/*

 * Copyright (c) 2014, 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 "code/codeCache.hpp"

#include "code/nmethod.hpp"

#include "gc/g1/g1CodeCacheRemSet.hpp"

#include "gc/g1/heapRegion.hpp"

#include "memory/heap.hpp"

#include "memory/iterator.hpp"

#include "oops/oop.inline.hpp"

#include "utilities/hashtable.inline.hpp"

#include "utilities/stack.inline.hpp"

class CodeRootSetTable : public Hashtable<nmethod*, mtGC> {

  friend class G1CodeRootSetTest;

  typedef HashtableEntry<nmethod*, mtGC> Entry;

  static CodeRootSetTable* volatile _purge_list;

  CodeRootSetTable* _purge_next;

  unsigned int compute_hash(nmethod* nm) {

    uintptr_t hash = (uintptr_t)nm;

    return hash ^ (hash >> 7); // code heap blocks are 128byte aligned

  }

  void remove_entry(Entry* e, Entry* previous);

  Entry* new_entry(nmethod* nm);

 public:

  CodeRootSetTable(int size) : Hashtable<nmethod*, mtGC>(size, sizeof(Entry)), _purge_next(NULL) {}

  ~CodeRootSetTable();

  // Needs to be protected locks

  bool add(nmethod* nm);

  bool remove(nmethod* nm);

  // Can be called without locking

  bool contains(nmethod* nm);

  int entry_size() const { return BasicHashtable<mtGC>::entry_size(); }

  void copy_to(CodeRootSetTable* new_table);

  void nmethods_do(CodeBlobClosure* blk);

  template<typename CB>

  int remove_if(CB& should_remove);

  static void purge_list_append(CodeRootSetTable* tbl);

  static void purge();

  static size_t static_mem_size() {

    return sizeof(_purge_list);

  }

  size_t mem_size();

};

CodeRootSetTable* volatile CodeRootSetTable::_purge_list = NULL;

size_t CodeRootSetTable::mem_size() {

  return sizeof(CodeRootSetTable) + (entry_size() * number_of_entries()) + (sizeof(HashtableBucket<mtGC>) * table_size());

}

CodeRootSetTable::Entry* CodeRootSetTable::new_entry(nmethod* nm) {

  unsigned int hash = compute_hash(nm);

  Entry* entry = (Entry*) new_entry_free_list();

  if (entry == NULL) {

    entry = (Entry*) NEW_C_HEAP_ARRAY2(char, entry_size(), mtGC, CURRENT_PC);

  }

  entry->set_next(NULL);

  entry->set_hash(hash);

  entry->set_literal(nm);

  return entry;

}

void CodeRootSetTable::remove_entry(Entry* e, Entry* previous) {

  int index = hash_to_index(e->hash());

  assert((e == bucket(index)) == (previous == NULL), "if e is the first entry then previous should be null");

  if (previous == NULL) {

    set_entry(index, e->next());

  } else {

    previous->set_next(e->next());

  }

  free_entry(e);

}

CodeRootSetTable::~CodeRootSetTable() {

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

    for (Entry* e = bucket(index); e != NULL; ) {

      Entry* to_remove = e;

      // read next before freeing.

      e = e->next();

      unlink_entry(to_remove);

      FREE_C_HEAP_ARRAY(char, to_remove);

    }

  }

  assert(number_of_entries() == 0, "should have removed all entries");

  free_buckets();

  for (BasicHashtableEntry<mtGC>* e = new_entry_free_list(); e != NULL; e = new_entry_free_list()) {

    FREE_C_HEAP_ARRAY(char, e);

  }

}

bool CodeRootSetTable::add(nmethod* nm) {

  if (!contains(nm)) {

    Entry* e = new_entry(nm);

    int index = hash_to_index(e->hash());

    add_entry(index, e);

    return true;

  }

  return false;

}

bool CodeRootSetTable::contains(nmethod* nm) {

  int index = hash_to_index(compute_hash(nm));

  for (Entry* e = bucket(index); e != NULL; e = e->next()) {

    if (e->literal() == nm) {

      return true;

    }

  }

  return false;

}

bool CodeRootSetTable::remove(nmethod* nm) {

  int index = hash_to_index(compute_hash(nm));

  Entry* previous = NULL;

  for (Entry* e = bucket(index); e != NULL; previous = e, e = e->next()) {

    if (e->literal() == nm) {

      remove_entry(e, previous);

      return true;

    }

  }

  return false;

}

void CodeRootSetTable::copy_to(CodeRootSetTable* new_table) {

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

    for (Entry* e = bucket(index); e != NULL; e = e->next()) {

      new_table->add(e->literal());

    }

  }

  new_table->copy_freelist(this);

}

void CodeRootSetTable::nmethods_do(CodeBlobClosure* blk) {

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

    for (Entry* e = bucket(index); e != NULL; e = e->next()) {

      blk->do_code_blob(e->literal());

    }

  }

}

template<typename CB>

int CodeRootSetTable::remove_if(CB& should_remove) {

  int num_removed = 0;

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

    Entry* previous = NULL;

    Entry* e = bucket(index);

    while (e != NULL) {

      Entry* next = e->next();

      if (should_remove(e->literal())) {

        remove_entry(e, previous);

        ++num_removed;

      } else {

        previous = e;

      }

      e = next;

    }

  }

  return num_removed;

}

G1CodeRootSet::~G1CodeRootSet() {

  delete _table;

}

CodeRootSetTable* G1CodeRootSet::load_acquire_table() {

  return (CodeRootSetTable*) OrderAccess::load_ptr_acquire(&_table);

}

void G1CodeRootSet::allocate_small_table() {

  CodeRootSetTable* temp = new CodeRootSetTable(SmallSize);

  OrderAccess::release_store_ptr(&_table, temp);

}

void CodeRootSetTable::purge_list_append(CodeRootSetTable* table) {

  for (;;) {

    table->_purge_next = _purge_list;

    CodeRootSetTable* old = (CodeRootSetTable*) Atomic::cmpxchg_ptr(table, &_purge_list, table->_purge_next);

    if (old == table->_purge_next) {

      break;

    }

  }

}

void CodeRootSetTable::purge() {

  CodeRootSetTable* table = _purge_list;

  _purge_list = NULL;

  while (table != NULL) {

    CodeRootSetTable* to_purge = table;

    table = table->_purge_next;

    delete to_purge;

  }

}

void G1CodeRootSet::move_to_large() {

  CodeRootSetTable* temp = new CodeRootSetTable(LargeSize);

  _table->copy_to(temp);

  CodeRootSetTable::purge_list_append(_table);

  OrderAccess::release_store_ptr(&_table, temp);

}

void G1CodeRootSet::purge() {

  CodeRootSetTable::purge();

}

size_t G1CodeRootSet::static_mem_size() {

  return CodeRootSetTable::static_mem_size();

}

void G1CodeRootSet::add(nmethod* method) {

  bool added = false;

  if (is_empty()) {

    allocate_small_table();

  }

  added = _table->add(method);

  if (added) {

    if (_length == Threshold) {

      move_to_large();

    }

    ++_length;

  }

  assert(_length == (size_t)_table->number_of_entries(), "sizes should match");

}

bool G1CodeRootSet::remove(nmethod* method) {

  bool removed = false;

  if (_table != NULL) {

    removed = _table->remove(method);

  }

  if (removed) {

    _length--;

    if (_length == 0) {

      clear();

    }

  }

  assert((_length == 0 && _table == NULL) ||

         (_length == (size_t)_table->number_of_entries()), "sizes should match");

  return removed;

}

bool G1CodeRootSet::contains(nmethod* method) {

  CodeRootSetTable* table = load_acquire_table(); // contains() may be called outside of lock, so ensure mem sync.

  if (table != NULL) {

    return table->contains(method);

  }

  return false;

}

void G1CodeRootSet::clear() {

  delete _table;

  _table = NULL;

  _length = 0;

}

size_t G1CodeRootSet::mem_size() {

  return sizeof(*this) + (_table != NULL ? _table->mem_size() : 0);

}

void G1CodeRootSet::nmethods_do(CodeBlobClosure* blk) const {

  if (_table != NULL) {

    _table->nmethods_do(blk);

  }

}

class CleanCallback : public StackObj {

  class PointsIntoHRDetectionClosure : public OopClosure {

    HeapRegion* _hr;

   public:

    bool _points_into;

    PointsIntoHRDetectionClosure(HeapRegion* hr) : _hr(hr), _points_into(false) {}

    void do_oop(narrowOop* o) {

      do_oop_work(o);

    }

    void do_oop(oop* o) {

      do_oop_work(o);

    }

    template <typename T>

    void do_oop_work(T* p) {

      if (_hr->is_in(oopDesc::load_decode_heap_oop(p))) {

        _points_into = true;

      }

    }

  };

  PointsIntoHRDetectionClosure _detector;

  CodeBlobToOopClosure _blobs;

 public:

  CleanCallback(HeapRegion* hr) : _detector(hr), _blobs(&_detector, !CodeBlobToOopClosure::FixRelocations) {}

  bool operator() (nmethod* nm) {

    _detector._points_into = false;

    _blobs.do_code_blob(nm);

    return !_detector._points_into;

  }

};

void G1CodeRootSet::clean(HeapRegion* owner) {

  CleanCallback should_clean(owner);

  if (_table != NULL) {

    int removed = _table->remove_if(should_clean);

    assert((size_t)removed <= _length, "impossible");

    _length -= removed;

  }

  if (_length == 0) {

    clear();

  }

}

#ifndef PRODUCT

class G1CodeRootSetTest {

 public:

  static void test() {

    {

      G1CodeRootSet set1;

      assert(set1.is_empty(), "Code root set must be initially empty but is not.");

      assert(G1CodeRootSet::static_mem_size() == sizeof(void*),

             "The code root set's static memory usage is incorrect, " SIZE_FORMAT " bytes", G1CodeRootSet::static_mem_size());

      set1.add((nmethod*)1);

      assert(set1.length() == 1, "Added exactly one element, but set contains "

             SIZE_FORMAT " elements", set1.length());

      const size_t num_to_add = (size_t)G1CodeRootSet::Threshold + 1;

      for (size_t i = 1; i <= num_to_add; i++) {

        set1.add((nmethod*)1);

      }

      assert(set1.length() == 1,

             "Duplicate detection should not have increased the set size but "

             "is " SIZE_FORMAT, set1.length());

      for (size_t i = 2; i <= num_to_add; i++) {

        set1.add((nmethod*)(uintptr_t)(i));

      }

      assert(set1.length() == num_to_add,

             "After adding in total " SIZE_FORMAT " distinct code roots, they "

             "need to be in the set, but there are only " SIZE_FORMAT,

             num_to_add, set1.length());

      assert(CodeRootSetTable::_purge_list != NULL, "should have grown to large hashtable");

      size_t num_popped = 0;

      for (size_t i = 1; i <= num_to_add; i++) {

        bool removed = set1.remove((nmethod*)i);

        if (removed) {

          num_popped += 1;

        } else {

          break;

        }

      }

      assert(num_popped == num_to_add,

             "Managed to pop " SIZE_FORMAT " code roots, but only " SIZE_FORMAT " "

             "were added", num_popped, num_to_add);

      assert(CodeRootSetTable::_purge_list != NULL, "should have grown to large hashtable");

      G1CodeRootSet::purge();

      assert(CodeRootSetTable::_purge_list == NULL, "should have purged old small tables");

    }

  }

};

void TestCodeCacheRemSet_test() {

  G1CodeRootSetTest::test();

}

#endif