/*

 * Copyright (c) 2017, 2018, 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/nativeInst.hpp"

#include "code/nmethod.hpp"

#include "gc/z/zGlobals.hpp"

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

#include "gc/z/zNMethodTable.hpp"

#include "logging/log.hpp"

#include "memory/allocation.inline.hpp"

#include "memory/resourceArea.hpp"

#include "oops/oop.inline.hpp"

#include "runtime/atomic.hpp"

#include "utilities/debug.hpp"

class ZNMethodWithImmediateOops {

private:

  nmethod* const _nm;

  const size_t   _nimmediate_oops;

  static size_t header_size();

  ZNMethodWithImmediateOops(nmethod* nm, const GrowableArray<oop*>& immediate_oops);

public:

  static ZNMethodWithImmediateOops* create(nmethod* nm, const GrowableArray<oop*>& immediate_oops);

  static void destroy(ZNMethodWithImmediateOops* nmi);

  nmethod* method() const;

  size_t immediate_oops_count() const;

  oop** immediate_oops_begin() const;

  oop** immediate_oops_end() const;

};

size_t ZNMethodWithImmediateOops::header_size() {

  const size_t size = sizeof(ZNMethodWithImmediateOops);

  assert(is_aligned(size, sizeof(oop*)), "Header misaligned");

  return size;

}

ZNMethodWithImmediateOops::ZNMethodWithImmediateOops(nmethod* nm, const GrowableArray<oop*>& immediate_oops) :

    _nm(nm),

    _nimmediate_oops(immediate_oops.length()) {

  // Save all immediate oops

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

    immediate_oops_begin()[i] = immediate_oops.at(i);

  }

}

ZNMethodWithImmediateOops* ZNMethodWithImmediateOops::create(nmethod* nm, const GrowableArray<oop*>& immediate_oops) {

  // Allocate memory for the ZNMethodWithImmediateOops object

  // plus the immediate oop* array that follows right after.

  const size_t size = header_size() + (sizeof(oop*) * immediate_oops.length());

  void* const method_with_immediate_oops = NEW_C_HEAP_ARRAY(uint8_t, size, mtGC);

  return ::new (method_with_immediate_oops) ZNMethodWithImmediateOops(nm, immediate_oops);

}

void ZNMethodWithImmediateOops::destroy(ZNMethodWithImmediateOops* nmi) {

  FREE_C_HEAP_ARRAY(uint8_t, nmi);

}

nmethod* ZNMethodWithImmediateOops::method() const {

  return _nm;

}

size_t ZNMethodWithImmediateOops::immediate_oops_count() const {

  return _nimmediate_oops;

}

oop** ZNMethodWithImmediateOops::immediate_oops_begin() const {

  // The immediate oop* array starts immediately after this object

  return (oop**)((uintptr_t)this + header_size());

}

oop** ZNMethodWithImmediateOops::immediate_oops_end() const {

  return immediate_oops_begin() + immediate_oops_count();

}

ZNMethodTableEntry* ZNMethodTable::_table = NULL;

size_t ZNMethodTable::_size = 0;

size_t ZNMethodTable::_nregistered = 0;

size_t ZNMethodTable::_nunregistered = 0;

volatile size_t ZNMethodTable::_claimed = 0;

ZNMethodTableEntry ZNMethodTable::create_entry(nmethod* nm) {

  GrowableArray<oop*> immediate_oops;

  bool non_immediate_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

      non_immediate_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.

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

    }

  }

  // oops_count() returns the number of oops in the oop table plus one

  if (immediate_oops.is_empty() && nm->oops_count() == 1) {

    // No oops found, return empty entry

    return ZNMethodTableEntry();

  }

  if (immediate_oops.is_empty()) {

    // No immediate oops found, return entry without immediate oops

    return ZNMethodTableEntry(nm, non_immediate_oops);

  }

  // Return entry with immediate oops

  return ZNMethodTableEntry(ZNMethodWithImmediateOops::create(nm, immediate_oops), non_immediate_oops);

}

void ZNMethodTable::destroy_entry(ZNMethodTableEntry entry) {

  if (entry.immediate_oops()) {

    ZNMethodWithImmediateOops::destroy(entry.method_with_immediate_oops());

  }

}

nmethod* ZNMethodTable::method(ZNMethodTableEntry entry) {

  return entry.immediate_oops() ? entry.method_with_immediate_oops()->method() : entry.method();

}

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, ZNMethodTableEntry entry) {

  const nmethod* const nm = method(entry);

  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() && method(table_entry) == nm) {

      // Replace existing entry

      destroy_entry(table_entry);

      table[index] = entry;

      return false;

    }

    index = next_index(index, size);

  }

}

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

  if (size == 0) {

    // Table is empty

    return false;

  }

  size_t index = first_index(nm, size);

  for (;;) {

    const ZNMethodTableEntry table_entry = table[index];

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

      // Entry not found

      return false;

    }

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

      // Remove entry

      destroy_entry(table_entry);

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

      return true;

    }

    index = next_index(index, size);

  }

}

void ZNMethodTable::rebuild(size_t new_size) {

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

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

                         SIZE_FORMAT "->" SIZE_FORMAT " entries, "

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

                         SIZE_FORMAT "(%.0lf%%->%.0lf%%) 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);

    }

  }

  // Delete old table

  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);

    }

  }

}

void ZNMethodTable::log_register(const nmethod* nm, ZNMethodTableEntry entry) {

  LogTarget(Trace, gc, nmethod) log;

  if (!log.is_enabled()) {

    return;

  }

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

            "Compiler: %s, Oops: %d, ImmediateOops: " SIZE_FORMAT ", NonImmediateOops: %s",

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

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

            p2i(nm),

            nm->compiler_name(),

            nm->oops_count() - 1,

            entry.immediate_oops() ? entry.method_with_immediate_oops()->immediate_oops_count() : 0,

            BOOL_TO_STR(entry.non_immediate_oops()));

  LogTarget(Trace, gc, nmethod, oops) log_oops;

  if (!log_oops.is_enabled()) {

    return;

  }

  // Print nmethod oops table

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

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

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

    log_oops.print("           Oop[" SIZE_FORMAT "] " PTR_FORMAT " (%s)",

                   (p - begin), p2i(*p), (*p)->klass()->external_name());

  }

  if (entry.immediate_oops()) {

    // Print nmethod immediate oops

    const ZNMethodWithImmediateOops* const nmi = entry.method_with_immediate_oops();

    oop** const begin = nmi->immediate_oops_begin();

    oop** const end = nmi->immediate_oops_end();

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

      log_oops.print("  ImmediateOop[" SIZE_FORMAT "] " PTR_FORMAT " @ " PTR_FORMAT " (%s)",

                     (p - begin), p2i(**p), p2i(*p), (**p)->klass()->external_name());

    }

  }

}

void ZNMethodTable::log_unregister(const nmethod* nm) {

  LogTarget(Debug, gc, nmethod) log;

  if (!log.is_enabled()) {

    return;

  }

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

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

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

            p2i(nm));

}

size_t ZNMethodTable::registered_nmethods() {

  return _nregistered;

}

size_t ZNMethodTable::unregistered_nmethods() {

  return _nunregistered;

}

void ZNMethodTable::register_nmethod(nmethod* nm) {

  ResourceMark rm;

  // Create entry

  const ZNMethodTableEntry entry = create_entry(nm);

  log_register(nm, entry);

  if (!entry.registered()) {

    // Method doesn't have any oops, ignore it

    return;

  }

  // Grow/Shrink/Prune table if needed

  rebuild_if_needed();

  // Insert new entry

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

    // 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::unregister_nmethod(nmethod* nm) {

  ResourceMark rm;

  log_unregister(nm);

  // Remove entry

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

    // Entry was unregistered. When unregister_entry() instead returns

    // false the nmethod was not in the table (because it didn't have

    // any oops) so we do not want to decrease the number of registered

    // entries in that case.

    _nregistered--;

    _nunregistered++;

  }

}

void ZNMethodTable::gc_prologue() {

  _claimed = 0;

}

void ZNMethodTable::gc_epilogue() {

  assert(_claimed >= _size, "Failed to claim all table entries");

}

void ZNMethodTable::entry_oops_do(ZNMethodTableEntry entry, OopClosure* cl) {

  nmethod* const nm = method(entry);

  if (!nm->is_alive()) {

    // No need to visit oops

    return;

  }

  // Process oops table

  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()) {

      cl->do_oop(p);

    }

  }

  if (entry.immediate_oops()) {

    // Process immediate oops

    const ZNMethodWithImmediateOops* const nmi = entry.method_with_immediate_oops();

    oop** const end = nmi->immediate_oops_end();

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

      cl->do_oop(*p);

    }

  }

  if (entry.non_immediate_oops()) {

    // Process non-immediate oops

    nm->fix_oop_relocations();

  }

}

void ZNMethodTable::oops_do(OopClosure* cl) {

  for (;;) {

    // Claim table partition. Each partition is currently sized to span

    // two cache lines. This number is just a guess, but seems to work well.

    const size_t partition_size = (ZCacheLineSize * 2) / sizeof(ZNMethodTableEntry);

    const size_t partition_start = MIN2(Atomic::add(partition_size, &_claimed) - partition_size, _size);

    const size_t partition_end = MIN2(partition_start + partition_size, _size);

    if (partition_start == partition_end) {

      // End of table

      break;

    }

    // Process table partition

    for (size_t i = partition_start; i < partition_end; i++) {

      const ZNMethodTableEntry entry = _table[i];

      if (entry.registered()) {

        entry_oops_do(entry, cl);

      }

    }

  }

}