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/synchronization/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.
12 static base::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
ACQUIRE_DTOA_LOCK(size_t n)30 inline static void ACQUIRE_DTOA_LOCK(size_t n) {
31 DCHECK(n < arraysize(dtoa_locks));
32 dtoa_locks[n].Acquire();
33 }
34
FREE_DTOA_LOCK(size_t n)35 inline 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