Index: components/arc/instance_holder.h |
diff --git a/components/arc/instance_holder.h b/components/arc/instance_holder.h |
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+// Copyright 2015 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. |
+ |
+#ifndef COMPONENTS_ARC_INSTANCE_HOLDER_H_ |
+#define COMPONENTS_ARC_INSTANCE_HOLDER_H_ |
+ |
+#include <utility> |
+ |
+#include "base/bind.h" |
+#include "base/macros.h" |
+#include "base/memory/weak_ptr.h" |
+#include "base/observer_list.h" |
+#include "base/threading/thread_checker.h" |
+#include "mojo/public/cpp/bindings/interface_ptr.h" |
+ |
+namespace arc { |
+ |
+// Holds a Mojo instance+version pair. This also allows for listening for state |
+// changes for the particular instance. T should be a Mojo interface type |
+// (arc::mojom::XxxInstance). |
+template <typename T> |
+class InstanceHolder { |
+ public: |
+ // Notifies about connection events for individual instances. |
+ class Observer { |
+ public: |
+ // Called once the instance is ready. |
+ virtual void OnInstanceReady() {} |
+ |
+ // Called when the connection to the instance is closed. |
+ virtual void OnInstanceClosed() {} |
+ |
+ protected: |
+ virtual ~Observer() = default; |
+ }; |
+ |
+ InstanceHolder() : weak_factory_(this) {} |
+ |
+ // Gets the Mojo interface for all the instance services. This will return |
+ // nullptr if that particular service is not ready yet. Use an Observer if you |
+ // want to be notified when this is ready. This can only be called on the |
+ // thread that this class was created on. |
+ T* instance() const { return raw_ptr_; } |
+ uint32_t version() const { return version_; } |
+ |
+ // Adds or removes observers. This can only be called on the thread that this |
+ // class was created on. RemoveObserver does nothing if |observer| is not in |
+ // the list. |
+ void AddObserver(Observer* observer) { |
+ DCHECK(thread_checker_.CalledOnValidThread()); |
+ observer_list_.AddObserver(observer); |
+ |
+ if (instance()) |
+ observer->OnInstanceReady(); |
+ } |
+ |
+ void RemoveObserver(Observer* observer) { |
+ DCHECK(thread_checker_.CalledOnValidThread()); |
+ observer_list_.RemoveObserver(observer); |
+ } |
+ |
+ // Called when the channel is closed. |
+ void CloseChannel() { |
+ if (!ptr_) |
+ return; |
+ |
+ ptr_.reset(); |
+ raw_ptr_ = nullptr; |
+ version_ = 0; |
+ if (observer_list_.might_have_observers()) { |
+ typename base::ObserverList<Observer>::Iterator it(&observer_list_); |
+ Observer* obs; |
+ while ((obs = it.GetNext()) != nullptr) |
+ obs->OnInstanceClosed(); |
+ } |
+ } |
+ |
+ // Sets the interface pointer to |ptr|, once the version is determined. This |
+ // will eventually invoke SetInstance(), which will notify the observers. |
+ void OnInstanceReady(mojo::InterfacePtr<T> ptr) { |
+ temporary_ptr_ = std::move(ptr); |
+ temporary_ptr_.QueryVersion(base::Bind(&InstanceHolder<T>::OnVersionReady, |
+ weak_factory_.GetWeakPtr())); |
+ } |
+ |
+ // This method is not intended to be called directly. Normally it is called by |
+ // OnInstanceReady once the version of the instance is determined, but it is |
+ // also exposed so that tests can directly inject a raw pointer+version |
+ // combination. |
+ void SetInstance(T* raw_ptr, uint32_t raw_version = T::Version_) { |
+ raw_ptr_ = raw_ptr; |
+ version_ = raw_version; |
+ if (observer_list_.might_have_observers()) { |
+ typename base::ObserverList<Observer>::Iterator it(&observer_list_); |
+ Observer* obs; |
+ while ((obs = it.GetNext()) != nullptr) |
+ obs->OnInstanceReady(); |
+ } |
+ } |
+ |
+ private: |
+ void OnVersionReady(uint32_t version) { |
+ ptr_ = std::move(temporary_ptr_); |
+ ptr_.set_connection_error_handler(base::Bind( |
+ &InstanceHolder<T>::CloseChannel, weak_factory_.GetWeakPtr())); |
+ SetInstance(ptr_.get(), version); |
+ } |
+ |
+ // These two are copies of the contents of ptr_. They are provided here just |
+ // so that tests can provide non-mojo implementations. |
+ T* raw_ptr_ = nullptr; |
+ uint32_t version_ = 0; |
+ |
+ mojo::InterfacePtr<T> ptr_; |
+ |
+ // Temporary Mojo interfaces. After a Mojo interface pointer has been |
+ // received from the other endpoint, we still need to asynchronously query its |
+ // version. While that is going on, we should still return nullptr on the |
+ // instance() function. |
+ // To keep the instance() functions being trivial, store the instance pointer |
+ // in a temporary variable to avoid losing its reference. |
+ mojo::InterfacePtr<T> temporary_ptr_; |
+ |
+ base::ThreadChecker thread_checker_; |
+ base::ObserverList<Observer> observer_list_; |
+ |
+ // This needs to be the last member in order to cancel all inflight callbacks |
+ // before destroying any other members. |
+ base::WeakPtrFactory<InstanceHolder<T>> weak_factory_; |
+ |
+ DISALLOW_COPY_AND_ASSIGN(InstanceHolder<T>); |
+}; |
+ |
+} // namespace arc |
+ |
+#endif // COMPONENTS_ARC_INSTANCE_HOLDER_H_ |