[OpenJDK 2D-Dev] [jdk17] RFR: 8267602: [macos] [lanai] java/awt/PrintJob/Text/stringwidth.sh doesn't exit on cancelling print dialog

[Jayathirth D V]

On Tue, 29 Jun 2021 23:31:33 GMT, Sergey Bylokhov <serb at openjdk.org> wrote:

>> Final blit operation in MTLLayer.blitTexture() is driven by CVDisplayLink in Metal.
>> In this test case we are hitting an invalid condition because of which we exit from MTLLayer.blitTexture(), but we are not stopping the CVDisplayLink. This is causing the CVDisplayLink callback to run in loop. Fix is to stop CVDisplayLink when we return without completing final blit operation in MTLLayer.blitTexture().
>> 
>> Sanity and performance analysis is green. More details in JBS.
>
> src/java.desktop/macosx/native/libawt_lwawt/java2d/metal/MTLLayer.m line 286:
> 
>> 284:     if (layer == NULL || ctx == NULL) {
>> 285:         J2dTraceLn(J2D_TRACE_VERBOSE, "MTLLayer_blit : Layer or Context is null");
>> 286:         [layer stopDisplayLink];
> 
> What happens if we exit before this "blitTexture" is called? Do not we need to stop(w/o possibility to restart it) that thread on toolkit shutdown or something like this?

At this point if we exit, we just return and unlock MTLRenderQueue for backbuffer rendering. And when it is done we again start CVDisplayLink in MTLRenderQueue which in turn calls setNeedsDisplay to get callback to MTLLayer.display().

This scenario is same as returning from CGLLayer.blitTexture() when textureID is 0. Appkit thread will be running in the background and we dont stop it.

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PR: https://git.openjdk.java.net/jdk17/pull/175