[OpenJDK 2D-Dev] Patch: fix race condition in UnixPrintServiceLookup

[Jennifer Godinez]

Hi Andrew,

Bug is filed on this with ID 6731826.  We are looking at your suggested fix and also looking at 
other ways to fix it.  Stay tuned.

Jennifer

Andrew Haley wrote:
> The JCK revealed a race condition in UnixPrintServiceLookup when either
> sun.java2d.print.polling=false or getDefaultPrintService() returns
> before the polling PrintServices thread has started.  This causes
> multiple copies of IPPPrintService to be instantiated.  The test below
> fails on all platforms with -Dsun.java2d.print.polling=false and on
> some platforms with -Dsun.java2d.print.polling=true, depending on how
> long it takes the polling loop to start.
> 
> The simple fix is to ensure that we call refreshServices() from the
> constructor, ensuring that everything is initialized before the first
> call to lookupDefaultPrintService().
> 
> Is this patch a good approach to fixing the problem?
> 
> Andrew.
> 
> 
> ----------------------------------------------------------------------------------
> import javax.print.PrintService;
> import javax.print.PrintServiceLookup;
> 
> 
> public class Test {
> 
>     public static void main(String argv[]) {
> 	trial();
>     }
> 
>     static void trial() {
>         PrintService pserv1 = PrintServiceLookup.lookupDefaultPrintService();
> 	PrintService[] pservs = PrintServiceLookup.lookupPrintServices(null, null);
>         PrintService pserv2 = PrintServiceLookup.lookupDefaultPrintService();
> 	
>         if (pserv1.hashCode() != pserv2.hashCode()) {
> 	    System.err.println("Different hashCodes for equal print "
>                             + "services: " + pserv1.hashCode() + " "
>                             + pserv2.hashCode());
> 	}
>     }
> }
> 
> ----------------------------------------------------------------------------------
> 
> --- /notnfs/user/TCK_candidate/icedtea6-1.2/openjdk/jdk/src/solaris/classes/sun/print/UnixPrintServiceLookup.java       2008-04-11 04:18:13.000000000 -0400
> +++ sun/print/UnixPrintServiceLookup.java       2008-07-30 12:45:40.000000000 -0400
> @@ -163,6 +163,12 @@
> 
> 
>      public UnixPrintServiceLookup() {
> +       try {
> +           refreshServices();
> +       } catch (Exception se) {
> +           IPPPrintService.debug_println(debugPrefix+"Exception in refreshServices()");
> +       }
> +
>          // start the printer listener thread
>          if (pollServices) {
>              PrinterChangeListener thr = new PrinterChangeListener();