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src/hotspot/share/gc/shenandoah/shenandoahHeap.inline.hpp

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*** 1,7 ***
--- 1,8 ---
  /*
   * Copyright (c) 2015, 2020, Red Hat, Inc. All rights reserved.
+  * Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.

*** 38,18 ***
  #include "gc/shenandoah/shenandoahCollectionSet.inline.hpp"
  #include "gc/shenandoah/shenandoahForwarding.inline.hpp"
  #include "gc/shenandoah/shenandoahWorkGroup.hpp"
  #include "gc/shenandoah/shenandoahHeapRegionSet.inline.hpp"
  #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
! #include "gc/shenandoah/shenandoahControlThread.hpp"
  #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
  #include "gc/shenandoah/shenandoahThreadLocalData.hpp"
  #include "oops/compressedOops.inline.hpp"
  #include "oops/oop.inline.hpp"
  #include "runtime/atomic.hpp"
  #include "runtime/javaThread.hpp"
  #include "runtime/prefetch.inline.hpp"
  #include "utilities/copy.hpp"
  #include "utilities/globalDefinitions.hpp"
  
  inline ShenandoahHeap* ShenandoahHeap::heap() {
    return named_heap<ShenandoahHeap>(CollectedHeap::Shenandoah);
--- 39,20 ---
  #include "gc/shenandoah/shenandoahCollectionSet.inline.hpp"
  #include "gc/shenandoah/shenandoahForwarding.inline.hpp"
  #include "gc/shenandoah/shenandoahWorkGroup.hpp"
  #include "gc/shenandoah/shenandoahHeapRegionSet.inline.hpp"
  #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
! #include "gc/shenandoah/shenandoahGeneration.hpp"
  #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
  #include "gc/shenandoah/shenandoahThreadLocalData.hpp"
+ #include "gc/shenandoah/mode/shenandoahMode.hpp"
  #include "oops/compressedOops.inline.hpp"
  #include "oops/oop.inline.hpp"
  #include "runtime/atomic.hpp"
  #include "runtime/javaThread.hpp"
  #include "runtime/prefetch.inline.hpp"
+ #include "runtime/objectMonitor.inline.hpp"
  #include "utilities/copy.hpp"
  #include "utilities/globalDefinitions.hpp"
  
  inline ShenandoahHeap* ShenandoahHeap::heap() {
    return named_heap<ShenandoahHeap>(CollectedHeap::Shenandoah);

*** 262,13 ***
      }
    }
    return cancelled_gc();
  }
  
! inline void ShenandoahHeap::clear_cancelled_gc() {
    _cancelled_gc.set(CANCELLABLE);
!   _oom_evac_handler.clear();
  }
  
  inline HeapWord* ShenandoahHeap::allocate_from_gclab(Thread* thread, size_t size) {
    assert(UseTLAB, "TLABs should be enabled");
  
--- 265,21 ---
      }
    }
    return cancelled_gc();
  }
  
! inline void ShenandoahHeap::clear_cancelled_gc(bool clear_oom_handler) {
    _cancelled_gc.set(CANCELLABLE);
!   if (_cancel_requested_time > 0) {
+     double cancel_time = os::elapsedTime() - _cancel_requested_time;
+     log_info(gc)("GC cancellation took %.3fs", cancel_time);
+     _cancel_requested_time = 0;
+   }
+ 
+   if (clear_oom_handler) {
+     _oom_evac_handler.clear();
+   }
  }
  
  inline HeapWord* ShenandoahHeap::allocate_from_gclab(Thread* thread, size_t size) {
    assert(UseTLAB, "TLABs should be enabled");
  

*** 281,91 ***
    }
    HeapWord* obj = gclab->allocate(size);
    if (obj != nullptr) {
      return obj;
    }
-   // Otherwise...
    return allocate_from_gclab_slow(thread, size);
  }
  
! inline oop ShenandoahHeap::evacuate_object(oop p, Thread* thread) {
!   if (ShenandoahThreadLocalData::is_oom_during_evac(Thread::current())) {
!     // This thread went through the OOM during evac protocol and it is safe to return
!     // the forward pointer. It must not attempt to evacuate any more.
!     return ShenandoahBarrierSet::resolve_forwarded(p);
    }
  
!   assert(ShenandoahThreadLocalData::is_evac_allowed(thread), "must be enclosed in oom-evac scope");
  
!   size_t size = p->size();
  
!   assert(!heap_region_containing(p)->is_humongous(), "never evacuate humongous objects");
  
!   bool alloc_from_gclab = true;
!   HeapWord* copy = nullptr;
  
! #ifdef ASSERT
!   if (ShenandoahOOMDuringEvacALot &&
!       (os::random() & 1) == 0) { // Simulate OOM every ~2nd slow-path call
!         copy = nullptr;
!   } else {
! #endif
!     if (UseTLAB) {
!       copy = allocate_from_gclab(thread, size);
!     }
!     if (copy == nullptr) {
!       ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared_gc(size);
!       copy = allocate_memory(req);
!       alloc_from_gclab = false;
!     }
! #ifdef ASSERT
    }
! #endif
  
!   if (copy == nullptr) {
!     control_thread()->handle_alloc_failure_evac(size);
  
!     _oom_evac_handler.handle_out_of_memory_during_evacuation();
  
!     return ShenandoahBarrierSet::resolve_forwarded(p);
!   }
  
!   // Copy the object:
!   Copy::aligned_disjoint_words(cast_from_oop<HeapWord*>(p), copy, size);
! 
!   // Try to install the new forwarding pointer.
!   oop copy_val = cast_to_oop(copy);
!   ContinuationGCSupport::relativize_stack_chunk(copy_val);
! 
!   oop result = ShenandoahForwarding::try_update_forwardee(p, copy_val);
!   if (result == copy_val) {
!     // Successfully evacuated. Our copy is now the public one!
!     shenandoah_assert_correct(nullptr, copy_val);
!     return copy_val;
!   }  else {
!     // Failed to evacuate. We need to deal with the object that is left behind. Since this
!     // new allocation is certainly after TAMS, it will be considered live in the next cycle.
!     // But if it happens to contain references to evacuated regions, those references would
!     // not get updated for this stale copy during this cycle, and we will crash while scanning
!     // it the next cycle.
!     //
!     // For GCLAB allocations, it is enough to rollback the allocation ptr. Either the next
!     // object will overwrite this stale copy, or the filler object on LAB retirement will
!     // do this. For non-GCLAB allocations, we have no way to retract the allocation, and
-     // have to explicitly overwrite the copy with the filler object. With that overwrite,
-     // we have to keep the fwdptr initialized and pointing to our (stale) copy.
-     if (alloc_from_gclab) {
-       ShenandoahThreadLocalData::gclab(thread)->undo_allocation(copy, size);
-     } else {
-       fill_with_object(copy, size);
-       shenandoah_assert_correct(nullptr, copy_val);
-     }
-     shenandoah_assert_correct(nullptr, result);
-     return result;
    }
  }
  
  inline bool ShenandoahHeap::requires_marking(const void* entry) const {
    oop obj = cast_to_oop(entry);
    return !_marking_context->is_marked_strong(obj);
  }
  
--- 292,155 ---
    }
    HeapWord* obj = gclab->allocate(size);
    if (obj != nullptr) {
      return obj;
    }
    return allocate_from_gclab_slow(thread, size);
  }
  
! inline ShenandoahAgeCensus* ShenandoahHeap::age_census() const {
!   assert(mode()->is_generational(), "Only in generational mode");
!   assert(_age_census != nullptr, "Error: not initialized");
!   return _age_census;
! }
+ 
+ void ShenandoahHeap::increase_object_age(oop obj, uint additional_age) {
+   // This operates on new copy of an object. This means that the object's mark-word
+   // is thread-local and therefore safe to access. However, when the mark is
+   // displaced (i.e. stack-locked or monitor-locked), then it must be considered
+   // a shared memory location. It can be accessed by other threads.
+   // In particular, a competing evacuating thread can succeed to install its copy
+   // as the forwardee and continue to unlock the object, at which point 'our'
+   // write to the foreign stack-location would potentially over-write random
+   // information on that stack. Writing to a monitor is less problematic,
+   // but still not safe: while the ObjectMonitor would not randomly disappear,
+   // the other thread would also write to the same displaced header location,
+   // possibly leading to increase the age twice.
+   // For all these reasons, we take the conservative approach and not attempt
+   // to increase the age when the header is displaced.
+   markWord w = obj->mark();
+   // The mark-word has been copied from the original object. It can not be
+   // inflating, because inflation can not be interrupted by a safepoint,
+   // and after a safepoint, a Java thread would first have to successfully
+   // evacuate the object before it could inflate the monitor.
+   assert(!w.is_being_inflated() || LockingMode == LM_LIGHTWEIGHT, "must not inflate monitor before evacuation of object succeeds");
+   // It is possible that we have copied the object after another thread has
+   // already successfully completed evacuation. While harmless (we would never
+   // publish our copy), don't even attempt to modify the age when that
+   // happens.
+   if (!w.has_displaced_mark_helper() && !w.is_marked()) {
+     w = w.set_age(MIN2(markWord::max_age, w.age() + additional_age));
+     obj->set_mark(w);
    }
+ }
  
! // Return the object's age, or a sentinel value when the age can't
+ // necessarily be determined because of concurrent locking by the
+ // mutator
+ uint ShenandoahHeap::get_object_age(oop obj) {
+   // This is impossible to do unless we "freeze" ABA-type oscillations
+   // With Lilliput, we can do this more easily.
+   markWord w = obj->mark();
+   assert(!w.is_marked(), "must not be forwarded");
+   if (w.has_monitor()) {
+     w = w.monitor()->header();
+   } else if (w.is_being_inflated() || w.has_displaced_mark_helper()) {
+     // Informs caller that we aren't able to determine the age
+     return markWord::max_age + 1; // sentinel
+   }
+   assert(w.age() <= markWord::max_age, "Impossible!");
+   return w.age();
+ }
  
! bool ShenandoahHeap::is_in(const void* p) const {
+   HeapWord* heap_base = (HeapWord*) base();
+   HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
+   return p >= heap_base && p < last_region_end;
+ }
  
! inline bool ShenandoahHeap::is_in_active_generation(oop obj) const {
+   if (!mode()->is_generational()) {
+     // everything is the same single generation
+     return true;
+   }
  
!   if (active_generation() == nullptr) {
!     // no collection is happening, only expect this to be called
+     // when concurrent processing is active, but that could change
+     return false;
+   }
  
!   assert(is_in(obj), "only check if is in active generation for objects (" PTR_FORMAT ") in heap", p2i(obj));
!   assert((active_generation() == (ShenandoahGeneration*) old_generation()) ||
!          (active_generation() == (ShenandoahGeneration*) young_generation()) ||
!          (active_generation() == global_generation()), "Active generation must be old, young, or global");
! 
!   size_t index = heap_region_containing(obj)->index();
!   switch (_affiliations[index]) {
!   case ShenandoahAffiliation::FREE:
!     // Free regions are in Old, Young, Global
!     return true;
!   case ShenandoahAffiliation::YOUNG_GENERATION:
!     // Young regions are in young_generation and global_generation, not in old_generation
!     return (active_generation() != (ShenandoahGeneration*) old_generation());
!   case ShenandoahAffiliation::OLD_GENERATION:
!     // Old regions are in old_generation and global_generation, not in young_generation
+     return (active_generation() != (ShenandoahGeneration*) young_generation());
+   default:
+     assert(false, "Bad affiliation (%d) for region " SIZE_FORMAT, _affiliations[index], index);
+     return false;
    }
! }
  
! inline bool ShenandoahHeap::is_in_young(const void* p) const {
!   return is_in(p) && (_affiliations[heap_region_index_containing(p)] == ShenandoahAffiliation::YOUNG_GENERATION);
+ }
  
! inline bool ShenandoahHeap::is_in_old(const void* p) const {
+   return is_in(p) && (_affiliations[heap_region_index_containing(p)] == ShenandoahAffiliation::OLD_GENERATION);
+ }
  
! inline bool ShenandoahHeap::is_old(oop obj) const {
!   return active_generation()->is_young() && is_in_old(obj);
+ }
  
! inline ShenandoahAffiliation ShenandoahHeap::region_affiliation(const ShenandoahHeapRegion *r) {
!   return (ShenandoahAffiliation) _affiliations[r->index()];
! }
! 
! inline void ShenandoahHeap::assert_lock_for_affiliation(ShenandoahAffiliation orig_affiliation,
!                                                         ShenandoahAffiliation new_affiliation) {
!   // A lock is required when changing from FREE to NON-FREE.  Though it may be possible to elide the lock when
!   // transitioning from in-use to FREE, the current implementation uses a lock for this transition.  A lock is
!   // not required to change from YOUNG to OLD (i.e. when promoting humongous region).
!   //
!   //         new_affiliation is:     FREE   YOUNG   OLD
!   //  orig_affiliation is:  FREE      X       L      L
!   //                       YOUNG      L       X
!   //                         OLD      L       X      X
!   //  X means state transition won't happen (so don't care)
!   //  L means lock should be held
!   //  Blank means no lock required because affiliation visibility will not be required until subsequent safepoint
!   //
!   // Note: during full GC, all transitions between states are possible.  During Full GC, we should be in a safepoint.
! 
!   if ((orig_affiliation == ShenandoahAffiliation::FREE) || (new_affiliation == ShenandoahAffiliation::FREE)) {
!     shenandoah_assert_heaplocked_or_fullgc_safepoint();
    }
  }
  
+ inline void ShenandoahHeap::set_affiliation(ShenandoahHeapRegion* r, ShenandoahAffiliation new_affiliation) {
+ #ifdef ASSERT
+   assert_lock_for_affiliation(region_affiliation(r), new_affiliation);
+ #endif
+   _affiliations[r->index()] = (uint8_t) new_affiliation;
+ }
+ 
+ inline ShenandoahAffiliation ShenandoahHeap::region_affiliation(size_t index) {
+   return (ShenandoahAffiliation) _affiliations[index];
+ }
+ 
  inline bool ShenandoahHeap::requires_marking(const void* entry) const {
    oop obj = cast_to_oop(entry);
    return !_marking_context->is_marked_strong(obj);
  }
  

*** 377,10 ***
--- 452,11 ---
  inline bool ShenandoahHeap::in_collection_set_loc(void* p) const {
    assert(collection_set() != nullptr, "Sanity");
    return collection_set()->is_in_loc(p);
  }
  
+ 
  inline bool ShenandoahHeap::is_stable() const {
    return _gc_state.is_clear();
  }
  
  inline bool ShenandoahHeap::is_idle() const {

*** 389,10 ***
--- 465,18 ---
  
  inline bool ShenandoahHeap::is_concurrent_mark_in_progress() const {
    return _gc_state.is_set(MARKING);
  }
  
+ inline bool ShenandoahHeap::is_concurrent_young_mark_in_progress() const {
+   return _gc_state.is_set(YOUNG_MARKING);
+ }
+ 
+ inline bool ShenandoahHeap::is_concurrent_old_mark_in_progress() const {
+   return _gc_state.is_set(OLD_MARKING);
+ }
+ 
  inline bool ShenandoahHeap::is_evacuation_in_progress() const {
    return _gc_state.is_set(EVACUATION);
  }
  
  inline bool ShenandoahHeap::is_degenerated_gc_in_progress() const {

*** 430,12 ***
  
  template<class T>
  inline void ShenandoahHeap::marked_object_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* limit) {
    assert(! region->is_humongous_continuation(), "no humongous continuation regions here");
  
!   ShenandoahMarkingContext* const ctx = complete_marking_context();
-   assert(ctx->is_complete(), "sanity");
  
    HeapWord* tams = ctx->top_at_mark_start(region);
  
    size_t skip_bitmap_delta = 1;
    HeapWord* start = region->bottom();
--- 514,11 ---
  
  template<class T>
  inline void ShenandoahHeap::marked_object_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* limit) {
    assert(! region->is_humongous_continuation(), "no humongous continuation regions here");
  
!   ShenandoahMarkingContext* const ctx = marking_context();
  
    HeapWord* tams = ctx->top_at_mark_start(region);
  
    size_t skip_bitmap_delta = 1;
    HeapWord* start = region->bottom();

*** 562,18 ***
    } else {
      return nullptr;
    }
  }
  
- inline void ShenandoahHeap::mark_complete_marking_context() {
-   _marking_context->mark_complete();
- }
- 
- inline void ShenandoahHeap::mark_incomplete_marking_context() {
-   _marking_context->mark_incomplete();
- }
- 
  inline ShenandoahMarkingContext* ShenandoahHeap::complete_marking_context() const {
    assert (_marking_context->is_complete()," sanity");
    return _marking_context;
  }
  
--- 645,10 ---
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