Massively simplify the NetworkChangeNotifier infrastructure:...

net/base/network_change_notifier_mac.cc

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// There are three classes involved here.  There's NetworkChangeNotifierMac,
-// which is the Mac specific implementation of NetworkChangeNotifier.  It is the
-// class with which clients can register themselves as network change
-// observers.  There's NetworkChangeNotifierThread, which is a base::Thread
-// subclass of MessageLoop::TYPE_UI (since it needs a CFRunLoop) that contains
-// the NetworkChangeNotifierImpl.  NetworkChangeNotifierImpl is the object
-// that receives the actual OS X notifications and posts them to the
-// NetworkChangeNotifierMac's message loop, so that NetworkChangeNotifierMac
-// can notify all its observers.
-//
-// When NetworkChangeNotifierMac is being deleted, it will delete the
-// NetworkChangeNotifierThread, which will Stop() it and also delete the
-// NetworkChangeNotifierImpl.  Therefore, NetworkChangeNotifierImpl and
-// NetworkChangeNotifierThread's lifetimes generally begin after and end before
-// NetworkChangeNotifierMac.  There is an edge case where a notification task
-// gets posted to the IO thread, thereby maintaining a reference to
-// NetworkChangeNotifierImpl beyond the lifetime of NetworkChangeNotifierThread.
-// In this case, the notification is cancelled, and NetworkChangeNotifierImpl
-// will be deleted once all notification tasks that reference it have been run.
+#include "net/base/network_change_notifier_mac.h"
 
-#include "net/base/network_change_notifier_mac.h"
-#include <SystemConfiguration/SCDynamicStore.h>
 #include <SystemConfiguration/SCDynamicStoreKey.h>
 #include <SystemConfiguration/SCSchemaDefinitions.h>
 #include <algorithm>
-#include "base/logging.h"
-#include "base/message_loop.h"
-#include "base/scoped_cftyperef.h"
+
 #include "base/thread.h"
 
+// We only post tasks to a child thread we own, so we don't need refcounting.
+DISABLE_RUNNABLE_METHOD_REFCOUNT(net::NetworkChangeNotifierMac);
+
 namespace net {
 
-namespace {
-
-// NetworkChangeNotifierImpl should be created on a thread with a CFRunLoop,
-// since it requires one to pump notifications.  However, it also runs some
-// methods on |notifier_loop_|, because it cannot post calls to |notifier_|
-// since NetworkChangeNotifier is not ref counted in a thread safe manner.
-class NetworkChangeNotifierImpl
-    : public base::RefCountedThreadSafe<NetworkChangeNotifierImpl> {
- public:
-  NetworkChangeNotifierImpl(MessageLoop* notifier_loop,
-                            NetworkChangeNotifierMac* notifier);
-
-  void Shutdown();
-
- private:
-  friend class base::RefCountedThreadSafe<NetworkChangeNotifierImpl>;
-  ~NetworkChangeNotifierImpl();
-
-  static void DynamicStoreCallback(SCDynamicStoreRef /* store */,
-                                   CFArrayRef changed_keys,
-                                   void* config);
-
-  void OnNetworkConfigChange(CFArrayRef changed_keys);
-
-  // Runs on |notifier_loop_|.
-  void OnIPAddressChanged();
-
-  // Raw pointers.  Note that |notifier_| _must_ outlive the
-  // NetworkChangeNotifierImpl.  For lifecycle management details, read the
-  // comment at the top of the file.
-  MessageLoop* const notifier_loop_;
-  NetworkChangeNotifierMac* notifier_;
-
-  scoped_cftyperef<CFRunLoopSourceRef> source_;
-
-  DISALLOW_COPY_AND_ASSIGN(NetworkChangeNotifierImpl);
-};
-
-NetworkChangeNotifierImpl::NetworkChangeNotifierImpl(
-    MessageLoop* notifier_loop, NetworkChangeNotifierMac* notifier)
-    : notifier_loop_(notifier_loop),
-      notifier_(notifier) {
-  DCHECK_EQ(MessageLoop::TYPE_UI, MessageLoop::current()->type());
-  SCDynamicStoreContext context = {
-    0,    // Version 0.
-    this, // User data.
-    NULL, // This is not reference counted.  No retain function.
-    NULL, // This is not reference counted.  No release function.
-    NULL, // No description for this.
-  };
-
-  // Get a reference to the dynamic store.
-  scoped_cftyperef<SCDynamicStoreRef> store(
-      SCDynamicStoreCreate(NULL /* use default allocator */,
-                           CFSTR("org.chromium"),
-                           DynamicStoreCallback, &context));
-
-  // Create a run loop source for the dynamic store.
-  source_.reset(SCDynamicStoreCreateRunLoopSource(
-      NULL /* use default allocator */,
-      store.get(),
-      0 /* 0 sounds like a fine source order to me! */));
-
-  // Add the run loop source to the current run loop.
-  CFRunLoopAddSource(CFRunLoopGetCurrent(),
-                     source_.get(),
-                     kCFRunLoopCommonModes);
-
-  // Set up the notification keys.
-  scoped_cftyperef<CFMutableArrayRef> notification_keys(
-      CFArrayCreateMutable(kCFAllocatorDefault, 0, &kCFTypeArrayCallBacks));
-
-  // Monitor interface changes.
-  scoped_cftyperef<CFStringRef> key(
-      SCDynamicStoreKeyCreateNetworkGlobalEntity(
-          NULL /* default allocator */, kSCDynamicStoreDomainState,
-          kSCEntNetInterface));
-  CFArrayAppendValue(notification_keys.get(), key.get());
-
-  // Monitor IP address changes.
-
-  key.reset(SCDynamicStoreKeyCreateNetworkGlobalEntity(
-      NULL /* default allocator */, kSCDynamicStoreDomainState,
-      kSCEntNetIPv4));
-  CFArrayAppendValue(notification_keys.get(), key.get());
-
-  key.reset(SCDynamicStoreKeyCreateNetworkGlobalEntity(
-      NULL /* default allocator */, kSCDynamicStoreDomainState,
-      kSCEntNetIPv6));
-  CFArrayAppendValue(notification_keys.get(), key.get());
-
-  // Ok, let's ask for notifications!
-  // TODO(willchan): Figure out a proper way to handle this rather than crash.
-  CHECK(SCDynamicStoreSetNotificationKeys(
-      store.get(), notification_keys.get(), NULL));
+NetworkChangeNotifierMac::NetworkChangeNotifierMac()
+    : notifier_thread_(new base::Thread("NetworkChangeNotifier")) {
+  // We create this notifier thread because the notification implementation
+  // needs a thread with a CFRunLoop, and there's no guarantee that
+  // MessageLoop::current() meets that criterion.
+  base::Thread::Options thread_options(MessageLoop::TYPE_UI, 0);
+  notifier_thread_->StartWithOptions(thread_options);
+  // TODO(willchan): Look to see if there's a better signal for when it's ok to
+  // initialize this, rather than just delaying it by a fixed time.
+  const int kNotifierThreadInitializationDelayMS = 1000;
+  notifier_thread_->message_loop()->PostDelayedTask(FROM_HERE,
+      NewRunnableMethod(this, &NetworkChangeNotifierMac::Init),
+      kNotifierThreadInitializationDelayMS);
 }
 
-NetworkChangeNotifierImpl::~NetworkChangeNotifierImpl() {
-  CFRunLoopRemoveSource(CFRunLoopGetCurrent(),
-                        source_.get(),
-                        kCFRunLoopCommonModes);
-}
-
-void NetworkChangeNotifierImpl::Shutdown() {
-  CHECK(notifier_);
-  notifier_ = NULL;
+NetworkChangeNotifierMac::~NetworkChangeNotifierMac() {
+  // We don't need to explicitly Stop(), but doing so allows us to sanity-
+  // check that the notifier thread shut down properly.
+  notifier_thread_->Stop();
+  DCHECK(run_loop_source_ == NULL);
 }
 
 // static
-void NetworkChangeNotifierImpl::DynamicStoreCallback(
+void NetworkChangeNotifierMac::DynamicStoreCallback(
     SCDynamicStoreRef /* store */,
     CFArrayRef changed_keys,
     void* config) {
-  NetworkChangeNotifierImpl* net_config =
-      static_cast<NetworkChangeNotifierImpl*>(config);
+  NetworkChangeNotifierMac* net_config =
+      static_cast<NetworkChangeNotifierMac*>(config);
   net_config->OnNetworkConfigChange(changed_keys);
 }
 
-void NetworkChangeNotifierImpl::OnNetworkConfigChange(CFArrayRef changed_keys) {
+void NetworkChangeNotifierMac::WillDestroyCurrentMessageLoop() {
+  DCHECK(notifier_thread_ != NULL);
+  // We can't check the notifier_thread_'s message_loop(), as it's now 0.
+  // DCHECK_EQ(notifier_thread_->message_loop(), MessageLoop::current());
+
+  DCHECK(run_loop_source_ != NULL);
+  CFRunLoopRemoveSource(CFRunLoopGetCurrent(), run_loop_source_.get(),
+                        kCFRunLoopCommonModes);
+  run_loop_source_.reset();
+}
+
+void NetworkChangeNotifierMac::Init() {
+  DCHECK(notifier_thread_ != NULL);
+  DCHECK_EQ(notifier_thread_->message_loop(), MessageLoop::current());
+
+  // Add a run loop source for a dynamic store to the current run loop.
+  SCDynamicStoreContext context = {
+    0,     // Version 0.
+    this,  // User data.
+    NULL,  // This is not reference counted.  No retain function.
+    NULL,  // This is not reference counted.  No release function.
+    NULL,  // No description for this.
+  };
+  scoped_cftyperef<SCDynamicStoreRef> store(SCDynamicStoreCreate(
+      NULL, CFSTR("org.chromium"), DynamicStoreCallback, &context));
+  run_loop_source_.reset(SCDynamicStoreCreateRunLoopSource(
+      NULL, store.get(), 0));
+  CFRunLoopAddSource(CFRunLoopGetCurrent(), run_loop_source_.get(),
+                     kCFRunLoopCommonModes);
+
+  // Set up notifications for interface and IP address changes.
+  scoped_cftyperef<CFMutableArrayRef> notification_keys(
+      CFArrayCreateMutable(kCFAllocatorDefault, 0, &kCFTypeArrayCallBacks));
+  scoped_cftyperef<CFStringRef> key(SCDynamicStoreKeyCreateNetworkGlobalEntity(
+      NULL, kSCDynamicStoreDomainState, kSCEntNetInterface));
+  CFArrayAppendValue(notification_keys.get(), key.get());
+  key.reset(SCDynamicStoreKeyCreateNetworkGlobalEntity(
+      NULL, kSCDynamicStoreDomainState, kSCEntNetIPv4));
+  CFArrayAppendValue(notification_keys.get(), key.get());
+  key.reset(SCDynamicStoreKeyCreateNetworkGlobalEntity(
+      NULL, kSCDynamicStoreDomainState, kSCEntNetIPv6));
+  CFArrayAppendValue(notification_keys.get(), key.get());
+
+  // Set the notification keys.  This starts us receiving notifications.
+  bool ret = SCDynamicStoreSetNotificationKeys(
+      store.get(), notification_keys.get(), NULL);
+  // TODO(willchan): Figure out a proper way to handle this rather than crash.
+  CHECK(ret);
+
+  MessageLoop::current()->AddDestructionObserver(this);
+}
+
+void NetworkChangeNotifierMac::OnNetworkConfigChange(CFArrayRef changed_keys) {
+  DCHECK(notifier_thread_ != NULL);
+  DCHECK_EQ(notifier_thread_->message_loop(), MessageLoop::current());
+
   for (CFIndex i = 0; i < CFArrayGetCount(changed_keys); ++i) {
     CFStringRef key = static_cast<CFStringRef>(
         CFArrayGetValueAtIndex(changed_keys, i));
     if (CFStringHasSuffix(key, kSCEntNetIPv4) ||
         CFStringHasSuffix(key, kSCEntNetIPv6)) {
-      notifier_loop_->PostTask(
-          FROM_HERE,
-          NewRunnableMethod(
-              this,
-              &NetworkChangeNotifierImpl::OnIPAddressChanged));
-    } else if (CFStringHasSuffix(key, kSCEntNetInterface)) {
+      NotifyObserversOfIPAddressChange();
+      return;
+    }
+    if (CFStringHasSuffix(key, kSCEntNetInterface)) {
       // TODO(willchan): Does not appear to be working.  Look into this.
       // Perhaps this isn't needed anyway.
     } else {
       NOTREACHED();
     }
   }
 }
 
-void NetworkChangeNotifierImpl::OnIPAddressChanged() {
-  // If |notifier_| doesn't exist, then that means we're shutting down, so
-  // notifications are all cancelled.
-  if (notifier_)
-    notifier_->OnIPAddressChanged();
-}
-
-class NetworkChangeNotifierThread : public base::Thread {
- public:
-  NetworkChangeNotifierThread(MessageLoop* notifier_loop,
-                              NetworkChangeNotifierMac* notifier);
-  ~NetworkChangeNotifierThread();
-
- protected:
-  virtual void Init();
-
- private:
-  MessageLoop* const notifier_loop_;
-  NetworkChangeNotifierMac* const notifier_;
-  scoped_refptr<NetworkChangeNotifierImpl> notifier_impl_;
-
-  DISALLOW_COPY_AND_ASSIGN(NetworkChangeNotifierThread);
-};
-
-NetworkChangeNotifierThread::NetworkChangeNotifierThread(
-    MessageLoop* notifier_loop, NetworkChangeNotifierMac* notifier)
-    : base::Thread("NetworkChangeNotifier"),
-      notifier_loop_(notifier_loop),
-      notifier_(notifier) {}
-
-NetworkChangeNotifierThread::~NetworkChangeNotifierThread() {
-  notifier_impl_->Shutdown();
-  Stop();
-}
-
-// Note that |notifier_impl_| is initialized on the network change
-// notifier thread, not whatever thread constructs the
-// NetworkChangeNotifierThread object.  This is important, because this thread
-// is the one that has a CFRunLoop.
-void NetworkChangeNotifierThread::Init() {
-  notifier_impl_ =
-      new NetworkChangeNotifierImpl(notifier_loop_, notifier_);
-}
-
-}  // namespace
-
-NetworkChangeNotifierMac::NetworkChangeNotifierMac()
-    : notifier_thread_(NULL),
-      method_factory_(this) {
-  // TODO(willchan): Look to see if there's a better signal for when it's ok to
-  // initialize this, rather than just delaying it by a fixed time.
-  const int kNotifierThreadInitializationDelayMS = 1000;
-  MessageLoop* loop = MessageLoop::current();
-  loop->PostDelayedTask(
-      FROM_HERE,
-      method_factory_.NewRunnableMethod(
-          &NetworkChangeNotifierMac::InitializeNotifierThread, loop),
-      kNotifierThreadInitializationDelayMS);
-}
-
-void NetworkChangeNotifierMac::OnIPAddressChanged() {
-  DCHECK(CalledOnValidThread());
-  FOR_EACH_OBSERVER(Observer, observers_, OnIPAddressChanged());
-}
-
-void NetworkChangeNotifierMac::AddObserver(Observer* observer) {
-  DCHECK(CalledOnValidThread());
-  observers_.AddObserver(observer);
-}
-
-void NetworkChangeNotifierMac::RemoveObserver(Observer* observer) {
-  DCHECK(CalledOnValidThread());
-  observers_.RemoveObserver(observer);
-}
-
-NetworkChangeNotifierMac::~NetworkChangeNotifierMac() {
-  DCHECK(CalledOnValidThread());
-}
-
-void NetworkChangeNotifierMac::InitializeNotifierThread(MessageLoop* loop) {
-  DCHECK(CalledOnValidThread());
-  notifier_thread_.reset(new NetworkChangeNotifierThread(loop, this));
-  base::Thread::Options thread_options;
-  thread_options.message_loop_type = MessageLoop::TYPE_UI;
-  notifier_thread_->StartWithOptions(thread_options);
-}
-
 }  // namespace net