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8221412: lookupPrintServices() does not always update the list of Windows remote printers

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Reviewed-by: prr, serb
This commit is contained in:
Alexey Ivanov 2019-03-28 14:52:41 +00:00
parent 21e9b4d59f
commit f883ffee64
2 changed files with 45 additions and 116 deletions
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60
src/java.desktop/windows/classes/sun/print/PrintServiceLookupProvider.java
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@ -1,5 +1,5 @@
/*
* Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -25,14 +25,8 @@
package sun.print;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.IOException;
import java.util.ArrayList;
import java.security.AccessController;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import java.util.ArrayList;
import javax.print.DocFlavor;
import javax.print.MultiDocPrintService;
import javax.print.PrintService;
@ -81,8 +75,9 @@ public class PrintServiceLookupProvider extends PrintServiceLookup {
if (refreshTimeStr != null) {
try {
minRefreshTime = (Integer.valueOf(refreshTimeStr)).intValue();
minRefreshTime = Integer.parseInt(refreshTimeStr);
} catch (NumberFormatException e) {
// ignore
}
if (minRefreshTime < DEFAULT_MINREFRESH) {
minRefreshTime = DEFAULT_MINREFRESH;
@ -139,7 +134,7 @@ public class PrintServiceLookupProvider extends PrintServiceLookup {
if (pollServices) {
// start the remote printer listener thread
Thread remThr = new Thread(null, new RemotePrinterChangeListener(),
"RemotePrinterListener", 0, false);
"RemotePrinterListener", 0, false);
remThr.setDaemon(true);
remThr.start();
}
@ -358,6 +353,7 @@ public class PrintServiceLookupProvider extends PrintServiceLookup {
}
return defaultPrintService;
}
class PrinterChangeListener implements Runnable {
long chgObj;
PrinterChangeListener() {
@ -387,10 +383,10 @@ public class PrintServiceLookupProvider extends PrintServiceLookup {
/* 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
Alternatively, Windows provides a way through 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
The Windows WMI offers an async and sync method to read through 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.
@ -398,18 +394,17 @@ public class PrintServiceLookupProvider extends PrintServiceLookup {
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
Hence an alternative mechanism is chosen 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 = null;
private String[] prevRemotePrinters;
RemotePrinterChangeListener() {
prevRemotePrinters = getRemotePrintersNames();
}
boolean doCompare(String[] str1, String[] str2) {
private boolean doCompare(String[] str1, String[] str2) {
if (str1 == null && str2 == null) {
return false;
} else if (str1 == null || str2 == null) {
@ -419,8 +414,8 @@ public class PrintServiceLookupProvider extends PrintServiceLookup {
if (str1.length != str2.length) {
return true;
} else {
for (int i = 0;i < str1.length;i++) {
for (int j = 0;j < str2.length;j++) {
for (int i = 0; i < str1.length; i++) {
for (int j = 0; j < str2.length; j++) {
// skip if both are nulls
if (str1[i] == null && str2[j] == null) {
continue;
@ -445,27 +440,26 @@ public class PrintServiceLookupProvider extends PrintServiceLookup {
@Override
public void run() {
// Init the list of remote printers
prevRemotePrinters = getRemotePrintersNames();
while (true) {
if (prevRemotePrinters != null && prevRemotePrinters.length > 0) {
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;
}
} else {
prevRemotePrinters = getRemotePrintersNames();
}
try {
Thread.sleep(minRefreshTime * 1000);
} catch (InterruptedException e) {
break;
}
String[] currentRemotePrinters = getRemotePrintersNames();
if (doCompare(prevRemotePrinters, currentRemotePrinters)) {
// The list of remote printers got updated,
// so update the cached list printers which
// includes both local and network printers
refreshServices();
// store the current data for next comparison
prevRemotePrinters = currentRemotePrinters;
}
}
}
}