), and the agent can
 *        store its
 *        state in the state.
 *        The state extends a standard Java Map.
 * 
 *        <b>Warning, this implementation is not thread-safe!</b>
 * 
 *        Usage:<br>
 *        AgentHost factory = AgentHost.getInstance(config);<br>
 *        FileState state = new State("agentId");<br>
 *        state.put("key", "value");<br>
 *        System.out.println(state.get("key")); // "value"<br>
 */
public class MemoryState extends AbstractState<Serializable> implements State {
    private static final Logger LOG = Logger.getLogger(MemoryState.class.getName());
    private final Map<String, Serializable> properties = new ConcurrentHashMap<String, Serializable>(10);

    /**
     * Instantiates a new memory state.
     */
    public MemoryState() {
    }

    /**
     * Instantiates a new memory state.
     * 
     * @param agentId
     *            the agent id
     * @param service
     *            the service
     * @param params
     *            the params
     */
    public MemoryState(final String agentId, final StateService service, final ObjectNode params) {
        super(agentId, service, params);
    }

    /*
     * (non-Javadoc)
     * 
     * @see com.almende.eve.state.State#clear()
     */
    @Override
    public void clear() {
        properties.clear();
    }

    /*
     * (non-Javadoc)
     * 
     * @see com.almende.eve.state.State#keySet()
     */
    @Override
    public Set<String> keySet() {
        return new HashSet<String>(properties.keySet());
    }

    /*
     * (non-Javadoc)
     * 
     * @see com.almende.eve.state.State#containsKey(java.lang.String)
     */
    @Override
    public boolean containsKey(final String key) {
        return properties.containsKey(key);
    }

    /*
     * (non-Javadoc)
     * 
     * @see com.almende.eve.state.AbstractState#get(java.lang.String)
     */
    @Override
    public Serializable get(final String key) {
        try {
            return properties.get(key);
        } catch (final Exception e) {
            LOG.log(Level.WARNING, "Couldn't clone object: " + key + ", returning pointer to original object.", e);
            return properties.get(key);
        }
    }

    /**
     * Checks if is empty.
     * 
     * @return true, if is empty
     */
    public boolean isEmpty() {
        return properties.isEmpty();
    }

    /*
     * (non-Javadoc)
     * 
     * @see com.almende.eve.state.AbstractState#locPut(java.lang.String,
     * java.io.Serializable)
     */
    @Override
    public Serializable locPut(final String key, final Serializable value) {
        return properties.put(key, value);
    }

    /*
     * (non-Javadoc)
     * 
     * @see
     * com.almende.eve.state.AbstractState#locPutIfUnchanged(java.lang.String,
     * java.io.Serializable, java.io.Serializable)
     */
    @Override
    public boolean locPutIfUnchanged(final String key, final Serializable newVal, final Serializable oldVal) {
        boolean result = false;
        if (!(oldVal == null && properties.containsKey(key) && properties.get(key) != null)
                || (properties.get(key) != null && properties.get(key).equals(oldVal))) {
            properties.put(key, newVal);
            result = true;
        }
        return result;
    }

    /*
     * (non-Javadoc)
     * 
     * @see com.almende.eve.state.State#remove(java.lang.String)
     */
    @Override
    public Serializable remove(final String key) {
        return properties.remove(key);
    }

    /*
     * (non-Javadoc)
     * 
     * @see com.almende.eve.state.State#size()
     */
    @Override
    public int size() {
        return properties.size();
    }

}