[OpenJDK 2D-Dev] RFR: 8263984: Invalidate printServices when there are no printers

[Jayathirth D V]

On Wed, 24 Mar 2021 20:44:26 GMT, Alexey Ivanov <aivanov at openjdk.org> wrote:

>> Since this is windows specific code, I am not sure if system will not have any printers. I guess by default, Microsoft XPS Document Writer, Microsoft Print-to-PDF, Fax are present in printers list. That is the reason we do not have getPrintService() return 0 printer although there may not be any real printer present in windows system...reason for some failure in jtreg test which caused us to use `@key printer `tag in those tests to make real printers are configured.
>
>> Since this is windows specific code, I am not sure if system will not have any printers. I guess by default, Microsoft XPS Document Writer, Microsoft Print-to-PDF, Fax are present in printers list.
> 
> Yes, that's correct. But you can remove them. You can also configure the image so that these are not installed by default.
> 
>> That is the reason we do not have getPrintService() return 0 printer although there may not be any real printer present in windows system...reason for some failure in jtreg test which caused us to use `@key printer `tag in those tests to make real printers are configured.
> 
> I agree that getting zero printers in Windows is unlikely. But it's still possible.
> 
> Consider the following scenario: Let's assume there are 10 printers in the system. The user removes 5 of them. In this case, `invalidateService()` is called on the instances of `Win32PrintService` which were removed from the system.
> 
> Then the user removes the remaining 5 printers. In this case, `invalidateService()` is not called at all. If an application has references to any of these instances, they will continue to appear operational. However, the flag `isInvalid` in `Win32PrintService` is used in two methods only: `getPrinterState` and `getPrinterStateReasons`.
> 
> This fix is minor, probably this situation never occurs in the real life.
> 
> The difference in handling the deleted services caught my attention. If everyone agrees it's not problem, I'll withdraw the PR and close the bug as _Not an Issue_.

Change looks like good practice and needed, eventhough it may occur rarely.

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PR: https://git.openjdk.java.net/jdk/pull/3151