[jboss-jira] [JBoss JIRA] Commented: (JGRP-591) IpAddress.hashCode() not unique per ip/port

[Bela Ban (JIRA)]

    [ http://jira.jboss.com/jira/browse/JGRP-591?page=comments#action_12376819 ] 
            
Bela Ban commented on JGRP-591:
-------------------------------

Forgot the code:

public static void main(String[] args) throws Exception {


        Map<Address,Integer> map=new HashMap<Address,Integer>();

        IpAddress addr1, addr2;


        InetAddress ip1 = InetAddress.getByAddress( new byte[] {1,2,3,4} );
        int port1 = 2;
        int hash1 = ip1.hashCode() + port1;
        System.out.println( "hash1 = " + hash1 );

        InetAddress ip2 = InetAddress.getByAddress( new byte[] {1,2,3,5} );
        int port2 = 1;
        int hash2 = ip2.hashCode() + port2;
        System.out.println( "hash2 = " + hash2 );


        addr1=new IpAddress(ip1, port1);
        addr2=new IpAddress(ip2, port2);

        System.out.println("addr1 = " + addr1);
        System.out.println("addr2 = " + addr2);

        System.out.println("addr1.hashCode()=" + addr1.hashCode());
        System.out.println("addr2.hashCode()=" + addr2.hashCode());


        int ret=addr1.compareTo(addr2);
        System.out.println("addr1.compareTo(addr2)=" + ret);

        ret=addr2.compareTo(addr1);
        System.out.println("addr2.compareTo(addr1)=" + ret);

        map.put(addr1, 1);
        map.put(addr2, 2);
        System.out.println("map = " + map + ", size=" + map.size());
    }


> IpAddress.hashCode() not unique per ip/port
> -------------------------------------------
>
>                 Key: JGRP-591
>                 URL: http://jira.jboss.com/jira/browse/JGRP-591
>             Project: JGroups
>          Issue Type: Bug
>    Affects Versions: 2.4.1 SP4
>         Environment: windows xp sp2, jdk 1.6 update 2
>            Reporter: robert chou
>         Assigned To: Bela Ban
>             Fix For: 2.6, 2.5.1, 2.4.1 SP5
>
>
> Current implementation produces hashcode where ip/port combos "1.2.3.4:2" and "1.2.3.5:1" result in the same hash code.
> Existing code:
>     public final int hashCode() {
>         return ip_addr != null ? ip_addr.hashCode() + port : port;
>     }
> Manual test code:
>          InetAddress ip1 = InetAddress.getByAddress( new byte[] {1,2,3,4} );
>          int         port1 = 2;
>          int         hash1 = ip1.hashCode() + port1;
>          System.out.println( "hash1 = " + hash1 );
>          
>          InetAddress ip2 = InetAddress.getByAddress( new byte[] {1,2,3,5} );
>          int         port2 = 1;
>          int         hash2 = ip2.hashCode() + port2;
>          System.out.println( "hash2 = " + hash2 );

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