1.1 --- a/src/share/vm/memory/iterator.hpp Fri Aug 14 13:44:15 2009 -0700
1.2 +++ b/src/share/vm/memory/iterator.hpp Mon Aug 24 10:36:31 2009 -0700
1.3 @@ -54,7 +54,12 @@
1.4
1.5 // In support of post-processing of weak links of KlassKlass objects;
1.6 // see KlassKlass::oop_oop_iterate().
1.7 - virtual const bool should_remember_klasses() const { return false; }
1.8 +
1.9 + virtual const bool should_remember_klasses() const {
1.10 + assert(!must_remember_klasses(), "Should have overriden this method.");
1.11 + return false;
1.12 + }
1.13 +
1.14 virtual void remember_klass(Klass* k) { /* do nothing */ }
1.15
1.16 // If "true", invoke on nmethods (when scanning compiled frames).
1.17 @@ -74,6 +79,12 @@
1.18 // location without an intervening "major reset" (like the end of a GC).
1.19 virtual bool idempotent() { return false; }
1.20 virtual bool apply_to_weak_ref_discovered_field() { return false; }
1.21 +
1.22 +#ifdef ASSERT
1.23 + static bool _must_remember_klasses;
1.24 + static bool must_remember_klasses();
1.25 + static void set_must_remember_klasses(bool v);
1.26 +#endif
1.27 };
1.28
1.29 // ObjectClosure is used for iterating through an object space
1.30 @@ -219,3 +230,38 @@
1.31 // correct length.
1.32 virtual void do_tag(int tag) = 0;
1.33 };
1.34 +
1.35 +#ifdef ASSERT
1.36 +// This class is used to flag phases of a collection that
1.37 +// can unload classes and which should override the
1.38 +// should_remember_klasses() and remember_klass() of OopClosure.
1.39 +// The _must_remember_klasses is set in the contructor and restored
1.40 +// in the destructor. _must_remember_klasses is checked in assertions
1.41 +// in the OopClosure implementations of should_remember_klasses() and
1.42 +// remember_klass() and the expectation is that the OopClosure
1.43 +// implementation should not be in use if _must_remember_klasses is set.
1.44 +// Instances of RememberKlassesChecker can be place in
1.45 +// marking phases of collections which can do class unloading.
1.46 +// RememberKlassesChecker can be passed "false" to turn off checking.
1.47 +// It is used by CMS when CMS yields to a different collector.
1.48 +class RememberKlassesChecker: StackObj {
1.49 + bool _state;
1.50 + bool _skip;
1.51 + public:
1.52 + RememberKlassesChecker(bool checking_on) : _state(false), _skip(false) {
1.53 + _skip = !(ClassUnloading && !UseConcMarkSweepGC ||
1.54 + CMSClassUnloadingEnabled && UseConcMarkSweepGC);
1.55 + if (_skip) {
1.56 + return;
1.57 + }
1.58 + _state = OopClosure::must_remember_klasses();
1.59 + OopClosure::set_must_remember_klasses(checking_on);
1.60 + }
1.61 + ~RememberKlassesChecker() {
1.62 + if (_skip) {
1.63 + return;
1.64 + }
1.65 + OopClosure::set_must_remember_klasses(_state);
1.66 + }
1.67 +};
1.68 +#endif // ASSERT
