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<p>Hi,<br>
a trivial downcall is supposed to target a native function that
(a) terminates quickly (so as not to block the GC for too long)
and (b) does not upcall into Java.</p>
<p>So, no, a trivial downcall cannot trigger upcalls (I don't think
we detect this, I believe the JVM just crashes if you do).</p>
<p>Also I notice that you speak of "JNI" upcall. Is that what you
really mean - e.g. a trivial FFM downcall making an upcall using
JNI? In general, I think it's a bit hard for downcalls to do
anything that has to do with JNI because the invoked native
function is not passed a JNIEnv - FFM really just bridges the Java
code with the native library function you want to call, nothing
more. (I suppose that function could get its hands on the VM using
the JNI attach API, but I feel that's a different question from
what you were asking?).</p>
<p>Maurizio<br>
</p>
<div class="moz-cite-prefix">On 26/07/2023 22:23, Cheng Jin wrote:<br>
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<blockquote type="cite" cite="mid:BN8PR15MB2577D1EF4EC51FEF11DC41B8F500A@BN8PR15MB2577.namprd15.prod.outlook.com">
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<p class="MsoNormal">Hi there,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I’ve got a couple of questions about the
behavior of a trivial downcall (with
<b>isTrivial</b> specified).<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Is a FFI downcall able to trigger a JNI
upcall ?<o:p></o:p></p>
<p class="MsoNormal">If so, should a JNI upcall should be
captured in this trivial downcall?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Best Regards<o:p></o:p></p>
<p class="MsoNormal">Cheng Jin<o:p></o:p></p>
</div>
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