--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/share/vm/memory/genMarkSweep.cpp	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,392 @@
+/*
+ * Copyright 2001-2007 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.
+ *
+ */
+
+#include "incls/_precompiled.incl"
+#include "incls/_genMarkSweep.cpp.incl"
+
+void GenMarkSweep::invoke_at_safepoint(int level, ReferenceProcessor* rp,
+  bool clear_all_softrefs) {
+  assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
+
+  // hook up weak ref data so it can be used during Mark-Sweep
+  assert(ref_processor() == NULL, "no stomping");
+  _ref_processor = rp;
+  assert(rp != NULL, "should be non-NULL");
+
+  TraceTime t1("Full GC", PrintGC && !PrintGCDetails, true, gclog_or_tty);
+
+  // When collecting the permanent generation methodOops may be moving,
+  // so we either have to flush all bcp data or convert it into bci.
+  CodeCache::gc_prologue();
+  Threads::gc_prologue();
+
+  // Increment the invocation count for the permanent generation, since it is
+  // implicitly collected whenever we do a full mark sweep collection.
+  GenCollectedHeap* gch = GenCollectedHeap::heap();
+  gch->perm_gen()->stat_record()->invocations++;
+
+  // Capture heap size before collection for printing.
+  size_t gch_prev_used = gch->used();
+
+  // Some of the card table updates below assume that the perm gen is
+  // also being collected.
+  assert(level == gch->n_gens() - 1,
+         "All generations are being collected, ergo perm gen too.");
+
+  // Capture used regions for each generation that will be
+  // subject to collection, so that card table adjustments can
+  // be made intelligently (see clear / invalidate further below).
+  gch->save_used_regions(level, true /* perm */);
+
+  allocate_stacks();
+
+  mark_sweep_phase1(level, clear_all_softrefs);
+
+  mark_sweep_phase2();
+
+  // Don't add any more derived pointers during phase3
+  COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));
+  COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
+
+  mark_sweep_phase3(level);
+
+  VALIDATE_MARK_SWEEP_ONLY(
+    if (ValidateMarkSweep) {
+      guarantee(_root_refs_stack->length() == 0,
+                "should be empty by now");
+    }
+  )
+
+  mark_sweep_phase4();
+
+  VALIDATE_MARK_SWEEP_ONLY(
+    if (ValidateMarkSweep) {
+      guarantee(_live_oops->length() == _live_oops_moved_to->length(),
+                "should be the same size");
+    }
+  )
+
+  restore_marks();
+
+  // Set saved marks for allocation profiler (and other things? -- dld)
+  // (Should this be in general part?)
+  gch->save_marks();
+
+  deallocate_stacks();
+
+  // If compaction completely evacuated all generations younger than this
+  // one, then we can clear the card table.  Otherwise, we must invalidate
+  // it (consider all cards dirty).  In the future, we might consider doing
+  // compaction within generations only, and doing card-table sliding.
+  bool all_empty = true;
+  for (int i = 0; all_empty && i < level; i++) {
+    Generation* g = gch->get_gen(i);
+    all_empty = all_empty && gch->get_gen(i)->used() == 0;
+  }
+  GenRemSet* rs = gch->rem_set();
+  // Clear/invalidate below make use of the "prev_used_regions" saved earlier.
+  if (all_empty) {
+    // We've evacuated all generations below us.
+    Generation* g = gch->get_gen(level);
+    rs->clear_into_younger(g, true /* perm */);
+  } else {
+    // Invalidate the cards corresponding to the currently used
+    // region and clear those corresponding to the evacuated region
+    // of all generations just collected (i.e. level and younger).
+    rs->invalidate_or_clear(gch->get_gen(level),
+                            true /* younger */,
+                            true /* perm */);
+  }
+
+  Threads::gc_epilogue();
+  CodeCache::gc_epilogue();
+
+  if (PrintGC && !PrintGCDetails) {
+    gch->print_heap_change(gch_prev_used);
+  }
+
+  // refs processing: clean slate
+  _ref_processor = NULL;
+
+  // Update heap occupancy information which is used as
+  // input to soft ref clearing policy at the next gc.
+  Universe::update_heap_info_at_gc();
+
+  // Update time of last gc for all generations we collected
+  // (which curently is all the generations in the heap).
+  gch->update_time_of_last_gc(os::javaTimeMillis());
+}
+
+void GenMarkSweep::allocate_stacks() {
+  GenCollectedHeap* gch = GenCollectedHeap::heap();
+  // Scratch request on behalf of oldest generation; will do no
+  // allocation.
+  ScratchBlock* scratch = gch->gather_scratch(gch->_gens[gch->_n_gens-1], 0);
+
+  // $$$ To cut a corner, we'll only use the first scratch block, and then
+  // revert to malloc.
+  if (scratch != NULL) {
+    _preserved_count_max =
+      scratch->num_words * HeapWordSize / sizeof(PreservedMark);
+  } else {
+    _preserved_count_max = 0;
+  }
+
+  _preserved_marks = (PreservedMark*)scratch;
+  _preserved_count = 0;
+  _preserved_mark_stack = NULL;
+  _preserved_oop_stack = NULL;
+
+  _marking_stack       = new (ResourceObj::C_HEAP) GrowableArray<oop>(4000, true);
+
+  int size = SystemDictionary::number_of_classes() * 2;
+  _revisit_klass_stack = new (ResourceObj::C_HEAP) GrowableArray<Klass*>(size, true);
+
+#ifdef VALIDATE_MARK_SWEEP
+  if (ValidateMarkSweep) {
+    _root_refs_stack    = new (ResourceObj::C_HEAP) GrowableArray<oop*>(100, true);
+    _other_refs_stack   = new (ResourceObj::C_HEAP) GrowableArray<oop*>(100, true);
+    _adjusted_pointers  = new (ResourceObj::C_HEAP) GrowableArray<oop*>(100, true);
+    _live_oops          = new (ResourceObj::C_HEAP) GrowableArray<oop>(100, true);
+    _live_oops_moved_to = new (ResourceObj::C_HEAP) GrowableArray<oop>(100, true);
+    _live_oops_size     = new (ResourceObj::C_HEAP) GrowableArray<size_t>(100, true);
+  }
+  if (RecordMarkSweepCompaction) {
+    if (_cur_gc_live_oops == NULL) {
+      _cur_gc_live_oops           = new(ResourceObj::C_HEAP) GrowableArray<HeapWord*>(100, true);
+      _cur_gc_live_oops_moved_to  = new(ResourceObj::C_HEAP) GrowableArray<HeapWord*>(100, true);
+      _cur_gc_live_oops_size      = new(ResourceObj::C_HEAP) GrowableArray<size_t>(100, true);
+      _last_gc_live_oops          = new(ResourceObj::C_HEAP) GrowableArray<HeapWord*>(100, true);
+      _last_gc_live_oops_moved_to = new(ResourceObj::C_HEAP) GrowableArray<HeapWord*>(100, true);
+      _last_gc_live_oops_size     = new(ResourceObj::C_HEAP) GrowableArray<size_t>(100, true);
+    } else {
+      _cur_gc_live_oops->clear();
+      _cur_gc_live_oops_moved_to->clear();
+      _cur_gc_live_oops_size->clear();
+    }
+  }
+#endif
+}
+
+
+void GenMarkSweep::deallocate_stacks() {
+  if (_preserved_oop_stack) {
+    delete _preserved_mark_stack;
+    _preserved_mark_stack = NULL;
+    delete _preserved_oop_stack;
+    _preserved_oop_stack = NULL;
+  }
+
+  delete _marking_stack;
+  delete _revisit_klass_stack;
+
+#ifdef VALIDATE_MARK_SWEEP
+  if (ValidateMarkSweep) {
+    delete _root_refs_stack;
+    delete _other_refs_stack;
+    delete _adjusted_pointers;
+    delete _live_oops;
+    delete _live_oops_size;
+    delete _live_oops_moved_to;
+    _live_oops_index = 0;
+    _live_oops_index_at_perm = 0;
+  }
+#endif
+}
+
+void GenMarkSweep::mark_sweep_phase1(int level,
+                                  bool clear_all_softrefs) {
+  // Recursively traverse all live objects and mark them
+  EventMark m("1 mark object");
+  TraceTime tm("phase 1", PrintGC && Verbose, true, gclog_or_tty);
+  trace(" 1");
+
+  VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(false));
+
+  GenCollectedHeap* gch = GenCollectedHeap::heap();
+
+  // Because follow_root_closure is created statically, cannot
+  // use OopsInGenClosure constructor which takes a generation,
+  // as the Universe has not been created when the static constructors
+  // are run.
+  follow_root_closure.set_orig_generation(gch->get_gen(level));
+
+  gch->gen_process_strong_roots(level,
+                                false, // Younger gens are not roots.
+                                true,  // Collecting permanent generation.
+                                SharedHeap::SO_SystemClasses,
+                                &follow_root_closure, &follow_root_closure);
+
+  // Process reference objects found during marking
+  {
+    ReferencePolicy *soft_ref_policy;
+    if (clear_all_softrefs) {
+      soft_ref_policy = new AlwaysClearPolicy();
+    } else {
+#ifdef COMPILER2
+      soft_ref_policy = new LRUMaxHeapPolicy();
+#else
+      soft_ref_policy = new LRUCurrentHeapPolicy();
+#endif // COMPILER2
+    }
+    assert(soft_ref_policy != NULL,"No soft reference policy");
+    ref_processor()->process_discovered_references(
+      soft_ref_policy, &is_alive, &keep_alive,
+      &follow_stack_closure, NULL);
+  }
+
+  // Follow system dictionary roots and unload classes
+  bool purged_class = SystemDictionary::do_unloading(&is_alive);
+
+  // Follow code cache roots
+  CodeCache::do_unloading(&is_alive, &keep_alive, purged_class);
+  follow_stack(); // Flush marking stack
+
+  // Update subklass/sibling/implementor links of live klasses
+  follow_weak_klass_links();
+  assert(_marking_stack->is_empty(), "just drained");
+
+  // Visit symbol and interned string tables and delete unmarked oops
+  SymbolTable::unlink(&is_alive);
+  StringTable::unlink(&is_alive);
+
+  assert(_marking_stack->is_empty(), "stack should be empty by now");
+}
+
+
+void GenMarkSweep::mark_sweep_phase2() {
+  // Now all live objects are marked, compute the new object addresses.
+
+  // It is imperative that we traverse perm_gen LAST. If dead space is
+  // allowed a range of dead object may get overwritten by a dead int
+  // array. If perm_gen is not traversed last a klassOop may get
+  // overwritten. This is fine since it is dead, but if the class has dead
+  // instances we have to skip them, and in order to find their size we
+  // need the klassOop!
+  //
+  // It is not required that we traverse spaces in the same order in
+  // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
+  // tracking expects us to do so. See comment under phase4.
+
+  GenCollectedHeap* gch = GenCollectedHeap::heap();
+  Generation* pg = gch->perm_gen();
+
+  EventMark m("2 compute new addresses");
+  TraceTime tm("phase 2", PrintGC && Verbose, true, gclog_or_tty);
+  trace("2");
+
+  VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(false));
+
+  gch->prepare_for_compaction();
+
+  VALIDATE_MARK_SWEEP_ONLY(_live_oops_index_at_perm = _live_oops_index);
+  CompactPoint perm_cp(pg, NULL, NULL);
+  pg->prepare_for_compaction(&perm_cp);
+}
+
+class GenAdjustPointersClosure: public GenCollectedHeap::GenClosure {
+public:
+  void do_generation(Generation* gen) {
+    gen->adjust_pointers();
+  }
+};
+
+void GenMarkSweep::mark_sweep_phase3(int level) {
+  GenCollectedHeap* gch = GenCollectedHeap::heap();
+  Generation* pg = gch->perm_gen();
+
+  // Adjust the pointers to reflect the new locations
+  EventMark m("3 adjust pointers");
+  TraceTime tm("phase 3", PrintGC && Verbose, true, gclog_or_tty);
+  trace("3");
+
+  VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(false));
+
+  // Needs to be done before the system dictionary is adjusted.
+  pg->pre_adjust_pointers();
+
+  // Because the two closures below are created statically, cannot
+  // use OopsInGenClosure constructor which takes a generation,
+  // as the Universe has not been created when the static constructors
+  // are run.
+  adjust_root_pointer_closure.set_orig_generation(gch->get_gen(level));
+  adjust_pointer_closure.set_orig_generation(gch->get_gen(level));
+
+  gch->gen_process_strong_roots(level,
+                                false, // Younger gens are not roots.
+                                true,  // Collecting permanent generation.
+                                SharedHeap::SO_AllClasses,
+                                &adjust_root_pointer_closure,
+                                &adjust_root_pointer_closure);
+
+  // Now adjust pointers in remaining weak roots.  (All of which should
+  // have been cleared if they pointed to non-surviving objects.)
+  gch->gen_process_weak_roots(&adjust_root_pointer_closure,
+                              &adjust_pointer_closure);
+
+  adjust_marks();
+  GenAdjustPointersClosure blk;
+  gch->generation_iterate(&blk, true);
+  pg->adjust_pointers();
+}
+
+class GenCompactClosure: public GenCollectedHeap::GenClosure {
+public:
+  void do_generation(Generation* gen) {
+    gen->compact();
+  }
+};
+
+void GenMarkSweep::mark_sweep_phase4() {
+  // All pointers are now adjusted, move objects accordingly
+
+  // It is imperative that we traverse perm_gen first in phase4. All
+  // classes must be allocated earlier than their instances, and traversing
+  // perm_gen first makes sure that all klassOops have moved to their new
+  // location before any instance does a dispatch through it's klass!
+
+  // The ValidateMarkSweep live oops tracking expects us to traverse spaces
+  // in the same order in phase2, phase3 and phase4. We don't quite do that
+  // here (perm_gen first rather than last), so we tell the validate code
+  // to use a higher index (saved from phase2) when verifying perm_gen.
+  GenCollectedHeap* gch = GenCollectedHeap::heap();
+  Generation* pg = gch->perm_gen();
+
+  EventMark m("4 compact heap");
+  TraceTime tm("phase 4", PrintGC && Verbose, true, gclog_or_tty);
+  trace("4");
+
+  VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(true));
+
+  pg->compact();
+
+  VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(false));
+
+  GenCompactClosure blk;
+  gch->generation_iterate(&blk, true);
+
+  VALIDATE_MARK_SWEEP_ONLY(compaction_complete());
+
+  pg->post_compact(); // Shared spaces verification.
+}