src/windows/classes/sun/print/PrintServiceLookupProvider.java

rev 13547 : 8055705: Rename UnixPrintServiceLookup and Win32PrintServiceLookup as a platform neutral class name
Reviewed-by: jgodinez, bae
rev 13548 : 8153732: Windows remote printer changes do not reflect in lookupPrintServices()
Reviewed-by: prr, psadhukhan

*** 51,62 ****
--- 51,96 ----
  
      private String defaultPrinter;
      private PrintService defaultPrintService;
      private String[] printers; /* excludes the default printer */
      private PrintService[] printServices; /* includes the default printer */
+     private static boolean pollServices = true;
+     private static final int DEFAULT_MINREFRESH = 240;  // 4 minutes
+     private static int minRefreshTime = DEFAULT_MINREFRESH;
  
      static {
+         /* The system property "sun.java2d.print.polling"
+          * can be used to force the printing code to poll or not poll
+          * for PrintServices.
+          */
+         String pollStr = java.security.AccessController.doPrivileged(
+             new sun.security.action.GetPropertyAction("sun.java2d.print.polling"));
+ 
+         if (pollStr != null) {
+             if (pollStr.equalsIgnoreCase("false")) {
+                 pollServices = false;
+             }
+         }
+ 
+         /* The system property "sun.java2d.print.minRefreshTime"
+          * can be used to specify minimum refresh time (in seconds)
+          * for polling PrintServices.  The default is 240.
+          */
+         String refreshTimeStr = java.security.AccessController.doPrivileged(
+             new sun.security.action.GetPropertyAction(
+                 "sun.java2d.print.minRefreshTime"));
+ 
+         if (refreshTimeStr != null) {
+             try {
+                 minRefreshTime = (Integer.valueOf(refreshTimeStr)).intValue();
+             } catch (NumberFormatException e) {
+             }
+             if (minRefreshTime < DEFAULT_MINREFRESH) {
+                 minRefreshTime = DEFAULT_MINREFRESH;
+             }
+         }
+ 
          java.security.AccessController.doPrivileged(
              new java.security.PrivilegedAction<Void>() {
                  public Void run() {
                      System.loadLibrary("awt");
                      return null;
*** 94,107 ****
              // There's no capability for Win98 to refresh printers.
              // See "OpenPrinter" for more info.
              if (osName != null && osName.startsWith("Windows 98")) {
                  return;
              }
!             // start the printer listener thread
!             PrinterChangeListener thr = new PrinterChangeListener();
              thr.setDaemon(true);
              thr.start();
          } /* else condition ought to never happen! */
      }
  
      /* Want the PrintService which is default print service to have
       * equality of reference with the equivalent in list of print services
--- 128,150 ----
              // There's no capability for Win98 to refresh printers.
              // See "OpenPrinter" for more info.
              if (osName != null && osName.startsWith("Windows 98")) {
                  return;
              }
!             // start the local printer listener thread
!             Thread thr = new Thread(null, new PrinterChangeListener(),
!                     "PrinterListener", 0);
              thr.setDaemon(true);
              thr.start();
+ 
+             if (pollServices) {
+                 // start the remote printer listener thread
+                 Thread remThr = new Thread(null, new RemotePrinterChangeListener(),
+                                   "RemotePrinterListener", 0);
+                 remThr.setDaemon(true);
+                 remThr.start();
+             }
          } /* else condition ought to never happen! */
      }
  
      /* Want the PrintService which is default print service to have
       * equality of reference with the equivalent in list of print services
*** 339,349 ****
--- 382,457 ----
                  }
              }
          }
      }
  
+     /* Windows provides *PrinterChangeNotification* functions that provides
+        information about printer status changes of the local printers but not
+        network printers.
+        Alternatively, Windows provides a way thro' which one can get the
+        network printer status changes by using WMI, RegistryKeyChange combination,
+        which is a slightly complex mechanism.
+        The Windows WMI offers an async and sync method to read thro' registry
+        via the WQL query. The async method is considered dangerous as it leaves
+        open a channel until we close it. But the async method has the advantage of
+        being notified of a change in registry by calling callback without polling for it.
+        The sync method uses the polling mechanism to notify.
+        RegistryValueChange cannot be used in combination with WMI to get registry
+        value change notification because of an error that may be generated because the
+        scope of the query would be too big to handle(at times).
+        Hence an alternative mechanism is choosen via the EnumPrinters by polling for the
+        count of printer status changes(add\remove) and based on it update the printers
+        list.
+     */
+     class RemotePrinterChangeListener implements Runnable {
+         private String[] prevRemotePrinters;
+ 
+         RemotePrinterChangeListener() {
+             prevRemotePrinters = getRemotePrintersNames();
+         }
+ 
+         boolean doCompare(String[] str1, String[] str2) {
+             if (str1.length != str2.length) {
+                 return true;
+             } else {
+                 for (int i = 0;i < str1.length;i++) {
+                     for (int j = 0;j < str2.length;j++) {
+                         if (!str1[i].equals(str2[j])) {
+                             return true;
+                         }
+                     }
+                 }
+             }
+ 
+             return false;
+         }
+ 
+         @Override
+         public void run() {
+             while (true) {
+                 String[] currentRemotePrinters = getRemotePrintersNames();
+                 if (doCompare(prevRemotePrinters, currentRemotePrinters)) {
+ 
+                     // updated the printers data
+                     // printers list now contains both local and network printer data
+                     refreshServices();
+ 
+                     // store the current data for next comparison
+                     prevRemotePrinters = currentRemotePrinters;
+                 }
+ 
+                 try {
+                     Thread.sleep(minRefreshTime * 1000);
+                 } catch (InterruptedException e) {
+                     break;
+                 }
+             }
+         }
+     }
+ 
      private native String getDefaultPrinterName();
      private native String[] getAllPrinterNames();
      private native long notifyFirstPrinterChange(String printer);
      private native void notifyClosePrinterChange(long chgObj);
      private native int notifyPrinterChange(long chgObj);
+     private native String[] getRemotePrintersNames();
  }