Re: RFR: 8162563: Fix double checked locking in System.console()

[David Holmes]

On 27/07/2016 3:45 PM, Martin Buchholz wrote:

Hi David,

I didn't even look at Console.java!  I just fixed the double-checked
locking in System.java.

Looking now at Console.cons, that is NOT safely statically initialized:

        SharedSecrets.setJavaIOAccess(new JavaIOAccess() {
            public Console console() {
                if (istty()) {
                    if (cons == null)
                        cons = new Console();
                    return cons;
                }
                return null;
            }

(but it's currently safe because only System.java accesses it)

The above code is in a static initialization block.

Cheers,
David

Now perhaps Console.cons is deserving of its own proper init-once code.
Perhaps we don't need a static Console field in both classes Console and
System?


On Tue, Jul 26, 2016 at 7:31 PM, David Holmes <david.hol...@oracle.com
<mailto:david.hol...@oracle.com>> wrote:

    On 27/07/2016 6:35 AM, Martin Buchholz wrote:

        Hi Xueming,

        I'd like you to do a wee code review,

        
http://cr.openjdk.java.net/~martin/webrevs/openjdk9/Console-double-checked-locking/


    Humour me - where is the bug? We're simply retrieving the existing
    Console singleton that is safely published through static
    initialization. All this seems to do is improve the performance if a
    race occurs.

    AFAICS the use of locking here isn't necessary at all.

    Cheers,
    David