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*** THIS VERSION UPLOADED FOR USE WITH CEDAR-COMMON, TO AVOID DEPENDENCIES ON GOOGLE CODE-BASED MAVEN REPOSITORIES. *** The simplest convenient interface to the Google App Engine datastore
The newest version!
package com.googlecode.objectify;

import com.google.appengine.api.datastore.ReadPolicy.Consistency;
import com.google.appengine.api.datastore.TransactionOptions;
import com.googlecode.objectify.util.DatastoreIntrospector;

/**
 * The options available when creating an Objectify instance.
 * 
 * The default options are:
 * 
 * 
 * Do NOT begin a transaction.
 * Do NOT use a session cache.
 * DO use a global cache.
 * Use STRONG consistency.
 * Apply no deadline to calls.
 * 
 * 
 * @author Jeff Schnitzer 
 */
public class ObjectifyOpts implements Cloneable
{
	/** If txnOpts is null, don't start a transaction */
	TransactionOptions txnOpts;
	boolean sessionCache = false;
	boolean globalCache = true;
	Consistency consistency = Consistency.STRONG;
	Double deadline;
	
	/** Gets the current value of beginTransaction */
	public boolean getBeginTransaction() { return this.txnOpts != null; }
	
	/**
	 * Sets whether or not the Objectify instance will start a transaction.  If
	 * true, the instance will hold a transaction that must be rolled back or
	 * committed.  Uses XG transactions when on the HRD; {@code setBeginTransaction(true)} is equivalent
	 * to {@code setTransactionOptions(TransactionOptions.Builder.withXG(true))}.
	 * There is no overhead for XG transactions on a single entity group, so there is
	 * no good reason to ever have this false.
	 */
	public ObjectifyOpts setBeginTransaction(boolean value)
	{
		this.txnOpts = value ? TransactionOptions.Builder.withXG(DatastoreIntrospector.SUPPORTS_XG) : null;
		return this;
	}

	/** Get the current transaction options - null if there is no transaction */
	TransactionOptions getTransactionOptions() { return this.txnOpts; }
	
	/**
	 * Set options for a transaction to start, or null for no transaction.
	 * You probably want to use {@code setBeginTransaction(true)} instead.
	 */
	public ObjectifyOpts setTransactionOptions(TransactionOptions opts)
	{
		this.txnOpts = opts;
		return this;
	}
	
	/** Gets whether or not the Objectify instance will maintain a session cache */
	public boolean getSessionCache() { return this.sessionCache; }
	
	/**
	 * Sets whether or not the Objectify instance will maintain a session cache.
	 * If true, all entities fetched from the datastore (or the 2nd level memcache)
	 * will be stored as-is in a hashmap within the Objectify instance.  Repeated
	 * get()s or queries for the same entity will return the same object.
	 */
	public ObjectifyOpts setSessionCache(boolean value)
	{
		this.sessionCache = value;
		return this;
	}
	
	/** Gets whether or not the Objectify instance will use a 2nd-level memcache */
	public boolean getGlobalCache() { return this.globalCache; }
	
	/**
	 * Sets whether or not the Objectify instance will use a 2nd-level memcache.
	 * If true, Objectify will obey the @Cached annotation on entity classes,
	 * saving entity data to the GAE memcache service.  Fetches from the datastore
	 * for @Cached entities will look in the memcache service first.  This cache
	 * is shared across all versions of your application across the entire GAE
	 * cluster.
	 */
	public ObjectifyOpts setGlobalCache(boolean value)
	{
		this.globalCache = value;
		return this;
	}
	
	/** Gets the initial consistency setting for the Objectify instance */
	public Consistency getConsistency() { return this.consistency; }
	
	/**
	 * Sets the initial consistency value for the Objectify instance.  See the 
	 * Appengine Docs
	 * for an explanation of Consistency. 
	 */
	public ObjectifyOpts setConsistency(Consistency value)
	{
		if (value == null)
			throw new IllegalArgumentException("Consistency cannot be null");
		
		this.consistency = value;
		return this;
	}

	/** Gets the deadline for datastore calls, in seconds */
	public Double getDeadline() { return this.deadline; }
	
	/**
	 * Sets a limit, in seconds, for datastore calls.  If datastore calls take longer
	 * than this amount, an exception will be thrown.
	 * 
	 * @param value can be null to indicate no deadline (other than the standard whole
	 * request deadline of 30s).
	 */
	public ObjectifyOpts setDeadline(Double value)
	{
		this.deadline = value;
		return this;
	}

	/** Make a copy of this object as-is. */
	@Override
	public ObjectifyOpts clone()
	{
		try
		{
			return (ObjectifyOpts)super.clone();
		}
		catch (CloneNotSupportedException e)
		{
			throw new RuntimeException(e);	// impossible
		}
	}
}