1.1 --- a/src/share/vm/memory/iterator.hpp Fri Sep 18 09:57:47 2009 -0700
1.2 +++ b/src/share/vm/memory/iterator.hpp Wed Sep 23 23:56:15 2009 -0700
1.3 @@ -26,6 +26,7 @@
1.4
1.5 class CodeBlob;
1.6 class ReferenceProcessor;
1.7 +class DataLayout;
1.8
1.9 // Closure provides abortability.
1.10
1.11 @@ -55,9 +56,23 @@
1.12
1.13 // In support of post-processing of weak links of KlassKlass objects;
1.14 // see KlassKlass::oop_oop_iterate().
1.15 - virtual const bool should_remember_klasses() const { return false; }
1.16 +
1.17 + virtual const bool should_remember_klasses() const {
1.18 + assert(!must_remember_klasses(), "Should have overriden this method.");
1.19 + return false;
1.20 + }
1.21 +
1.22 virtual void remember_klass(Klass* k) { /* do nothing */ }
1.23
1.24 + // In support of post-processing of weak references in
1.25 + // ProfileData (MethodDataOop) objects; see, for example,
1.26 + // VirtualCallData::oop_iterate().
1.27 + virtual const bool should_remember_mdo() const { return false; }
1.28 + virtual void remember_mdo(DataLayout* v) { /* do nothing */ }
1.29 +
1.30 + // If "true", invoke on nmethods (when scanning compiled frames).
1.31 + virtual const bool do_nmethods() const { return false; }
1.32 +
1.33 // The methods below control how object iterations invoking this closure
1.34 // should be performed:
1.35
1.36 @@ -72,6 +87,12 @@
1.37 // location without an intervening "major reset" (like the end of a GC).
1.38 virtual bool idempotent() { return false; }
1.39 virtual bool apply_to_weak_ref_discovered_field() { return false; }
1.40 +
1.41 +#ifdef ASSERT
1.42 + static bool _must_remember_klasses;
1.43 + static bool must_remember_klasses();
1.44 + static void set_must_remember_klasses(bool v);
1.45 +#endif
1.46 };
1.47
1.48 // ObjectClosure is used for iterating through an object space
1.49 @@ -262,3 +283,38 @@
1.50 // correct length.
1.51 virtual void do_tag(int tag) = 0;
1.52 };
1.53 +
1.54 +#ifdef ASSERT
1.55 +// This class is used to flag phases of a collection that
1.56 +// can unload classes and which should override the
1.57 +// should_remember_klasses() and remember_klass() of OopClosure.
1.58 +// The _must_remember_klasses is set in the contructor and restored
1.59 +// in the destructor. _must_remember_klasses is checked in assertions
1.60 +// in the OopClosure implementations of should_remember_klasses() and
1.61 +// remember_klass() and the expectation is that the OopClosure
1.62 +// implementation should not be in use if _must_remember_klasses is set.
1.63 +// Instances of RememberKlassesChecker can be place in
1.64 +// marking phases of collections which can do class unloading.
1.65 +// RememberKlassesChecker can be passed "false" to turn off checking.
1.66 +// It is used by CMS when CMS yields to a different collector.
1.67 +class RememberKlassesChecker: StackObj {
1.68 + bool _state;
1.69 + bool _skip;
1.70 + public:
1.71 + RememberKlassesChecker(bool checking_on) : _state(false), _skip(false) {
1.72 + _skip = !(ClassUnloading && !UseConcMarkSweepGC ||
1.73 + CMSClassUnloadingEnabled && UseConcMarkSweepGC);
1.74 + if (_skip) {
1.75 + return;
1.76 + }
1.77 + _state = OopClosure::must_remember_klasses();
1.78 + OopClosure::set_must_remember_klasses(checking_on);
1.79 + }
1.80 + ~RememberKlassesChecker() {
1.81 + if (_skip) {
1.82 + return;
1.83 + }
1.84 + OopClosure::set_must_remember_klasses(_state);
1.85 + }
1.86 +};
1.87 +#endif // ASSERT
