dtoa_wrapper.cc revision 201ade2fbba22bfb27ae029f4d23fca6ded109a0 
1// Copyright (c) 2010 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4//
5// The purpose of this file is to supply the macro definintions necessary
6// to make third_party/dmg_fp/dtoa.cc threadsafe.
7#include "base/lock.h"
8#include "base/logging.h"
9
10// We need two locks because they're sometimes grabbed at the same time.
11// A single lock would lead to an attempted recursive grab.
12static Lock dtoa_locks[2];
13
14/*
15 * This define and the code below is to trigger thread-safe behavior
16 * in dtoa.cc, per this comment from the file:
17 *
18 * #define MULTIPLE_THREADS if the system offers preemptively scheduled
19 *	multiple threads.  In this case, you must provide (or suitably
20 *	#define) two locks, acquired by ACQUIRE_DTOA_LOCK(n) and freed
21 *	by FREE_DTOA_LOCK(n) for n = 0 or 1.  (The second lock, accessed
22 *	in pow5mult, ensures lazy evaluation of only one copy of high
23 *	powers of 5; omitting this lock would introduce a small
24 *	probability of wasting memory, but would otherwise be harmless.)
25 *	You must also invoke freedtoa(s) to free the value s returned by
26 *	dtoa.  You may do so whether or not MULTIPLE_THREADS is #defined.
27 */
28#define MULTIPLE_THREADS
29
30inline static void ACQUIRE_DTOA_LOCK(size_t n) {
31  DCHECK(n < arraysize(dtoa_locks));
32  dtoa_locks[n].Acquire();
33}
34
35inline static void FREE_DTOA_LOCK(size_t n) {
36  DCHECK(n < arraysize(dtoa_locks));
37  dtoa_locks[n].Release();
38}
39
40#include "base/third_party/dmg_fp/dtoa.cc"
41