Track active references in ShillClientHelper (Take 2)

To prevent Shill Service DBus ObjectProxy instances from accumulating,
remove them when the service becomes inactive.

Original CL: https://codereview.chromium.org/23658053/

BUG=223483
TBR=hashimoto@chromium.org

Review URL: https://codereview.chromium.org/24558004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@227100 0039d316-1c4b-4281-b951-d872f2087c98

7 files changed, 140 insertions, 29 deletions

diff --git a/chromeos/dbus/shill_client_helper.cc b/chromeos/dbus/shill_client_helper.cc
index b430609..c927180 100644
--- a/chromeos/dbus/shill_client_helper.cc
+++ b/chromeos/dbus/shill_client_helper.cc
@@ -5,6 +5,7 @@
 #include "chromeos/dbus/shill_client_helper.h"
 
 #include "base/bind.h"
+#include "base/callback_helpers.h"
 #include "base/values.h"
 #include "dbus/message.h"
 #include "dbus/object_proxy.h"
@@ -13,12 +14,36 @@
 
 namespace chromeos {
 
+// Class to hold onto a reference to a ShillClientHelper. This calss
+// is owned by callbacks and released once the callback completes.
+// Note: Only success callbacks hold the reference. If an error callback is
+// invoked instead, the success callback will still be destroyed and the
+// RefHolder with it, once the callback chain completes.
+class ShillClientHelper::RefHolder {
+ public:
+  explicit RefHolder(base::WeakPtr<ShillClientHelper> helper)
+      : helper_(helper) {
+    helper_->AddRef();
+  }
+  ~RefHolder() {
+    if (helper_)
+      helper_->Release();
+  }
+
+ private:
+  base::WeakPtr<ShillClientHelper> helper_;
+};
+
 namespace {
 
 const char kInvalidResponseErrorName[] = "";  // No error name.
 const char kInvalidResponseErrorMessage[] = "Invalid response.";
 
+// Note: here and below, |ref_holder| is unused in the function body. It only
+// exists so that it will be destroyed (and the reference released) with the
+// Callback object once completed.
 void OnBooleanMethodWithErrorCallback(
+    ShillClientHelper::RefHolder* ref_holder,
     const ShillClientHelper::BooleanCallback& callback,
     const ShillClientHelper::ErrorCallback& error_callback,
     dbus::Response* response) {
@@ -36,6 +61,7 @@ void OnBooleanMethodWithErrorCallback(
 }
 
 void OnStringMethodWithErrorCallback(
+    ShillClientHelper::RefHolder* ref_holder,
     const ShillClientHelper::StringCallback& callback,
     const ShillClientHelper::ErrorCallback& error_callback,
     dbus::Response* response) {
@@ -53,7 +79,8 @@ void OnStringMethodWithErrorCallback(
 }
 
 // Handles responses for methods without results.
-void OnVoidMethod(const VoidDBusMethodCallback& callback,
+void OnVoidMethod(ShillClientHelper::RefHolder* ref_holder,
+                  const VoidDBusMethodCallback& callback,
                   dbus::Response* response) {
   if (!response) {
     callback.Run(DBUS_METHOD_CALL_FAILURE);
@@ -64,6 +91,7 @@ void OnVoidMethod(const VoidDBusMethodCallback& callback,
 
 // Handles responses for methods with ObjectPath results.
 void OnObjectPathMethod(
+    ShillClientHelper::RefHolder* ref_holder,
     const ObjectPathDBusMethodCallback& callback,
     dbus::Response* response) {
   if (!response) {
@@ -81,6 +109,7 @@ void OnObjectPathMethod(
 
 // Handles responses for methods with ObjectPath results and no status.
 void OnObjectPathMethodWithoutStatus(
+    ShillClientHelper::RefHolder* ref_holder,
     const ObjectPathCallback& callback,
     const ShillClientHelper::ErrorCallback& error_callback,
     dbus::Response* response) {
@@ -99,6 +128,7 @@ void OnObjectPathMethodWithoutStatus(
 
 // Handles responses for methods with DictionaryValue results.
 void OnDictionaryValueMethod(
+    ShillClientHelper::RefHolder* ref_holder,
     const ShillClientHelper::DictionaryValueCallback& callback,
     dbus::Response* response) {
   if (!response) {
@@ -119,6 +149,7 @@ void OnDictionaryValueMethod(
 
 // Handles responses for methods without results.
 void OnVoidMethodWithErrorCallback(
+    ShillClientHelper::RefHolder* ref_holder,
     const base::Closure& callback,
     dbus::Response* response) {
   callback.Run();
@@ -127,6 +158,7 @@ void OnVoidMethodWithErrorCallback(
 // Handles responses for methods with DictionaryValue results.
 // Used by CallDictionaryValueMethodWithErrorCallback().
 void OnDictionaryValueMethodWithErrorCallback(
+    ShillClientHelper::RefHolder* ref_holder,
     const ShillClientHelper::DictionaryValueCallbackWithoutStatus& callback,
     const ShillClientHelper::ErrorCallback& error_callback,
     dbus::Response* response) {
@@ -142,6 +174,7 @@ void OnDictionaryValueMethodWithErrorCallback(
 
 // Handles responses for methods with ListValue results.
 void OnListValueMethodWithErrorCallback(
+    ShillClientHelper::RefHolder* ref_holder,
     const ShillClientHelper::ListValueCallback& callback,
     const ShillClientHelper::ErrorCallback& error_callback,
     dbus::Response* response) {
@@ -171,9 +204,9 @@ void OnError(const ShillClientHelper::ErrorCallback& error_callback,
 
 }  // namespace
 
-ShillClientHelper::ShillClientHelper(dbus::Bus* bus,
-                                     dbus::ObjectProxy* proxy)
+ShillClientHelper::ShillClientHelper(dbus::ObjectProxy* proxy)
     : proxy_(proxy),
+      active_refs_(0),
       weak_ptr_factory_(this) {
 }
 
@@ -182,8 +215,16 @@ ShillClientHelper::~ShillClientHelper() {
       << "ShillClientHelper destroyed with active observers";
 }
 
+void ShillClientHelper::SetReleasedCallback(ReleasedCallback callback) {
+  CHECK(released_callback_.is_null());
+  released_callback_ = callback;
+}
+
 void ShillClientHelper::AddPropertyChangedObserver(
     ShillPropertyChangedObserver* observer) {
+  if (observer_list_.HasObserver(observer))
+    return;
+  AddRef();
   // Excecute all the pending MonitorPropertyChanged calls.
   for (size_t i = 0; i < interfaces_to_be_monitored_.size(); ++i) {
     MonitorPropertyChangedInternal(interfaces_to_be_monitored_[i]);
@@ -195,7 +236,10 @@ void ShillClientHelper::AddPropertyChangedObserver(
 
 void ShillClientHelper::RemovePropertyChangedObserver(
     ShillPropertyChangedObserver* observer) {
+  if (!observer_list_.HasObserver(observer))
+    return;
   observer_list_.RemoveObserver(observer);
+  Release();
 }
 
 void ShillClientHelper::MonitorPropertyChanged(
@@ -225,18 +269,22 @@ void ShillClientHelper::CallVoidMethod(
     dbus::MethodCall* method_call,
     const VoidDBusMethodCallback& callback) {
   DCHECK(!callback.is_null());
-  proxy_->CallMethod(method_call, dbus::ObjectProxy::TIMEOUT_USE_DEFAULT,
-                     base::Bind(&OnVoidMethod,
-                                callback));
+  proxy_->CallMethod(
+      method_call, dbus::ObjectProxy::TIMEOUT_USE_DEFAULT,
+      base::Bind(&OnVoidMethod,
+                 base::Owned(new RefHolder(weak_ptr_factory_.GetWeakPtr())),
+                 callback));
 }
 
 void ShillClientHelper::CallObjectPathMethod(
     dbus::MethodCall* method_call,
     const ObjectPathDBusMethodCallback& callback) {
   DCHECK(!callback.is_null());
-  proxy_->CallMethod(method_call, dbus::ObjectProxy::TIMEOUT_USE_DEFAULT,
-                     base::Bind(&OnObjectPathMethod,
-                                callback));
+  proxy_->CallMethod(
+      method_call, dbus::ObjectProxy::TIMEOUT_USE_DEFAULT,
+      base::Bind(&OnObjectPathMethod,
+                 base::Owned(new RefHolder(weak_ptr_factory_.GetWeakPtr())),
+                 callback));
 }
 
 void ShillClientHelper::CallObjectPathMethodWithErrorCallback(
@@ -249,6 +297,7 @@ void ShillClientHelper::CallObjectPathMethodWithErrorCallback(
       method_call,
       dbus::ObjectProxy::TIMEOUT_USE_DEFAULT,
       base::Bind(&OnObjectPathMethodWithoutStatus,
+                 base::Owned(new RefHolder(weak_ptr_factory_.GetWeakPtr())),
                  callback,
                  error_callback),
       base::Bind(&OnError,
@@ -259,9 +308,11 @@ void ShillClientHelper::CallDictionaryValueMethod(
     dbus::MethodCall* method_call,
     const DictionaryValueCallback& callback) {
   DCHECK(!callback.is_null());
-  proxy_->CallMethod(method_call, dbus::ObjectProxy::TIMEOUT_USE_DEFAULT,
-                     base::Bind(&OnDictionaryValueMethod,
-                                callback));
+  proxy_->CallMethod(
+      method_call, dbus::ObjectProxy::TIMEOUT_USE_DEFAULT,
+      base::Bind(&OnDictionaryValueMethod,
+                 base::Owned(new RefHolder(weak_ptr_factory_.GetWeakPtr())),
+                 callback));
 }
 
 void ShillClientHelper::CallVoidMethodWithErrorCallback(
@@ -273,6 +324,7 @@ void ShillClientHelper::CallVoidMethodWithErrorCallback(
   proxy_->CallMethodWithErrorCallback(
       method_call, dbus::ObjectProxy::TIMEOUT_USE_DEFAULT,
       base::Bind(&OnVoidMethodWithErrorCallback,
+                 base::Owned(new RefHolder(weak_ptr_factory_.GetWeakPtr())),
                  callback),
       base::Bind(&OnError,
                  error_callback));
@@ -287,6 +339,7 @@ void ShillClientHelper::CallBooleanMethodWithErrorCallback(
   proxy_->CallMethodWithErrorCallback(
       method_call, dbus::ObjectProxy::TIMEOUT_USE_DEFAULT,
       base::Bind(&OnBooleanMethodWithErrorCallback,
+                 base::Owned(new RefHolder(weak_ptr_factory_.GetWeakPtr())),
                  callback,
                  error_callback),
       base::Bind(&OnError,
@@ -302,6 +355,7 @@ void ShillClientHelper::CallStringMethodWithErrorCallback(
   proxy_->CallMethodWithErrorCallback(
       method_call, dbus::ObjectProxy::TIMEOUT_USE_DEFAULT,
       base::Bind(&OnStringMethodWithErrorCallback,
+                 base::Owned(new RefHolder(weak_ptr_factory_.GetWeakPtr())),
                  callback,
                  error_callback),
       base::Bind(&OnError,
@@ -316,10 +370,10 @@ void ShillClientHelper::CallDictionaryValueMethodWithErrorCallback(
   DCHECK(!error_callback.is_null());
   proxy_->CallMethodWithErrorCallback(
       method_call, dbus::ObjectProxy::TIMEOUT_USE_DEFAULT,
-      base::Bind(
-          &OnDictionaryValueMethodWithErrorCallback,
-          callback,
-          error_callback),
+      base::Bind(&OnDictionaryValueMethodWithErrorCallback,
+                 base::Owned(new RefHolder(weak_ptr_factory_.GetWeakPtr())),
+                 callback,
+                 error_callback),
       base::Bind(&OnError,
                  error_callback));
 }
@@ -332,10 +386,10 @@ void ShillClientHelper::CallListValueMethodWithErrorCallback(
   DCHECK(!error_callback.is_null());
   proxy_->CallMethodWithErrorCallback(
       method_call, dbus::ObjectProxy::TIMEOUT_USE_DEFAULT,
-      base::Bind(
-          &OnListValueMethodWithErrorCallback,
-          callback,
-          error_callback),
+      base::Bind(&OnListValueMethodWithErrorCallback,
+                 base::Owned(new RefHolder(weak_ptr_factory_.GetWeakPtr())),
+                 callback,
+                 error_callback),
       base::Bind(&OnError,
                  error_callback));
 }
@@ -420,6 +474,16 @@ void ShillClientHelper::AppendServicePropertiesDictionary(
   writer->CloseContainer(&array_writer);
 }
 
+void ShillClientHelper::AddRef() {
+  ++active_refs_;
+}
+
+void ShillClientHelper::Release() {
+  --active_refs_;
+  if (active_refs_ == 0 && !released_callback_.is_null())
+    base::ResetAndReturn(&released_callback_).Run(this);  // May delete this
+}
+
 void ShillClientHelper::OnSignalConnected(const std::string& interface,
                                           const std::string& signal,
                                           bool success) {
@@ -443,5 +507,4 @@ void ShillClientHelper::OnPropertyChanged(dbus::Signal* signal) {
                     OnPropertyChanged(name, *value));
 }
 
-
 }  // namespace chromeos
diff --git a/chromeos/dbus/shill_client_helper.h b/chromeos/dbus/shill_client_helper.h
index 12cd994..a52fc22 100644
--- a/chromeos/dbus/shill_client_helper.h
+++ b/chromeos/dbus/shill_client_helper.h
@@ -41,6 +41,8 @@ namespace chromeos {
 // A class to help implement Shill clients.
 class ShillClientHelper {
  public:
+  class RefHolder;
+
   // A callback to handle PropertyChanged signals.
   typedef base::Callback<void(const std::string& name,
                               const base::Value& value)> PropertyChangedHandler;
@@ -68,11 +70,17 @@ class ShillClientHelper {
   // A callback that handles responses for methods with boolean results.
   typedef base::Callback<void(bool result)> BooleanCallback;
 
+  // Callback used to notify owner when this can be safely released.
+  typedef base::Callback<void(ShillClientHelper* helper)> ReleasedCallback;
 
-  ShillClientHelper(dbus::Bus* bus, dbus::ObjectProxy* proxy);
+  explicit ShillClientHelper(dbus::ObjectProxy* proxy);
 
   virtual ~ShillClientHelper();
 
+  // Sets |released_callback_|. This is optional and should only be called at
+  // most once.
+  void SetReleasedCallback(ReleasedCallback callback);
+
   // Adds an |observer| of the PropertyChanged signal.
   void AddPropertyChangedObserver(ShillPropertyChangedObserver* observer);
 
@@ -131,6 +139,8 @@ class ShillClientHelper {
       const ListValueCallback& callback,
       const ErrorCallback& error_callback);
 
+  const dbus::ObjectProxy* object_proxy() const { return proxy_; }
+
   // Appends the value (basic types and string-to-string dictionary) to the
   // writer as a variant.
   static void AppendValueDataAsVariant(dbus::MessageWriter* writer,
@@ -141,6 +151,13 @@ class ShillClientHelper {
       dbus::MessageWriter* writer,
       const base::DictionaryValue& dictionary);
 
+ protected:
+  // Reference / Ownership management. If the number of active refs (observers
+  // + in-progress method calls) becomes 0, |released_callback_| (if set) will
+  // be called.
+  void AddRef();
+  void Release();
+
  private:
   // Starts monitoring PropertyChanged signal.
   void MonitorPropertyChangedInternal(const std::string& interface_name);
@@ -154,6 +171,8 @@ class ShillClientHelper {
   void OnPropertyChanged(dbus::Signal* signal);
 
   dbus::ObjectProxy* proxy_;
+  ReleasedCallback released_callback_;
+  int active_refs_;
   PropertyChangedHandler property_changed_handler_;
   ObserverList<ShillPropertyChangedObserver, true /* check_empty */>
       observer_list_;
diff --git a/chromeos/dbus/shill_device_client.cc b/chromeos/dbus/shill_device_client.cc
index 931e71a..5aa4332 100644
--- a/chromeos/dbus/shill_device_client.cc
+++ b/chromeos/dbus/shill_device_client.cc
@@ -215,7 +215,7 @@ class ShillDeviceClientImpl : public ShillDeviceClient {
     // There is no helper for the profile, create it.
     dbus::ObjectProxy* object_proxy =
         bus_->GetObjectProxy(shill::kFlimflamServiceName, device_path);
-    ShillClientHelper* helper = new ShillClientHelper(bus_, object_proxy);
+    ShillClientHelper* helper = new ShillClientHelper(object_proxy);
     CHECK(helper) << "Unable to create Shill client helper.";
     helper->MonitorPropertyChanged(shill::kFlimflamDeviceInterface);
     helpers_.insert(HelperMap::value_type(device_path.value(), helper));
diff --git a/chromeos/dbus/shill_ipconfig_client.cc b/chromeos/dbus/shill_ipconfig_client.cc
index 4483078..46aeb71 100644
--- a/chromeos/dbus/shill_ipconfig_client.cc
+++ b/chromeos/dbus/shill_ipconfig_client.cc
@@ -70,7 +70,7 @@ class ShillIPConfigClientImpl : public ShillIPConfigClient {
     // There is no helper for the profile, create it.
     dbus::ObjectProxy* object_proxy =
         bus_->GetObjectProxy(shill::kFlimflamServiceName, ipconfig_path);
-    ShillClientHelper* helper = new ShillClientHelper(bus_, object_proxy);
+    ShillClientHelper* helper = new ShillClientHelper(object_proxy);
     helper->MonitorPropertyChanged(shill::kFlimflamIPConfigInterface);
     helpers_.insert(HelperMap::value_type(ipconfig_path.value(), helper));
     return helper;
diff --git a/chromeos/dbus/shill_manager_client.cc b/chromeos/dbus/shill_manager_client.cc
index f3cd1bb..cae9b68 100644
--- a/chromeos/dbus/shill_manager_client.cc
+++ b/chromeos/dbus/shill_manager_client.cc
@@ -219,7 +219,7 @@ class ShillManagerClientImpl : public ShillManagerClient {
   virtual void Init(dbus::Bus* bus) OVERRIDE {
     proxy_ = bus->GetObjectProxy(shill::kFlimflamServiceName,
                                  dbus::ObjectPath(shill::kFlimflamServicePath));
-    helper_.reset(new ShillClientHelper(bus, proxy_));
+    helper_.reset(new ShillClientHelper(proxy_));
     helper_->MonitorPropertyChanged(shill::kFlimflamManagerInterface);
   }
 
diff --git a/chromeos/dbus/shill_profile_client.cc b/chromeos/dbus/shill_profile_client.cc
index e0d8a71..0e63354 100644
--- a/chromeos/dbus/shill_profile_client.cc
+++ b/chromeos/dbus/shill_profile_client.cc
@@ -86,7 +86,7 @@ ShillClientHelper* ShillProfileClientImpl::GetHelper(
   // There is no helper for the profile, create it.
   dbus::ObjectProxy* object_proxy =
       bus_->GetObjectProxy(shill::kFlimflamServiceName, profile_path);
-  ShillClientHelper* helper = new ShillClientHelper(bus_, object_proxy);
+  ShillClientHelper* helper = new ShillClientHelper(object_proxy);
   helper->MonitorPropertyChanged(shill::kFlimflamProfileInterface);
   helpers_.insert(HelperMap::value_type(profile_path.value(), helper));
   return helper;
diff --git a/chromeos/dbus/shill_service_client.cc b/chromeos/dbus/shill_service_client.cc
index 40143f6..faaf75a 100644
--- a/chromeos/dbus/shill_service_client.cc
+++ b/chromeos/dbus/shill_service_client.cc
@@ -5,11 +5,13 @@
 #include "chromeos/dbus/shill_service_client.h"
 
 #include "base/bind.h"
+#include "base/memory/weak_ptr.h"
 #include "base/message_loop/message_loop.h"
 #include "base/stl_util.h"
 #include "base/values.h"
 #include "chromeos/dbus/shill_property_changed_observer.h"
 #include "chromeos/dbus/shill_service_client_stub.h"
+#include "chromeos/network/network_event_log.h"
 #include "dbus/bus.h"
 #include "dbus/message.h"
 #include "dbus/object_proxy.h"
@@ -54,7 +56,18 @@ class ShillServiceClientImpl : public ShillServiceClient {
  public:
   explicit ShillServiceClientImpl()
       : bus_(NULL),
-        helpers_deleter_(&helpers_) {
+        weak_ptr_factory_(this) {
+  }
+
+  virtual ~ShillServiceClientImpl() {
+    for (HelperMap::iterator iter = helpers_.begin();
+         iter != helpers_.end(); ++iter) {
+      ShillClientHelper* helper = iter->second;
+      bus_->RemoveObjectProxy(shill::kFlimflamServiceName,
+                              helper->object_proxy()->object_path(),
+                              base::Bind(&base::DoNothing));
+      delete helper;
+    }
   }
 
   virtual void AddPropertyChangedObserver(
@@ -222,17 +235,33 @@ class ShillServiceClientImpl : public ShillServiceClient {
       return it->second;
 
     // There is no helper for the profile, create it.
+    NET_LOG_DEBUG("AddShillClientHelper", service_path.value());
     dbus::ObjectProxy* object_proxy =
         bus_->GetObjectProxy(shill::kFlimflamServiceName, service_path);
-    ShillClientHelper* helper = new ShillClientHelper(bus_, object_proxy);
+    ShillClientHelper* helper = new ShillClientHelper(object_proxy);
+    helper->SetReleasedCallback(
+        base::Bind(&ShillServiceClientImpl::NotifyReleased,
+                   weak_ptr_factory_.GetWeakPtr()));
     helper->MonitorPropertyChanged(shill::kFlimflamServiceInterface);
     helpers_.insert(HelperMap::value_type(service_path.value(), helper));
     return helper;
   }
 
+  void NotifyReleased(ShillClientHelper* helper) {
+    // New Shill Service DBus objects are created relatively frequently, so
+    // remove them when they become inactive (no observers and no active method
+    // calls).
+    const dbus::ObjectPath& object_path = helper->object_proxy()->object_path();
+    NET_LOG_DEBUG("RemoveShillClientHelper", object_path.value());
+    bus_->RemoveObjectProxy(shill::kFlimflamServiceName,
+                            object_path, base::Bind(&base::DoNothing));
+    helpers_.erase(object_path.value());
+    delete helper;
+  }
+
   dbus::Bus* bus_;
   HelperMap helpers_;
-  STLValueDeleter<HelperMap> helpers_deleter_;
+  base::WeakPtrFactory<ShillServiceClientImpl> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ShillServiceClientImpl);
 };