7991 // to do (for now) is to exit with an error. However, that may
7992 // be too draconian in some cases because the caller may be
7993 // able to recover without much harm. For such cases, we
7994 // should probably introduce a "soft_push" method which returns
7995 // an indication of success or failure with the assumption that
7996 // the caller may be able to recover from a failure; code in
7997 // the VM can then be changed, incrementally, to deal with such
7998 // failures where possible, thus, incrementally hardening the VM
7999 // in such low resource situations.
8000 void CMSCollector::preserve_mark_work(oop p, markWord m) {
8001 _preserved_oop_stack.push(p);
8002 _preserved_mark_stack.push(m);
8003 assert(m == p->mark_raw(), "Mark word changed");
8004 assert(_preserved_oop_stack.size() == _preserved_mark_stack.size(),
8005 "bijection");
8006 }
8007
8008 // Single threaded
8009 void CMSCollector::preserve_mark_if_necessary(oop p) {
8010 markWord m = p->mark_raw();
8011 if (m.must_be_preserved(p)) {
8012 preserve_mark_work(p, m);
8013 }
8014 }
8015
8016 void CMSCollector::par_preserve_mark_if_necessary(oop p) {
8017 markWord m = p->mark_raw();
8018 if (m.must_be_preserved(p)) {
8019 MutexLocker x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
8020 // Even though we read the mark word without holding
8021 // the lock, we are assured that it will not change
8022 // because we "own" this oop, so no other thread can
8023 // be trying to push it on the overflow list; see
8024 // the assertion in preserve_mark_work() that checks
8025 // that m == p->mark_raw().
8026 preserve_mark_work(p, m);
8027 }
8028 }
8029
8030 // We should be able to do this multi-threaded,
8031 // a chunk of stack being a task (this is
8032 // correct because each oop only ever appears
8033 // once in the overflow list. However, it's
8034 // not very easy to completely overlap this with
8035 // other operations, so will generally not be done
8036 // until all work's been completed. Because we
8037 // expect the preserved oop stack (set) to be small,
8038 // it's probably fine to do this single-threaded.
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7991 // to do (for now) is to exit with an error. However, that may
7992 // be too draconian in some cases because the caller may be
7993 // able to recover without much harm. For such cases, we
7994 // should probably introduce a "soft_push" method which returns
7995 // an indication of success or failure with the assumption that
7996 // the caller may be able to recover from a failure; code in
7997 // the VM can then be changed, incrementally, to deal with such
7998 // failures where possible, thus, incrementally hardening the VM
7999 // in such low resource situations.
8000 void CMSCollector::preserve_mark_work(oop p, markWord m) {
8001 _preserved_oop_stack.push(p);
8002 _preserved_mark_stack.push(m);
8003 assert(m == p->mark_raw(), "Mark word changed");
8004 assert(_preserved_oop_stack.size() == _preserved_mark_stack.size(),
8005 "bijection");
8006 }
8007
8008 // Single threaded
8009 void CMSCollector::preserve_mark_if_necessary(oop p) {
8010 markWord m = p->mark_raw();
8011 if (p->mark_must_be_preserved(m)) {
8012 preserve_mark_work(p, m);
8013 }
8014 }
8015
8016 void CMSCollector::par_preserve_mark_if_necessary(oop p) {
8017 markWord m = p->mark_raw();
8018 if (p->mark_must_be_preserved(m)) {
8019 MutexLocker x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
8020 // Even though we read the mark word without holding
8021 // the lock, we are assured that it will not change
8022 // because we "own" this oop, so no other thread can
8023 // be trying to push it on the overflow list; see
8024 // the assertion in preserve_mark_work() that checks
8025 // that m == p->mark_raw().
8026 preserve_mark_work(p, m);
8027 }
8028 }
8029
8030 // We should be able to do this multi-threaded,
8031 // a chunk of stack being a task (this is
8032 // correct because each oop only ever appears
8033 // once in the overflow list. However, it's
8034 // not very easy to completely overlap this with
8035 // other operations, so will generally not be done
8036 // until all work's been completed. Because we
8037 // expect the preserved oop stack (set) to be small,
8038 // it's probably fine to do this single-threaded.
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