JDK14/Java14源码在线阅读

/*
 * Copyright (c) 2014, 2017, 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 "services/mallocSiteTable.hpp"
#include "services/mallocTracker.hpp"
#include "services/mallocTracker.inline.hpp"
#include "services/memTracker.hpp"

size_t MallocMemorySummary::_snapshot[CALC_OBJ_SIZE_IN_TYPE(MallocMemorySnapshot, size_t)];

// Total malloc'd memory amount
size_t MallocMemorySnapshot::total() const {
  size_t amount = 0;
  for (int index = 0; index < mt_number_of_types; index ++) {
    amount += _malloc[index].malloc_size();
  }
  amount += _tracking_header.size() + total_arena();
  return amount;
}

// Total malloc'd memory used by arenas
size_t MallocMemorySnapshot::total_arena() const {
  size_t amount = 0;
  for (int index = 0; index < mt_number_of_types; index ++) {
    amount += _malloc[index].arena_size();
  }
  return amount;
}

// Make adjustment by subtracting chunks used by arenas
// from total chunks to get total free chunk size
void MallocMemorySnapshot::make_adjustment() {
  size_t arena_size = total_arena();
  int chunk_idx = NMTUtil::flag_to_index(mtChunk);
  _malloc[chunk_idx].record_free(arena_size);
}


void MallocMemorySummary::initialize() {
  assert(sizeof(_snapshot) >= sizeof(MallocMemorySnapshot), "Sanity Check");
  // Uses placement new operator to initialize static area.
  ::new ((void*)_snapshot)MallocMemorySnapshot();
}

void MallocHeader::release() const {
  // Tracking already shutdown, no housekeeping is needed anymore
  if (MemTracker::tracking_level() <= NMT_minimal) return;

  MallocMemorySummary::record_free(size(), flags());
  MallocMemorySummary::record_free_malloc_header(sizeof(MallocHeader));
  if (MemTracker::tracking_level() == NMT_detail) {
    MallocSiteTable::deallocation_at(size(), _bucket_idx, _pos_idx);
  }
}

bool MallocHeader::record_malloc_site(const NativeCallStack& stack, size_t size,
  size_t* bucket_idx, size_t* pos_idx, MEMFLAGS flags) const {
  bool ret = MallocSiteTable::allocation_at(stack, size, bucket_idx, pos_idx, flags);

  // Something went wrong, could be OOM or overflow malloc site table.
  // We want to keep tracking data under OOM circumstance, so transition to
  // summary tracking.
  if (!ret) {
    MemTracker::transition_to(NMT_summary);
  }
  return ret;
}

bool MallocHeader::get_stack(NativeCallStack& stack) const {
  return MallocSiteTable::access_stack(stack, _bucket_idx, _pos_idx);
}

bool MallocTracker::initialize(NMT_TrackingLevel level) {
  if (level >= NMT_summary) {
    MallocMemorySummary::initialize();
  }

  if (level == NMT_detail) {
    return MallocSiteTable::initialize();
  }
  return true;
}

bool MallocTracker::transition(NMT_TrackingLevel from, NMT_TrackingLevel to) {
  assert(from != NMT_off, "Can not transition from off state");
  assert(to != NMT_off, "Can not transition to off state");
  assert (from != NMT_minimal, "cannot transition from minimal state");

  if (from == NMT_detail) {
    assert(to == NMT_minimal || to == NMT_summary, "Just check");
    MallocSiteTable::shutdown();
  }
  return true;
}

// Record a malloc memory allocation
void* MallocTracker::record_malloc(void* malloc_base, size_t size, MEMFLAGS flags,
  const NativeCallStack& stack, NMT_TrackingLevel level) {
  assert(level != NMT_off, "precondition");
  void*         memblock;      // the address for user data
  MallocHeader* header = NULL;

  if (malloc_base == NULL) {
    return NULL;
  }

  // Uses placement global new operator to initialize malloc header

  header = ::new (malloc_base)MallocHeader(size, flags, stack, level);
  memblock = (void*)((char*)malloc_base + sizeof(MallocHeader));

  // The alignment check: 8 bytes alignment for 32 bit systems.

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