1 /*
2 * Copyright (c) 2001, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
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23 */
24
25 #ifndef SHARE_VM_GC_SHARED_COLLECTEDHEAP_HPP
26 #define SHARE_VM_GC_SHARED_COLLECTEDHEAP_HPP
27
28 #include "gc/shared/gcCause.hpp"
29 #include "gc/shared/gcWhen.hpp"
30 #include "memory/allocation.hpp"
31 #include "runtime/handles.hpp"
32 #include "runtime/perfData.hpp"
33 #include "runtime/safepoint.hpp"
34 #include "utilities/events.hpp"
35
36 // A "CollectedHeap" is an implementation of a java heap for HotSpot. This
37 // is an abstract class: there may be many different kinds of heaps. This
38 // class defines the functions that a heap must implement, and contains
39 // infrastructure common to all heaps.
40
41 class AdaptiveSizePolicy;
42 class BarrierSet;
43 class CollectorPolicy;
44 class GCHeapSummary;
45 class GCTimer;
46 class GCTracer;
47 class MetaspaceSummary;
48 class Thread;
49 class ThreadClosure;
50 class VirtualSpaceSummary;
51 class nmethod;
52
53 class GCMessage : public FormatBuffer<1024> {
54 public:
55 bool is_before;
56
57 public:
58 GCMessage() {}
59 };
60
61 class CollectedHeap;
62
63 class GCHeapLog : public EventLogBase<GCMessage> {
64 private:
65 void log_heap(CollectedHeap* heap, bool before);
66
67 public:
68 GCHeapLog() : EventLogBase<GCMessage>("GC Heap History") {}
69
70 void log_heap_before(CollectedHeap* heap) {
71 log_heap(heap, true);
72 }
73 void log_heap_after(CollectedHeap* heap) {
74 log_heap(heap, false);
75 }
76 };
77
78 //
79 // CollectedHeap
80 // GenCollectedHeap
81 // G1CollectedHeap
82 // ParallelScavengeHeap
83 //
84 class CollectedHeap : public CHeapObj<mtInternal> {
85 friend class VMStructs;
86 friend class JVMCIVMStructs;
87 friend class IsGCActiveMark; // Block structured external access to _is_gc_active
88
89 private:
90 #ifdef ASSERT
91 static int _fire_out_of_memory_count;
92 #endif
93
94 GCHeapLog* _gc_heap_log;
95
96 MemRegion _reserved;
97
98 protected:
99 BarrierSet* _barrier_set;
100 bool _is_gc_active;
101
102 // Used for filler objects (static, but initialized in ctor).
103 static size_t _filler_array_max_size;
104
105 unsigned int _total_collections; // ... started
106 unsigned int _total_full_collections; // ... started
107 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;)
108 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;)
109
110 // Reason for current garbage collection. Should be set to
111 // a value reflecting no collection between collections.
112 GCCause::Cause _gc_cause;
113 GCCause::Cause _gc_lastcause;
114 PerfStringVariable* _perf_gc_cause;
115 PerfStringVariable* _perf_gc_lastcause;
116
117 // Constructor
118 CollectedHeap();
119
120 // Do common initializations that must follow instance construction,
121 // for example, those needing virtual calls.
122 // This code could perhaps be moved into initialize() but would
123 // be slightly more awkward because we want the latter to be a
124 // pure virtual.
125 void pre_initialize();
126
127 // Create a new tlab. All TLAB allocations must go through this.
128 virtual HeapWord* allocate_new_tlab(size_t size);
129
130 // Accumulate statistics on all tlabs.
131 virtual void accumulate_statistics_all_tlabs();
132
133 // Reinitialize tlabs before resuming mutators.
134 virtual void resize_all_tlabs();
135
136 // Allocate from the current thread's TLAB, with broken-out slow path.
137 inline static HeapWord* allocate_from_tlab(Klass* klass, Thread* thread, size_t size);
138 static HeapWord* allocate_from_tlab_slow(Klass* klass, Thread* thread, size_t size);
139
140 // Allocate an uninitialized block of the given size, or returns NULL if
141 // this is impossible.
142 inline static HeapWord* common_mem_allocate_noinit(Klass* klass, size_t size, TRAPS);
143
144 // Like allocate_init, but the block returned by a successful allocation
145 // is guaranteed initialized to zeros.
146 inline static HeapWord* common_mem_allocate_init(Klass* klass, size_t size, TRAPS);
147
148 // Helper functions for (VM) allocation.
149 inline static void post_allocation_setup_common(Klass* klass, HeapWord* obj);
150 inline static void post_allocation_setup_no_klass_install(Klass* klass,
151 HeapWord* objPtr);
152
153 inline static void post_allocation_setup_obj(Klass* klass, HeapWord* obj, int size);
154
155 inline static void post_allocation_setup_array(Klass* klass,
156 HeapWord* obj, int length);
157
158 inline static void post_allocation_setup_class(Klass* klass, HeapWord* obj, int size);
159
160 // Clears an allocated object.
161 inline static void init_obj(HeapWord* obj, size_t size);
162
163 // Filler object utilities.
164 static inline size_t filler_array_hdr_size();
165 static inline size_t filler_array_min_size();
166
167 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);)
168 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);)
169
170 // Fill with a single array; caller must ensure filler_array_min_size() <=
171 // words <= filler_array_max_size().
172 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true);
173
174 // Fill with a single object (either an int array or a java.lang.Object).
175 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true);
176
177 virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer);
178
179 // Verification functions
180 virtual void check_for_bad_heap_word_value(HeapWord* addr, size_t size)
181 PRODUCT_RETURN;
182 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)
183 PRODUCT_RETURN;
184 debug_only(static void check_for_valid_allocation_state();)
185
186 public:
187 enum Name {
188 GenCollectedHeap,
189 ParallelScavengeHeap,
190 G1CollectedHeap
191 };
192
193 static inline size_t filler_array_max_size() {
194 return _filler_array_max_size;
195 }
196
197 virtual Name kind() const = 0;
198
199 virtual const char* name() const = 0;
200
201 /**
202 * Returns JNI error code JNI_ENOMEM if memory could not be allocated,
203 * and JNI_OK on success.
204 */
205 virtual jint initialize() = 0;
206
207 // In many heaps, there will be a need to perform some initialization activities
208 // after the Universe is fully formed, but before general heap allocation is allowed.
209 // This is the correct place to place such initialization methods.
210 virtual void post_initialize() = 0;
211
212 // Stop any onging concurrent work and prepare for exit.
213 virtual void stop() {}
214
215 // Stop and resume concurrent GC threads interfering with safepoint operations
216 virtual void safepoint_synchronize_begin() {}
217 virtual void safepoint_synchronize_end() {}
218
219 void initialize_reserved_region(HeapWord *start, HeapWord *end);
220 MemRegion reserved_region() const { return _reserved; }
221 address base() const { return (address)reserved_region().start(); }
222
223 virtual size_t capacity() const = 0;
224 virtual size_t used() const = 0;
225
226 // Return "true" if the part of the heap that allocates Java
227 // objects has reached the maximal committed limit that it can
228 // reach, without a garbage collection.
229 virtual bool is_maximal_no_gc() const = 0;
230
231 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of
232 // memory that the vm could make available for storing 'normal' java objects.
233 // This is based on the reserved address space, but should not include space
234 // that the vm uses internally for bookkeeping or temporary storage
235 // (e.g., in the case of the young gen, one of the survivor
236 // spaces).
237 virtual size_t max_capacity() const = 0;
238
239 // Returns "TRUE" if "p" points into the reserved area of the heap.
240 bool is_in_reserved(const void* p) const {
241 return _reserved.contains(p);
242 }
243
244 bool is_in_reserved_or_null(const void* p) const {
245 return p == NULL || is_in_reserved(p);
246 }
247
248 // Returns "TRUE" iff "p" points into the committed areas of the heap.
249 // This method can be expensive so avoid using it in performance critical
250 // code.
251 virtual bool is_in(const void* p) const = 0;
252
253 DEBUG_ONLY(bool is_in_or_null(const void* p) const { return p == NULL || is_in(p); })
254
255 // Let's define some terms: a "closed" subset of a heap is one that
256 //
257 // 1) contains all currently-allocated objects, and
258 //
259 // 2) is closed under reference: no object in the closed subset
260 // references one outside the closed subset.
261 //
262 // Membership in a heap's closed subset is useful for assertions.
263 // Clearly, the entire heap is a closed subset, so the default
264 // implementation is to use "is_in_reserved". But this may not be too
265 // liberal to perform useful checking. Also, the "is_in" predicate
266 // defines a closed subset, but may be too expensive, since "is_in"
267 // verifies that its argument points to an object head. The
268 // "closed_subset" method allows a heap to define an intermediate
269 // predicate, allowing more precise checking than "is_in_reserved" at
270 // lower cost than "is_in."
271
272 // One important case is a heap composed of disjoint contiguous spaces,
273 // such as the Garbage-First collector. Such heaps have a convenient
274 // closed subset consisting of the allocated portions of those
275 // contiguous spaces.
276
277 // Return "TRUE" iff the given pointer points into the heap's defined
278 // closed subset (which defaults to the entire heap).
279 virtual bool is_in_closed_subset(const void* p) const {
280 return is_in_reserved(p);
281 }
282
283 bool is_in_closed_subset_or_null(const void* p) const {
284 return p == NULL || is_in_closed_subset(p);
285 }
286
287 // An object is scavengable if its location may move during a scavenge.
288 // (A scavenge is a GC which is not a full GC.)
289 virtual bool is_scavengable(const void *p) = 0;
290
291 void set_gc_cause(GCCause::Cause v) {
292 if (UsePerfData) {
293 _gc_lastcause = _gc_cause;
294 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause));
295 _perf_gc_cause->set_value(GCCause::to_string(v));
296 }
297 _gc_cause = v;
298 }
299 GCCause::Cause gc_cause() { return _gc_cause; }
300
301 // General obj/array allocation facilities.
302 inline static oop obj_allocate(Klass* klass, int size, TRAPS);
303 inline static oop array_allocate(Klass* klass, int size, int length, TRAPS);
304 inline static oop array_allocate_nozero(Klass* klass, int size, int length, TRAPS);
305 inline static oop class_allocate(Klass* klass, int size, TRAPS);
306
307 // Raw memory allocation facilities
308 // The obj and array allocate methods are covers for these methods.
309 // mem_allocate() should never be
310 // called to allocate TLABs, only individual objects.
311 virtual HeapWord* mem_allocate(size_t size,
312 bool* gc_overhead_limit_was_exceeded) = 0;
313
314 // Utilities for turning raw memory into filler objects.
315 //
316 // min_fill_size() is the smallest region that can be filled.
317 // fill_with_objects() can fill arbitrary-sized regions of the heap using
318 // multiple objects. fill_with_object() is for regions known to be smaller
319 // than the largest array of integers; it uses a single object to fill the
320 // region and has slightly less overhead.
321 static size_t min_fill_size() {
322 return size_t(align_object_size(oopDesc::header_size()));
323 }
324
325 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true);
326
327 static void fill_with_object(HeapWord* start, size_t words, bool zap = true);
328 static void fill_with_object(MemRegion region, bool zap = true) {
329 fill_with_object(region.start(), region.word_size(), zap);
330 }
331 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) {
332 fill_with_object(start, pointer_delta(end, start), zap);
333 }
334
335 // Return the address "addr" aligned by "alignment_in_bytes" if such
336 // an address is below "end". Return NULL otherwise.
337 inline static HeapWord* align_allocation_or_fail(HeapWord* addr,
338 HeapWord* end,
339 unsigned short alignment_in_bytes);
340
341 // Some heaps may offer a contiguous region for shared non-blocking
342 // allocation, via inlined code (by exporting the address of the top and
343 // end fields defining the extent of the contiguous allocation region.)
344
345 // This function returns "true" iff the heap supports this kind of
346 // allocation. (Default is "no".)
347 virtual bool supports_inline_contig_alloc() const {
348 return false;
349 }
350 // These functions return the addresses of the fields that define the
351 // boundaries of the contiguous allocation area. (These fields should be
352 // physically near to one another.)
353 virtual HeapWord* volatile* top_addr() const {
354 guarantee(false, "inline contiguous allocation not supported");
355 return NULL;
356 }
357 virtual HeapWord** end_addr() const {
358 guarantee(false, "inline contiguous allocation not supported");
359 return NULL;
360 }
361
362 // Some heaps may be in an unparseable state at certain times between
363 // collections. This may be necessary for efficient implementation of
364 // certain allocation-related activities. Calling this function before
365 // attempting to parse a heap ensures that the heap is in a parsable
366 // state (provided other concurrent activity does not introduce
367 // unparsability). It is normally expected, therefore, that this
368 // method is invoked with the world stopped.
369 // NOTE: if you override this method, make sure you call
370 // super::ensure_parsability so that the non-generational
371 // part of the work gets done. See implementation of
372 // CollectedHeap::ensure_parsability and, for instance,
373 // that of GenCollectedHeap::ensure_parsability().
374 // The argument "retire_tlabs" controls whether existing TLABs
375 // are merely filled or also retired, thus preventing further
376 // allocation from them and necessitating allocation of new TLABs.
377 virtual void ensure_parsability(bool retire_tlabs);
378
379 // Section on thread-local allocation buffers (TLABs)
380 // If the heap supports thread-local allocation buffers, it should override
381 // the following methods:
382 // Returns "true" iff the heap supports thread-local allocation buffers.
383 // The default is "no".
384 virtual bool supports_tlab_allocation() const = 0;
385
386 // The amount of space available for thread-local allocation buffers.
387 virtual size_t tlab_capacity(Thread *thr) const = 0;
388
389 // The amount of used space for thread-local allocation buffers for the given thread.
390 virtual size_t tlab_used(Thread *thr) const = 0;
391
392 virtual size_t max_tlab_size() const;
393
394 virtual void verify_nmethod_roots(nmethod* nmethod);
395
396 // An estimate of the maximum allocation that could be performed
397 // for thread-local allocation buffers without triggering any
398 // collection or expansion activity.
399 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const {
400 guarantee(false, "thread-local allocation buffers not supported");
401 return 0;
402 }
403
404 // Perform a collection of the heap; intended for use in implementing
405 // "System.gc". This probably implies as full a collection as the
406 // "CollectedHeap" supports.
407 virtual void collect(GCCause::Cause cause) = 0;
408
409 // Perform a full collection
410 virtual void do_full_collection(bool clear_all_soft_refs) = 0;
411
412 // This interface assumes that it's being called by the
413 // vm thread. It collects the heap assuming that the
414 // heap lock is already held and that we are executing in
415 // the context of the vm thread.
416 virtual void collect_as_vm_thread(GCCause::Cause cause);
417
418 // Returns the barrier set for this heap
419 BarrierSet* barrier_set() { return _barrier_set; }
420 void set_barrier_set(BarrierSet* barrier_set);
421
422 // Returns "true" iff there is a stop-world GC in progress. (I assume
423 // that it should answer "false" for the concurrent part of a concurrent
424 // collector -- dld).
425 bool is_gc_active() const { return _is_gc_active; }
426
427 // Total number of GC collections (started)
428 unsigned int total_collections() const { return _total_collections; }
429 unsigned int total_full_collections() const { return _total_full_collections;}
430
431 // Increment total number of GC collections (started)
432 // Should be protected but used by PSMarkSweep - cleanup for 1.4.2
433 void increment_total_collections(bool full = false) {
434 _total_collections++;
435 if (full) {
436 increment_total_full_collections();
437 }
438 }
439
440 void increment_total_full_collections() { _total_full_collections++; }
441
442 // Return the AdaptiveSizePolicy for the heap.
443 virtual AdaptiveSizePolicy* size_policy() = 0;
444
445 // Return the CollectorPolicy for the heap
446 virtual CollectorPolicy* collector_policy() const = 0;
447
448 // Iterate over all objects, calling "cl.do_object" on each.
449 virtual void object_iterate(ObjectClosure* cl) = 0;
450
451 // Similar to object_iterate() except iterates only
452 // over live objects.
453 virtual void safe_object_iterate(ObjectClosure* cl) = 0;
454
455 // NOTE! There is no requirement that a collector implement these
456 // functions.
457 //
458 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
459 // each address in the (reserved) heap is a member of exactly
460 // one block. The defining characteristic of a block is that it is
461 // possible to find its size, and thus to progress forward to the next
462 // block. (Blocks may be of different sizes.) Thus, blocks may
463 // represent Java objects, or they might be free blocks in a
464 // free-list-based heap (or subheap), as long as the two kinds are
465 // distinguishable and the size of each is determinable.
466
467 // Returns the address of the start of the "block" that contains the
468 // address "addr". We say "blocks" instead of "object" since some heaps
469 // may not pack objects densely; a chunk may either be an object or a
470 // non-object.
471 virtual HeapWord* block_start(const void* addr) const = 0;
472
473 // Requires "addr" to be the start of a chunk, and returns its size.
474 // "addr + size" is required to be the start of a new chunk, or the end
475 // of the active area of the heap.
476 virtual size_t block_size(const HeapWord* addr) const = 0;
477
478 // Requires "addr" to be the start of a block, and returns "TRUE" iff
479 // the block is an object.
480 virtual bool block_is_obj(const HeapWord* addr) const = 0;
481
482 // Returns the longest time (in ms) that has elapsed since the last
483 // time that any part of the heap was examined by a garbage collection.
484 virtual jlong millis_since_last_gc() = 0;
485
486 // Perform any cleanup actions necessary before allowing a verification.
487 virtual void prepare_for_verify() = 0;
488
489 // Generate any dumps preceding or following a full gc
490 private:
491 void full_gc_dump(GCTimer* timer, bool before);
492 public:
493 void pre_full_gc_dump(GCTimer* timer);
494 void post_full_gc_dump(GCTimer* timer);
495
496 VirtualSpaceSummary create_heap_space_summary();
497 GCHeapSummary create_heap_summary();
498
499 MetaspaceSummary create_metaspace_summary();
500
501 // Print heap information on the given outputStream.
502 virtual void print_on(outputStream* st) const = 0;
503 // The default behavior is to call print_on() on tty.
504 virtual void print() const {
505 print_on(tty);
506 }
507 // Print more detailed heap information on the given
508 // outputStream. The default behavior is to call print_on(). It is
509 // up to each subclass to override it and add any additional output
510 // it needs.
511 virtual void print_extended_on(outputStream* st) const {
512 print_on(st);
513 }
514
515 virtual void print_on_error(outputStream* st) const;
516
517 // Print all GC threads (other than the VM thread)
518 // used by this heap.
519 virtual void print_gc_threads_on(outputStream* st) const = 0;
520 // The default behavior is to call print_gc_threads_on() on tty.
521 void print_gc_threads() {
522 print_gc_threads_on(tty);
523 }
524 // Iterator for all GC threads (other than VM thread)
525 virtual void gc_threads_do(ThreadClosure* tc) const = 0;
526
527 // Print any relevant tracing info that flags imply.
528 // Default implementation does nothing.
529 virtual void print_tracing_info() const = 0;
530
531 void print_heap_before_gc();
532 void print_heap_after_gc();
533
534 // Registering and unregistering an nmethod (compiled code) with the heap.
535 // Override with specific mechanism for each specialized heap type.
536 virtual void register_nmethod(nmethod* nm);
537 virtual void unregister_nmethod(nmethod* nm);
538
539 void trace_heap_before_gc(const GCTracer* gc_tracer);
540 void trace_heap_after_gc(const GCTracer* gc_tracer);
541
542 // Heap verification
543 virtual void verify(VerifyOption option) = 0;
544
545 // Return true if concurrent phase control (via
546 // request_concurrent_phase_control) is supported by this collector.
547 // The default implementation returns false.
548 virtual bool supports_concurrent_phase_control() const;
549
550 // Return a NULL terminated array of concurrent phase names provided
551 // by this collector. Supports Whitebox testing. These are the
552 // names recognized by request_concurrent_phase(). The default
553 // implementation returns an array of one NULL element.
554 virtual const char* const* concurrent_phases() const;
555
556 // Request the collector enter the indicated concurrent phase, and
557 // wait until it does so. Supports WhiteBox testing. Only one
558 // request may be active at a time. Phases are designated by name;
559 // the set of names and their meaning is GC-specific. Once the
560 // requested phase has been reached, the collector will attempt to
561 // avoid transitioning to a new phase until a new request is made.
562 // [Note: A collector might not be able to remain in a given phase.
563 // For example, a full collection might cancel an in-progress
564 // concurrent collection.]
565 //
566 // Returns true when the phase is reached. Returns false for an
567 // unknown phase. The default implementation returns false.
568 virtual bool request_concurrent_phase(const char* phase);
569
570 // Non product verification and debugging.
571 #ifndef PRODUCT
572 // Support for PromotionFailureALot. Return true if it's time to cause a
573 // promotion failure. The no-argument version uses
574 // this->_promotion_failure_alot_count as the counter.
575 inline bool promotion_should_fail(volatile size_t* count);
576 inline bool promotion_should_fail();
577
578 // Reset the PromotionFailureALot counters. Should be called at the end of a
579 // GC in which promotion failure occurred.
580 inline void reset_promotion_should_fail(volatile size_t* count);
581 inline void reset_promotion_should_fail();
582 #endif // #ifndef PRODUCT
583
584 #ifdef ASSERT
585 static int fired_fake_oom() {
586 return (CIFireOOMAt > 1 && _fire_out_of_memory_count >= CIFireOOMAt);
587 }
588 #endif
589
590 public:
591 // Copy the current allocation context statistics for the specified contexts.
592 // For each context in contexts, set the corresponding entries in the totals
593 // and accuracy arrays to the current values held by the statistics. Each
594 // array should be of length len.
595 // Returns true if there are more stats available.
596 virtual bool copy_allocation_context_stats(const jint* contexts,
597 jlong* totals,
598 jbyte* accuracy,
599 jint len) {
600 return false;
601 }
602
603 };
604
605 // Class to set and reset the GC cause for a CollectedHeap.
606
607 class GCCauseSetter : StackObj {
608 CollectedHeap* _heap;
609 GCCause::Cause _previous_cause;
610 public:
611 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) {
612 assert(SafepointSynchronize::is_at_safepoint(),
613 "This method manipulates heap state without locking");
614 _heap = heap;
615 _previous_cause = _heap->gc_cause();
616 _heap->set_gc_cause(cause);
617 }
618
619 ~GCCauseSetter() {
620 assert(SafepointSynchronize::is_at_safepoint(),
621 "This method manipulates heap state without locking");
622 _heap->set_gc_cause(_previous_cause);
623 }
624 };
625
626 #endif // SHARE_VM_GC_SHARED_COLLECTEDHEAP_HPP