/*
  Copyright 2014 Red Hat, Inc. and/or its affiliates.
*/

#include "code/codeCache.hpp"
#include "gc/shared/isGCActiveMark.hpp"
#include "gc/shenandoah/brooksPointer.hpp"
#include "gc/shenandoah/shenandoahMarkCompact.hpp"
#include "gc/shenandoah/shenandoahBarrierSet.hpp"
#include "gc/shenandoah/shenandoahHeap.hpp"
#include "gc/shenandoah/shenandoahHeap.inline.hpp"
#include "gc/shenandoah/shenandoahRootProcessor.hpp"
#include "gc/shenandoah/vm_operations_shenandoah.hpp"
#include "gc/serial/markSweep.inline.hpp"
#include "oops/oop.inline.hpp"
#include "runtime/biasedLocking.hpp"
#include "runtime/thread.hpp"
#include "utilities/copy.hpp"
#include "gc/shared/taskqueue.inline.hpp"
#include "gc/shared/workgroup.hpp"



void ShenandoahMarkCompact::allocate_stacks() {
  MarkSweep::_preserved_count_max = 0;
  MarkSweep::_preserved_marks = NULL;
  MarkSweep::_preserved_count = 0;
}

void ShenandoahMarkCompact::do_mark_compact() {

  COMPILER2_PRESENT(DerivedPointerTable::clear());

  ShenandoahHeap* _heap = ShenandoahHeap::heap();

  assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
  IsGCActiveMark is_active;

  assert(Thread::current()->is_VM_thread(), "Do full GC only while world is stopped");
  assert(_heap->is_bitmap_clear(), "require cleared bitmap");
  assert(!_heap->concurrent_mark_in_progress(), "can't do full-GC while marking is in progress");
  assert(!_heap->is_evacuation_in_progress(), "can't do full-GC while evacuation is in progress");
  assert(!_heap->is_update_references_in_progress(), "can't do full-GC while updating of references is in progress");
  BarrierSet* _old_barrier_set = oopDesc::bs();

  oopDesc::set_bs(new ShenandoahMarkCompactBarrierSet());
 
  _heap->shenandoahPolicy()->record_phase_start(ShenandoahCollectorPolicy::full_gc);
 
  // We need to clear the is_in_collection_set flag in all regions.
  ShenandoahHeapRegion** regions = _heap->heap_regions();
  size_t num_regions = _heap->num_regions();
  for (size_t i = 0; i < num_regions; i++) {
    regions[i]->set_is_in_collection_set(false);
  }
  _heap->clear_cset_fast_test();

  /*
  if (ShenandoahVerify) {
    // Full GC should only be called between regular concurrent cycles, therefore
    // those verifications should be valid.
    _heap->verify_heap_after_evacuation();
    _heap->verify_heap_after_update_refs();
  }
  */

  if (ShenandoahTraceFullGC) {
    gclog_or_tty->print_cr("Shenandoah-full-gc: start with heap used: "SIZE_FORMAT" MB", _heap->used() / M);
    gclog_or_tty->print_cr("Shenandoah-full-gc: phase 1: marking the heap");
    // _heap->print_heap_regions();
  }
 
  if (UseTLAB) {
    _heap->ensure_parsability(true);
  }
  
  _heap->cleanup_after_cancelconcgc();
  
  ReferenceProcessor* rp = _heap->ref_processor();
 
  // hook up weak ref data so it can be used during Mark-Sweep
  assert(MarkSweep::ref_processor() == NULL, "no stomping");
  assert(rp != NULL, "should be non-NULL");
  assert(rp == ShenandoahHeap::heap()->ref_processor(), "Precondition"); 
  bool clear_all_softrefs = true;  //fixme
  MarkSweep::_ref_processor = rp;
  rp->setup_policy(clear_all_softrefs);

  CodeCache::gc_prologue();
  allocate_stacks();

  // We should save the marks of the currently locked biased monitors.
  // The marking doesn't preserve the marks of biased objects.
  BiasedLocking::preserve_marks();

  phase1_mark_heap();
 
  if (ShenandoahTraceFullGC) {
    gclog_or_tty->print_cr("Shenandoah-full-gc: phase 2: calculating target addresses");
  }
  phase2_calculate_target_addresses();
 
  if (ShenandoahTraceFullGC) {
    gclog_or_tty->print_cr("Shenandoah-full-gc: phase 3: updating references");
  }

  // Don't add any more derived pointers during phase3
  COMPILER2_PRESENT(DerivedPointerTable::set_active(false));

  phase3_update_references();
 
  if (ShenandoahTraceFullGC) {
    gclog_or_tty->print_cr("Shenandoah-full-gc: phase 4: compacting objects");
  }

  phase4_compact_objects();

 
  MarkSweep::restore_marks();
  BiasedLocking::restore_marks();
  GenMarkSweep::deallocate_stacks();

  CodeCache::gc_epilogue();
  JvmtiExport::gc_epilogue();

  // refs processing: clean slate
  MarkSweep::_ref_processor = NULL;

 
  if (ShenandoahVerify) {
    _heap->verify_heap_after_evacuation();
    _heap->verify_heap_after_update_refs();
  }

  if (ShenandoahTraceFullGC) {
    gclog_or_tty->print_cr("Shenandoah-full-gc: finish with heap used: "SIZE_FORMAT" MB", _heap->used() / M);
  }

  _heap->_bytesAllocSinceCM = 0;

  oopDesc::set_bs(_old_barrier_set); 

  _heap->set_need_update_refs(false);

  COMPILER2_PRESENT(DerivedPointerTable::update_pointers());

  _heap->shenandoahPolicy()->record_phase_end(ShenandoahCollectorPolicy::full_gc);
}

class UpdateRefsClosure: public ExtendedOopClosure {
public:
  virtual void do_oop(oop* p) {
    oop obj = oopDesc::load_heap_oop(p);
    if (! oopDesc::is_null(obj)) {
      ShenandoahBarrierSet::resolve_and_update_oop_static(p, obj);
    }
  }
  virtual void do_oop(narrowOop* p) {
    Unimplemented();
  }
};

void ShenandoahMarkCompact::phase1_mark_heap() {
  ShenandoahHeap* _heap = ShenandoahHeap::heap();
  ReferenceProcessor* rp = _heap->ref_processor();

  MarkSweep::_ref_processor = rp;
 
  // First, update _all_ references in GC roots to point to to-space.
  {
    // Need cleared claim bits for the roots processing
    /*
    ClassLoaderDataGraph::clear_claimed_marks();
    UpdateRefsClosure uprefs;
    CLDToOopClosure cld_uprefs(&uprefs);
    CodeBlobToOopClosure code_uprefs(&uprefs, CodeBlobToOopClosure::FixRelocations);
    ShenandoahRootProcessor rp(_heap, 1);
    rp.process_all_roots(&uprefs,
			 &cld_uprefs,
			 &code_uprefs);
    */
  }

  {
    MarkingCodeBlobClosure follow_code_closure(&MarkSweep::follow_root_closure, CodeBlobToOopClosure::FixRelocations);
    // Need cleared claim bits for the roots processing
    ClassLoaderDataGraph::clear_claimed_marks();
    ShenandoahRootProcessor rp(_heap, 1);
    rp.process_strong_roots(&MarkSweep::follow_root_closure,
			    &MarkSweep::follow_cld_closure,
			    &follow_code_closure);

    // Also update (without marking) weak CLD refs, in case they're reachable.
    UpdateRefsClosure uprefs;
    CLDToOopClosure cld_uprefs(&uprefs);
    ClassLoaderDataGraph::roots_cld_do(NULL, &cld_uprefs);

    // Same for weak JNI handles.
    ShenandoahAlwaysTrueClosure always_true;
    JNIHandles::weak_oops_do(&always_true, &uprefs);
  }
 
  _heap->shenandoahPolicy()->record_phase_start(ShenandoahCollectorPolicy::weakrefs);
  bool clear_soft_refs = false; //fixme 
  rp->setup_policy(clear_soft_refs);
 
  const ReferenceProcessorStats& stats =
    rp->process_discovered_references(&MarkSweep::is_alive,
				      &MarkSweep::keep_alive,
				      &MarkSweep::follow_stack_closure,
				      NULL,
				      NULL,
				      _heap->tracer()->gc_id());
 
  //     heap->tracer()->report_gc_reference_stats(stats);
 
  _heap->shenandoahPolicy()->record_phase_end(ShenandoahCollectorPolicy::weakrefs);
 
  // Unload classes and purge the SystemDictionary.
  bool purged_class = SystemDictionary::do_unloading(&MarkSweep::is_alive);
 
  // Unload nmethods.
  CodeCache::do_unloading(&MarkSweep::is_alive, purged_class);
 
  // Prune dead klasses from subklass/sibling/implementor lists.
  Klass::clean_weak_klass_links(&MarkSweep::is_alive);
 
  // Delete entries for dead interned string and clean up unreferenced symbols in symbol table.
  _heap->unlink_string_and_symbol_table(&MarkSweep::is_alive);
 
  if (VerifyDuringGC) {
    HandleMark hm;  // handle scope
    COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact);
    //    Universe::heap()->prepare_for_verify();
    _heap->prepare_for_verify();
    // Note: we can verify only the heap here. When an object is
    // marked, the previous value of the mark word (including
    // identity hash values, ages, etc) is preserved, and the mark
    // word is set to markOop::marked_value - effectively removing
    // any hash values from the mark word. These hash values are
    // used when verifying the dictionaries and so removing them
    // from the mark word can make verification of the dictionaries
    // fail. At the end of the GC, the original mark word values
    // (including hash values) are restored to the appropriate
    // objects.
    if (!VerifySilently) {
      gclog_or_tty->print(" VerifyDuringGC:(full)[Verifying ");
    }
    //    Universe::heap()->verify(VerifySilently, VerifyOption_G1UseMarkWord);
    _heap->verify(VerifySilently, VerifyOption_G1UseMarkWord);
    if (!VerifySilently) {
      gclog_or_tty->print_cr("]");
    }
  }
}
 
class ShenandoahPrepareForCompaction : public ShenandoahHeapRegionClosure {
  CompactPoint _cp;
  ShenandoahHeap* _heap;
  bool _dead_humongous;

public:
  ShenandoahPrepareForCompaction() :
    _heap(ShenandoahHeap::heap()),
    _dead_humongous(false) {
  }

  bool doHeapRegion(ShenandoahHeapRegion* r) {
    // We need to save the contents
    if (!r->is_humongous()) {
      if (_cp.space == NULL) {
	_cp.space = r;
	_cp.threshold = r->initialize_threshold();
      }
      _dead_humongous = false;
      r->prepare_for_compaction(&_cp);
    }  else {
      if (r->is_humongous_start()) {
        oop obj = oop(r->bottom() + BrooksPointer::BROOKS_POINTER_OBJ_SIZE);
	if (obj->is_gc_marked()) {
	  obj->forward_to(obj);
	  _dead_humongous = false;
	} else {
	  if (_cp.space == NULL) {
	    _cp.space = r;
	    _cp.threshold = r->initialize_threshold();
	  }
	  _dead_humongous = true;
	  guarantee(r->region_number() >= ((ShenandoahHeapRegion*)_cp.space)->region_number(),
		    "only reset regions that are not yet used for compaction");
	  r->reset();
	  r->prepare_for_compaction(&_cp);
	}
      } else {
	assert(r->is_humongous_continuation(), "expect humongous continuation");
	if (_dead_humongous) {
	  guarantee(r->region_number() > ((ShenandoahHeapRegion*)_cp.space)->region_number(),
		    "only reset regions that are not yet used for compaction");
	  r->reset();
	  r->prepare_for_compaction(&_cp);
	}
      }
    }
    return false;
  }
};
  
void ShenandoahMarkCompact::phase2_calculate_target_addresses() {
  ShenandoahPrepareForCompaction prepare;
  ShenandoahHeap::heap()->heap_region_iterate(&prepare);
}
 

class ShenandoahMarkCompactAdjustPointersClosure : public ShenandoahHeapRegionClosure {
  bool doHeapRegion(ShenandoahHeapRegion* r) {
    if (r->is_humongous()) {
      if (r->is_humongous_start()) {
        // We must adjust the pointers on the single H object.
        oop obj = oop(r->bottom() + BrooksPointer::BROOKS_POINTER_OBJ_SIZE);
	assert(obj->is_gc_marked(), "should be marked");
	// point all the oops to the new location
	MarkSweep::adjust_pointers(obj);
      }
    } else {
      r->adjust_pointers();
    }
    return false;
  }
};

void ShenandoahMarkCompact::phase3_update_references() {
  ShenandoahHeap* heap = ShenandoahHeap::heap();
 
    // Need cleared claim bits for the roots processing
  ClassLoaderDataGraph::clear_claimed_marks();

  CodeBlobToOopClosure adjust_code_closure(&MarkSweep::adjust_pointer_closure,
					   CodeBlobToOopClosure::FixRelocations);

  {
    ShenandoahRootProcessor rp(heap, 1);
    rp.process_all_roots(&MarkSweep::adjust_pointer_closure,
			 &MarkSweep::adjust_cld_closure,
			 &adjust_code_closure);
  }

  assert(MarkSweep::ref_processor() == heap->ref_processor(), "Sanity");

  // Now adjust pointers in remaining weak roots.  (All of which should
  // have been cleared if they pointed to non-surviving objects.)
  heap->weak_roots_iterate(&MarkSweep::adjust_pointer_closure);

  //  if (G1StringDedup::is_enabled()) {
  //    G1StringDedup::oops_do(&MarkSweep::adjust_pointer_closure);
  //  }

  MarkSweep::adjust_marks();

  ShenandoahMarkCompactAdjustPointersClosure apc;
  heap->heap_region_iterate(&apc);
}

class ShenandoahCleanupObjectClosure : public ObjectClosure {
  void  do_object(oop p) {
    ShenandoahHeap::heap()->initialize_brooks_ptr(p);
  }
};

class CompactObjectsClosure : public ShenandoahHeapRegionClosure {

public:

  CompactObjectsClosure() {
  }

  bool doHeapRegion(ShenandoahHeapRegion* r) {
    if (r->is_humongous()) {
      if (r->is_humongous_start()) {
        oop obj = oop(r->bottom() + BrooksPointer::BROOKS_POINTER_OBJ_SIZE);
	assert(obj->is_gc_marked(), "expect marked humongous object");
	obj->init_mark();
      }
    } else {
      r->compact();
    }

    return false;
  }

};

class ShenandoahPostCompactClosure : public ShenandoahHeapRegionClosure {
  size_t _live;
  ShenandoahHeap* _heap;
public:

  ShenandoahPostCompactClosure() : _live(0), _heap(ShenandoahHeap::heap()) { 
    _heap->clear_free_regions();
  }

  bool doHeapRegion(ShenandoahHeapRegion* r) {
    if (r->is_humongous()) {
      _live += ShenandoahHeapRegion::RegionSizeBytes;

    } else {
      size_t live = r->used();
      if (live == 0) {
	r->recycle();
	_heap->add_free_region(r);
      }
      r->setLiveData(live);
      _live += live;
    }

    return false;
  }
  
  size_t getLive() { return _live;}

};

void ShenandoahMarkCompact::phase4_compact_objects() {
  ShenandoahHeap* heap = ShenandoahHeap::heap();
  CompactObjectsClosure coc;
  heap->heap_region_iterate(&coc);
  
  ShenandoahCleanupObjectClosure cleanup;
  heap->object_iterate(&cleanup);

  ShenandoahPostCompactClosure post_compact;
  heap->heap_region_iterate(&post_compact);

  heap->set_used(post_compact.getLive());
}