Chromium Code Reviews
chromiumcodereview-hr@appspot.gserviceaccount.com (chromiumcodereview-hr) | Please choose your nickname with Settings | Help | Chromium Project | Gerrit Changes | Sign out
(267)

Side by Side Diff: base/atomic_ref_count.h

Issue 16554: WaitableEvent (Closed)
Patch Set: Addresssing darin's comments (round 2) Created 11 years, 11 months ago
Use n/p to move between diff chunks; N/P to move between comments. Draft comments are only viewable by you.
Jump to:
View unified diff | Download patch
« no previous file with comments | « no previous file | base/base_lib.scons » ('j') | no next file with comments »
Toggle Intra-line Diffs ('i') | Expand Comments ('e') | Collapse Comments ('c') | Show Comments Hide Comments ('s')
OLDNEW
1 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved. 1 // Copyright (c) 2006-2008 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 // This is a low level implementation of atomic semantics for reference 5 // This is a low level implementation of atomic semantics for reference
6 // counting. Please use base/ref_counted.h directly instead. 6 // counting. Please use base/ref_counted.h directly instead.
7 7
8 #ifndef BASE_ATOMIC_REF_COUNT_H_ 8 #ifndef BASE_ATOMIC_REF_COUNT_H_
9 #define BASE_ATOMIC_REF_COUNT_H_ 9 #define BASE_ATOMIC_REF_COUNT_H_
10 10
11 #include "base/atomicops.h" 11 #include "base/atomicops.h"
12 #include "base/basictypes.h" 12 #include "base/basictypes.h"
13 13
14 namespace base { 14 namespace base {
15 15
16 typedef base::subtle::Atomic32 AtomicRefCount; 16 typedef subtle::Atomic32 AtomicRefCount;
17 17
18 // Increment a reference count by "increment", which must exceed 0. 18 // Increment a reference count by "increment", which must exceed 0.
19 inline void AtomicRefCountIncN(volatile AtomicRefCount *ptr, 19 inline void AtomicRefCountIncN(volatile AtomicRefCount *ptr,
20 AtomicRefCount increment) { 20 AtomicRefCount increment) {
21 base::subtle::NoBarrier_AtomicIncrement(ptr, increment); 21 subtle::NoBarrier_AtomicIncrement(ptr, increment);
22 } 22 }
23 23
24 // Decrement a reference count by "decrement", which must exceed 0, 24 // Decrement a reference count by "decrement", which must exceed 0,
25 // and return whether the result is non-zero. 25 // and return whether the result is non-zero.
26 // Insert barriers to ensure that state written before the reference count 26 // Insert barriers to ensure that state written before the reference count
27 // became zero will be visible to a thread that has just made the count zero. 27 // became zero will be visible to a thread that has just made the count zero.
28 inline bool AtomicRefCountDecN(volatile AtomicRefCount *ptr, 28 inline bool AtomicRefCountDecN(volatile AtomicRefCount *ptr,
29 AtomicRefCount decrement) { 29 AtomicRefCount decrement) {
30 return base::subtle::Barrier_AtomicIncrement(ptr, -decrement) != 0; 30 return subtle::Barrier_AtomicIncrement(ptr, -decrement) != 0;
31 } 31 }
32 32
33 // Increment a reference count by 1. 33 // Increment a reference count by 1.
34 inline void AtomicRefCountInc(volatile AtomicRefCount *ptr) { 34 inline void AtomicRefCountInc(volatile AtomicRefCount *ptr) {
35 base::AtomicRefCountIncN(ptr, 1); 35 base::AtomicRefCountIncN(ptr, 1);
36 } 36 }
37 37
38 // Decrement a reference count by 1 and return whether the result is non-zero. 38 // Decrement a reference count by 1 and return whether the result is non-zero.
39 // Insert barriers to ensure that state written before the reference count 39 // Insert barriers to ensure that state written before the reference count
40 // became zero will be visible to a thread that has just made the count zero. 40 // became zero will be visible to a thread that has just made the count zero.
41 inline bool AtomicRefCountDec(volatile AtomicRefCount *ptr) { 41 inline bool AtomicRefCountDec(volatile AtomicRefCount *ptr) {
42 return base::AtomicRefCountDecN(ptr, 1); 42 return base::AtomicRefCountDecN(ptr, 1);
43 } 43 }
44 44
45 // Return whether the reference count is one. If the reference count is used 45 // Return whether the reference count is one. If the reference count is used
46 // in the conventional way, a refrerence count of 1 implies that the current 46 // in the conventional way, a refrerence count of 1 implies that the current
47 // thread owns the reference and no other thread shares it. This call performs 47 // thread owns the reference and no other thread shares it. This call performs
48 // the test for a reference count of one, and performs the memory barrier 48 // the test for a reference count of one, and performs the memory barrier
49 // needed for the owning thread to act on the object, knowing that it has 49 // needed for the owning thread to act on the object, knowing that it has
50 // exclusive access to the object. 50 // exclusive access to the object.
51 inline bool AtomicRefCountIsOne(volatile AtomicRefCount *ptr) { 51 inline bool AtomicRefCountIsOne(volatile AtomicRefCount *ptr) {
52 return base::subtle::Acquire_Load(ptr) == 1; 52 return subtle::Acquire_Load(ptr) == 1;
53 } 53 }
54 54
55 // Return whether the reference count is zero. With conventional object 55 // Return whether the reference count is zero. With conventional object
56 // referencing counting, the object will be destroyed, so the reference count 56 // referencing counting, the object will be destroyed, so the reference count
57 // should never be zero. Hence this is generally used for a debug check. 57 // should never be zero. Hence this is generally used for a debug check.
58 inline bool AtomicRefCountIsZero(volatile AtomicRefCount *ptr) { 58 inline bool AtomicRefCountIsZero(volatile AtomicRefCount *ptr) {
59 return base::subtle::Acquire_Load(ptr) == 0; 59 return subtle::Acquire_Load(ptr) == 0;
60 } 60 }
61 61
62 } // namespace base 62 } // namespace base
63 63
64 #endif // BASE_ATOMIC_REF_COUNT_H_ 64 #endif // BASE_ATOMIC_REF_COUNT_H_
65 65
OLDNEW
« no previous file with comments | « no previous file | base/base_lib.scons » ('j') | no next file with comments »

Powered by Google App Engine
This is Rietveld 408576698