0N/A

1879N/A#ifndef SHARE_VM_GC_INTERFACE_COLLECTEDHEAP_HPP

1879N/A#define SHARE_VM_GC_INTERFACE_COLLECTEDHEAP_HPP

1879N/A

1879N/A#include "gc_interface/gcCause.hpp"

1879N/A#include "memory/allocation.hpp"

1879N/A#include "memory/barrierSet.hpp"

1879N/A#include "runtime/handles.hpp"

1879N/A#include "runtime/perfData.hpp"

1879N/A#include "runtime/safepoint.hpp"

1879N/A#include "utilities/events.hpp"

1879N/A

1879N/A

1879N/Aclass BarrierSet;

0N/Aclass ThreadClosure;

0N/Aclass AdaptiveSizePolicy;

0N/Aclass Thread;

0N/Aclass CollectorPolicy;

0N/A

0N/Aclass GCMessage : public FormatBuffer<1024> {

481N/A public:

481N/A bool is_before;

0N/A

0N/A public:

1753N/A GCMessage() {}

1753N/A};

1753N/A

481N/Aclass GCHeapLog : public EventLogBase<GCMessage> {

481N/A private:

481N/A void log_heap(bool before);

481N/A

481N/A public:

481N/A GCHeapLog() : EventLogBase<GCMessage>("GC Heap History") {}

481N/A

481N/A void log_heap_before() {

481N/A log_heap(true);

481N/A }

0N/A void log_heap_after() {

0N/A log_heap(false);

0N/A }

0N/A};

0N/A

0N/Aclass CollectedHeap : public CHeapObj {

0N/A friend class VMStructs;

1166N/A friend class IsGCActiveMark; // Block structured external access to _is_gc_active

0N/A friend class constantPoolCacheKlass; // allocate() method inserts is_conc_safe

0N/A

1166N/A#ifdef ASSERT

1166N/A static int _fire_out_of_memory_count;

1166N/A#endif

1468N/A

1194N/A // Used for filler objects (static, but initialized in ctor).

1194N/A static size_t _filler_array_max_size;

1166N/A

1166N/A GCHeapLog* _gc_heap_log;

1166N/A

1166N/A // Used in support of ReduceInitialCardMarks; only consulted if COMPILER2 is being used

0N/A bool _defer_initial_card_mark;

0N/A

0N/A protected:

0N/A MemRegion _reserved;

0N/A BarrierSet* _barrier_set;

0N/A bool _is_gc_active;

0N/A uint _n_par_threads;

0N/A

0N/A unsigned int _total_collections; // ... started

0N/A unsigned int _total_full_collections; // ... started

0N/A NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;)

0N/A NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;)

0N/A

0N/A // Reason for current garbage collection. Should be set to

0N/A // a value reflecting no collection between collections.

0N/A GCCause::Cause _gc_cause;

0N/A GCCause::Cause _gc_lastcause;

0N/A PerfStringVariable* _perf_gc_cause;

0N/A PerfStringVariable* _perf_gc_lastcause;

0N/A

0N/A // Constructor

0N/A CollectedHeap();

0N/A

0N/A // Do common initializations that must follow instance construction,

0N/A // for example, those needing virtual calls.

0N/A // This code could perhaps be moved into initialize() but would

0N/A // be slightly more awkward because we want the latter to be a

0N/A // pure virtual.

0N/A void pre_initialize();

0N/A

0N/A // Create a new tlab. All TLAB allocations must go through this.

0N/A virtual HeapWord* allocate_new_tlab(size_t size);

0N/A

0N/A // Accumulate statistics on all tlabs.

0N/A virtual void accumulate_statistics_all_tlabs();

0N/A

0N/A // Reinitialize tlabs before resuming mutators.

0N/A virtual void resize_all_tlabs();

0N/A

0N/A protected:

0N/A // Allocate from the current thread's TLAB, with broken-out slow path.

0N/A inline static HeapWord* allocate_from_tlab(Thread* thread, size_t size);

0N/A static HeapWord* allocate_from_tlab_slow(Thread* thread, size_t size);

0N/A

0N/A // Allocate an uninitialized block of the given size, or returns NULL if

0N/A // this is impossible.

0N/A inline static HeapWord* common_mem_allocate_noinit(size_t size, TRAPS);

0N/A

0N/A // Like allocate_init, but the block returned by a successful allocation

0N/A // is guaranteed initialized to zeros.

0N/A inline static HeapWord* common_mem_allocate_init(size_t size, TRAPS);

0N/A

0N/A // Same as common_mem version, except memory is allocated in the permanent area

0N/A // If there is no permanent area, revert to common_mem_allocate_noinit

0N/A inline static HeapWord* common_permanent_mem_allocate_noinit(size_t size, TRAPS);

0N/A

0N/A // Same as common_mem version, except memory is allocated in the permanent area

0N/A // If there is no permanent area, revert to common_mem_allocate_init

0N/A inline static HeapWord* common_permanent_mem_allocate_init(size_t size, TRAPS);

0N/A

0N/A // Helper functions for (VM) allocation.

0N/A inline static void post_allocation_setup_common(KlassHandle klass,

0N/A HeapWord* obj, size_t size);

0N/A inline static void post_allocation_setup_no_klass_install(KlassHandle klass,

0N/A HeapWord* objPtr,

0N/A size_t size);

0N/A

0N/A inline static void post_allocation_setup_obj(KlassHandle klass,

0N/A HeapWord* obj, size_t size);

0N/A

0N/A inline static void post_allocation_setup_array(KlassHandle klass,

0N/A HeapWord* obj, size_t size,

0N/A int length);

0N/A

0N/A // Clears an allocated object.

0N/A inline static void init_obj(HeapWord* obj, size_t size);

1027N/A

1027N/A // Filler object utilities.

1027N/A static inline size_t filler_array_hdr_size();

1166N/A static inline size_t filler_array_min_size();

1027N/A static inline size_t filler_array_max_size();

1027N/A

1027N/A DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);)

1027N/A DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);)

1027N/A

1166N/A // Fill with a single array; caller must ensure filler_array_min_size() <=

1027N/A // words <= filler_array_max_size().

1027N/A static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true);

1027N/A

1027N/A // Fill with a single object (either an int array or a java.lang.Object).

1027N/A static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true);

1027N/A

1027N/A // Verification functions

1027N/A virtual void check_for_bad_heap_word_value(HeapWord* addr, size_t size)

1027N/A PRODUCT_RETURN;

1027N/A virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)

1027N/A PRODUCT_RETURN;

1027N/A debug_only(static void check_for_valid_allocation_state();)

1027N/A

1027N/A public:

1027N/A enum Name {

1027N/A Abstract,

1027N/A SharedHeap,

1027N/A GenCollectedHeap,

1027N/A ParallelScavengeHeap,

1027N/A G1CollectedHeap

1027N/A };

1027N/A

1027N/A virtual CollectedHeap::Name kind() const { return CollectedHeap::Abstract; }

1027N/A

1027N/A /**

1166N/A virtual jint initialize() = 0;

1027N/A

1027N/A // In many heaps, there will be a need to perform some initialization activities

1027N/A // after the Universe is fully formed, but before general heap allocation is allowed.

1027N/A // This is the correct place to place such initialization methods.

1027N/A virtual void post_initialize() = 0;

1027N/A

1027N/A MemRegion reserved_region() const { return _reserved; }

1027N/A address base() const { return (address)reserved_region().start(); }

1027N/A

1027N/A // Future cleanup here. The following functions should specify bytes or

1027N/A // heapwords as part of their signature.

1027N/A virtual size_t capacity() const = 0;

1027N/A virtual size_t used() const = 0;

1027N/A

1027N/A // Return "true" if the part of the heap that allocates Java

1027N/A // objects has reached the maximal committed limit that it can

1027N/A // reach, without a garbage collection.

1027N/A virtual bool is_maximal_no_gc() const = 0;

1027N/A

1027N/A virtual size_t permanent_capacity() const = 0;

1027N/A virtual size_t permanent_used() const = 0;

1027N/A

1166N/A // Support for java.lang.Runtime.maxMemory(): return the maximum amount of

1166N/A // memory that the vm could make available for storing 'normal' java objects.

1027N/A // This is based on the reserved address space, but should not include space

1166N/A // that the vm uses internally for bookkeeping or temporary storage (e.g.,

1166N/A // perm gen space or, in the case of the young gen, one of the survivor

1166N/A // spaces).

1166N/A virtual size_t max_capacity() const = 0;

1027N/A

1027N/A // Returns "TRUE" if "p" points into the reserved area of the heap.

1027N/A bool is_in_reserved(const void* p) const {

1027N/A return _reserved.contains(p);

1027N/A }

1027N/A

1027N/A bool is_in_reserved_or_null(const void* p) const {

1166N/A return p == NULL || is_in_reserved(p);

1166N/A }

1166N/A

1166N/A // Returns "TRUE" iff "p" points into the committed areas of the heap.

1166N/A // Since this method can be expensive in general, we restrict its

1166N/A // use to assertion checking only.

1166N/A virtual bool is_in(const void* p) const = 0;

1166N/A

1166N/A bool is_in_or_null(const void* p) const {

1166N/A return p == NULL || is_in(p);

1166N/A }

1027N/A

1027N/A // Let's define some terms: a "closed" subset of a heap is one that

1027N/A //

1027N/A // 1) contains all currently-allocated objects, and

481N/A //

1491N/A // 2) is closed under reference: no object in the closed subset

481N/A // references one outside the closed subset.

481N/A //

481N/A // Membership in a heap's closed subset is useful for assertions.

1491N/A // Clearly, the entire heap is a closed subset, so the default

481N/A // implementation is to use "is_in_reserved". But this may not be too

481N/A // liberal to perform useful checking. Also, the "is_in" predicate

481N/A // defines a closed subset, but may be too expensive, since "is_in"

481N/A // verifies that its argument points to an object head. The

481N/A // "closed_subset" method allows a heap to define an intermediate

481N/A // predicate, allowing more precise checking than "is_in_reserved" at

481N/A // lower cost than "is_in."

481N/A

481N/A // One important case is a heap composed of disjoint contiguous spaces,

481N/A // such as the Garbage-First collector. Such heaps have a convenient

481N/A // closed subset consisting of the allocated portions of those

481N/A // contiguous spaces.

481N/A

481N/A // Return "TRUE" iff the given pointer points into the heap's defined

481N/A // closed subset (which defaults to the entire heap).

1165N/A virtual bool is_in_closed_subset(const void* p) const {

481N/A return is_in_reserved(p);

1165N/A }

481N/A

481N/A bool is_in_closed_subset_or_null(const void* p) const {

481N/A return p == NULL || is_in_closed_subset(p);

481N/A }

481N/A

481N/A // XXX is_permanent() and is_in_permanent() should be better named

481N/A // to distinguish one from the other.

1165N/A

481N/A // Returns "TRUE" if "p" is allocated as "permanent" data.

481N/A // If the heap does not use "permanent" data, returns the same

481N/A // value is_in_reserved() would return.

481N/A // NOTE: this actually returns true if "p" is in reserved space

481N/A // for the space not that it is actually allocated (i.e. in committed

481N/A // space). If you need the more conservative answer use is_permanent().

481N/A virtual bool is_in_permanent(const void *p) const = 0;

481N/A

481N/A

494N/A#ifdef ASSERT

1165N/A // Returns true if "p" is in the part of the

481N/A // heap being collected.

481N/A virtual bool is_in_partial_collection(const void *p) = 0;

481N/A#endif

1165N/A

481N/A bool is_in_permanent_or_null(const void *p) const {

481N/A return p == NULL || is_in_permanent(p);

481N/A }

481N/A

1165N/A // Returns "TRUE" if "p" is in the committed area of "permanent" data.

481N/A // If the heap does not use "permanent" data, returns the same

481N/A // value is_in() would return.

1142N/A virtual bool is_permanent(const void *p) const = 0;

481N/A

481N/A bool is_permanent_or_null(const void *p) const {

481N/A return p == NULL || is_permanent(p);

481N/A }

1165N/A

481N/A // An object is scavengable if its location may move during a scavenge.

481N/A // (A scavenge is a GC which is not a full GC.)

481N/A virtual bool is_scavengable(const void *p) = 0;

1165N/A

481N/A // Returns "TRUE" if "p" is a method oop in the

481N/A // current heap, with high probability. This predicate

1165N/A // is not stable, in general.

481N/A bool is_valid_method(oop p) const;

481N/A

481N/A void set_gc_cause(GCCause::Cause v) {

481N/A if (UsePerfData) {

1469N/A _gc_lastcause = _gc_cause;

481N/A _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause));

481N/A _perf_gc_cause->set_value(GCCause::to_string(v));

481N/A }

481N/A _gc_cause = v;

481N/A }

481N/A GCCause::Cause gc_cause() { return _gc_cause; }

481N/A

1165N/A // Number of threads currently working on GC tasks.

481N/A uint n_par_threads() { return _n_par_threads; }

481N/A

481N/A // May be overridden to set additional parallelism.

481N/A virtual void set_par_threads(uint t) { _n_par_threads = t; };

481N/A

1165N/A // Preload classes into the shared portion of the heap, and then dump

481N/A // that data to a file so that it can be loaded directly by another

481N/A // VM (then terminate).

0N/A virtual void preload_and_dump(TRAPS) { ShouldNotReachHere(); }

0N/A

0N/A // Allocate and initialize instances of Class

0N/A static oop Class_obj_allocate(KlassHandle klass, int size, KlassHandle real_klass, TRAPS);

0N/A

0N/A // General obj/array allocation facilities.

0N/A inline static oop obj_allocate(KlassHandle klass, int size, TRAPS);

0N/A inline static oop array_allocate(KlassHandle klass, int size, int length, TRAPS);

0N/A inline static oop array_allocate_nozero(KlassHandle klass, int size, int length, TRAPS);

0N/A

0N/A // Special obj/array allocation facilities.

0N/A // Some heaps may want to manage "permanent" data uniquely. These default

0N/A // to the general routines if the heap does not support such handling.

0N/A inline static oop permanent_obj_allocate(KlassHandle klass, int size, TRAPS);

0N/A // permanent_obj_allocate_no_klass_install() does not do the installation of

0N/A // the klass pointer in the newly created object (as permanent_obj_allocate()

0N/A // above does). This allows for a delay in the installation of the klass

0N/A // pointer that is needed during the create of klassKlass's. The

0N/A // method post_allocation_install_obj_klass() is used to install the

1166N/A // klass pointer.

1166N/A inline static oop permanent_obj_allocate_no_klass_install(KlassHandle klass,

1166N/A int size,

1166N/A TRAPS);

1166N/A inline static void post_allocation_install_obj_klass(KlassHandle klass,

1166N/A oop obj,

1166N/A int size);

1166N/A inline static oop permanent_array_allocate(KlassHandle klass, int size, int length, TRAPS);

1166N/A

1166N/A // Raw memory allocation facilities

1166N/A // The obj and array allocate methods are covers for these methods.

1166N/A // The permanent allocation method should default to mem_allocate if

1166N/A // permanent memory isn't supported. mem_allocate() should never be

1166N/A // called to allocate TLABs, only individual objects.

1166N/A virtual HeapWord* mem_allocate(size_t size,

1166N/A bool* gc_overhead_limit_was_exceeded) = 0;

1166N/A virtual HeapWord* permanent_mem_allocate(size_t size) = 0;

1166N/A

0N/A // Utilities for turning raw memory into filler objects.

0N/A //

0N/A // min_fill_size() is the smallest region that can be filled.

0N/A // fill_with_objects() can fill arbitrary-sized regions of the heap using

0N/A // multiple objects. fill_with_object() is for regions known to be smaller

0N/A // than the largest array of integers; it uses a single object to fill the

0N/A // region and has slightly less overhead.

0N/A static size_t min_fill_size() {

0N/A return size_t(align_object_size(oopDesc::header_size()));

0N/A }

0N/A

0N/A static void fill_with_objects(HeapWord* start, size_t words, bool zap = true);

0N/A

0N/A static void fill_with_object(HeapWord* start, size_t words, bool zap = true);

0N/A static void fill_with_object(MemRegion region, bool zap = true) {

0N/A fill_with_object(region.start(), region.word_size(), zap);

0N/A }

0N/A static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) {

0N/A fill_with_object(start, pointer_delta(end, start), zap);

0N/A }

0N/A

0N/A // Some heaps may offer a contiguous region for shared non-blocking

615N/A // allocation, via inlined code (by exporting the address of the top and

615N/A // end fields defining the extent of the contiguous allocation region.)

615N/A

615N/A // This function returns "true" iff the heap supports this kind of

615N/A // allocation. (Default is "no".)

615N/A virtual bool supports_inline_contig_alloc() const {

615N/A return false;

615N/A }

615N/A // These functions return the addresses of the fields that define the

615N/A // boundaries of the contiguous allocation area. (These fields should be

615N/A // physically near to one another.)

615N/A virtual HeapWord** top_addr() const {

615N/A guarantee(false, "inline contiguous allocation not supported");

615N/A return NULL;

615N/A }

615N/A virtual HeapWord** end_addr() const {

615N/A guarantee(false, "inline contiguous allocation not supported");

615N/A return NULL;

615N/A }

615N/A

615N/A // Some heaps may be in an unparseable state at certain times between

615N/A // collections. This may be necessary for efficient implementation of

615N/A // certain allocation-related activities. Calling this function before

615N/A // attempting to parse a heap ensures that the heap is in a parsable

615N/A // state (provided other concurrent activity does not introduce

615N/A // 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. If such permission

// is granted for this heap type, the compiler promises to call

// defer_store_barrier() below on any slow path allocation of

// a new object for which such initializing store barriers will

// have been elided.

virtual bool can_elide_tlab_store_barriers() const = 0;

// 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_pre_barrier(JavaThread* thread, oop new_obj);

// Answers whether an initializing store to a new object currently

// allocated at the given address doesn't need a store

// barrier. Returns "true" if it doesn't need an initializing

// store barrier; answers "false" if it does.

virtual bool can_elide_initializing_store_barrier(oop new_obj) = 0;

// If a compiler is eliding store barriers for TLAB-allocated objects,

// we will be informed of a slow-path allocation by a call

// to new_store_pre_barrier() above. Such a call precedes the

// initialization of the object itself, and no post-store-barriers will

// be issued. Some heap types require that the barrier strictly follows

// the initializing stores. (This is currently implemented by deferring the

// barrier until the next slow-path allocation or gc-related safepoint.)

// This interface answers whether a particular heap type needs the card

// mark to be thus strictly sequenced after the stores.

virtual bool card_mark_must_follow_store() const = 0;

// If the CollectedHeap was asked to defer a store barrier above,

// this informs it to flush such a deferred store barrier to the

// remembered set.

virtual void flush_deferred_store_barrier(JavaThread* thread);

// 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 = 0;

// Does this heap support heap inspection (+PrintClassHistogram?)

virtual bool supports_heap_inspection() const = 0;

// 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;

// Return the CollectorPolicy for the heap

virtual CollectorPolicy* collector_policy() const = 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;

// Similar to object_iterate() except iterates only

// over live objects.

virtual void safe_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;

// Generate any dumps preceding or following a full gc

void pre_full_gc_dump();

void post_full_gc_dump();

// Print heap information on the given outputStream.

virtual void print_on(outputStream* st) const = 0;

// The default behavior is to call print_on() on tty.

virtual void print() const {

print_on(tty);

}

// Print more detailed heap information on the given

// outputStream. The default behaviour is to call print_on(). It is

// up to each subclass to override it and add any additional output

// it needs.

virtual void print_extended_on(outputStream* st) const {

print_on(st);

}

// Print all GC threads (other than the VM thread)

// used by this heap.

virtual void print_gc_threads_on(outputStream* st) const = 0;

// The default behavior is to call print_gc_threads_on() on tty.

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;

// If PrintHeapAtGC is set call the appropriate routi

void print_heap_before_gc() {

if (PrintHeapAtGC) {

Universe::print_heap_before_gc();

}

if (_gc_heap_log != NULL) {

_gc_heap_log->log_heap_before();

}

}

void print_heap_after_gc() {

if (PrintHeapAtGC) {

Universe::print_heap_after_gc();

}

if (_gc_heap_log != NULL) {

_gc_heap_log->log_heap_after();

}

}

// Allocate GCHeapLog during VM startup

static void initialize_heap_log();

// Heap verification

virtual void verify(bool allow_dirty, bool silent, VerifyOption option) = 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

public:

// This is a convenience method that is used in cases where

// the actual number of GC worker threads is not pertinent but

// only whether there more than 0. Use of this method helps

// reduce the occurrence of ParallelGCThreads to uses where the

// actual number may be germane.

static bool use_parallel_gc_threads() { return ParallelGCThreads > 0; }

/////////////// Unit tests ///////////////

NOT_PRODUCT(static void test_is_in();)

};

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);

}

};

#endif // SHARE_VM_GC_INTERFACE_COLLECTEDHEAP_HPP