jyapayne/swig
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Avoid possible GC issues in Java example code

Browse source 
This prevents the previously-set element value from being collected
before or during the call to setElement. Since C++ could still have
a reference to during that time, it could lead to misbehavior.
This commit is contained in:
Jesse Rusak 2017-08-29 11:00:23 -04:00
commit 175ab4e720
1 changed files with 6 additions and 11 deletions
Download patch file Download diff file Expand all files Collapse all files

17
Doc/Manual/Java.html
View file

@ -8165,13 +8165,10 @@ public class Container {
// Ensure that the GC doesn't collect any Element set from Java // Ensure that the GC doesn't collect any Element set from Java
// as the underlying C++ class stores a shallow copy // as the underlying C++ class stores a shallow copy
private Element elementReference; private Element elementReference;
private long getCPtrAndAddReference(Element element) {
elementReference = element;
return Element.getCPtr(element);
}
public void setElement(Element e) { public void setElement(Element e) {
exampleJNI.Container_setElement(swigCPtr, this, getCPtrAndAddReference(e), e); exampleJNI.Container_setElement(swigCPtr, this, Element.getCPtr(e), e);
elementReference = e;
} }
} }
</pre> </pre>
@ -8179,22 +8176,20 @@ public class Container {
<p> <p>
The following typemaps will generate the desired code. The following typemaps will generate the desired code.
The 'javain' typemap matches the input parameter type for the <tt>setElement</tt> method. The 'javain' typemap matches the input parameter type for the <tt>setElement</tt> method and allows adding code after the call.
The 'javacode' typemap simply adds in the specified code into the Java proxy class. The 'javacode' typemap simply adds in the specified code into the Java proxy class.
</p> </p>
<div class="code"> <div class="code">
<pre> <pre>
%typemap(javain) Element *e "getCPtrAndAddReference($javainput)" %typemap(javain,
post="elementReference = $javainput;\n"
) Element *e "Element.getCPtr($javainput)"
%typemap(javacode) Container %{ %typemap(javacode) Container %{
// Ensure that the GC doesn't collect any element set from Java // Ensure that the GC doesn't collect any element set from Java
// as the underlying C++ class stores a shallow copy // as the underlying C++ class stores a shallow copy
private Element elementReference; private Element elementReference;
private long getCPtrAndAddReference(Element element) {
elementReference = element;
return Element.getCPtr(element);
}
%} %}
</pre> </pre>
</div> </div>