[OpenJDK 2D-Dev] [PATCH] FontManager refactoring

[Phil Race]

Roman Kennke wrote:
> Hi Phil,
>   
>>  >> I'm not sure about the movement of addToPool() to TrueTypeFont.java
>>  >> Theoretically its independent of the font format, and could apply
>>  >> to any FileFont subclass.
>>  >> also the file closer shut down hook isn't needed except for created
>>  >> fonts from tmp files, so that shouldn't be started unless needed.
>>  >
>>  > I moved this code to a new class called FontChannelPool, and only start
>>  > the hook when needed.
>>
>> I see that in FontChannelPool.java you start the closer when the TT font is a copy.
>> I don't have your previous webrev any more to compare but isn't
>> quite what I expected. The "closer" hook is so we can delete
>> files, and its started from the createFont2D() code, which is
>> the only case when we'd want to delete the files. You even
>> left it in there, called fileCloser, but it no longer closes
>> the files, just deletes them.
>>
>> So: there should be no need to add the "isCopy" to TrueTypeFont,
>> nor to pass a variable to addToPool().
>>     
>
> I removed these isCopy things. Somehow, I tried to be close in behaviour
> to the original behaviour, but it actually doesn't make any sense (only
> closing channels if somebody called createFont(InputStream) ? Must be a
> mistake). I hope that this is what you were critizing, no?
>
>   

I haven't yet looked at the new webrev, but the issue is this :

Most apps use only "system" installed fonts, or other ones that are 
permanently on disk.
There can be a lot of these.
Closing files in the pool happens routinely as we limit the number that 
are open at one time.

When the VM exits normally (ie via System.exit(int)), then the 
underlying operating system
will close the file descriptors for us and we have no clean up (*)  we 
need to do, so there
is no need to explicitly close these files.

 However in the case of fonts created via Font.createFont(InputStream) 
the implementation
always copies this data into a temporary disk file before doing 
anything. So when the
JRE exits we do need to do some clean up. ie delete the temp files from 
the temp dir.
On UFS based systems, and likely all filesystems on Unix systems, this means
calling the system "unlink" (which is what File.delete does) and it 
matters not one whit
whether rhe file is open at the time we call unlink(). The O/S and 
filesystem more or
less immediately hides it from new readers of the containing directory. When
the last process already using that file exits, the file is "gone" - 
deleted.

But on MS-Windows, if any process has the file open, then File.delete 
simply fails
So in order to delete these files, they need to be first closed.

Hopefully you can see this applies *only* to fonts created by a 
Font.createFont(InputStream)

-phil.