--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/share/vm/gc_interface/collectedHeap.hpp	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,539 @@
+/*
+ * 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.
+ *
+ */
+
+// A "CollectedHeap" 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 BarrierSet;
+class ThreadClosure;
+class AdaptiveSizePolicy;
+class Thread;
+
+//
+// CollectedHeap
+//   SharedHeap
+//     GenCollectedHeap
+//     G1CollectedHeap
+//   ParallelScavengeHeap
+//
+class CollectedHeap : public CHeapObj {
+  friend class VMStructs;
+  friend class IsGCActiveMark; // Block structured external access to _is_gc_active
+
+#ifdef ASSERT
+  static int       _fire_out_of_memory_count;
+#endif
+
+ protected:
+  MemRegion _reserved;
+  BarrierSet* _barrier_set;
+  bool _is_gc_active;
+  unsigned int _total_collections;          // ... started
+  unsigned int _total_full_collections;     // ... started
+  size_t _max_heap_capacity;
+  NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;)
+  NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;)
+
+  // Reason for current garbage collection.  Should be set to
+  // a value reflecting no collection between collections.
+  GCCause::Cause _gc_cause;
+  GCCause::Cause _gc_lastcause;
+  PerfStringVariable* _perf_gc_cause;
+  PerfStringVariable* _perf_gc_lastcause;
+
+  // Constructor
+  CollectedHeap();
+
+  // Create a new tlab
+  virtual HeapWord* allocate_new_tlab(size_t size);
+
+  // Fix up tlabs to make the heap well-formed again,
+  // optionally retiring the tlabs.
+  virtual void fill_all_tlabs(bool retire);
+
+  // Accumulate statistics on all tlabs.
+  virtual void accumulate_statistics_all_tlabs();
+
+  // Reinitialize tlabs before resuming mutators.
+  virtual void resize_all_tlabs();
+
+  debug_only(static void check_for_valid_allocation_state();)
+
+ protected:
+  // Allocate from the current thread's TLAB, with broken-out slow path.
+  inline static HeapWord* allocate_from_tlab(Thread* thread, size_t size);
+  static HeapWord* allocate_from_tlab_slow(Thread* thread, size_t size);
+
+  // Allocate an uninitialized block of the given size, or returns NULL if
+  // this is impossible.
+  inline static HeapWord* common_mem_allocate_noinit(size_t size, bool is_noref, TRAPS);
+
+  // Like allocate_init, but the block returned by a successful allocation
+  // is guaranteed initialized to zeros.
+  inline static HeapWord* common_mem_allocate_init(size_t size, bool is_noref, TRAPS);
+
+  // Same as common_mem version, except memory is allocated in the permanent area
+  // If there is no permanent area, revert to common_mem_allocate_noinit
+  inline static HeapWord* common_permanent_mem_allocate_noinit(size_t size, TRAPS);
+
+  // Same as common_mem version, except memory is allocated in the permanent area
+  // If there is no permanent area, revert to common_mem_allocate_init
+  inline static HeapWord* common_permanent_mem_allocate_init(size_t size, TRAPS);
+
+  // Helper functions for (VM) allocation.
+  inline static void post_allocation_setup_common(KlassHandle klass,
+                                                  HeapWord* obj, size_t size);
+  inline static void post_allocation_setup_no_klass_install(KlassHandle klass,
+                                                            HeapWord* objPtr,
+                                                            size_t size);
+
+  inline static void post_allocation_setup_obj(KlassHandle klass,
+                                               HeapWord* obj, size_t size);
+
+  inline static void post_allocation_setup_array(KlassHandle klass,
+                                                 HeapWord* obj, size_t size,
+                                                 int length);
+
+  // Clears an allocated object.
+  inline static void init_obj(HeapWord* obj, size_t size);
+
+  // Verification functions
+  virtual void check_for_bad_heap_word_value(HeapWord* addr, size_t size)
+    PRODUCT_RETURN;
+  virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)
+    PRODUCT_RETURN;
+
+ public:
+  enum Name {
+    Abstract,
+    SharedHeap,
+    GenCollectedHeap,
+    ParallelScavengeHeap,
+    G1CollectedHeap
+  };
+
+  virtual CollectedHeap::Name kind() const { return CollectedHeap::Abstract; }
+
+  /**
+   * Returns JNI error code JNI_ENOMEM if memory could not be allocated,
+   * and JNI_OK on success.
+   */
+  virtual jint initialize() = 0;
+
+  // In many heaps, there will be a need to perform some initialization activities
+  // after the Universe is fully formed, but before general heap allocation is allowed.
+  // This is the correct place to place such initialization methods.
+  virtual void post_initialize() = 0;
+
+  MemRegion reserved_region() const { return _reserved; }
+
+  // Return the number of bytes currently reserved, committed, and used,
+  // respectively, for holding objects.
+  size_t reserved_obj_bytes() const { return _reserved.byte_size(); }
+
+  // Future cleanup here. The following functions should specify bytes or
+  // heapwords as part of their signature.
+  virtual size_t capacity() const = 0;
+  virtual size_t used() const = 0;
+
+  // Return "true" if the part of the heap that allocates Java
+  // objects has reached the maximal committed limit that it can
+  // reach, without a garbage collection.
+  virtual bool is_maximal_no_gc() const = 0;
+
+  virtual size_t permanent_capacity() const = 0;
+  virtual size_t permanent_used() const = 0;
+
+  // Support for java.lang.Runtime.maxMemory():  return the maximum amount of
+  // memory that the vm could make available for storing 'normal' java objects.
+  // This is based on the reserved address space, but should not include space
+  // that the vm uses internally for bookkeeping or temporary storage (e.g.,
+  // perm gen space or, in the case of the young gen, one of the survivor
+  // spaces).
+  virtual size_t max_capacity() const = 0;
+
+  // Returns "TRUE" if "p" points into the reserved area of the heap.
+  bool is_in_reserved(const void* p) const {
+    return _reserved.contains(p);
+  }
+
+  bool is_in_reserved_or_null(const void* p) const {
+    return p == NULL || is_in_reserved(p);
+  }
+
+  // Returns "TRUE" if "p" points to the head of an allocated object in the
+  // heap. Since this method can be expensive in general, we restrict its
+  // use to assertion checking only.
+  virtual bool is_in(const void* p) const = 0;
+
+  bool is_in_or_null(const void* p) const {
+    return p == NULL || is_in(p);
+  }
+
+  // Let's define some terms: a "closed" subset of a heap is one that
+  //
+  // 1) contains all currently-allocated objects, and
+  //
+  // 2) is closed under reference: no object in the closed subset
+  //    references one outside the closed subset.
+  //
+  // Membership in a heap's closed subset is useful for assertions.
+  // Clearly, the entire heap is a closed subset, so the default
+  // implementation is to use "is_in_reserved".  But this may not be too
+  // liberal to perform useful checking.  Also, the "is_in" predicate
+  // defines a closed subset, but may be too expensive, since "is_in"
+  // verifies that its argument points to an object head.  The
+  // "closed_subset" method allows a heap to define an intermediate
+  // predicate, allowing more precise checking than "is_in_reserved" at
+  // lower cost than "is_in."
+
+  // One important case is a heap composed of disjoint contiguous spaces,
+  // such as the Garbage-First collector.  Such heaps have a convenient
+  // closed subset consisting of the allocated portions of those
+  // contiguous spaces.
+
+  // Return "TRUE" iff the given pointer points into the heap's defined
+  // closed subset (which defaults to the entire heap).
+  virtual bool is_in_closed_subset(const void* p) const {
+    return is_in_reserved(p);
+  }
+
+  bool is_in_closed_subset_or_null(const void* p) const {
+    return p == NULL || is_in_closed_subset(p);
+  }
+
+  // Returns "TRUE" if "p" is allocated as "permanent" data.
+  // If the heap does not use "permanent" data, returns the same
+  // value is_in_reserved() would return.
+  // NOTE: this actually returns true if "p" is in reserved space
+  // for the space not that it is actually allocated (i.e. in committed
+  // space). If you need the more conservative answer use is_permanent().
+  virtual bool is_in_permanent(const void *p) const = 0;
+
+  // Returns "TRUE" if "p" is in the committed area of  "permanent" data.
+  // If the heap does not use "permanent" data, returns the same
+  // value is_in() would return.
+  virtual bool is_permanent(const void *p) const = 0;
+
+  bool is_in_permanent_or_null(const void *p) const {
+    return p == NULL || is_in_permanent(p);
+  }
+
+  // Returns "TRUE" if "p" is a method oop in the
+  // current heap, with high probability. This predicate
+  // is not stable, in general.
+  bool is_valid_method(oop p) const;
+
+  void set_gc_cause(GCCause::Cause v) {
+     if (UsePerfData) {
+       _gc_lastcause = _gc_cause;
+       _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause));
+       _perf_gc_cause->set_value(GCCause::to_string(v));
+     }
+    _gc_cause = v;
+  }
+  GCCause::Cause gc_cause() { return _gc_cause; }
+
+  // Preload classes into the shared portion of the heap, and then dump
+  // that data to a file so that it can be loaded directly by another
+  // VM (then terminate).
+  virtual void preload_and_dump(TRAPS) { ShouldNotReachHere(); }
+
+  // General obj/array allocation facilities.
+  inline static oop obj_allocate(KlassHandle klass, int size, TRAPS);
+  inline static oop array_allocate(KlassHandle klass, int size, int length, TRAPS);
+  inline static oop large_typearray_allocate(KlassHandle klass, int size, int length, TRAPS);
+
+  // Special obj/array allocation facilities.
+  // Some heaps may want to manage "permanent" data uniquely. These default
+  // to the general routines if the heap does not support such handling.
+  inline static oop permanent_obj_allocate(KlassHandle klass, int size, TRAPS);
+  // permanent_obj_allocate_no_klass_install() does not do the installation of
+  // the klass pointer in the newly created object (as permanent_obj_allocate()
+  // above does).  This allows for a delay in the installation of the klass
+  // pointer that is needed during the create of klassKlass's.  The
+  // method post_allocation_install_obj_klass() is used to install the
+  // klass pointer.
+  inline static oop permanent_obj_allocate_no_klass_install(KlassHandle klass,
+                                                            int size,
+                                                            TRAPS);
+  inline static void post_allocation_install_obj_klass(KlassHandle klass,
+                                                       oop obj,
+                                                       int size);
+  inline static oop permanent_array_allocate(KlassHandle klass, int size, int length, TRAPS);
+
+  // Raw memory allocation facilities
+  // The obj and array allocate methods are covers for these methods.
+  // The permanent allocation method should default to mem_allocate if
+  // permanent memory isn't supported.
+  virtual HeapWord* mem_allocate(size_t size,
+                                 bool is_noref,
+                                 bool is_tlab,
+                                 bool* gc_overhead_limit_was_exceeded) = 0;
+  virtual HeapWord* permanent_mem_allocate(size_t size) = 0;
+
+  // The boundary between a "large" and "small" array of primitives, in words.
+  virtual size_t large_typearray_limit() = 0;
+
+  // Some heaps may offer a contiguous region for shared non-blocking
+  // allocation, via inlined code (by exporting the address of the top and
+  // end fields defining the extent of the contiguous allocation region.)
+
+  // This function returns "true" iff the heap supports this kind of
+  // allocation.  (Default is "no".)
+  virtual bool supports_inline_contig_alloc() const {
+    return false;
+  }
+  // These functions return the addresses of the fields that define the
+  // boundaries of the contiguous allocation area.  (These fields should be
+  // physically near to one another.)
+  virtual HeapWord** top_addr() const {
+    guarantee(false, "inline contiguous allocation not supported");
+    return NULL;
+  }
+  virtual HeapWord** end_addr() const {
+    guarantee(false, "inline contiguous allocation not supported");
+    return NULL;
+  }
+
+  // Some heaps may be in an unparseable state at certain times between
+  // collections. This may be necessary for efficient implementation of
+  // certain allocation-related activities. Calling this function before
+  // attempting to parse a heap ensures that the heap is in a parsable
+  // state (provided other concurrent activity does not introduce
+  // unparsability). It is normally expected, therefore, that this
+  // method is invoked with the world stopped.
+  // NOTE: if you override this method, make sure you call
+  // super::ensure_parsability so that the non-generational
+  // part of the work gets done. See implementation of
+  // CollectedHeap::ensure_parsability and, for instance,
+  // that of GenCollectedHeap::ensure_parsability().
+  // The argument "retire_tlabs" controls whether existing TLABs
+  // are merely filled or also retired, thus preventing further
+  // allocation from them and necessitating allocation of new TLABs.
+  virtual void ensure_parsability(bool retire_tlabs);
+
+  // Return an estimate of the maximum allocation that could be performed
+  // without triggering any collection or expansion activity.  In a
+  // generational collector, for example, this is probably the largest
+  // allocation that could be supported (without expansion) in the youngest
+  // generation.  It is "unsafe" because no locks are taken; the result
+  // should be treated as an approximation, not a guarantee, for use in
+  // heuristic resizing decisions.
+  virtual size_t unsafe_max_alloc() = 0;
+
+  // Section on thread-local allocation buffers (TLABs)
+  // If the heap supports thread-local allocation buffers, it should override
+  // the following methods:
+  // Returns "true" iff the heap supports thread-local allocation buffers.
+  // The default is "no".
+  virtual bool supports_tlab_allocation() const {
+    return false;
+  }
+  // The amount of space available for thread-local allocation buffers.
+  virtual size_t tlab_capacity(Thread *thr) const {
+    guarantee(false, "thread-local allocation buffers not supported");
+    return 0;
+  }
+  // An estimate of the maximum allocation that could be performed
+  // for thread-local allocation buffers without triggering any
+  // collection or expansion activity.
+  virtual size_t unsafe_max_tlab_alloc(Thread *thr) const {
+    guarantee(false, "thread-local allocation buffers not supported");
+    return 0;
+  }
+  // Can a compiler initialize a new object without store barriers?
+  // This permission only extends from the creation of a new object
+  // via a TLAB up to the first subsequent safepoint.
+  virtual bool can_elide_tlab_store_barriers() const {
+    guarantee(kind() < CollectedHeap::G1CollectedHeap, "else change or refactor this");
+    return true;
+  }
+  // If a compiler is eliding store barriers for TLAB-allocated objects,
+  // there is probably a corresponding slow path which can produce
+  // an object allocated anywhere.  The compiler's runtime support
+  // promises to call this function on such a slow-path-allocated
+  // object before performing initializations that have elided
+  // store barriers.  Returns new_obj, or maybe a safer copy thereof.
+  virtual oop new_store_barrier(oop new_obj);
+
+  // Can a compiler elide a store barrier when it writes
+  // a permanent oop into the heap?  Applies when the compiler
+  // is storing x to the heap, where x->is_perm() is true.
+  virtual bool can_elide_permanent_oop_store_barriers() const;
+
+  // Does this heap support heap inspection (+PrintClassHistogram?)
+  virtual bool supports_heap_inspection() const {
+    return false;   // Until RFE 5023697 is implemented
+  }
+
+  // Perform a collection of the heap; intended for use in implementing
+  // "System.gc".  This probably implies as full a collection as the
+  // "CollectedHeap" supports.
+  virtual void collect(GCCause::Cause cause) = 0;
+
+  // This interface assumes that it's being called by the
+  // vm thread. It collects the heap assuming that the
+  // heap lock is already held and that we are executing in
+  // the context of the vm thread.
+  virtual void collect_as_vm_thread(GCCause::Cause cause) = 0;
+
+  // Returns the barrier set for this heap
+  BarrierSet* barrier_set() { return _barrier_set; }
+
+  // Returns "true" iff there is a stop-world GC in progress.  (I assume
+  // that it should answer "false" for the concurrent part of a concurrent
+  // collector -- dld).
+  bool is_gc_active() const { return _is_gc_active; }
+
+  // Total number of GC collections (started)
+  unsigned int total_collections() const { return _total_collections; }
+  unsigned int total_full_collections() const { return _total_full_collections;}
+
+  // Increment total number of GC collections (started)
+  // Should be protected but used by PSMarkSweep - cleanup for 1.4.2
+  void increment_total_collections(bool full = false) {
+    _total_collections++;
+    if (full) {
+      increment_total_full_collections();
+    }
+  }
+
+  void increment_total_full_collections() { _total_full_collections++; }
+
+  // Return the AdaptiveSizePolicy for the heap.
+  virtual AdaptiveSizePolicy* size_policy() = 0;
+
+  // Iterate over all the ref-containing fields of all objects, calling
+  // "cl.do_oop" on each. This includes objects in permanent memory.
+  virtual void oop_iterate(OopClosure* cl) = 0;
+
+  // Iterate over all objects, calling "cl.do_object" on each.
+  // This includes objects in permanent memory.
+  virtual void object_iterate(ObjectClosure* cl) = 0;
+
+  // Behaves the same as oop_iterate, except only traverses
+  // interior pointers contained in permanent memory. If there
+  // is no permanent memory, does nothing.
+  virtual void permanent_oop_iterate(OopClosure* cl) = 0;
+
+  // Behaves the same as object_iterate, except only traverses
+  // object contained in permanent memory. If there is no
+  // permanent memory, does nothing.
+  virtual void permanent_object_iterate(ObjectClosure* cl) = 0;
+
+  // NOTE! There is no requirement that a collector implement these
+  // functions.
+  //
+  // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
+  // each address in the (reserved) heap is a member of exactly
+  // one block.  The defining characteristic of a block is that it is
+  // possible to find its size, and thus to progress forward to the next
+  // block.  (Blocks may be of different sizes.)  Thus, blocks may
+  // represent Java objects, or they might be free blocks in a
+  // free-list-based heap (or subheap), as long as the two kinds are
+  // distinguishable and the size of each is determinable.
+
+  // Returns the address of the start of the "block" that contains the
+  // address "addr".  We say "blocks" instead of "object" since some heaps
+  // may not pack objects densely; a chunk may either be an object or a
+  // non-object.
+  virtual HeapWord* block_start(const void* addr) const = 0;
+
+  // Requires "addr" to be the start of a chunk, and returns its size.
+  // "addr + size" is required to be the start of a new chunk, or the end
+  // of the active area of the heap.
+  virtual size_t block_size(const HeapWord* addr) const = 0;
+
+  // Requires "addr" to be the start of a block, and returns "TRUE" iff
+  // the block is an object.
+  virtual bool block_is_obj(const HeapWord* addr) const = 0;
+
+  // Returns the longest time (in ms) that has elapsed since the last
+  // time that any part of the heap was examined by a garbage collection.
+  virtual jlong millis_since_last_gc() = 0;
+
+  // Perform any cleanup actions necessary before allowing a verification.
+  virtual void prepare_for_verify() = 0;
+
+  virtual void print() const = 0;
+  virtual void print_on(outputStream* st) const = 0;
+
+  // Print all GC threads (other than the VM thread)
+  // used by this heap.
+  virtual void print_gc_threads_on(outputStream* st) const = 0;
+  void print_gc_threads() { print_gc_threads_on(tty); }
+  // Iterator for all GC threads (other than VM thread)
+  virtual void gc_threads_do(ThreadClosure* tc) const = 0;
+
+  // Print any relevant tracing info that flags imply.
+  // Default implementation does nothing.
+  virtual void print_tracing_info() const = 0;
+
+  // Heap verification
+  virtual void verify(bool allow_dirty, bool silent) = 0;
+
+  // Non product verification and debugging.
+#ifndef PRODUCT
+  // Support for PromotionFailureALot.  Return true if it's time to cause a
+  // promotion failure.  The no-argument version uses
+  // this->_promotion_failure_alot_count as the counter.
+  inline bool promotion_should_fail(volatile size_t* count);
+  inline bool promotion_should_fail();
+
+  // Reset the PromotionFailureALot counters.  Should be called at the end of a
+  // GC in which promotion failure ocurred.
+  inline void reset_promotion_should_fail(volatile size_t* count);
+  inline void reset_promotion_should_fail();
+#endif  // #ifndef PRODUCT
+
+#ifdef ASSERT
+  static int fired_fake_oom() {
+    return (CIFireOOMAt > 1 && _fire_out_of_memory_count >= CIFireOOMAt);
+  }
+#endif
+};
+
+// Class to set and reset the GC cause for a CollectedHeap.
+
+class GCCauseSetter : StackObj {
+  CollectedHeap* _heap;
+  GCCause::Cause _previous_cause;
+ public:
+  GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) {
+    assert(SafepointSynchronize::is_at_safepoint(),
+           "This method manipulates heap state without locking");
+    _heap = heap;
+    _previous_cause = _heap->gc_cause();
+    _heap->set_gc_cause(cause);
+  }
+
+  ~GCCauseSetter() {
+    assert(SafepointSynchronize::is_at_safepoint(),
+          "This method manipulates heap state without locking");
+    _heap->set_gc_cause(_previous_cause);
+  }
+};