/*

 * Copyright (c) 2016, Oracle and/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.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

#include "precompiled.hpp"

#include "logging/log.hpp"

#include "gc/g1/concurrentMarkThread.hpp"

#include "gc/g1/g1CollectedHeap.hpp"

#include "gc/g1/g1CollectedHeap.inline.hpp"

#include "gc/g1/g1HeapVerifier.hpp"

#include "gc/g1/g1MarkSweep.hpp"

#include "gc/g1/g1Policy.hpp"

#include "gc/g1/g1RemSet.hpp"

#include "gc/g1/g1RootProcessor.hpp"

#include "gc/g1/heapRegion.hpp"

#include "gc/g1/heapRegion.inline.hpp"

#include "gc/g1/heapRegionRemSet.hpp"

#include "gc/g1/g1StringDedup.hpp"

#include "memory/resourceArea.hpp"

#include "oops/oop.inline.hpp"

class VerifyRootsClosure: public OopClosure {

private:

  G1CollectedHeap* _g1h;

  VerifyOption     _vo;

  bool             _failures;

public:

  // _vo == UsePrevMarking -> use "prev" marking information,

  // _vo == UseNextMarking -> use "next" marking information,

  // _vo == UseMarkWord    -> use mark word from object header.

  VerifyRootsClosure(VerifyOption vo) :

    _g1h(G1CollectedHeap::heap()),

    _vo(vo),

    _failures(false) { }

  bool failures() { return _failures; }

  template <class T> void do_oop_nv(T* p) {

    T heap_oop = oopDesc::load_heap_oop(p);

    if (!oopDesc::is_null(heap_oop)) {

      oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);

      if (_g1h->is_obj_dead_cond(obj, _vo)) {

        Log(gc, verify) log;

        log.info("Root location " PTR_FORMAT " points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));

        if (_vo == VerifyOption_G1UseMarkWord) {

          log.error("  Mark word: " PTR_FORMAT, p2i(obj->mark()));

        }

        ResourceMark rm;

        obj->print_on(log.error_stream());

        _failures = true;

      }

    }

  }

  void do_oop(oop* p)       { do_oop_nv(p); }

  void do_oop(narrowOop* p) { do_oop_nv(p); }

};

class G1VerifyCodeRootOopClosure: public OopClosure {

  G1CollectedHeap* _g1h;

  OopClosure* _root_cl;

  nmethod* _nm;

  VerifyOption _vo;

  bool _failures;

  template <class T> void do_oop_work(T* p) {

    // First verify that this root is live

    _root_cl->do_oop(p);

    if (!G1VerifyHeapRegionCodeRoots) {

      // We're not verifying the code roots attached to heap region.

      return;

    }

    // Don't check the code roots during marking verification in a full GC

    if (_vo == VerifyOption_G1UseMarkWord) {

      return;

    }

    // Now verify that the current nmethod (which contains p) is

    // in the code root list of the heap region containing the

    // object referenced by p.

    T heap_oop = oopDesc::load_heap_oop(p);

    if (!oopDesc::is_null(heap_oop)) {

      oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);

      // Now fetch the region containing the object

      HeapRegion* hr = _g1h->heap_region_containing(obj);

      HeapRegionRemSet* hrrs = hr->rem_set();

      // Verify that the strong code root list for this region

      // contains the nmethod

      if (!hrrs->strong_code_roots_list_contains(_nm)) {

        log_error(gc, verify)("Code root location " PTR_FORMAT " "

                              "from nmethod " PTR_FORMAT " not in strong "

                              "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",

                              p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));

        _failures = true;

      }

    }

  }

public:

  G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):

    _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}

  void do_oop(oop* p) { do_oop_work(p); }

  void do_oop(narrowOop* p) { do_oop_work(p); }

  void set_nmethod(nmethod* nm) { _nm = nm; }

  bool failures() { return _failures; }

};

class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {

  G1VerifyCodeRootOopClosure* _oop_cl;

public:

  G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):

    _oop_cl(oop_cl) {}

  void do_code_blob(CodeBlob* cb) {

    nmethod* nm = cb->as_nmethod_or_null();

    if (nm != NULL) {

      _oop_cl->set_nmethod(nm);

      nm->oops_do(_oop_cl);

    }

  }

};

class YoungRefCounterClosure : public OopClosure {

  G1CollectedHeap* _g1h;

  int              _count;

 public:

  YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}

  void do_oop(oop* p)       { if (_g1h->is_in_young(*p)) { _count++; } }

  void do_oop(narrowOop* p) { ShouldNotReachHere(); }

  int count() { return _count; }

  void reset_count() { _count = 0; };

};

class VerifyKlassClosure: public KlassClosure {

  YoungRefCounterClosure _young_ref_counter_closure;

  OopClosure *_oop_closure;

 public:

  VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}

  void do_klass(Klass* k) {

    k->oops_do(_oop_closure);

    _young_ref_counter_closure.reset_count();

    k->oops_do(&_young_ref_counter_closure);

    if (_young_ref_counter_closure.count() > 0) {

      guarantee(k->has_modified_oops(), "Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k));

    }

  }

};

class VerifyLivenessOopClosure: public OopClosure {

  G1CollectedHeap* _g1h;

  VerifyOption _vo;

public:

  VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):

    _g1h(g1h), _vo(vo)

  { }

  void do_oop(narrowOop *p) { do_oop_work(p); }

  void do_oop(      oop *p) { do_oop_work(p); }

  template <class T> void do_oop_work(T *p) {

    oop obj = oopDesc::load_decode_heap_oop(p);

    guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),

              "Dead object referenced by a not dead object");

  }

};

class VerifyObjsInRegionClosure: public ObjectClosure {

private:

  G1CollectedHeap* _g1h;

  size_t _live_bytes;

  HeapRegion *_hr;

  VerifyOption _vo;

public:

  // _vo == UsePrevMarking -> use "prev" marking information,

  // _vo == UseNextMarking -> use "next" marking information,

  // _vo == UseMarkWord    -> use mark word from object header.

  VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)

    : _live_bytes(0), _hr(hr), _vo(vo) {

    _g1h = G1CollectedHeap::heap();

  }

  void do_object(oop o) {

    VerifyLivenessOopClosure isLive(_g1h, _vo);

    assert(o != NULL, "Huh?");

    if (!_g1h->is_obj_dead_cond(o, _vo)) {

      // If the object is alive according to the mark word,

      // then verify that the marking information agrees.

      // Note we can't verify the contra-positive of the

      // above: if the object is dead (according to the mark

      // word), it may not be marked, or may have been marked

      // but has since became dead, or may have been allocated

      // since the last marking.

      if (_vo == VerifyOption_G1UseMarkWord) {

        guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");

      }

      o->oop_iterate_no_header(&isLive);

      if (!_hr->obj_allocated_since_prev_marking(o)) {

        size_t obj_size = o->size();    // Make sure we don't overflow

        _live_bytes += (obj_size * HeapWordSize);

      }

    }

  }

  size_t live_bytes() { return _live_bytes; }

};

class VerifyArchiveOopClosure: public OopClosure {

public:

  VerifyArchiveOopClosure(HeapRegion *hr) { }

  void do_oop(narrowOop *p) { do_oop_work(p); }

  void do_oop(      oop *p) { do_oop_work(p); }

  template <class T> void do_oop_work(T *p) {

    oop obj = oopDesc::load_decode_heap_oop(p);

    guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),

              "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,

              p2i(p), p2i(obj));

  }

};

class VerifyArchiveRegionClosure: public ObjectClosure {

public:

  VerifyArchiveRegionClosure(HeapRegion *hr) { }

  // Verify that all object pointers are to archive regions.

  void do_object(oop o) {

    VerifyArchiveOopClosure checkOop(NULL);

    assert(o != NULL, "Should not be here for NULL oops");

    o->oop_iterate_no_header(&checkOop);

  }

};

class VerifyRegionClosure: public HeapRegionClosure {

private:

  bool             _par;

  VerifyOption     _vo;

  bool             _failures;

public:

  // _vo == UsePrevMarking -> use "prev" marking information,

  // _vo == UseNextMarking -> use "next" marking information,

  // _vo == UseMarkWord    -> use mark word from object header.

  VerifyRegionClosure(bool par, VerifyOption vo)

    : _par(par),

      _vo(vo),

      _failures(false) {}

  bool failures() {

    return _failures;

  }

  bool doHeapRegion(HeapRegion* r) {

    // For archive regions, verify there are no heap pointers to

    // non-pinned regions. For all others, verify liveness info.

    if (r->is_archive()) {

      VerifyArchiveRegionClosure verify_oop_pointers(r);

      r->object_iterate(&verify_oop_pointers);

      return true;

    }

    if (!r->is_continues_humongous()) {

      bool failures = false;

      r->verify(_vo, &failures);

      if (failures) {

        _failures = true;

      } else if (!r->is_starts_humongous()) {

        VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);

        r->object_iterate(&not_dead_yet_cl);

        if (_vo != VerifyOption_G1UseNextMarking) {

          if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {

            log_error(gc, verify)("[" PTR_FORMAT "," PTR_FORMAT "] max_live_bytes " SIZE_FORMAT " < calculated " SIZE_FORMAT,

                                  p2i(r->bottom()), p2i(r->end()), r->max_live_bytes(), not_dead_yet_cl.live_bytes());

            _failures = true;

          }

        } else {

          // When vo == UseNextMarking we cannot currently do a sanity

          // check on the live bytes as the calculation has not been

          // finalized yet.

        }

      }

    }

    return false; // stop the region iteration if we hit a failure

  }

};

// This is the task used for parallel verification of the heap regions

class G1ParVerifyTask: public AbstractGangTask {

private:

  G1CollectedHeap*  _g1h;

  VerifyOption      _vo;

  bool              _failures;

  HeapRegionClaimer _hrclaimer;

public:

  // _vo == UsePrevMarking -> use "prev" marking information,

  // _vo == UseNextMarking -> use "next" marking information,

  // _vo == UseMarkWord    -> use mark word from object header.

  G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :

      AbstractGangTask("Parallel verify task"),

      _g1h(g1h),

      _vo(vo),

      _failures(false),

      _hrclaimer(g1h->workers()->active_workers()) {}

  bool failures() {

    return _failures;

  }

  void work(uint worker_id) {

    HandleMark hm;

    VerifyRegionClosure blk(true, _vo);

    _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);

    if (blk.failures()) {

      _failures = true;

    }

  }

};

void G1HeapVerifier::verify(VerifyOption vo) {

  if (!SafepointSynchronize::is_at_safepoint()) {

    log_info(gc, verify)("Skipping verification. Not at safepoint.");

  }

  assert(Thread::current()->is_VM_thread(),

         "Expected to be executed serially by the VM thread at this point");

  log_debug(gc, verify)("Roots");

  VerifyRootsClosure rootsCl(vo);

  VerifyKlassClosure klassCl(_g1h, &rootsCl);

  CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);

  // We apply the relevant closures to all the oops in the

  // system dictionary, class loader data graph, the string table

  // and the nmethods in the code cache.

  G1VerifyCodeRootOopClosure codeRootsCl(_g1h, &rootsCl, vo);

  G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);

  {

    G1RootProcessor root_processor(_g1h, 1);

    root_processor.process_all_roots(&rootsCl,

                                     &cldCl,

                                     &blobsCl);

  }

  bool failures = rootsCl.failures() || codeRootsCl.failures();

  if (vo != VerifyOption_G1UseMarkWord) {

    // If we're verifying during a full GC then the region sets

    // will have been torn down at the start of the GC. Therefore

    // verifying the region sets will fail. So we only verify

    // the region sets when not in a full GC.

    log_debug(gc, verify)("HeapRegionSets");

    verify_region_sets();

  }

  log_debug(gc, verify)("HeapRegions");

  if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {

    G1ParVerifyTask task(_g1h, vo);

    _g1h->workers()->run_task(&task);

    if (task.failures()) {

      failures = true;

    }

  } else {

    VerifyRegionClosure blk(false, vo);

    _g1h->heap_region_iterate(&blk);

    if (blk.failures()) {

      failures = true;

    }

  }

  if (G1StringDedup::is_enabled()) {

    log_debug(gc, verify)("StrDedup");

    G1StringDedup::verify();

  }

  if (failures) {

    log_error(gc, verify)("Heap after failed verification:");

    // It helps to have the per-region information in the output to

    // help us track down what went wrong. This is why we call

    // print_extended_on() instead of print_on().

    Log(gc, verify) log;

    ResourceMark rm;

    _g1h->print_extended_on(log.error_stream());

  }

  guarantee(!failures, "there should not have been any failures");

}

// Heap region set verification

class VerifyRegionListsClosure : public HeapRegionClosure {

private:

  HeapRegionSet*   _old_set;

  HeapRegionSet*   _humongous_set;

  HeapRegionManager*   _hrm;

public:

  uint _old_count;

  uint _humongous_count;

  uint _free_count;

  VerifyRegionListsClosure(HeapRegionSet* old_set,

                           HeapRegionSet* humongous_set,

                           HeapRegionManager* hrm) :

    _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),

    _old_count(), _humongous_count(), _free_count(){ }

  bool doHeapRegion(HeapRegion* hr) {

    if (hr->is_young()) {

      // TODO

    } else if (hr->is_humongous()) {

      assert(hr->containing_set() == _humongous_set, "Heap region %u is humongous but not in humongous set.", hr->hrm_index());

      _humongous_count++;

    } else if (hr->is_empty()) {

      assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index());

      _free_count++;

    } else if (hr->is_old()) {

      assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index());

      _old_count++;

    } else {

      // There are no other valid region types. Check for one invalid

      // one we can identify: pinned without old or humongous set.

      assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index());

      ShouldNotReachHere();

    }

    return false;

  }

  void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {

    guarantee(old_set->length() == _old_count, "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count);

    guarantee(humongous_set->length() == _humongous_count, "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count);

    guarantee(free_list->num_free_regions() == _free_count, "Free list count mismatch. Expected %u, actual %u.", free_list->num_free_regions(), _free_count);

  }

};

void G1HeapVerifier::verify_region_sets() {

  assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);

  // First, check the explicit lists.

  _g1h->_hrm.verify();

  {

    // Given that a concurrent operation might be adding regions to

    // the secondary free list we have to take the lock before

    // verifying it.

    MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);

    _g1h->_secondary_free_list.verify_list();

  }

  // If a concurrent region freeing operation is in progress it will

  // be difficult to correctly attributed any free regions we come

  // across to the correct free list given that they might belong to

  // one of several (free_list, secondary_free_list, any local lists,

  // etc.). So, if that's the case we will skip the rest of the

  // verification operation. Alternatively, waiting for the concurrent

  // operation to complete will have a non-trivial effect on the GC's

  // operation (no concurrent operation will last longer than the

  // interval between two calls to verification) and it might hide

  // any issues that we would like to catch during testing.

  if (_g1h->free_regions_coming()) {

    return;

  }

  // Make sure we append the secondary_free_list on the free_list so

  // that all free regions we will come across can be safely

  // attributed to the free_list.

  _g1h->append_secondary_free_list_if_not_empty_with_lock();

  // Finally, make sure that the region accounting in the lists is

  // consistent with what we see in the heap.

  VerifyRegionListsClosure cl(&_g1h->_old_set, &_g1h->_humongous_set, &_g1h->_hrm);

  _g1h->heap_region_iterate(&cl);

  cl.verify_counts(&_g1h->_old_set, &_g1h->_humongous_set, &_g1h->_hrm);

}

void G1HeapVerifier::prepare_for_verify() {

  if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {

    _g1h->ensure_parsability(false);

  }

  _g1h->g1_rem_set()->prepare_for_verify();

}

double G1HeapVerifier::verify(bool guard, const char* msg) {

  double verify_time_ms = 0.0;

  if (guard && _g1h->total_collections() >= VerifyGCStartAt) {

    double verify_start = os::elapsedTime();

    HandleMark hm;  // Discard invalid handles created during verification

    prepare_for_verify();

    Universe::verify(VerifyOption_G1UsePrevMarking, msg);

    verify_time_ms = (os::elapsedTime() - verify_start) * 1000;

  }

  return verify_time_ms;

}

void G1HeapVerifier::verify_before_gc() {

  double verify_time_ms = verify(VerifyBeforeGC, "Before GC");

  _g1h->g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);