duke@435: /*
xdono@631:  * Copyright 2001-2008 Sun Microsystems, Inc.  All Rights Reserved.
duke@435:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435:  *
duke@435:  * This code is free software; you can redistribute it and/or modify it
duke@435:  * under the terms of the GNU General Public License version 2 only, as
duke@435:  * published by the Free Software Foundation.
duke@435:  *
duke@435:  * This code is distributed in the hope that it will be useful, but WITHOUT
duke@435:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
duke@435:  * version 2 for more details (a copy is included in the LICENSE file that
duke@435:  * accompanied this code).
duke@435:  *
duke@435:  * You should have received a copy of the GNU General Public License version
duke@435:  * 2 along with this work; if not, write to the Free Software Foundation,
duke@435:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435:  *
duke@435:  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
duke@435:  * CA 95054 USA or visit www.sun.com if you need additional information or
duke@435:  * have any questions.
duke@435:  *
duke@435:  */
duke@435: 
duke@435: // A "CollectedHeap" is an implementation of a java heap for HotSpot.  This
duke@435: // is an abstract class: there may be many different kinds of heaps.  This
duke@435: // class defines the functions that a heap must implement, and contains
duke@435: // infrastructure common to all heaps.
duke@435: 
duke@435: class BarrierSet;
duke@435: class ThreadClosure;
duke@435: class AdaptiveSizePolicy;
duke@435: class Thread;
duke@435: 
duke@435: //
duke@435: // CollectedHeap
duke@435: //   SharedHeap
duke@435: //     GenCollectedHeap
duke@435: //     G1CollectedHeap
duke@435: //   ParallelScavengeHeap
duke@435: //
duke@435: class CollectedHeap : public CHeapObj {
duke@435:   friend class VMStructs;
duke@435:   friend class IsGCActiveMark; // Block structured external access to _is_gc_active
jmasa@977:   friend class constantPoolCacheKlass; // allocate() method inserts is_conc_safe
duke@435: 
duke@435: #ifdef ASSERT
duke@435:   static int       _fire_out_of_memory_count;
duke@435: #endif
duke@435: 
jcoomes@916:   // Used for filler objects (static, but initialized in ctor).
jcoomes@916:   static size_t _filler_array_max_size;
jcoomes@916: 
duke@435:  protected:
duke@435:   MemRegion _reserved;
duke@435:   BarrierSet* _barrier_set;
duke@435:   bool _is_gc_active;
duke@435:   unsigned int _total_collections;          // ... started
duke@435:   unsigned int _total_full_collections;     // ... started
duke@435:   NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;)
duke@435:   NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;)
duke@435: 
duke@435:   // Reason for current garbage collection.  Should be set to
duke@435:   // a value reflecting no collection between collections.
duke@435:   GCCause::Cause _gc_cause;
duke@435:   GCCause::Cause _gc_lastcause;
duke@435:   PerfStringVariable* _perf_gc_cause;
duke@435:   PerfStringVariable* _perf_gc_lastcause;
duke@435: 
duke@435:   // Constructor
duke@435:   CollectedHeap();
duke@435: 
duke@435:   // Create a new tlab
duke@435:   virtual HeapWord* allocate_new_tlab(size_t size);
duke@435: 
duke@435:   // Fix up tlabs to make the heap well-formed again,
duke@435:   // optionally retiring the tlabs.
duke@435:   virtual void fill_all_tlabs(bool retire);
duke@435: 
duke@435:   // Accumulate statistics on all tlabs.
duke@435:   virtual void accumulate_statistics_all_tlabs();
duke@435: 
duke@435:   // Reinitialize tlabs before resuming mutators.
duke@435:   virtual void resize_all_tlabs();
duke@435: 
duke@435:  protected:
duke@435:   // Allocate from the current thread's TLAB, with broken-out slow path.
duke@435:   inline static HeapWord* allocate_from_tlab(Thread* thread, size_t size);
duke@435:   static HeapWord* allocate_from_tlab_slow(Thread* thread, size_t size);
duke@435: 
duke@435:   // Allocate an uninitialized block of the given size, or returns NULL if
duke@435:   // this is impossible.
duke@435:   inline static HeapWord* common_mem_allocate_noinit(size_t size, bool is_noref, TRAPS);
duke@435: 
duke@435:   // Like allocate_init, but the block returned by a successful allocation
duke@435:   // is guaranteed initialized to zeros.
duke@435:   inline static HeapWord* common_mem_allocate_init(size_t size, bool is_noref, TRAPS);
duke@435: 
duke@435:   // Same as common_mem version, except memory is allocated in the permanent area
duke@435:   // If there is no permanent area, revert to common_mem_allocate_noinit
duke@435:   inline static HeapWord* common_permanent_mem_allocate_noinit(size_t size, TRAPS);
duke@435: 
duke@435:   // Same as common_mem version, except memory is allocated in the permanent area
duke@435:   // If there is no permanent area, revert to common_mem_allocate_init
duke@435:   inline static HeapWord* common_permanent_mem_allocate_init(size_t size, TRAPS);
duke@435: 
duke@435:   // Helper functions for (VM) allocation.
duke@435:   inline static void post_allocation_setup_common(KlassHandle klass,
duke@435:                                                   HeapWord* obj, size_t size);
duke@435:   inline static void post_allocation_setup_no_klass_install(KlassHandle klass,
duke@435:                                                             HeapWord* objPtr,
duke@435:                                                             size_t size);
duke@435: 
duke@435:   inline static void post_allocation_setup_obj(KlassHandle klass,
duke@435:                                                HeapWord* obj, size_t size);
duke@435: 
duke@435:   inline static void post_allocation_setup_array(KlassHandle klass,
duke@435:                                                  HeapWord* obj, size_t size,
duke@435:                                                  int length);
duke@435: 
duke@435:   // Clears an allocated object.
duke@435:   inline static void init_obj(HeapWord* obj, size_t size);
duke@435: 
jcoomes@916:   // Filler object utilities.
jcoomes@916:   static inline size_t filler_array_hdr_size();
jcoomes@916:   static inline size_t filler_array_min_size();
jcoomes@916:   static inline size_t filler_array_max_size();
jcoomes@916: 
jcoomes@916:   DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);)
jcoomes@916:   DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words);)
jcoomes@916: 
jcoomes@916:   // Fill with a single array; caller must ensure filler_array_min_size() <=
jcoomes@916:   // words <= filler_array_max_size().
jcoomes@916:   static inline void fill_with_array(HeapWord* start, size_t words);
jcoomes@916: 
jcoomes@916:   // Fill with a single object (either an int array or a java.lang.Object).
jcoomes@916:   static inline void fill_with_object_impl(HeapWord* start, size_t words);
jcoomes@916: 
duke@435:   // Verification functions
duke@435:   virtual void check_for_bad_heap_word_value(HeapWord* addr, size_t size)
duke@435:     PRODUCT_RETURN;
duke@435:   virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)
duke@435:     PRODUCT_RETURN;
jmasa@977:   debug_only(static void check_for_valid_allocation_state();)
duke@435: 
duke@435:  public:
duke@435:   enum Name {
duke@435:     Abstract,
duke@435:     SharedHeap,
duke@435:     GenCollectedHeap,
duke@435:     ParallelScavengeHeap,
duke@435:     G1CollectedHeap
duke@435:   };
duke@435: 
duke@435:   virtual CollectedHeap::Name kind() const { return CollectedHeap::Abstract; }
duke@435: 
duke@435:   /**
duke@435:    * Returns JNI error code JNI_ENOMEM if memory could not be allocated,
duke@435:    * and JNI_OK on success.
duke@435:    */
duke@435:   virtual jint initialize() = 0;
duke@435: 
duke@435:   // In many heaps, there will be a need to perform some initialization activities
duke@435:   // after the Universe is fully formed, but before general heap allocation is allowed.
duke@435:   // This is the correct place to place such initialization methods.
duke@435:   virtual void post_initialize() = 0;
duke@435: 
duke@435:   MemRegion reserved_region() const { return _reserved; }
coleenp@548:   address base() const { return (address)reserved_region().start(); }
duke@435: 
duke@435:   // Future cleanup here. The following functions should specify bytes or
duke@435:   // heapwords as part of their signature.
duke@435:   virtual size_t capacity() const = 0;
duke@435:   virtual size_t used() const = 0;
duke@435: 
duke@435:   // Return "true" if the part of the heap that allocates Java
duke@435:   // objects has reached the maximal committed limit that it can
duke@435:   // reach, without a garbage collection.
duke@435:   virtual bool is_maximal_no_gc() const = 0;
duke@435: 
duke@435:   virtual size_t permanent_capacity() const = 0;
duke@435:   virtual size_t permanent_used() const = 0;
duke@435: 
duke@435:   // Support for java.lang.Runtime.maxMemory():  return the maximum amount of
duke@435:   // memory that the vm could make available for storing 'normal' java objects.
duke@435:   // This is based on the reserved address space, but should not include space
duke@435:   // that the vm uses internally for bookkeeping or temporary storage (e.g.,
duke@435:   // perm gen space or, in the case of the young gen, one of the survivor
duke@435:   // spaces).
duke@435:   virtual size_t max_capacity() const = 0;
duke@435: 
duke@435:   // Returns "TRUE" if "p" points into the reserved area of the heap.
duke@435:   bool is_in_reserved(const void* p) const {
duke@435:     return _reserved.contains(p);
duke@435:   }
duke@435: 
duke@435:   bool is_in_reserved_or_null(const void* p) const {
duke@435:     return p == NULL || is_in_reserved(p);
duke@435:   }
duke@435: 
duke@435:   // Returns "TRUE" if "p" points to the head of an allocated object in the
duke@435:   // heap. Since this method can be expensive in general, we restrict its
duke@435:   // use to assertion checking only.
duke@435:   virtual bool is_in(const void* p) const = 0;
duke@435: 
duke@435:   bool is_in_or_null(const void* p) const {
duke@435:     return p == NULL || is_in(p);
duke@435:   }
duke@435: 
duke@435:   // Let's define some terms: a "closed" subset of a heap is one that
duke@435:   //
duke@435:   // 1) contains all currently-allocated objects, and
duke@435:   //
duke@435:   // 2) is closed under reference: no object in the closed subset
duke@435:   //    references one outside the closed subset.
duke@435:   //
duke@435:   // Membership in a heap's closed subset is useful for assertions.
duke@435:   // Clearly, the entire heap is a closed subset, so the default
duke@435:   // implementation is to use "is_in_reserved".  But this may not be too
duke@435:   // liberal to perform useful checking.  Also, the "is_in" predicate
duke@435:   // defines a closed subset, but may be too expensive, since "is_in"
duke@435:   // verifies that its argument points to an object head.  The
duke@435:   // "closed_subset" method allows a heap to define an intermediate
duke@435:   // predicate, allowing more precise checking than "is_in_reserved" at
duke@435:   // lower cost than "is_in."
duke@435: 
duke@435:   // One important case is a heap composed of disjoint contiguous spaces,
duke@435:   // such as the Garbage-First collector.  Such heaps have a convenient
duke@435:   // closed subset consisting of the allocated portions of those
duke@435:   // contiguous spaces.
duke@435: 
duke@435:   // Return "TRUE" iff the given pointer points into the heap's defined
duke@435:   // closed subset (which defaults to the entire heap).
duke@435:   virtual bool is_in_closed_subset(const void* p) const {
duke@435:     return is_in_reserved(p);
duke@435:   }
duke@435: 
duke@435:   bool is_in_closed_subset_or_null(const void* p) const {
duke@435:     return p == NULL || is_in_closed_subset(p);
duke@435:   }
duke@435: 
duke@435:   // Returns "TRUE" if "p" is allocated as "permanent" data.
duke@435:   // If the heap does not use "permanent" data, returns the same
duke@435:   // value is_in_reserved() would return.
duke@435:   // NOTE: this actually returns true if "p" is in reserved space
duke@435:   // for the space not that it is actually allocated (i.e. in committed
duke@435:   // space). If you need the more conservative answer use is_permanent().
duke@435:   virtual bool is_in_permanent(const void *p) const = 0;
duke@435: 
duke@435:   // Returns "TRUE" if "p" is in the committed area of  "permanent" data.
duke@435:   // If the heap does not use "permanent" data, returns the same
duke@435:   // value is_in() would return.
duke@435:   virtual bool is_permanent(const void *p) const = 0;
duke@435: 
duke@435:   bool is_in_permanent_or_null(const void *p) const {
duke@435:     return p == NULL || is_in_permanent(p);
duke@435:   }
duke@435: 
duke@435:   // Returns "TRUE" if "p" is a method oop in the
duke@435:   // current heap, with high probability. This predicate
duke@435:   // is not stable, in general.
duke@435:   bool is_valid_method(oop p) const;
duke@435: 
duke@435:   void set_gc_cause(GCCause::Cause v) {
duke@435:      if (UsePerfData) {
duke@435:        _gc_lastcause = _gc_cause;
duke@435:        _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause));
duke@435:        _perf_gc_cause->set_value(GCCause::to_string(v));
duke@435:      }
duke@435:     _gc_cause = v;
duke@435:   }
duke@435:   GCCause::Cause gc_cause() { return _gc_cause; }
duke@435: 
duke@435:   // Preload classes into the shared portion of the heap, and then dump
duke@435:   // that data to a file so that it can be loaded directly by another
duke@435:   // VM (then terminate).
duke@435:   virtual void preload_and_dump(TRAPS) { ShouldNotReachHere(); }
duke@435: 
duke@435:   // General obj/array allocation facilities.
duke@435:   inline static oop obj_allocate(KlassHandle klass, int size, TRAPS);
duke@435:   inline static oop array_allocate(KlassHandle klass, int size, int length, TRAPS);
duke@435:   inline static oop large_typearray_allocate(KlassHandle klass, int size, int length, TRAPS);
duke@435: 
duke@435:   // Special obj/array allocation facilities.
duke@435:   // Some heaps may want to manage "permanent" data uniquely. These default
duke@435:   // to the general routines if the heap does not support such handling.
duke@435:   inline static oop permanent_obj_allocate(KlassHandle klass, int size, TRAPS);
duke@435:   // permanent_obj_allocate_no_klass_install() does not do the installation of
duke@435:   // the klass pointer in the newly created object (as permanent_obj_allocate()
duke@435:   // above does).  This allows for a delay in the installation of the klass
duke@435:   // pointer that is needed during the create of klassKlass's.  The
duke@435:   // method post_allocation_install_obj_klass() is used to install the
duke@435:   // klass pointer.
duke@435:   inline static oop permanent_obj_allocate_no_klass_install(KlassHandle klass,
duke@435:                                                             int size,
duke@435:                                                             TRAPS);
duke@435:   inline static void post_allocation_install_obj_klass(KlassHandle klass,
duke@435:                                                        oop obj,
duke@435:                                                        int size);
duke@435:   inline static oop permanent_array_allocate(KlassHandle klass, int size, int length, TRAPS);
duke@435: 
duke@435:   // Raw memory allocation facilities
duke@435:   // The obj and array allocate methods are covers for these methods.
duke@435:   // The permanent allocation method should default to mem_allocate if
duke@435:   // permanent memory isn't supported.
duke@435:   virtual HeapWord* mem_allocate(size_t size,
duke@435:                                  bool is_noref,
duke@435:                                  bool is_tlab,
duke@435:                                  bool* gc_overhead_limit_was_exceeded) = 0;
duke@435:   virtual HeapWord* permanent_mem_allocate(size_t size) = 0;
duke@435: 
duke@435:   // The boundary between a "large" and "small" array of primitives, in words.
duke@435:   virtual size_t large_typearray_limit() = 0;
duke@435: 
jcoomes@916:   // Utilities for turning raw memory into filler objects.
jcoomes@916:   //
jcoomes@916:   // min_fill_size() is the smallest region that can be filled.
jcoomes@916:   // fill_with_objects() can fill arbitrary-sized regions of the heap using
jcoomes@916:   // multiple objects.  fill_with_object() is for regions known to be smaller
jcoomes@916:   // than the largest array of integers; it uses a single object to fill the
jcoomes@916:   // region and has slightly less overhead.
jcoomes@916:   static size_t min_fill_size() {
jcoomes@916:     return size_t(align_object_size(oopDesc::header_size()));
jcoomes@916:   }
jcoomes@916: 
jcoomes@916:   static void fill_with_objects(HeapWord* start, size_t words);
jcoomes@916: 
jcoomes@916:   static void fill_with_object(HeapWord* start, size_t words);
jcoomes@916:   static void fill_with_object(MemRegion region) {
jcoomes@916:     fill_with_object(region.start(), region.word_size());
jcoomes@916:   }
jcoomes@916:   static void fill_with_object(HeapWord* start, HeapWord* end) {
jcoomes@916:     fill_with_object(start, pointer_delta(end, start));
jcoomes@916:   }
jcoomes@916: 
duke@435:   // Some heaps may offer a contiguous region for shared non-blocking
duke@435:   // allocation, via inlined code (by exporting the address of the top and
duke@435:   // end fields defining the extent of the contiguous allocation region.)
duke@435: 
duke@435:   // This function returns "true" iff the heap supports this kind of
duke@435:   // allocation.  (Default is "no".)
duke@435:   virtual bool supports_inline_contig_alloc() const {
duke@435:     return false;
duke@435:   }
duke@435:   // These functions return the addresses of the fields that define the
duke@435:   // boundaries of the contiguous allocation area.  (These fields should be
duke@435:   // physically near to one another.)
duke@435:   virtual HeapWord** top_addr() const {
duke@435:     guarantee(false, "inline contiguous allocation not supported");
duke@435:     return NULL;
duke@435:   }
duke@435:   virtual HeapWord** end_addr() const {
duke@435:     guarantee(false, "inline contiguous allocation not supported");
duke@435:     return NULL;
duke@435:   }
duke@435: 
duke@435:   // Some heaps may be in an unparseable state at certain times between
duke@435:   // collections. This may be necessary for efficient implementation of
duke@435:   // certain allocation-related activities. Calling this function before
duke@435:   // attempting to parse a heap ensures that the heap is in a parsable
duke@435:   // state (provided other concurrent activity does not introduce
duke@435:   // unparsability). It is normally expected, therefore, that this
duke@435:   // method is invoked with the world stopped.
duke@435:   // NOTE: if you override this method, make sure you call
duke@435:   // super::ensure_parsability so that the non-generational
duke@435:   // part of the work gets done. See implementation of
duke@435:   // CollectedHeap::ensure_parsability and, for instance,
duke@435:   // that of GenCollectedHeap::ensure_parsability().
duke@435:   // The argument "retire_tlabs" controls whether existing TLABs
duke@435:   // are merely filled or also retired, thus preventing further
duke@435:   // allocation from them and necessitating allocation of new TLABs.
duke@435:   virtual void ensure_parsability(bool retire_tlabs);
duke@435: 
duke@435:   // Return an estimate of the maximum allocation that could be performed
duke@435:   // without triggering any collection or expansion activity.  In a
duke@435:   // generational collector, for example, this is probably the largest
duke@435:   // allocation that could be supported (without expansion) in the youngest
duke@435:   // generation.  It is "unsafe" because no locks are taken; the result
duke@435:   // should be treated as an approximation, not a guarantee, for use in
duke@435:   // heuristic resizing decisions.
duke@435:   virtual size_t unsafe_max_alloc() = 0;
duke@435: 
duke@435:   // Section on thread-local allocation buffers (TLABs)
duke@435:   // If the heap supports thread-local allocation buffers, it should override
duke@435:   // the following methods:
duke@435:   // Returns "true" iff the heap supports thread-local allocation buffers.
duke@435:   // The default is "no".
duke@435:   virtual bool supports_tlab_allocation() const {
duke@435:     return false;
duke@435:   }
duke@435:   // The amount of space available for thread-local allocation buffers.
duke@435:   virtual size_t tlab_capacity(Thread *thr) const {
duke@435:     guarantee(false, "thread-local allocation buffers not supported");
duke@435:     return 0;
duke@435:   }
duke@435:   // An estimate of the maximum allocation that could be performed
duke@435:   // for thread-local allocation buffers without triggering any
duke@435:   // collection or expansion activity.
duke@435:   virtual size_t unsafe_max_tlab_alloc(Thread *thr) const {
duke@435:     guarantee(false, "thread-local allocation buffers not supported");
duke@435:     return 0;
duke@435:   }
duke@435:   // Can a compiler initialize a new object without store barriers?
duke@435:   // This permission only extends from the creation of a new object
duke@435:   // via a TLAB up to the first subsequent safepoint.
ysr@777:   virtual bool can_elide_tlab_store_barriers() const = 0;
ysr@777: 
duke@435:   // If a compiler is eliding store barriers for TLAB-allocated objects,
duke@435:   // there is probably a corresponding slow path which can produce
duke@435:   // an object allocated anywhere.  The compiler's runtime support
duke@435:   // promises to call this function on such a slow-path-allocated
duke@435:   // object before performing initializations that have elided
duke@435:   // store barriers.  Returns new_obj, or maybe a safer copy thereof.
duke@435:   virtual oop new_store_barrier(oop new_obj);
duke@435: 
duke@435:   // Can a compiler elide a store barrier when it writes
duke@435:   // a permanent oop into the heap?  Applies when the compiler
duke@435:   // is storing x to the heap, where x->is_perm() is true.
ysr@777:   virtual bool can_elide_permanent_oop_store_barriers() const = 0;
duke@435: 
duke@435:   // Does this heap support heap inspection (+PrintClassHistogram?)
ysr@777:   virtual bool supports_heap_inspection() const = 0;
duke@435: 
duke@435:   // Perform a collection of the heap; intended for use in implementing
duke@435:   // "System.gc".  This probably implies as full a collection as the
duke@435:   // "CollectedHeap" supports.
duke@435:   virtual void collect(GCCause::Cause cause) = 0;
duke@435: 
duke@435:   // This interface assumes that it's being called by the
duke@435:   // vm thread. It collects the heap assuming that the
duke@435:   // heap lock is already held and that we are executing in
duke@435:   // the context of the vm thread.
duke@435:   virtual void collect_as_vm_thread(GCCause::Cause cause) = 0;
duke@435: 
duke@435:   // Returns the barrier set for this heap
duke@435:   BarrierSet* barrier_set() { return _barrier_set; }
duke@435: 
duke@435:   // Returns "true" iff there is a stop-world GC in progress.  (I assume
duke@435:   // that it should answer "false" for the concurrent part of a concurrent
duke@435:   // collector -- dld).
duke@435:   bool is_gc_active() const { return _is_gc_active; }
duke@435: 
duke@435:   // Total number of GC collections (started)
duke@435:   unsigned int total_collections() const { return _total_collections; }
duke@435:   unsigned int total_full_collections() const { return _total_full_collections;}
duke@435: 
duke@435:   // Increment total number of GC collections (started)
duke@435:   // Should be protected but used by PSMarkSweep - cleanup for 1.4.2
duke@435:   void increment_total_collections(bool full = false) {
duke@435:     _total_collections++;
duke@435:     if (full) {
duke@435:       increment_total_full_collections();
duke@435:     }
duke@435:   }
duke@435: 
duke@435:   void increment_total_full_collections() { _total_full_collections++; }
duke@435: 
duke@435:   // Return the AdaptiveSizePolicy for the heap.
duke@435:   virtual AdaptiveSizePolicy* size_policy() = 0;
duke@435: 
duke@435:   // Iterate over all the ref-containing fields of all objects, calling
duke@435:   // "cl.do_oop" on each. This includes objects in permanent memory.
duke@435:   virtual void oop_iterate(OopClosure* cl) = 0;
duke@435: 
duke@435:   // Iterate over all objects, calling "cl.do_object" on each.
duke@435:   // This includes objects in permanent memory.
duke@435:   virtual void object_iterate(ObjectClosure* cl) = 0;
duke@435: 
jmasa@952:   // Similar to object_iterate() except iterates only
jmasa@952:   // over live objects.
jmasa@952:   virtual void safe_object_iterate(ObjectClosure* cl) = 0;
jmasa@952: 
duke@435:   // Behaves the same as oop_iterate, except only traverses
duke@435:   // interior pointers contained in permanent memory. If there
duke@435:   // is no permanent memory, does nothing.
duke@435:   virtual void permanent_oop_iterate(OopClosure* cl) = 0;
duke@435: 
duke@435:   // Behaves the same as object_iterate, except only traverses
duke@435:   // object contained in permanent memory. If there is no
duke@435:   // permanent memory, does nothing.
duke@435:   virtual void permanent_object_iterate(ObjectClosure* cl) = 0;
duke@435: 
duke@435:   // NOTE! There is no requirement that a collector implement these
duke@435:   // functions.
duke@435:   //
duke@435:   // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
duke@435:   // each address in the (reserved) heap is a member of exactly
duke@435:   // one block.  The defining characteristic of a block is that it is
duke@435:   // possible to find its size, and thus to progress forward to the next
duke@435:   // block.  (Blocks may be of different sizes.)  Thus, blocks may
duke@435:   // represent Java objects, or they might be free blocks in a
duke@435:   // free-list-based heap (or subheap), as long as the two kinds are
duke@435:   // distinguishable and the size of each is determinable.
duke@435: 
duke@435:   // Returns the address of the start of the "block" that contains the
duke@435:   // address "addr".  We say "blocks" instead of "object" since some heaps
duke@435:   // may not pack objects densely; a chunk may either be an object or a
duke@435:   // non-object.
duke@435:   virtual HeapWord* block_start(const void* addr) const = 0;
duke@435: 
duke@435:   // Requires "addr" to be the start of a chunk, and returns its size.
duke@435:   // "addr + size" is required to be the start of a new chunk, or the end
duke@435:   // of the active area of the heap.
duke@435:   virtual size_t block_size(const HeapWord* addr) const = 0;
duke@435: 
duke@435:   // Requires "addr" to be the start of a block, and returns "TRUE" iff
duke@435:   // the block is an object.
duke@435:   virtual bool block_is_obj(const HeapWord* addr) const = 0;
duke@435: 
duke@435:   // Returns the longest time (in ms) that has elapsed since the last
duke@435:   // time that any part of the heap was examined by a garbage collection.
duke@435:   virtual jlong millis_since_last_gc() = 0;
duke@435: 
duke@435:   // Perform any cleanup actions necessary before allowing a verification.
duke@435:   virtual void prepare_for_verify() = 0;
duke@435: 
duke@435:   virtual void print() const = 0;
duke@435:   virtual void print_on(outputStream* st) const = 0;
duke@435: 
duke@435:   // Print all GC threads (other than the VM thread)
duke@435:   // used by this heap.
duke@435:   virtual void print_gc_threads_on(outputStream* st) const = 0;
duke@435:   void print_gc_threads() { print_gc_threads_on(tty); }
duke@435:   // Iterator for all GC threads (other than VM thread)
duke@435:   virtual void gc_threads_do(ThreadClosure* tc) const = 0;
duke@435: 
duke@435:   // Print any relevant tracing info that flags imply.
duke@435:   // Default implementation does nothing.
duke@435:   virtual void print_tracing_info() const = 0;
duke@435: 
duke@435:   // Heap verification
duke@435:   virtual void verify(bool allow_dirty, bool silent) = 0;
duke@435: 
duke@435:   // Non product verification and debugging.
duke@435: #ifndef PRODUCT
duke@435:   // Support for PromotionFailureALot.  Return true if it's time to cause a
duke@435:   // promotion failure.  The no-argument version uses
duke@435:   // this->_promotion_failure_alot_count as the counter.
duke@435:   inline bool promotion_should_fail(volatile size_t* count);
duke@435:   inline bool promotion_should_fail();
duke@435: 
duke@435:   // Reset the PromotionFailureALot counters.  Should be called at the end of a
duke@435:   // GC in which promotion failure ocurred.
duke@435:   inline void reset_promotion_should_fail(volatile size_t* count);
duke@435:   inline void reset_promotion_should_fail();
duke@435: #endif  // #ifndef PRODUCT
duke@435: 
duke@435: #ifdef ASSERT
duke@435:   static int fired_fake_oom() {
duke@435:     return (CIFireOOMAt > 1 && _fire_out_of_memory_count >= CIFireOOMAt);
duke@435:   }
duke@435: #endif
duke@435: };
duke@435: 
duke@435: // Class to set and reset the GC cause for a CollectedHeap.
duke@435: 
duke@435: class GCCauseSetter : StackObj {
duke@435:   CollectedHeap* _heap;
duke@435:   GCCause::Cause _previous_cause;
duke@435:  public:
duke@435:   GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) {
duke@435:     assert(SafepointSynchronize::is_at_safepoint(),
duke@435:            "This method manipulates heap state without locking");
duke@435:     _heap = heap;
duke@435:     _previous_cause = _heap->gc_cause();
duke@435:     _heap->set_gc_cause(cause);
duke@435:   }
duke@435: 
duke@435:   ~GCCauseSetter() {
duke@435:     assert(SafepointSynchronize::is_at_safepoint(),
duke@435:           "This method manipulates heap state without locking");
duke@435:     _heap->set_gc_cause(_previous_cause);
duke@435:   }
duke@435: };