globalxact.java

derby database source code.good for you.

/*

   Derby - Class org.apache.derby.iapi.store.access.GlobalXact

   Copyright 1999, 2004 The Apache Software Foundation or its licensors, as applicable.

   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.derby.iapi.store.access;


/**

This abstract class represents a global transaction id which can be tested
for equality against other transaction ids, which can be hashed into a
hash table, and which can be output as a string. 
<P>
This class has 2 direct subclasses. 
<UL>
<LI> org.apache.derby.iapi.store.access.xa.XAXactId : 
this class is a specific implementation of the JTA Xid interface
<LI> org.apache.derby.impl.store.access.GlobalXactId : 
this class represents internal cloudscape transaction ids
</UL>
<P>
The main reason for this class is to ensure that equality etc. works in a
consistent way across both subclasses. 
**/

public abstract class GlobalXact {
    
    /**************************************************************************
     * Protected Fields of the class
     **************************************************************************
     */
    protected int     format_id;
    protected byte[]  global_id;
    protected byte[]  branch_id;

    public boolean equals(Object other) 
    {
		if (other == this)
			return true;

		if (other instanceof GlobalXact) {
	
			GlobalXact other_xact = (GlobalXact) other;
		
			return(
				   java.util.Arrays.equals(
									other_xact.global_id,
									this.global_id)          &&
				   java.util.Arrays.equals(
									other_xact.branch_id,
									this.branch_id)          &&
				   other_xact.format_id == this.format_id);
		
	    }

		return false;	
    }

    public String toString()
    {
		String globalhex = "";
		String branchhex = "";
		if (global_id != null) 
	    {
			int mask = 0;
			for (int i = 0; i < global_id.length; i++)
		    {
				mask = (global_id[i] & 0xFF);
				globalhex += Integer.toHexString(mask);
		    }
	    }
	
		if (branch_id != null)
	    {
			int mask = 0;
			for (int i = 0; i < branch_id.length; i++)
		    {
				mask = (branch_id[i] & 0xFF);
				branchhex += Integer.toHexString(mask);
		    }
	    }

		return("(" + format_id + "," + globalhex + "," + branchhex + ")");
	
    }


    /**
       Provide a hashCode which is compatable with the equals() method.
       
       @see java.lang.Object#hashCode
    **/
    public int hashCode()
    {
		// make sure hash does not overflow int, the only unknown is
		// format_id.  Lop off top bits.
		int hash = global_id.length + branch_id.length + (format_id & 0xFFFFFFF);

		for (int i = 0; i < global_id.length; i++) 
	    {
			hash += global_id[i];
	    }
		for (int i = 0; i < branch_id.length; i++) 
	    {
			hash += branch_id[i];
	    }
	
		return(hash);
    }
    
}