--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/share/vm/memory/sharedHeap.hpp	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,272 @@
+/*
+ * Copyright 2000-2006 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.
+ *
+ */
+
+// A "SharedHeap" is an implementation of a java heap for HotSpot.  This
+// is an abstract class: there may be many different kinds of heaps.  This
+// class defines the functions that a heap must implement, and contains
+// infrastructure common to all heaps.
+
+class PermGen;
+class Generation;
+class BarrierSet;
+class GenRemSet;
+class Space;
+class SpaceClosure;
+class OopClosure;
+class OopsInGenClosure;
+class ObjectClosure;
+class SubTasksDone;
+class WorkGang;
+class CollectorPolicy;
+class KlassHandle;
+
+class SharedHeap : public CollectedHeap {
+  friend class VMStructs;
+
+private:
+  // For claiming strong_roots tasks.
+  SubTasksDone* _process_strong_tasks;
+
+protected:
+  // There should be only a single instance of "SharedHeap" in a program.
+  // This is enforced with the protected constructor below, which will also
+  // set the static pointer "_sh" to that instance.
+  static SharedHeap* _sh;
+
+  // All heaps contain a "permanent generation."  This is some ways
+  // similar to a generation in a generational system, in other ways not.
+  // See the "PermGen" class.
+  PermGen* _perm_gen;
+
+  // and the Gen Remembered Set, at least one good enough to scan the perm
+  // gen.
+  GenRemSet* _rem_set;
+
+  // A gc policy, controls global gc resource issues
+  CollectorPolicy *_collector_policy;
+
+  // See the discussion below, in the specification of the reader function
+  // for this variable.
+  int _strong_roots_parity;
+
+  // If we're doing parallel GC, use this gang of threads.
+  WorkGang* _workers;
+
+  // Number of parallel threads currently working on GC tasks.
+  // O indicates use sequential code; 1 means use parallel code even with
+  // only one thread, for performance testing purposes.
+  int _n_par_threads;
+
+  // Full initialization is done in a concrete subtype's "initialize"
+  // function.
+  SharedHeap(CollectorPolicy* policy_);
+
+public:
+  static SharedHeap* heap() { return _sh; }
+
+  CollectorPolicy *collector_policy() const { return _collector_policy; }
+
+  void set_barrier_set(BarrierSet* bs);
+
+  // Does operations required after initialization has been done.
+  virtual void post_initialize();
+
+  // Initialization of ("weak") reference processing support
+  virtual void ref_processing_init();
+
+  void set_perm(PermGen* perm_gen) { _perm_gen = perm_gen; }
+
+  // A helper function that fills an allocated-but-not-yet-initialized
+  // region with a garbage object.
+  static void fill_region_with_object(MemRegion mr);
+
+  // Minimum garbage fill object size
+  static size_t min_fill_size()          { return (size_t)align_object_size(oopDesc::header_size()); }
+  static size_t min_fill_size_in_bytes() { return min_fill_size() * HeapWordSize; }
+
+  // This function returns the "GenRemSet" object that allows us to scan
+  // generations; at least the perm gen, possibly more in a fully
+  // generational heap.
+  GenRemSet* rem_set() { return _rem_set; }
+
+  // These function return the "permanent" generation, in which
+  // reflective objects are allocated and stored.  Two versions, the second
+  // of which returns the view of the perm gen as a generation.
+  PermGen* perm() const { return _perm_gen; }
+  Generation* perm_gen() const { return _perm_gen->as_gen(); }
+
+  // Iteration functions.
+  void oop_iterate(OopClosure* cl) = 0;
+
+  // Same as above, restricted to a memory region.
+  virtual void oop_iterate(MemRegion mr, OopClosure* cl) = 0;
+
+  // Iterate over all objects allocated since the last collection, calling
+  // "cl->do_object" on each.  The heap must have been initialized properly
+  // to support this function, or else this call will fail.
+  virtual void object_iterate_since_last_GC(ObjectClosure* cl) = 0;
+
+  // Iterate over all spaces in use in the heap, in an undefined order.
+  virtual void space_iterate(SpaceClosure* cl) = 0;
+
+  // A SharedHeap will contain some number of spaces.  This finds the
+  // space whose reserved area contains the given address, or else returns
+  // NULL.
+  virtual Space* space_containing(const void* addr) const = 0;
+
+  bool no_gc_in_progress() { return !is_gc_active(); }
+
+  // Some collectors will perform "process_strong_roots" in parallel.
+  // Such a call will involve claiming some fine-grained tasks, such as
+  // scanning of threads.  To make this process simpler, we provide the
+  // "strong_roots_parity()" method.  Collectors that start parallel tasks
+  // whose threads invoke "process_strong_roots" must
+  // call "change_strong_roots_parity" in sequential code starting such a
+  // task.  (This also means that a parallel thread may only call
+  // process_strong_roots once.)
+  //
+  // For calls to process_strong_roots by sequential code, the parity is
+  // updated automatically.
+  //
+  // The idea is that objects representing fine-grained tasks, such as
+  // threads, will contain a "parity" field.  A task will is claimed in the
+  // current "process_strong_roots" call only if its parity field is the
+  // same as the "strong_roots_parity"; task claiming is accomplished by
+  // updating the parity field to the strong_roots_parity with a CAS.
+  //
+  // If the client meats this spec, then strong_roots_parity() will have
+  // the following properties:
+  //   a) to return a different value than was returned before the last
+  //      call to change_strong_roots_parity, and
+  //   c) to never return a distinguished value (zero) with which such
+  //      task-claiming variables may be initialized, to indicate "never
+  //      claimed".
+  void change_strong_roots_parity();
+  int strong_roots_parity() { return _strong_roots_parity; }
+
+  enum ScanningOption {
+    SO_None                = 0x0,
+    SO_AllClasses          = 0x1,
+    SO_SystemClasses       = 0x2,
+    SO_Symbols             = 0x4,
+    SO_Strings             = 0x8,
+    SO_CodeCache           = 0x10
+  };
+
+  WorkGang* workers() const { return _workers; }
+
+  // Sets the number of parallel threads that will be doing tasks
+  // (such as process strong roots) subsequently.
+  virtual void set_par_threads(int t);
+
+  // Number of threads currently working on GC tasks.
+  int n_par_threads() { return _n_par_threads; }
+
+  // Invoke the "do_oop" method the closure "roots" on all root locations.
+  // If "collecting_perm_gen" is false, then roots that may only contain
+  // references to permGen objects are not scanned.  If true, the
+  // "perm_gen" closure is applied to all older-to-younger refs in the
+  // permanent generation.  The "so" argument determines which of roots
+  // the closure is applied to:
+  // "SO_None" does none;
+  // "SO_AllClasses" applies the closure to all entries in the SystemDictionary;
+  // "SO_SystemClasses" to all the "system" classes and loaders;
+  // "SO_Symbols" applies the closure to all entries in SymbolsTable;
+  // "SO_Strings" applies the closure to all entries in StringTable;
+  // "SO_CodeCache" applies the closure to all elements of the CodeCache.
+  void process_strong_roots(bool collecting_perm_gen,
+                            ScanningOption so,
+                            OopClosure* roots,
+                            OopsInGenClosure* perm_blk);
+
+  // Apply "blk" to all the weak roots of the system.  These include
+  // JNI weak roots, the code cache, system dictionary, symbol table,
+  // string table.
+  void process_weak_roots(OopClosure* root_closure,
+                          OopClosure* non_root_closure);
+
+
+  // Like CollectedHeap::collect, but assume that the caller holds the Heap_lock.
+  virtual void collect_locked(GCCause::Cause cause) = 0;
+
+  // The functions below are helper functions that a subclass of
+  // "SharedHeap" can use in the implementation of its virtual
+  // functions.
+
+protected:
+
+  // Do anything common to GC's.
+  virtual void gc_prologue(bool full) = 0;
+  virtual void gc_epilogue(bool full) = 0;
+
+public:
+  //
+  // New methods from CollectedHeap
+  //
+
+  size_t permanent_capacity() const {
+    assert(perm_gen(), "NULL perm gen");
+    return perm_gen()->capacity();
+  }
+
+  size_t permanent_used() const {
+    assert(perm_gen(), "NULL perm gen");
+    return perm_gen()->used();
+  }
+
+  bool is_in_permanent(const void *p) const {
+    assert(perm_gen(), "NULL perm gen");
+    return perm_gen()->is_in_reserved(p);
+  }
+
+  // Different from is_in_permanent in that is_in_permanent
+  // only checks if p is in the reserved area of the heap
+  // and this checks to see if it in the commited area.
+  // This is typically used by things like the forte stackwalker
+  // during verification of suspicious frame values.
+  bool is_permanent(const void *p) const {
+    assert(perm_gen(), "NULL perm gen");
+    return perm_gen()->is_in(p);
+  }
+
+  HeapWord* permanent_mem_allocate(size_t size) {
+    assert(perm_gen(), "NULL perm gen");
+    return _perm_gen->mem_allocate(size);
+  }
+
+  void permanent_oop_iterate(OopClosure* cl) {
+    assert(perm_gen(), "NULL perm gen");
+    _perm_gen->oop_iterate(cl);
+  }
+
+  void permanent_object_iterate(ObjectClosure* cl) {
+    assert(perm_gen(), "NULL perm gen");
+    _perm_gen->object_iterate(cl);
+  }
+
+  // Some utilities.
+  void print_size_transition(size_t bytes_before,
+                             size_t bytes_after,
+                             size_t capacity);
+};