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hotspot/src/share/vm/memory/modRefBarrierSet.hpp

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+/*
+ * Copyright 2000-2002 Sun Microsystems, Inc.  All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+// This kind of "BarrierSet" allows a "CollectedHeap" to detect and
+// enumerate ref fields that have been modified (since the last
+// enumeration), using a card table.
+
+class OopClosure;
+class Generation;
+
+class ModRefBarrierSet: public BarrierSet {
+public:
+  // Barriers only on ref writes.
+  bool has_read_ref_barrier() { return false; }
+  bool has_read_prim_barrier() { return false; }
+  bool has_write_ref_barrier() { return true; }
+  bool has_write_prim_barrier() { return false; }
+
+  bool read_ref_needs_barrier(oop* field) { return false; }
+  bool read_prim_needs_barrier(HeapWord* field, size_t bytes) { return false; }
+  virtual bool write_ref_needs_barrier(oop* field, oop new_val) = 0;
+  bool write_prim_needs_barrier(HeapWord* field, size_t bytes,
+                                juint val1, juint val2) { return false; }
+
+  void write_prim_field(oop obj, size_t offset, size_t bytes,
+                        juint val1, juint val2) {}
+
+  void read_ref_field(oop* field) {}
+  void read_prim_field(HeapWord* field, size_t bytes) {}
+protected:
+  virtual void write_ref_field_work(oop* field, oop new_val) = 0;
+public:
+  void write_prim_field(HeapWord* field, size_t bytes,
+                        juint val1, juint val2) {}
+
+  bool has_read_ref_array_opt() { return false; }
+  bool has_read_prim_array_opt() { return false; }
+  bool has_write_prim_array_opt() { return false; }
+
+  bool has_read_region_opt() { return false; }
+
+
+  // These operations should assert false unless the correponding operation
+  // above returns true.
+  void read_ref_array(MemRegion mr) {
+    assert(false, "can't call");
+  }
+  void read_prim_array(MemRegion mr) {
+    assert(false, "can't call");
+  }
+  void write_prim_array(MemRegion mr) {
+    assert(false, "can't call");
+  }
+  void read_region(MemRegion mr) {
+    assert(false, "can't call");
+  }
+
+  // Invoke "cl->do_oop" on (the address of) every possibly-modifed
+  // reference field in objects in "sp".  If "clear" is "true", the oops
+  // are no longer considered possibly modified after application of the
+  // closure.  If' "before_save_marks" is true, oops in objects allocated
+  // after the last call to "save_marks" on "sp" will not be considered.
+  virtual void mod_oop_in_space_iterate(Space* sp, OopClosure* cl,
+                                        bool clear = false,
+                                        bool before_save_marks = false) = 0;
+
+  // Causes all refs in "mr" to be assumed to be modified.
+  virtual void invalidate(MemRegion mr) = 0;
+
+  // The caller guarantees that "mr" contains no references.  (Perhaps it's
+  // objects have been moved elsewhere.)
+  virtual void clear(MemRegion mr) = 0;
+
+  // Pass along the argument to the superclass.
+  ModRefBarrierSet(int max_covered_regions) :
+    BarrierSet(max_covered_regions) {}
+
+#ifndef PRODUCT
+  // Verifies that the given region contains no modified references.
+  virtual void verify_clean_region(MemRegion mr) = 0;
+#endif
+
+};