1/* Copyright (c) 2010, Google Inc.
2 * All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions are
6 * met:
7 *
8 *     * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 *     * Redistributions in binary form must reproduce the above
11 * copyright notice, this list of conditions and the following disclaimer
12 * in the documentation and/or other materials provided with the
13 * distribution.
14 *     * Neither the name of Google Inc. nor the names of its
15 * contributors may be used to endorse or promote products derived from
16 * this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 *
30 * ---
31 * This file is an internal part spinlock.cc and once.cc
32 * It may not be used directly by code outside of //base.
33 */
34
35#ifndef BASE_SPINLOCK_INTERNAL_H_
36#define BASE_SPINLOCK_INTERNAL_H_
37
38#include <config.h>
39#include "base/basictypes.h"
40#include "base/atomicops.h"
41
42namespace base {
43namespace internal {
44
45// SpinLockWait() waits until it can perform one of several transitions from
46// "from" to "to".  It returns when it performs a transition where done==true.
47struct SpinLockWaitTransition {
48  int32 from;
49  int32 to;
50  bool done;
51};
52
53// Wait until *w can transition from trans[i].from to trans[i].to for some i
54// satisfying 0<=i<n && trans[i].done, atomically make the transition,
55// then return the old value of *w.   Make any other atomic tranistions
56// where !trans[i].done, but continue waiting.
57int32 SpinLockWait(volatile Atomic32 *w, int n,
58                   const SpinLockWaitTransition trans[]);
59void SpinLockWake(volatile Atomic32 *w, bool all);
60void SpinLockDelay(volatile Atomic32 *w, int32 value, int loop);
61
62} // namespace internal
63} // namespace base
64#endif
65