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author | Kent Hansen <kent.hansen@nokia.com> | 2012-06-28 15:29:22 +0200 |
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committer | Qt by Nokia <qt-info@nokia.com> | 2012-07-03 19:30:46 +0200 |
commit | 378416af7542e34196908896c9a69573b995adb0 (patch) | |
tree | 750186a60e69cf0e9335b23ce3e1ca245f176de2 /src/script/api | |
parent | b9a5e257882c6418e28a82b9af1e9a6ac3044aea (diff) | |
download | qtscript-378416af7542e34196908896c9a69573b995adb0.tar.gz |
Ensure QObject wrappers are garbage-collected if appropriate
Address the "###" comment.
When QScriptEngine::newQObject() is called with the option
PreferExistingWrapperObject, the resulting wrapper object is cached
by the engine, in case it will be needed later (e.g., by a subsequent
newQObject() call for the same QObject, with the same wrap options).
But if a QObject wrapper object is only referenced by the QtScript
internals (i.e., not reachable from the JSC stack/heap, or kept in a
QScriptValue), the wrapper should not be kept alive if the ownership
is ScriptOwnership, or if the ownership is AutoOwnership and the C++
object has no parent.
If the wrapper is marked in that case, it won't get collected, and
hence the C++ object will be kept alive, too. In practice, QtScript
appears to leak memory (the objects will only be destroyed when the
engine is destroyed).
Our copy of JSC doesn't have a concept of weak references; the
ClientData callback in the JSC markRoots() function (which causes
QScriptEnginePrivate::mark() to be called) was moved to the end. This
enables the wrapper and connection marking logic to determine whether
a wrapper can be safely discarded (if it hasn't been marked by JSC by
this point, it must be a weak reference).
Task-number: QTBUG-21993
Change-Id: I61f6aafc91f080b80d3f5859148e645b80d9b653
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
Diffstat (limited to 'src/script/api')
-rw-r--r-- | src/script/api/qscriptengine.cpp | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/src/script/api/qscriptengine.cpp b/src/script/api/qscriptengine.cpp index 8b3b844..3b1cb9d 100644 --- a/src/script/api/qscriptengine.cpp +++ b/src/script/api/qscriptengine.cpp @@ -1253,6 +1253,9 @@ void QScriptEnginePrivate::setContextFlags(JSC::ExecState *exec, uint flags) } +// This function is called by JSC after all objects reachable by JSC itself +// have been processed (see JSC::Heap::markRoots()). +// Here we should mark additional objects managed by QtScript. void QScriptEnginePrivate::mark(JSC::MarkStack& markStack) { Q_Q(QScriptEngine); |