1 /*
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  3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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  6  * under the terms of the GNU General Public License version 2 only, as
  7  * published by the Free Software Foundation.
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  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  *
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 18  *
 19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 24 
 25 #ifndef SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_INLINE_HPP
 26 #define SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_INLINE_HPP
 27 
 28 #include "gc/shenandoah/shenandoahHeap.hpp"
 29 
 30 #include "classfile/javaClasses.inline.hpp"
 31 #include "gc/shared/markBitMap.inline.hpp"
 32 #include "gc/shared/threadLocalAllocBuffer.inline.hpp"
 33 #include "gc/shared/suspendibleThreadSet.hpp"
 34 #include "gc/shared/tlab_globals.hpp"
 35 #include "gc/shenandoah/shenandoahAsserts.hpp"
 36 #include "gc/shenandoah/shenandoahBarrierSet.inline.hpp"
 37 #include "gc/shenandoah/shenandoahCollectionSet.inline.hpp"
 38 #include "gc/shenandoah/shenandoahForwarding.inline.hpp"
 39 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
 40 #include "gc/shenandoah/shenandoahHeapRegionSet.inline.hpp"
 41 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
 42 #include "gc/shenandoah/shenandoahControlThread.hpp"
 43 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
 44 #include "gc/shenandoah/shenandoahObjectUtils.inline.hpp"
 45 #include "gc/shenandoah/shenandoahThreadLocalData.hpp"
 46 #include "oops/compressedOops.inline.hpp"
 47 #include "oops/oop.inline.hpp"
 48 #include "runtime/atomic.hpp"
 49 #include "runtime/prefetch.inline.hpp"
 50 #include "runtime/thread.hpp"
 51 #include "utilities/copy.hpp"
 52 #include "utilities/globalDefinitions.hpp"
 53 
 54 inline ShenandoahHeap* ShenandoahHeap::heap() {
 55   return named_heap<ShenandoahHeap>(CollectedHeap::Shenandoah);
 56 }
 57 
 58 inline ShenandoahHeapRegion* ShenandoahRegionIterator::next() {
 59   size_t new_index = Atomic::add(&_index, (size_t) 1, memory_order_relaxed);
 60   // get_region() provides the bounds-check and returns NULL on OOB.
 61   return _heap->get_region(new_index - 1);
 62 }
 63 
 64 inline bool ShenandoahHeap::has_forwarded_objects() const {
 65   return _gc_state.is_set(HAS_FORWARDED);
 66 }
 67 
 68 inline WorkGang* ShenandoahHeap::workers() const {
 69   return _workers;
 70 }
 71 
 72 inline WorkGang* ShenandoahHeap::safepoint_workers() {
 73   return _safepoint_workers;
 74 }
 75 
 76 inline size_t ShenandoahHeap::heap_region_index_containing(const void* addr) const {
 77   uintptr_t region_start = ((uintptr_t) addr);
 78   uintptr_t index = (region_start - (uintptr_t) base()) >> ShenandoahHeapRegion::region_size_bytes_shift();
 79   assert(index < num_regions(), "Region index is in bounds: " PTR_FORMAT, p2i(addr));
 80   return index;
 81 }
 82 
 83 inline ShenandoahHeapRegion* const ShenandoahHeap::heap_region_containing(const void* addr) const {
 84   size_t index = heap_region_index_containing(addr);
 85   ShenandoahHeapRegion* const result = get_region(index);
 86   assert(addr >= result->bottom() && addr < result->end(), "Heap region contains the address: " PTR_FORMAT, p2i(addr));
 87   return result;
 88 }
 89 
 90 inline void ShenandoahHeap::enter_evacuation(Thread* t) {
 91   _oom_evac_handler.enter_evacuation(t);
 92 }
 93 
 94 inline void ShenandoahHeap::leave_evacuation(Thread* t) {
 95   _oom_evac_handler.leave_evacuation(t);
 96 }
 97 
 98 template <class T>
 99 inline void ShenandoahHeap::update_with_forwarded(T* p) {
100   T o = RawAccess<>::oop_load(p);
101   if (!CompressedOops::is_null(o)) {
102     oop obj = CompressedOops::decode_not_null(o);
103     if (in_collection_set(obj)) {
104       // Corner case: when evacuation fails, there are objects in collection
105       // set that are not really forwarded. We can still go and try and update them
106       // (uselessly) to simplify the common path.
107       shenandoah_assert_forwarded_except(p, obj, cancelled_gc());
108       oop fwd = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
109       shenandoah_assert_not_in_cset_except(p, fwd, cancelled_gc());
110 
111       // Unconditionally store the update: no concurrent updates expected.
112       RawAccess<IS_NOT_NULL>::oop_store(p, fwd);
113     }
114   }
115 }
116 
117 template <class T>
118 inline void ShenandoahHeap::conc_update_with_forwarded(T* p) {
119   T o = RawAccess<>::oop_load(p);
120   if (!CompressedOops::is_null(o)) {
121     oop obj = CompressedOops::decode_not_null(o);
122     if (in_collection_set(obj)) {
123       // Corner case: when evacuation fails, there are objects in collection
124       // set that are not really forwarded. We can still go and try CAS-update them
125       // (uselessly) to simplify the common path.
126       shenandoah_assert_forwarded_except(p, obj, cancelled_gc());
127       oop fwd = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
128       shenandoah_assert_not_in_cset_except(p, fwd, cancelled_gc());
129 
130       // Sanity check: we should not be updating the cset regions themselves,
131       // unless we are recovering from the evacuation failure.
132       shenandoah_assert_not_in_cset_loc_except(p, !is_in(p) || cancelled_gc());
133 
134       // Either we succeed in updating the reference, or something else gets in our way.
135       // We don't care if that is another concurrent GC update, or another mutator update.
136       // We only check that non-NULL store still updated with non-forwarded reference.
137       oop witness = cas_oop(fwd, p, obj);
138       shenandoah_assert_not_forwarded_except(p, witness, (witness == NULL) || (witness == obj));
139     }
140   }
141 }
142 
143 inline oop ShenandoahHeap::cas_oop(oop n, oop* addr, oop c) {
144   assert(is_aligned(addr, HeapWordSize), "Address should be aligned: " PTR_FORMAT, p2i(addr));
145   return (oop) Atomic::cmpxchg(addr, c, n);
146 }
147 
148 inline oop ShenandoahHeap::cas_oop(oop n, narrowOop* addr, narrowOop c) {
149   assert(is_aligned(addr, sizeof(narrowOop)), "Address should be aligned: " PTR_FORMAT, p2i(addr));
150   narrowOop val = CompressedOops::encode(n);
151   return CompressedOops::decode(Atomic::cmpxchg(addr, c, val));
152 }
153 
154 inline oop ShenandoahHeap::cas_oop(oop n, narrowOop* addr, oop c) {
155   assert(is_aligned(addr, sizeof(narrowOop)), "Address should be aligned: " PTR_FORMAT, p2i(addr));
156   narrowOop cmp = CompressedOops::encode(c);
157   narrowOop val = CompressedOops::encode(n);
158   return CompressedOops::decode(Atomic::cmpxchg(addr, cmp, val));
159 }
160 
161 inline bool ShenandoahHeap::cancelled_gc() const {
162   return _cancelled_gc.get() == CANCELLED;
163 }
164 
165 inline bool ShenandoahHeap::check_cancelled_gc_and_yield(bool sts_active) {
166   if (sts_active && ShenandoahSuspendibleWorkers && !cancelled_gc()) {
167     if (SuspendibleThreadSet::should_yield()) {
168       SuspendibleThreadSet::yield();
169     }
170   }
171   return cancelled_gc();
172 }
173 
174 inline void ShenandoahHeap::clear_cancelled_gc() {
175   _cancelled_gc.set(CANCELLABLE);
176   _oom_evac_handler.clear();
177 }
178 
179 inline HeapWord* ShenandoahHeap::allocate_from_gclab(Thread* thread, size_t size) {
180   assert(UseTLAB, "TLABs should be enabled");
181 
182   PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
183   if (gclab == NULL) {
184     assert(!thread->is_Java_thread() && !thread->is_Worker_thread(),
185            "Performance: thread should have GCLAB: %s", thread->name());
186     // No GCLABs in this thread, fallback to shared allocation
187     return NULL;
188   }
189   HeapWord* obj = gclab->allocate(size);
190   if (obj != NULL) {
191     return obj;
192   }
193   // Otherwise...
194   return allocate_from_gclab_slow(thread, size);
195 }
196 
197 inline oop ShenandoahHeap::evacuate_object(oop p, Thread* thread) {
198   if (ShenandoahThreadLocalData::is_oom_during_evac(Thread::current())) {
199     // This thread went through the OOM during evac protocol and it is safe to return
200     // the forward pointer. It must not attempt to evacuate any more.
201     return ShenandoahBarrierSet::resolve_forwarded(p);
202   }
203 
204   assert(ShenandoahThreadLocalData::is_evac_allowed(thread), "must be enclosed in oom-evac scope");
205 
206   size_t size = ShenandoahObjectUtils::size(p);
207 
208   assert(!heap_region_containing(p)->is_humongous(), "never evacuate humongous objects");
209 
210   bool alloc_from_gclab = true;
211   HeapWord* copy = NULL;
212 
213 #ifdef ASSERT
214   if (ShenandoahOOMDuringEvacALot &&
215       (os::random() & 1) == 0) { // Simulate OOM every ~2nd slow-path call
216         copy = NULL;
217   } else {
218 #endif
219     if (UseTLAB) {
220       copy = allocate_from_gclab(thread, size);
221     }
222     if (copy == NULL) {
223       ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared_gc(size);
224       copy = allocate_memory(req);
225       alloc_from_gclab = false;
226     }
227 #ifdef ASSERT
228   }
229 #endif
230 
231   if (copy == NULL) {
232     control_thread()->handle_alloc_failure_evac(size);
233 
234     _oom_evac_handler.handle_out_of_memory_during_evacuation();
235 
236     return ShenandoahBarrierSet::resolve_forwarded(p);
237   }
238 
239   // Copy the object:
240   Copy::aligned_disjoint_words(cast_from_oop<HeapWord*>(p), copy, size);
241 
242   // Try to install the new forwarding pointer.
243   oop copy_val = cast_to_oop(copy);
244   oop result = ShenandoahForwarding::try_update_forwardee(p, copy_val);
245   if (result == copy_val) {
246     // Successfully evacuated. Our copy is now the public one!
247     shenandoah_assert_correct(NULL, copy_val);
248     return copy_val;
249   }  else {
250     // Failed to evacuate. We need to deal with the object that is left behind. Since this
251     // new allocation is certainly after TAMS, it will be considered live in the next cycle.
252     // But if it happens to contain references to evacuated regions, those references would
253     // not get updated for this stale copy during this cycle, and we will crash while scanning
254     // it the next cycle.
255     //
256     // For GCLAB allocations, it is enough to rollback the allocation ptr. Either the next
257     // object will overwrite this stale copy, or the filler object on LAB retirement will
258     // do this. For non-GCLAB allocations, we have no way to retract the allocation, and
259     // have to explicitly overwrite the copy with the filler object. With that overwrite,
260     // we have to keep the fwdptr initialized and pointing to our (stale) copy.
261     if (alloc_from_gclab) {
262       ShenandoahThreadLocalData::gclab(thread)->undo_allocation(copy, size);
263     } else {
264       fill_with_object(copy, size);
265       shenandoah_assert_correct(NULL, copy_val);
266     }
267     shenandoah_assert_correct(NULL, result);
268     return result;
269   }
270 }
271 
272 inline bool ShenandoahHeap::requires_marking(const void* entry) const {
273   oop obj = cast_to_oop(entry);
274   return !_marking_context->is_marked_strong(obj);
275 }
276 
277 inline bool ShenandoahHeap::in_collection_set(oop p) const {
278   assert(collection_set() != NULL, "Sanity");
279   return collection_set()->is_in(p);
280 }
281 
282 inline bool ShenandoahHeap::in_collection_set_loc(void* p) const {
283   assert(collection_set() != NULL, "Sanity");
284   return collection_set()->is_in_loc(p);
285 }
286 
287 inline bool ShenandoahHeap::is_stable() const {
288   return _gc_state.is_clear();
289 }
290 
291 inline bool ShenandoahHeap::is_idle() const {
292   return _gc_state.is_unset(MARKING | EVACUATION | UPDATEREFS);
293 }
294 
295 inline bool ShenandoahHeap::is_concurrent_mark_in_progress() const {
296   return _gc_state.is_set(MARKING);
297 }
298 
299 inline bool ShenandoahHeap::is_evacuation_in_progress() const {
300   return _gc_state.is_set(EVACUATION);
301 }
302 
303 inline bool ShenandoahHeap::is_gc_in_progress_mask(uint mask) const {
304   return _gc_state.is_set(mask);
305 }
306 
307 inline bool ShenandoahHeap::is_degenerated_gc_in_progress() const {
308   return _degenerated_gc_in_progress.is_set();
309 }
310 
311 inline bool ShenandoahHeap::is_full_gc_in_progress() const {
312   return _full_gc_in_progress.is_set();
313 }
314 
315 inline bool ShenandoahHeap::is_full_gc_move_in_progress() const {
316   return _full_gc_move_in_progress.is_set();
317 }
318 
319 inline bool ShenandoahHeap::is_update_refs_in_progress() const {
320   return _gc_state.is_set(UPDATEREFS);
321 }
322 
323 inline bool ShenandoahHeap::is_stw_gc_in_progress() const {
324   return is_full_gc_in_progress() || is_degenerated_gc_in_progress();
325 }
326 
327 inline bool ShenandoahHeap::is_concurrent_strong_root_in_progress() const {
328   return _concurrent_strong_root_in_progress.is_set();
329 }
330 
331 inline bool ShenandoahHeap::is_concurrent_weak_root_in_progress() const {
332   return _gc_state.is_set(WEAK_ROOTS);
333 }
334 
335 template<class T>
336 inline void ShenandoahHeap::marked_object_iterate(ShenandoahHeapRegion* region, T* cl) {
337   marked_object_iterate(region, cl, region->top());
338 }
339 
340 template<class T>
341 inline void ShenandoahHeap::marked_object_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* limit) {
342   assert(! region->is_humongous_continuation(), "no humongous continuation regions here");
343 
344   ShenandoahMarkingContext* const ctx = complete_marking_context();
345   assert(ctx->is_complete(), "sanity");
346 
347   HeapWord* tams = ctx->top_at_mark_start(region);
348 
349   size_t skip_bitmap_delta = 1;
350   HeapWord* start = region->bottom();
351   HeapWord* end = MIN2(tams, region->end());
352 
353   // Step 1. Scan below the TAMS based on bitmap data.
354   HeapWord* limit_bitmap = MIN2(limit, tams);
355 
356   // Try to scan the initial candidate. If the candidate is above the TAMS, it would
357   // fail the subsequent "< limit_bitmap" checks, and fall through to Step 2.
358   HeapWord* cb = ctx->get_next_marked_addr(start, end);
359 
360   intx dist = ShenandoahMarkScanPrefetch;
361   if (dist > 0) {
362     // Batched scan that prefetches the oop data, anticipating the access to
363     // either header, oop field, or forwarding pointer. Not that we cannot
364     // touch anything in oop, while it still being prefetched to get enough
365     // time for prefetch to work. This is why we try to scan the bitmap linearly,
366     // disregarding the object size. However, since we know forwarding pointer
367     // preceeds the object, we can skip over it. Once we cannot trust the bitmap,
368     // there is no point for prefetching the oop contents, as oop->size() will
369     // touch it prematurely.
370 
371     // No variable-length arrays in standard C++, have enough slots to fit
372     // the prefetch distance.
373     static const int SLOT_COUNT = 256;
374     guarantee(dist <= SLOT_COUNT, "adjust slot count");
375     HeapWord* slots[SLOT_COUNT];
376 
377     int avail;
378     do {
379       avail = 0;
380       for (int c = 0; (c < dist) && (cb < limit_bitmap); c++) {
381         Prefetch::read(cb, oopDesc::mark_offset_in_bytes());
382         slots[avail++] = cb;
383         cb += skip_bitmap_delta;
384         if (cb < limit_bitmap) {
385           cb = ctx->get_next_marked_addr(cb, limit_bitmap);
386         }
387       }
388 
389       for (int c = 0; c < avail; c++) {
390         assert (slots[c] < tams,  "only objects below TAMS here: "  PTR_FORMAT " (" PTR_FORMAT ")", p2i(slots[c]), p2i(tams));
391         assert (slots[c] < limit, "only objects below limit here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(slots[c]), p2i(limit));
392         oop obj = cast_to_oop(slots[c]);
393         assert(oopDesc::is_oop(obj), "sanity");
394         assert(ctx->is_marked(obj), "object expected to be marked");
395         cl->do_object(obj);
396       }
397     } while (avail > 0);
398   } else {
399     while (cb < limit_bitmap) {
400       assert (cb < tams,  "only objects below TAMS here: "  PTR_FORMAT " (" PTR_FORMAT ")", p2i(cb), p2i(tams));
401       assert (cb < limit, "only objects below limit here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(cb), p2i(limit));
402       oop obj = cast_to_oop(cb);
403       assert(oopDesc::is_oop(obj), "sanity");
404       assert(ctx->is_marked(obj), "object expected to be marked");
405       cl->do_object(obj);
406       cb += skip_bitmap_delta;
407       if (cb < limit_bitmap) {
408         cb = ctx->get_next_marked_addr(cb, limit_bitmap);
409       }
410     }
411   }
412 
413   // Step 2. Accurate size-based traversal, happens past the TAMS.
414   // This restarts the scan at TAMS, which makes sure we traverse all objects,
415   // regardless of what happened at Step 1.
416   HeapWord* cs = tams;
417   while (cs < limit) {
418     assert (cs >= tams, "only objects past TAMS here: "   PTR_FORMAT " (" PTR_FORMAT ")", p2i(cs), p2i(tams));
419     assert (cs < limit, "only objects below limit here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(cs), p2i(limit));
420     oop obj = cast_to_oop(cs);
421     assert(oopDesc::is_oop(obj), "sanity");
422     assert(ctx->is_marked(obj), "object expected to be marked");
423     size_t size = ShenandoahObjectUtils::size(obj);
424     cl->do_object(obj);
425     cs += size;
426   }
427 }
428 
429 template <class T>
430 class ShenandoahObjectToOopClosure : public ObjectClosure {
431   T* _cl;
432 public:
433   ShenandoahObjectToOopClosure(T* cl) : _cl(cl) {}
434 
435   void do_object(oop obj) {
436     obj->oop_iterate(_cl);
437   }
438 };
439 
440 template <class T>
441 class ShenandoahObjectToOopBoundedClosure : public ObjectClosure {
442   T* _cl;
443   MemRegion _bounds;
444 public:
445   ShenandoahObjectToOopBoundedClosure(T* cl, HeapWord* bottom, HeapWord* top) :
446     _cl(cl), _bounds(bottom, top) {}
447 
448   void do_object(oop obj) {
449     obj->oop_iterate(_cl, _bounds);
450   }
451 };
452 
453 template<class T>
454 inline void ShenandoahHeap::marked_object_oop_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* top) {
455   if (region->is_humongous()) {
456     HeapWord* bottom = region->bottom();
457     if (top > bottom) {
458       region = region->humongous_start_region();
459       ShenandoahObjectToOopBoundedClosure<T> objs(cl, bottom, top);
460       marked_object_iterate(region, &objs);
461     }
462   } else {
463     ShenandoahObjectToOopClosure<T> objs(cl);
464     marked_object_iterate(region, &objs, top);
465   }
466 }
467 
468 inline ShenandoahHeapRegion* const ShenandoahHeap::get_region(size_t region_idx) const {
469   if (region_idx < _num_regions) {
470     return _regions[region_idx];
471   } else {
472     return NULL;
473   }
474 }
475 
476 inline void ShenandoahHeap::mark_complete_marking_context() {
477   _marking_context->mark_complete();
478 }
479 
480 inline void ShenandoahHeap::mark_incomplete_marking_context() {
481   _marking_context->mark_incomplete();
482 }
483 
484 inline ShenandoahMarkingContext* ShenandoahHeap::complete_marking_context() const {
485   assert (_marking_context->is_complete()," sanity");
486   return _marking_context;
487 }
488 
489 inline ShenandoahMarkingContext* ShenandoahHeap::marking_context() const {
490   return _marking_context;
491 }
492 
493 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_INLINE_HPP
--- EOF ---