jdk-sandbox: comparison hotspot/src/share/vm/memory/referenceProcessor.hpp

equal deleted inserted replaced

-:cfa6efbbc1b3
+:4ea0e7d2ffbc
 // (with appropriate modifications) to any "non-convex interval".
 // forward references
 class ReferencePolicy;
 class AbstractRefProcTaskExecutor;
-class DiscoveredList;
+// List of discovered references.
+class DiscoveredList {
+public:
+DiscoveredList() : _len(0), _compressed_head(0), _oop_head(NULL) { }
+oop head() const     {
+return UseCompressedOops ?  oopDesc::decode_heap_oop(_compressed_head) :
+_oop_head;
+}
+HeapWord* adr_head() {
+return UseCompressedOops ? (HeapWord*)&_compressed_head :
+(HeapWord*)&_oop_head;
+}
+void set_head(oop o) {
+if (UseCompressedOops) {
+// Must compress the head ptr.
+_compressed_head = oopDesc::encode_heap_oop(o);
+} else {
+_oop_head = o;
+}
+}
+bool   is_empty() const       { return head() == NULL; }
+size_t length()               { return _len; }
+void   set_length(size_t len) { _len = len;  }
+void   inc_length(size_t inc) { _len += inc; assert(_len > 0, "Error"); }
+void   dec_length(size_t dec) { _len -= dec; }
+private:
+// Set value depending on UseCompressedOops. This could be a template class
+// but then we have to fix all the instantiations and declarations that use this class.
+oop       _oop_head;
+narrowOop _compressed_head;
+size_t _len;
+};
+// Iterator for the list of discovered references.
+class DiscoveredListIterator {
+private:
+DiscoveredList&    _refs_list;
+HeapWord*          _prev_next;
+oop                _prev;
+oop                _ref;
+HeapWord*          _discovered_addr;
+oop                _next;
+HeapWord*          _referent_addr;
+oop                _referent;
+OopClosure*        _keep_alive;
+BoolObjectClosure* _is_alive;
+DEBUG_ONLY(
+oop                _first_seen; // cyclic linked list check
+)
+NOT_PRODUCT(
+size_t             _processed;
+size_t             _removed;
+)
+public:
+inline DiscoveredListIterator(DiscoveredList&    refs_list,
+OopClosure*        keep_alive,
+BoolObjectClosure* is_alive):
+_refs_list(refs_list),
+_prev_next(refs_list.adr_head()),
+_prev(NULL),
+_ref(refs_list.head()),
+#ifdef ASSERT
+_first_seen(refs_list.head()),
+#endif
+#ifndef PRODUCT
+_processed(0),
+_removed(0),
+#endif
+_next(NULL),
+_keep_alive(keep_alive),
+_is_alive(is_alive)
+{ }
+// End Of List.
+inline bool has_next() const { return _ref != NULL; }
+// Get oop to the Reference object.
+inline oop obj() const { return _ref; }
+// Get oop to the referent object.
+inline oop referent() const { return _referent; }
+// Returns true if referent is alive.
+inline bool is_referent_alive() const {
+return _is_alive->do_object_b(_referent);
+}
+// Loads data for the current reference.
+// The "allow_null_referent" argument tells us to allow for the possibility
+// of a NULL referent in the discovered Reference object. This typically
+// happens in the case of concurrent collectors that may have done the
+// discovery concurrently, or interleaved, with mutator execution.
+void load_ptrs(DEBUG_ONLY(bool allow_null_referent));
+// Move to the next discovered reference.
+inline void next() {
+_prev_next = _discovered_addr;
+_prev = _ref;
+move_to_next();
+}
+// Remove the current reference from the list
+void remove();
+// Make the Reference object active again.
+void make_active();
+// Make the referent alive.
+inline void make_referent_alive() {
+if (UseCompressedOops) {
+_keep_alive->do_oop((narrowOop*)_referent_addr);
+} else {
+_keep_alive->do_oop((oop*)_referent_addr);
+}
+}
+// Update the discovered field.
+inline void update_discovered() {
+// First _prev_next ref actually points into DiscoveredList (gross).
+if (UseCompressedOops) {
+if (!oopDesc::is_null(*(narrowOop*)_prev_next)) {
+_keep_alive->do_oop((narrowOop*)_prev_next);
+}
+} else {
+if (!oopDesc::is_null(*(oop*)_prev_next)) {
+_keep_alive->do_oop((oop*)_prev_next);
+}
+}
+}
+// NULL out referent pointer.
+void clear_referent();
+// Statistics
+NOT_PRODUCT(
+inline size_t processed() const { return _processed; }
+inline size_t removed() const   { return _removed; }
+)
+inline void move_to_next() {
+if (_ref == _next) {
+// End of the list.
+_ref = NULL;
+} else {
+_ref = _next;
+}
+assert(_ref != _first_seen, "cyclic ref_list found");
+NOT_PRODUCT(_processed++);
+}
+};
 class ReferenceProcessor : public CHeapObj {
 protected:
 // Compatibility with pre-4965777 JDK's
 static bool _pending_list_uses_discovered_field;
-MemRegion   _span; // (right-open) interval of heap
-// subject to wkref discovery
+MemRegion   _span;                    // (right-open) interval of heap
-bool        _discovering_refs;      // true when discovery enabled
+// subject to wkref discovery
-bool        _discovery_is_atomic;   // if discovery is atomic wrt
-// other collectors in configuration
+bool        _discovering_refs;        // true when discovery enabled
-bool        _discovery_is_mt;       // true if reference discovery is MT.
+bool        _discovery_is_atomic;     // if discovery is atomic wrt
+// other collectors in configuration
+bool        _discovery_is_mt;         // true if reference discovery is MT.
 // If true, setting "next" field of a discovered refs list requires
 // write barrier(s).  (Must be true if used in a collector in which
 // elements of a discovered list may be moved during discovery: for
 // example, a collector like Garbage-First that moves objects during a
 // long-term concurrent marking phase that does weak reference
 // discovery.)
 bool        _discovered_list_needs_barrier;
-BarrierSet* _bs;                    // Cached copy of BarrierSet.
-bool        _enqueuing_is_done;     // true if all weak references enqueued
+BarrierSet* _bs;                      // Cached copy of BarrierSet.
-bool        _processing_is_mt;      // true during phases when
+bool        _enqueuing_is_done;       // true if all weak references enqueued
-// reference processing is MT.
+bool        _processing_is_mt;        // true during phases when
-int         _next_id;               // round-robin mod _num_q counter in
+// reference processing is MT.
-// support of work distribution
+int         _next_id;                 // round-robin mod _num_q counter in
+// support of work distribution
-// For collectors that do not keep GC marking information
+// For collectors that do not keep GC liveness information
 // in the object header, this field holds a closure that
 // helps the reference processor determine the reachability
-// of an oop (the field is currently initialized to NULL for
+// of an oop. It is currently initialized to NULL for all
-// all collectors but the CMS collector).
+// collectors except for CMS and G1.
 BoolObjectClosure* _is_alive_non_header;
 // Soft ref clearing policies
 // . the default policy
 static ReferencePolicy*   _default_soft_ref_policy;
 DiscoveredList* _discoveredWeakRefs;
 DiscoveredList* _discoveredFinalRefs;
 DiscoveredList* _discoveredPhantomRefs;
 public:
-int num_q()                            { return _num_q; }
+static int number_of_subclasses_of_ref() { return (REF_PHANTOM - REF_OTHER); }
-int max_num_q()                        { return _max_num_q; }
-void set_active_mt_degree(int v)       { _num_q = v; }
+int num_q()                              { return _num_q; }
-DiscoveredList* discovered_soft_refs() { return _discoveredSoftRefs; }
+int max_num_q()                          { return _max_num_q; }
+void set_active_mt_degree(int v)         { _num_q = v; }
+DiscoveredList* discovered_soft_refs()   { return _discoveredSoftRefs; }
 ReferencePolicy* setup_policy(bool always_clear) {
 _current_soft_ref_policy = always_clear ?
 _always_clear_soft_ref_policy : _default_soft_ref_policy;
 _current_soft_ref_policy->setup();   // snapshot the policy threshold
 return _current_soft_ref_policy;
 const char* list_name(int i);
 void enqueue_discovered_reflists(HeapWord* pending_list_addr, AbstractRefProcTaskExecutor* task_executor);
 protected:
+// Set the 'discovered' field of the given reference to
+// the given value - emitting barriers depending upon
+// the value of _discovered_list_needs_barrier.
+void set_discovered(oop ref, oop value);
 // "Preclean" the given discovered reference list
 // by removing references with strongly reachable referents.
 // Currently used in support of CMS only.
 void preclean_discovered_reflist(DiscoveredList&    refs_list,
 BoolObjectClosure* is_alive,
 // get and set span
 MemRegion span()                   { return _span; }
 void      set_span(MemRegion span) { _span = span; }
 // start and stop weak ref discovery
-void enable_discovery()   { _discovering_refs = true;  }
+void enable_discovery(bool verify_disabled, bool check_no_refs) {
+#ifdef ASSERT
+// Verify that we're not currently discovering refs
+assert(!verify_disabled || !_discovering_refs, "nested call?");
+if (check_no_refs) {
+// Verify that the discovered lists are empty
+verify_no_references_recorded();
+}
+#endif // ASSERT
+_discovering_refs = true;
+}
 void disable_discovery()  { _discovering_refs = false; }
 bool discovery_enabled()  { return _discovering_refs;  }
 // whether discovery is atomic wrt other collectors
 bool discovery_is_atomic() const { return _discovery_is_atomic; }
 }
 }
 ~NoRefDiscovery() {
 if (_was_discovering_refs) {
-_rp->enable_discovery();
+_rp->enable_discovery(true /*verify_disabled*/, false /*check_no_refs*/);
 }
 }
 };

changeset 10670	4ea0e7d2ffbc
parent 10526	3e92f211533f
child 10683	4b5a5a507864