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

/*
 * Copyright (c) 2019, 2021, Red Hat, Inc. 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
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#ifndef SHARE_GC_SHENANDOAH_SHENANDOAHROOTPROCESSOR_INLINE_HPP
#define SHARE_GC_SHENANDOAH_SHENANDOAHROOTPROCESSOR_INLINE_HPP

#include "gc/shenandoah/shenandoahRootProcessor.hpp"

#include "classfile/classLoaderDataGraph.hpp"
#include "gc/shared/oopStorageSetParState.inline.hpp"
#include "gc/shenandoah/heuristics/shenandoahHeuristics.hpp"
#include "gc/shenandoah/shenandoahClosures.inline.hpp"
#include "gc/shenandoah/shenandoahHeap.inline.hpp"
#include "gc/shenandoah/shenandoahPhaseTimings.hpp"
#include "gc/shenandoah/shenandoahUtils.hpp"
#include "memory/resourceArea.hpp"
#include "runtime/mutexLocker.hpp"
#include "runtime/safepoint.hpp"

template <bool CONCURRENT>
ShenandoahVMWeakRoots<CONCURRENT>::ShenandoahVMWeakRoots(ShenandoahPhaseTimings::Phase phase) :
  _phase(phase) {
}

template <bool CONCURRENT>
template <typename T>
void ShenandoahVMWeakRoots<CONCURRENT>::oops_do(T* cl, uint worker_id) {
  ShenandoahWorkerTimingsTracker timer(_phase, ShenandoahPhaseTimings::VMWeakRoots, worker_id);
  _weak_roots.oops_do(cl);
}

template <bool CONCURRENT>
template <typename IsAlive, typename KeepAlive>
void ShenandoahVMWeakRoots<CONCURRENT>::weak_oops_do(IsAlive* is_alive, KeepAlive* keep_alive, uint worker_id) {
  ShenandoahCleanUpdateWeakOopsClosure<CONCURRENT, IsAlive, KeepAlive> cl(is_alive, keep_alive);
  ShenandoahWorkerTimingsTracker timer(_phase, ShenandoahPhaseTimings::VMWeakRoots, worker_id);
  _weak_roots.oops_do(&cl);
}

template <bool CONCURRENT>
void ShenandoahVMWeakRoots<CONCURRENT>::report_num_dead() {
  _weak_roots.report_num_dead();
}

template <bool CONCURRENT>
ShenandoahVMRoots<CONCURRENT>::ShenandoahVMRoots(ShenandoahPhaseTimings::Phase phase) :
  _phase(phase) {
}

template <bool CONCURRENT>
template <typename T>
void ShenandoahVMRoots<CONCURRENT>::oops_do(T* cl, uint worker_id) {
  ShenandoahWorkerTimingsTracker timer(_phase, ShenandoahPhaseTimings::VMStrongRoots, worker_id);
  _strong_roots.oops_do(cl);
}

template <bool CONCURRENT>
ShenandoahClassLoaderDataRoots<CONCURRENT>::ShenandoahClassLoaderDataRoots(ShenandoahPhaseTimings::Phase phase, uint n_workers, bool heap_iteration) :
  _semaphore(worker_count(n_workers)),
  _phase(phase) {
  if (heap_iteration) {
    ClassLoaderDataGraph::clear_claimed_marks(ClassLoaderData::_claim_other);
  } else {
    ClassLoaderDataGraph::clear_claimed_marks(ClassLoaderData::_claim_strong);
  }

  if (CONCURRENT) {
    ClassLoaderDataGraph_lock->lock();
  }

  // Non-concurrent mode only runs at safepoints
  assert(CONCURRENT || SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
}

template <bool CONCURRENT>
ShenandoahClassLoaderDataRoots<CONCURRENT>::~ShenandoahClassLoaderDataRoots() {
  if (CONCURRENT) {
    ClassLoaderDataGraph_lock->unlock();
  }
}

template <bool CONCURRENT>
void ShenandoahClassLoaderDataRoots<CONCURRENT>::cld_do_impl(CldDo f, CLDClosure* clds, uint worker_id) {
  if (CONCURRENT) {
    if (_semaphore.try_acquire()) {
      ShenandoahWorkerTimingsTracker timer(_phase, ShenandoahPhaseTimings::CLDGRoots, worker_id);
      f(clds);
      _semaphore.claim_all();
    }
  } else {
    ShenandoahWorkerTimingsTracker timer(_phase, ShenandoahPhaseTimings::CLDGRoots, worker_id);
    f(clds);
  }
}

template <bool CONCURRENT>
void ShenandoahClassLoaderDataRoots<CONCURRENT>::always_strong_cld_do(CLDClosure* clds, uint worker_id) {
  cld_do_impl(&ClassLoaderDataGraph::always_strong_cld_do, clds, worker_id);
}

template <bool CONCURRENT>
void ShenandoahClassLoaderDataRoots<CONCURRENT>::cld_do(CLDClosure* clds, uint worker_id) {
  cld_do_impl(&ClassLoaderDataGraph::cld_do, clds, worker_id);
}

class ShenandoahParallelOopsDoThreadClosure : public ThreadClosure {
private:
  OopClosure* _f;
  NMethodClosure* _cf;
  ThreadClosure* _thread_cl;
public:
  ShenandoahParallelOopsDoThreadClosure(OopClosure* f, NMethodClosure* cf, ThreadClosure* thread_cl) :
    _f(f), _cf(cf), _thread_cl(thread_cl) {}

  void do_thread(Thread* t) {
    if (_thread_cl != nullptr) {
      _thread_cl->do_thread(t);
    }
    t->oops_do(_f, _cf);
  }
};

// The rationale for selecting the roots to scan is as follows:
//   a. With unload_classes = true, we only want to scan the actual strong roots from the
//      code cache. This will allow us to identify the dead classes, unload them, *and*
//      invalidate the relevant code cache blobs. This could be only done together with
//      class unloading.
//   b. With unload_classes = false, we have to nominally retain all the references from code
//      cache, because there could be the case of embedded class/oop in the generated code,
//      which we will never visit during mark. Without code cache invalidation, as in (a),
//      we risk executing that code cache blob, and crashing.
template <typename T>
void ShenandoahSTWRootScanner::roots_do(T* oops, uint worker_id) {
  MarkingNMethodClosure nmethods_cl(oops, !NMethodToOopClosure::FixRelocations, true /*FIXME*/);
  CLDToOopClosure clds(oops, ClassLoaderData::_claim_strong);
  ResourceMark rm;

  if (_unload_classes) {
    _thread_roots.oops_do(oops, &nmethods_cl, worker_id);
    _cld_roots.always_strong_cld_do(&clds, worker_id);
  } else {
    _thread_roots.oops_do(oops, nullptr, worker_id);
    _code_roots.nmethods_do(&nmethods_cl, worker_id);
    _cld_roots.cld_do(&clds, worker_id);
  }

  _vm_roots.oops_do<T>(oops, worker_id);
}

template <typename IsAlive, typename KeepAlive>
void ShenandoahRootUpdater::roots_do(uint worker_id, IsAlive* is_alive, KeepAlive* keep_alive) {
  NMethodToOopClosure update_nmethods(keep_alive, NMethodToOopClosure::FixRelocations);
  ShenandoahNMethodAndDisarmClosure nmethods_and_disarm_Cl(keep_alive);
  NMethodToOopClosure* codes_cl = ShenandoahCodeRoots::use_nmethod_barriers_for_mark() ?
                                  static_cast<NMethodToOopClosure*>(&nmethods_and_disarm_Cl) :
                                  static_cast<NMethodToOopClosure*>(&update_nmethods);

  CLDToOopClosure clds(keep_alive, ClassLoaderData::_claim_strong);

  // Process light-weight/limited parallel roots then
  _vm_roots.oops_do(keep_alive, worker_id);
  _weak_roots.weak_oops_do<IsAlive, KeepAlive>(is_alive, keep_alive, worker_id);
  _cld_roots.cld_do(&clds, worker_id);

  // Process heavy-weight/fully parallel roots the last
  _code_roots.nmethods_do(codes_cl, worker_id);
  _thread_roots.oops_do(keep_alive, nullptr, worker_id);
}

#endif // SHARE_GC_SHENANDOAH_SHENANDOAHROOTPROCESSOR_INLINE_HPP