/*

 * Copyright (c) 2017, 2019, 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/relocInfo.hpp"

#include "code/nmethod.hpp"

#include "code/icBuffer.hpp"

#include "gc/shared/barrierSet.hpp"

#include "gc/shared/barrierSetNMethod.hpp"

#include "gc/z/zGlobals.hpp"

#include "gc/z/zHash.inline.hpp"

#include "gc/z/zLock.inline.hpp"

#include "gc/z/zNMethodData.hpp"

#include "gc/z/zNMethodTable.hpp"

#include "gc/z/zNMethodTableEntry.hpp"

#include "gc/z/zNMethodTableIteration.hpp"

#include "gc/z/zOopClosures.inline.hpp"

#include "gc/z/zSafeDelete.inline.hpp"

#include "gc/z/zTask.hpp"

#include "gc/z/zWorkers.hpp"

#include "logging/log.hpp"

#include "memory/allocation.hpp"

#include "memory/iterator.hpp"

#include "memory/resourceArea.hpp"

#include "runtime/atomic.hpp"

#include "utilities/debug.hpp"

ZNMethodTableEntry* ZNMethodTable::_table = NULL;

size_t ZNMethodTable::_size = 0;

size_t ZNMethodTable::_nregistered = 0;

size_t ZNMethodTable::_nunregistered = 0;

ZNMethodTableIteration ZNMethodTable::_iteration;

ZSafeDeleteNoLock<ZNMethodTableEntry[]> ZNMethodTable::_safe_delete;

size_t ZNMethodTable::first_index(const nmethod* nm, size_t size) {

  assert(is_power_of_2(size), "Invalid size");

  const size_t mask = size - 1;

  const size_t hash = ZHash::address_to_uint32((uintptr_t)nm);

  return hash & mask;

}

size_t ZNMethodTable::next_index(size_t prev_index, size_t size) {

  assert(is_power_of_2(size), "Invalid size");

  const size_t mask = size - 1;

  return (prev_index + 1) & mask;

}

bool ZNMethodTable::register_entry(ZNMethodTableEntry* table, size_t size, nmethod* nm) {

  const ZNMethodTableEntry entry(nm);

  size_t index = first_index(nm, size);

  for (;;) {

    const ZNMethodTableEntry table_entry = table[index];

    if (!table_entry.registered() && !table_entry.unregistered()) {

      // Insert new entry

      table[index] = entry;

      return true;

    }

    if (table_entry.registered() && table_entry.method() == nm) {

      // Replace existing entry

      table[index] = entry;

      return false;

    }

    index = next_index(index, size);

  }

}

void ZNMethodTable::unregister_entry(ZNMethodTableEntry* table, size_t size, nmethod* nm) {

  size_t index = first_index(nm, size);

  for (;;) {

    const ZNMethodTableEntry table_entry = table[index];

    assert(table_entry.registered() || table_entry.unregistered(), "Entry not found");

    if (table_entry.registered() && table_entry.method() == nm) {

      // Remove entry

      table[index] = ZNMethodTableEntry(true /* unregistered */);

      return;

    }

    index = next_index(index, size);

  }

}

void ZNMethodTable::rebuild(size_t new_size) {

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

  assert(is_power_of_2(new_size), "Invalid size");

  log_debug(gc, nmethod)("Rebuilding NMethod Table: "

                         SIZE_FORMAT "->" SIZE_FORMAT " entries, "

                         SIZE_FORMAT "(%.0f%%->%.0f%%) registered, "

                         SIZE_FORMAT "(%.0f%%->%.0f%%) unregistered",

                         _size, new_size,

                         _nregistered, percent_of(_nregistered, _size), percent_of(_nregistered, new_size),

                         _nunregistered, percent_of(_nunregistered, _size), 0.0);

  // Allocate new table

  ZNMethodTableEntry* const new_table = new ZNMethodTableEntry[new_size];

  // Transfer all registered entries

  for (size_t i = 0; i < _size; i++) {

    const ZNMethodTableEntry entry = _table[i];

    if (entry.registered()) {

      register_entry(new_table, new_size, entry.method());

    }

  }

  // Free old table

  _safe_delete(_table);

  // Install new table

  _table = new_table;

  _size = new_size;

  _nunregistered = 0;

}

void ZNMethodTable::rebuild_if_needed() {

  // The hash table uses linear probing. To avoid wasting memory while

  // at the same time maintaining good hash collision behavior we want

  // to keep the table occupancy between 30% and 70%. The table always

  // grows/shrinks by doubling/halving its size. Pruning of unregistered

  // entries is done by rebuilding the table with or without resizing it.

  const size_t min_size = 1024;

  const size_t shrink_threshold = _size * 0.30;

  const size_t prune_threshold = _size * 0.65;

  const size_t grow_threshold = _size * 0.70;

  if (_size == 0) {

    // Initialize table

    rebuild(min_size);

  } else if (_nregistered < shrink_threshold && _size > min_size) {

    // Shrink table

    rebuild(_size / 2);

  } else if (_nregistered + _nunregistered > grow_threshold) {

    // Prune or grow table

    if (_nregistered < prune_threshold) {

      // Prune table

      rebuild(_size);

    } else {

      // Grow table

      rebuild(_size * 2);

    }

  }

}

size_t ZNMethodTable::registered_nmethods() {

  return _nregistered;

}

size_t ZNMethodTable::unregistered_nmethods() {

  return _nunregistered;

}

void ZNMethodTable::register_nmethod(nmethod* nm) {

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

  // Grow/Shrink/Prune table if needed

  rebuild_if_needed();

  // Insert new entry

  if (register_entry(_table, _size, nm)) {

    // New entry registered. When register_entry() instead returns

    // false the nmethod was already in the table so we do not want

    // to increase number of registered entries in that case.

    _nregistered++;

  }

}

void ZNMethodTable::wait_until_iteration_done() {

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

  while (_iteration.in_progress()) {

    CodeCache_lock->wait_without_safepoint_check();

  }

}

void ZNMethodTable::unregister_nmethod(nmethod* nm) {

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

  // Remove entry

  unregister_entry(_table, _size, nm);

  _nunregistered++;

  _nregistered--;

}

void ZNMethodTable::nmethods_do_begin() {

  MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);

  // Do not allow the table to be deleted while iterating

  _safe_delete.enable_deferred_delete();

  // Prepare iteration

  _iteration.nmethods_do_begin(_table, _size);

}

void ZNMethodTable::nmethods_do_end() {

  MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);

  // Finish iteration

  _iteration.nmethods_do_end();

  // Allow the table to be deleted

  _safe_delete.disable_deferred_delete();

  // Notify iteration done

  CodeCache_lock->notify_all();

}

void ZNMethodTable::nmethods_do(NMethodClosure* cl) {

  _iteration.nmethods_do(cl);

}