doubly-linked free-lists for thread caches and page heaps

third_party/tcmalloc/chromium/src/linked_list.h

-// Copyright (c) 2008, Google Inc.
-// All rights reserved.
-//
-// Redistribution and use in source and binary forms, with or without
-// modification, are permitted provided that the following conditions are
-// met:
-//
-//     * Redistributions of source code must retain the above copyright
-// notice, this list of conditions and the following disclaimer.
-//     * Redistributions in binary form must reproduce the above
-// copyright notice, this list of conditions and the following disclaimer
-// in the documentation and/or other materials provided with the
-// distribution.
-//     * Neither the name of Google Inc. nor the names of its
-// contributors may be used to endorse or promote products derived from
-// this software without specific prior written permission.
-//
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-// ---
-// Author: Sanjay Ghemawat <opensource@google.com>
-//
-// Some very basic linked list functions for dealing with using void * as
-// storage.
-
-#ifndef TCMALLOC_LINKED_LIST_H_
-#define TCMALLOC_LINKED_LIST_H_
-
-#include <stddef.h>
-
-namespace tcmalloc {
-
-inline void *SLL_Next(void *t) {
-  return *(reinterpret_cast<void**>(t));
-}
-
-inline void SLL_SetNext(void *t, void *n) {
-  *(reinterpret_cast<void**>(t)) = n;
-}
-
-inline void SLL_Push(void **list, void *element) {
-  SLL_SetNext(element, *list);
-  *list = element;
-}
-
-inline void *SLL_Pop(void **list) {
-  void *result = *list;
-  *list = SLL_Next(*list);
-  return result;
-}
-
-// Remove N elements from a linked list to which head points.  head will be
-// modified to point to the new head.  start and end will point to the first
-// and last nodes of the range.  Note that end will point to NULL after this
-// function is called.
-inline void SLL_PopRange(void **head, int N, void **start, void **end) {
-  if (N == 0) {
-    *start = NULL;
-    *end = NULL;
-    return;
-  }
-
-  void *tmp = *head;
-  for (int i = 1; i < N; ++i) {
-    tmp = SLL_Next(tmp);
-  }
-
-  *start = *head;
-  *end = tmp;
-  *head = SLL_Next(tmp);
-  // Unlink range from list.
-  SLL_SetNext(tmp, NULL);
-}
-
-inline void SLL_PushRange(void **head, void *start, void *end) {
-  if (!start) return;
-  SLL_SetNext(end, *head);
-  *head = start;
-}
-
-inline size_t SLL_Size(void *head) {
-  int count = 0;
-  while (head) {
-    count++;
-    head = SLL_Next(head);
-  }
-  return count;
-}
-
-}  // namespace tcmalloc
-
-#endif  // TCMALLOC_LINKED_LIST_H_