/*

 * Copyright (c) 2019, Red Hat, Inc. All rights reserved.

 *

 * 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 "gc/shenandoah/shenandoahClosures.inline.hpp"

#include "gc/shenandoah/shenandoahConcurrentRoots.hpp"

#include "gc/shenandoah/shenandoahHeap.inline.hpp"

#include "gc/shenandoah/shenandoahNMethod.inline.hpp"

#include "memory/resourceArea.hpp"

ShenandoahNMethod::ShenandoahNMethod(nmethod* nm, GrowableArray<oop*>& oops, bool non_immediate_oops) :

  _nm(nm), _oops(NULL), _oops_count(0), _unregistered(false) {

  if (!oops.is_empty()) {

    _oops_count = oops.length();

    _oops = NEW_C_HEAP_ARRAY(oop*, _oops_count, mtGC);

    for (int c = 0; c < _oops_count; c++) {

      _oops[c] = oops.at(c);

    }

  }

  _has_non_immed_oops = non_immediate_oops;

  assert_same_oops();

}

ShenandoahNMethod::~ShenandoahNMethod() {

  if (_oops != NULL) {

    FREE_C_HEAP_ARRAY(oop*, _oops);

  }

}

class ShenandoahHasCSetOopClosure : public OopClosure {

private:

  ShenandoahHeap* const _heap;

  bool                  _has_cset_oops;

public:

  ShenandoahHasCSetOopClosure() :

    _heap(ShenandoahHeap::heap()),

    _has_cset_oops(false) {

  }

  bool has_cset_oops() const {

    return _has_cset_oops;

  }

  void do_oop(oop* p) {

    oop value = RawAccess<>::oop_load(p);

    if (!_has_cset_oops && _heap->in_collection_set(value)) {

      _has_cset_oops = true;

    }

  }

  void do_oop(narrowOop* p) {

    ShouldNotReachHere();

  }

};

bool ShenandoahNMethod::has_cset_oops(ShenandoahHeap *heap) {

  ShenandoahHasCSetOopClosure cl;

  oops_do(&cl);

  return cl.has_cset_oops();

}

void ShenandoahNMethod::update() {

  ResourceMark rm;

  bool non_immediate_oops = false;

  GrowableArray<oop*> oops;

  detect_reloc_oops(nm(), oops, non_immediate_oops);

  if (oops.length() != _oops_count) {

    if (_oops != NULL) {

      FREE_C_HEAP_ARRAY(oop*, _oops);

      _oops = NULL;

    }

    _oops_count = oops.length();

    if (_oops_count > 0) {

      _oops = NEW_C_HEAP_ARRAY(oop*, _oops_count, mtGC);

    }

  }

  for (int index = 0; index < _oops_count; index ++) {

    _oops[index] = oops.at(index);

  }

  _has_non_immed_oops = non_immediate_oops;

  assert_same_oops();

}

void ShenandoahNMethod::oops_do(OopClosure* oops, bool fix_relocations) {

  for (int c = 0; c < _oops_count; c ++) {

    oops->do_oop(_oops[c]);

  }

  oop* const begin = _nm->oops_begin();

  oop* const end = _nm->oops_end();

  for (oop* p = begin; p < end; p++) {

    if (*p != Universe::non_oop_word()) {

      oops->do_oop(p);

    }

  }

  if (fix_relocations && _has_non_immed_oops) {

    _nm->fix_oop_relocations();

  }

}

void ShenandoahNMethod::detect_reloc_oops(nmethod* nm, GrowableArray<oop*>& oops, bool& has_non_immed_oops) {

  has_non_immed_oops = false;

  // Find all oops relocations

  RelocIterator iter(nm);

  while (iter.next()) {

    if (iter.type() != relocInfo::oop_type) {

      // Not an oop

      continue;

    }

    oop_Relocation* r = iter.oop_reloc();

    if (!r->oop_is_immediate()) {

      // Non-immediate oop found

      has_non_immed_oops = true;

      continue;

    }

    if (r->oop_value() != NULL) {

      // Non-NULL immediate oop found. NULL oops can safely be

      // ignored since the method will be re-registered if they

      // are later patched to be non-NULL.

      oops.push(r->oop_addr());

    }

  }

}

ShenandoahNMethod* ShenandoahNMethod::for_nmethod(nmethod* nm) {

  ResourceMark rm;

  bool non_immediate_oops = false;

  GrowableArray<oop*> oops;

  detect_reloc_oops(nm, oops, non_immediate_oops);

  // No embedded oops

  if(!ShenandoahConcurrentRoots::can_do_concurrent_class_unloading() &&

    oops.is_empty() && nm->oops_begin() >= nm->oops_end()) {

    return NULL;

  }

  return new ShenandoahNMethod(nm, oops, non_immediate_oops);

}

void ShenandoahNMethod::heal_nmethod(nmethod* nm) {

  ShenandoahNMethod* data = gc_data(nm);

  assert(data != NULL, "Sanity");

  assert(data->lock()->owned_by_self(), "Must hold the lock");

  ShenandoahEvacuateUpdateRootsClosure cl;

  data->oops_do(&cl, true /*fix relocation*/);

}

#ifdef ASSERT

void ShenandoahNMethod::assert_alive_and_correct() {

  assert(_nm->is_alive(), "only alive nmethods here");

  ShenandoahHeap* heap = ShenandoahHeap::heap();

  for (int c = 0; c < _oops_count; c++) {

    oop *loc = _oops[c];

    assert(_nm->code_contains((address) loc) || _nm->oops_contains(loc), "nmethod should contain the oop*");

    oop o = RawAccess<>::oop_load(loc);

    shenandoah_assert_correct_except(loc, o, o == NULL || heap->is_full_gc_move_in_progress());

  }

  oop* const begin = _nm->oops_begin();

  oop* const end = _nm->oops_end();

  for (oop* p = begin; p < end; p++) {

    if (*p != Universe::non_oop_word()) {

      oop o = RawAccess<>::oop_load(p);

      shenandoah_assert_correct_except(p, o, o == NULL || heap->is_full_gc_move_in_progress());

    }

  }

}

class ShenandoahNMethodOopDetector : public OopClosure {

private:

  ResourceMark rm; // For growable array allocation below.

  GrowableArray<oop*> _oops;

public:

  ShenandoahNMethodOopDetector() : _oops(10) {};

  void do_oop(oop* o) {

    _oops.append(o);

  }

  void do_oop(narrowOop* o) {

    fatal("NMethods should not have compressed oops embedded.");

  }

  GrowableArray<oop*>* oops() {

    return &_oops;

  }

  bool has_oops() {

    return !_oops.is_empty();

  }

};

void ShenandoahNMethod::assert_same_oops(bool allow_dead) {

  ShenandoahNMethodOopDetector detector;

  nm()->oops_do(&detector, allow_dead);

  GrowableArray<oop*>* oops = detector.oops();

  assert(oops->length() == oop_count(), "Must match");

  for (int index = 0; index < _oops_count; index ++) {

    assert(oops->contains(_oops[index]), "Must contain this oop");

  }

  for (oop* p = nm()->oops_begin(); p < nm()->oops_end(); p ++) {

    assert(oops->contains(p), "Must contain this oop");

  }

}

void ShenandoahNMethod::assert_no_oops(nmethod* nm, bool allow_dead) {

  ShenandoahNMethodOopDetector detector;

  nm->oops_do(&detector, allow_dead);

  assert(detector.oops()->length() == 0, "Should not have oops");

}

#endif

ShenandoahNMethodTable::ShenandoahNMethodTable() :

  _heap(ShenandoahHeap::heap()),

  _size(minSize),

  _index(0),

  _iteration_in_progress(false) {

  _array = NEW_C_HEAP_ARRAY(ShenandoahNMethod*, _size, mtGC);

}

ShenandoahNMethodTable::~ShenandoahNMethodTable() {

  assert(_array != NULL, "Sanity");

  FREE_C_HEAP_ARRAY(ShenandoahNMethod*, _array);

}

void ShenandoahNMethodTable::register_nmethod(nmethod* nm) {

  assert(CodeCache_lock->owned_by_self(), "Must have CodeCache_lock held");

  assert(_index >= 0 && _index <= _size, "Sanity");

  ShenandoahNMethod* data = ShenandoahNMethod::gc_data(nm);

  ShenandoahReentrantLocker data_locker(data != NULL ? data->lock() : NULL);

  if (data != NULL) {

    assert(contain(nm), "Must have been registered");

    data->update();

  } else {

    data = ShenandoahNMethod::for_nmethod(nm);

    if (data == NULL) {

      assert(!ShenandoahConcurrentRoots::can_do_concurrent_class_unloading(),

             "Only possible when concurrent class unloading is off");

      return;

    }

    ShenandoahNMethod::attach_gc_data(nm, data);

    ShenandoahLocker locker(&_lock);

    log_register_nmethod(nm);

    append(data);

  }

  // Disarm new nmethod

  ShenandoahNMethod::disarm_nmethod(nm);

}

void ShenandoahNMethodTable::unregister_nmethod(nmethod* nm) {

  assert_locked_or_safepoint(CodeCache_lock);

  ShenandoahNMethod* data = ShenandoahNMethod::gc_data(nm);

  if (data == NULL) {

    assert(!ShenandoahConcurrentRoots::can_do_concurrent_class_unloading(),

           "Only possible when concurrent class unloading is off");

    ShenandoahNMethod::assert_no_oops(nm, true /*allow_dead*/);

    return;

  }

  if (Thread::current()->is_Code_cache_sweeper_thread()) {

    wait_until_concurrent_iteration_done();

  }

  log_unregister_nmethod(nm);

  ShenandoahLocker locker(&_lock);

  assert(contain(nm), "Must have been registered");

  ShenandoahReentrantLocker data_locker(data->lock());

  data->mark_unregistered();

}

void ShenandoahNMethodTable::flush_nmethod(nmethod* nm) {

  assert(CodeCache_lock->owned_by_self(), "Must have CodeCache_lock held");

  assert(Thread::current()->is_Code_cache_sweeper_thread(), "Must from Sweep thread");

  ShenandoahNMethod* data = ShenandoahNMethod::gc_data(nm);

  assert(data != NULL || !ShenandoahConcurrentRoots::can_do_concurrent_class_unloading(),

         "Only possible when concurrent class unloading is off");

  if (data == NULL) {

    ShenandoahNMethod::assert_no_oops(nm, true /*allow_dead*/);

    return;

  }

  // Can not alter the array when iteration is in progress

  wait_until_concurrent_iteration_done();

  log_flush_nmethod(nm);

  ShenandoahLocker locker(&_lock);

  int idx = index_of(nm);

  assert(idx >= 0 && idx < _index, "Invalid index");

  ShenandoahNMethod::attach_gc_data(nm, NULL);

  remove(idx);

}

bool ShenandoahNMethodTable::contain(nmethod* nm) const {

  return index_of(nm) != -1;

}

ShenandoahNMethod* ShenandoahNMethodTable::at(int index) const {

  assert(index >= 0 && index < _index, "Out of bound");

  return _array[index];

}

int ShenandoahNMethodTable::index_of(nmethod* nm) const {

  for (int index = 0; index < length(); index ++) {

    if (_array[index]->nm() == nm) {

      return index;

    }

  }

  return -1;

}

void ShenandoahNMethodTable::remove(int idx) {

  shenandoah_assert_locked_or_safepoint(CodeCache_lock);

  assert(!_iteration_in_progress, "Can not happen");

  assert(_index >= 0 && _index <= _size, "Sanity");

  assert(idx >= 0 && idx < _index, "Out of bound");

  ShenandoahNMethod* snm = _array[idx];

  _index --;

  _array[idx] = _array[_index];

  delete snm;

}

void ShenandoahNMethodTable::wait_until_concurrent_iteration_done() {

  assert(CodeCache_lock->owned_by_self(), "Lock must be held");

  while (iteration_in_progress()) {

    CodeCache_lock->wait_without_safepoint_check();

  }

}

void ShenandoahNMethodTable::append(ShenandoahNMethod* snm) {

  if (is_full()) {

    int new_size = 2 * _size;

    ShenandoahNMethod** old_table = _array;

    // Rebuild table and replace current one

    rebuild(new_size);

    // An iteration is in progress over early snapshot,

    // can not release the array until iteration is completed

    if (!iteration_in_progress()) {

      FREE_C_HEAP_ARRAY(ShenandoahNMethod*, old_table);

    }

  }

  _array[_index ++] = snm;

  assert(_index >= 0 && _index <= _size, "Sanity");

}

void ShenandoahNMethodTable::rebuild(int size) {

  ShenandoahNMethod** arr = NEW_C_HEAP_ARRAY(ShenandoahNMethod*, size, mtGC);

  for (int index = 0; index < _index; index ++) {

      arr[index] = _array[index];

  }

  _array = arr;

  _size = size;

}

ShenandoahNMethodTableSnapshot* ShenandoahNMethodTable::snapshot_for_iteration() {

  assert(!iteration_in_progress(), "Already in progress");

  _iteration_in_progress = true;

  return new ShenandoahNMethodTableSnapshot(this);

}

void ShenandoahNMethodTable::finish_iteration(ShenandoahNMethodTableSnapshot* snapshot) {

  assert(iteration_in_progress(), "Why we here?");

  assert(snapshot != NULL, "No snapshot");

  _iteration_in_progress = false;

  // Table has been rebuilt during iteration, free old table

  if (snapshot->_array != _array) {

    FREE_C_HEAP_ARRAY(ShenandoahNMethod*, snapshot->_array);

  }

  delete snapshot;

}

void ShenandoahNMethodTable::log_register_nmethod(nmethod* nm) {

  LogTarget(Debug, gc, nmethod) log;

  if (!log.is_enabled()) {

    return;

  }

  ResourceMark rm;

  log.print("Register NMethod: %s.%s [" PTR_FORMAT "] (%s)",

            nm->method()->method_holder()->external_name(),

            nm->method()->name()->as_C_string(),

            p2i(nm),

            nm->compiler_name());

}

void ShenandoahNMethodTable::log_unregister_nmethod(nmethod* nm) {

  LogTarget(Debug, gc, nmethod) log;

  if (!log.is_enabled()) {

    return;

  }

  ResourceMark rm;

  log.print("Unregister NMethod: %s.%s [" PTR_FORMAT "]",

            nm->method()->method_holder()->external_name(),

            nm->method()->name()->as_C_string(),

            p2i(nm));

}

void ShenandoahNMethodTable::log_flush_nmethod(nmethod* nm) {

  LogTarget(Debug, gc, nmethod) log;

  if (!log.is_enabled()) {

    return;

  }

  ResourceMark rm;

  log.print("Flush NMethod: (" PTR_FORMAT ")", p2i(nm));

}

#ifdef ASSERT

void ShenandoahNMethodTable::assert_nmethods_alive_and_correct() {

  assert_locked_or_safepoint(CodeCache_lock);

  for (int index = 0; index < length(); index ++) {

    ShenandoahNMethod* m = _array[index];

    // Concurrent unloading may have dead nmethods to be cleaned by sweeper

    if (m->is_unregistered()) continue;

    m->assert_alive_and_correct();

  }

}

#endif

ShenandoahNMethodTableSnapshot::ShenandoahNMethodTableSnapshot(ShenandoahNMethodTable* table) :

  _heap(ShenandoahHeap::heap()), _table(table), _array(table->_array), _length(table->_index), _claimed(0) {

}

void ShenandoahNMethodTableSnapshot::concurrent_nmethods_do(NMethodClosure* cl) {

  size_t stride = 256; // educated guess

  ShenandoahNMethod** list = _array;

  size_t max = (size_t)_length;

  while (_claimed < max) {

    size_t cur = Atomic::add(&_claimed, stride) - stride;

    size_t start = cur;

    size_t end = MIN2(cur + stride, max);

    if (start >= max) break;

    for (size_t idx = start; idx < end; idx++) {

      ShenandoahNMethod* data = list[idx];

      assert(data != NULL, "Should not be NULL");

      if (!data->is_unregistered()) {

        cl->do_nmethod(data->nm());

      }

    }

  }

}

ShenandoahConcurrentNMethodIterator::ShenandoahConcurrentNMethodIterator(ShenandoahNMethodTable* table) :

  _table(table), _table_snapshot(NULL) {

}

void ShenandoahConcurrentNMethodIterator::nmethods_do_begin() {

  assert(CodeCache_lock->owned_by_self(), "Lock must be held");

  assert(ShenandoahConcurrentRoots::can_do_concurrent_class_unloading(),

         "Only for concurrent class unloading");

  _table_snapshot = _table->snapshot_for_iteration();

}

void ShenandoahConcurrentNMethodIterator::nmethods_do(NMethodClosure* cl) {

  assert(_table_snapshot != NULL, "Must first call nmethod_do_begin()");

  _table_snapshot->concurrent_nmethods_do(cl);

}

void ShenandoahConcurrentNMethodIterator::nmethods_do_end() {

  assert(CodeCache_lock->owned_by_self(), "Lock must be held");

  assert(ShenandoahConcurrentRoots::can_do_concurrent_class_unloading(),

         "Only for concurrent class unloading");

  _table->finish_iteration(_table_snapshot);

  CodeCache_lock->notify_all();

}