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
3 // found in the LICENSE file.
4
5 #include "content/public/browser/notification_registrar.h"
6
7 #include <stddef.h>
8
9 #include <algorithm>
10
11 #include "base/logging.h"
12 #include "base/stl_util.h"
13 #include "content/browser/notification_service_impl.h"
14
15 namespace content {
16
17 struct NotificationRegistrar::Record {
18 bool operator==(const Record& other) const;
19
20 NotificationObserver* observer;
21 int type;
22 NotificationSource source;
23 };
24
operator ==(const Record & other) const25 bool NotificationRegistrar::Record::operator==(const Record& other) const {
26 return observer == other.observer &&
27 type == other.type &&
28 source == other.source;
29 }
30
NotificationRegistrar()31 NotificationRegistrar::NotificationRegistrar() {
32 // Force the NotificationService to be constructed (if it isn't already).
33 // This ensures the NotificationService will be registered on the
34 // AtExitManager before any objects which access it via NotificationRegistrar.
35 // This in turn means it will be destroyed after these objects, so they will
36 // never try to access the NotificationService after it's been destroyed.
37 NotificationServiceImpl::current();
38 // It is OK to create a NotificationRegistrar instance on one thread and then
39 // use it (exclusively) on another, so we detach from the initial thread.
40 DETACH_FROM_SEQUENCE(sequence_checker_);
41 }
42
~NotificationRegistrar()43 NotificationRegistrar::~NotificationRegistrar() {
44 DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
45 RemoveAll();
46 }
47
Add(NotificationObserver * observer,int type,const NotificationSource & source)48 void NotificationRegistrar::Add(NotificationObserver* observer,
49 int type,
50 const NotificationSource& source) {
51 DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
52 DCHECK(!IsRegistered(observer, type, source)) << "Duplicate registration.";
53 DCHECK(NotificationServiceImpl::current());
54
55 Record record = { observer, type, source };
56 registered_.push_back(record);
57
58 NotificationServiceImpl::current()->AddObserver(observer, type, source);
59 }
60
Remove(NotificationObserver * observer,int type,const NotificationSource & source)61 void NotificationRegistrar::Remove(NotificationObserver* observer,
62 int type,
63 const NotificationSource& source) {
64 DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
65
66 Record record = { observer, type, source };
67 RecordVector::iterator found =
68 std::find(registered_.begin(), registered_.end(), record);
69 DCHECK(found != registered_.end());
70
71 registered_.erase(found);
72
73 // This can be nullptr if our owner outlives the NotificationService, e.g. if
74 // our owner is a Singleton.
75 NotificationServiceImpl* service = NotificationServiceImpl::current();
76 if (service)
77 service->RemoveObserver(observer, type, source);
78 }
79
RemoveAll()80 void NotificationRegistrar::RemoveAll() {
81 DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
82 // Early-exit if no registrations, to avoid calling
83 // NotificationService::current. If we've constructed an object with a
84 // NotificationRegistrar member, but haven't actually used the notification
85 // service, and we reach prgram exit, then calling current() below could try
86 // to initialize the service's lazy TLS pointer during exit, which throws
87 // wrenches at things.
88 if (registered_.empty())
89 return;
90
91 // This can be nullptr if our owner outlives the NotificationService, e.g. if
92 // our owner is a Singleton.
93 NotificationServiceImpl* service = NotificationServiceImpl::current();
94 if (service) {
95 for (size_t i = 0; i < registered_.size(); i++) {
96 service->RemoveObserver(registered_[i].observer,
97 registered_[i].type,
98 registered_[i].source);
99 }
100 }
101 registered_.clear();
102 }
103
IsEmpty() const104 bool NotificationRegistrar::IsEmpty() const {
105 DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
106 return registered_.empty();
107 }
108
IsRegistered(NotificationObserver * observer,int type,const NotificationSource & source)109 bool NotificationRegistrar::IsRegistered(NotificationObserver* observer,
110 int type,
111 const NotificationSource& source) {
112 DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
113 Record record = { observer, type, source };
114 return base::Contains(registered_, record);
115 }
116
117 } // namespace content
118