content/public/browser/notification_registrar.cc

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