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1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 // | 4 // |
5 // The purpose of this file is to supply the macro definintions necessary | 5 // The purpose of this file is to supply the macro definintions necessary |
6 // to make third_party/dmg_fp/dtoa.cc threadsafe. | 6 // to make third_party/dmg_fp/dtoa.cc threadsafe. |
7 #include "base/lazy_instance.h" | 7 #include "base/lazy_instance.h" |
8 #include "base/logging.h" | 8 #include "base/logging.h" |
9 #include "base/synchronization/lock.h" | 9 #include "base/synchronization/lock.h" |
10 | 10 |
11 // We need two locks because they're sometimes grabbed at the same time. | 11 // We need two locks because they're sometimes grabbed at the same time. |
12 // A single lock would lead to an attempted recursive grab. | 12 // A single lock would lead to an attempted recursive grab. |
13 static base::LazyInstance<base::Lock, | 13 static base::LazyInstance<base::Lock>::Leaky |
14 base::LeakyLazyInstanceTraits<base::Lock> > | |
15 dtoa_lock_0 = LAZY_INSTANCE_INITIALIZER; | 14 dtoa_lock_0 = LAZY_INSTANCE_INITIALIZER; |
16 static base::LazyInstance<base::Lock, | 15 static base::LazyInstance<base::Lock>::Leaky |
17 base::LeakyLazyInstanceTraits<base::Lock> > | |
18 dtoa_lock_1 = LAZY_INSTANCE_INITIALIZER; | 16 dtoa_lock_1 = LAZY_INSTANCE_INITIALIZER; |
19 | 17 |
20 /* | 18 /* |
21 * This define and the code below is to trigger thread-safe behavior | 19 * This define and the code below is to trigger thread-safe behavior |
22 * in dtoa.cc, per this comment from the file: | 20 * in dtoa.cc, per this comment from the file: |
23 * | 21 * |
24 * #define MULTIPLE_THREADS if the system offers preemptively scheduled | 22 * #define MULTIPLE_THREADS if the system offers preemptively scheduled |
25 * multiple threads. In this case, you must provide (or suitably | 23 * multiple threads. In this case, you must provide (or suitably |
26 * #define) two locks, acquired by ACQUIRE_DTOA_LOCK(n) and freed | 24 * #define) two locks, acquired by ACQUIRE_DTOA_LOCK(n) and freed |
27 * by FREE_DTOA_LOCK(n) for n = 0 or 1. (The second lock, accessed | 25 * by FREE_DTOA_LOCK(n) for n = 0 or 1. (The second lock, accessed |
28 * in pow5mult, ensures lazy evaluation of only one copy of high | 26 * in pow5mult, ensures lazy evaluation of only one copy of high |
29 * powers of 5; omitting this lock would introduce a small | 27 * powers of 5; omitting this lock would introduce a small |
30 * probability of wasting memory, but would otherwise be harmless.) | 28 * probability of wasting memory, but would otherwise be harmless.) |
31 * You must also invoke freedtoa(s) to free the value s returned by | 29 * You must also invoke freedtoa(s) to free the value s returned by |
32 * dtoa. You may do so whether or not MULTIPLE_THREADS is #defined. | 30 * dtoa. You may do so whether or not MULTIPLE_THREADS is #defined. |
33 */ | 31 */ |
34 #define MULTIPLE_THREADS | 32 #define MULTIPLE_THREADS |
35 | 33 |
36 inline static void ACQUIRE_DTOA_LOCK(size_t n) { | 34 inline static void ACQUIRE_DTOA_LOCK(size_t n) { |
37 DCHECK(n < 2); | 35 DCHECK(n < 2); |
38 base::Lock* lock = n == 0 ? dtoa_lock_0.Pointer() : dtoa_lock_1.Pointer(); | 36 base::Lock* lock = n == 0 ? dtoa_lock_0.Pointer() : dtoa_lock_1.Pointer(); |
39 lock->Acquire(); | 37 lock->Acquire(); |
40 } | 38 } |
41 | 39 |
42 inline static void FREE_DTOA_LOCK(size_t n) { | 40 inline static void FREE_DTOA_LOCK(size_t n) { |
43 DCHECK(n < 2); | 41 DCHECK(n < 2); |
44 base::Lock* lock = n == 0 ? dtoa_lock_0.Pointer() : dtoa_lock_1.Pointer(); | 42 base::Lock* lock = n == 0 ? dtoa_lock_0.Pointer() : dtoa_lock_1.Pointer(); |
45 lock->Release(); | 43 lock->Release(); |
46 } | 44 } |
47 | 45 |
48 #include "base/third_party/dmg_fp/dtoa.cc" | 46 #include "base/third_party/dmg_fp/dtoa.cc" |
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