Mojo C++ bindings: introduce public associated-interface-related types.

mojo/public/cpp/bindings/associated_group.h

Index: mojo/public/cpp/bindings/associated_group.h
diff --git a/mojo/public/cpp/bindings/associated_group.h b/mojo/public/cpp/bindings/associated_group.h
new file mode 100644
index 0000000000000000000000000000000000000000..b6934e09eb48728d380c728f15998b5c44b15d33
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+++ b/mojo/public/cpp/bindings/associated_group.h
@@ -0,0 +1,91 @@
+// 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 MOJO_PUBLIC_CPP_BINDINGS_ASSOCIATED_GROUP_H_
+#define MOJO_PUBLIC_CPP_BINDINGS_ASSOCIATED_GROUP_H_
+
+#include "base/memory/ref_counted.h"
+#include "mojo/public/cpp/bindings/associated_interface_ptr_info.h"
+#include "mojo/public/cpp/bindings/associated_interface_request.h"
+#include "mojo/public/cpp/bindings/lib/scoped_interface_endpoint_handle.h"
+
+namespace mojo {
+
+namespace internal {
+class MultiplexRouter;
+}
+
+// AssociatedGroup refers to all the interface endpoints running at one end of a
+// message pipe. It is used to create associated interfaces for that message
+// pipe.
+// It is thread safe and cheap to make copies.
+class AssociatedGroup {
+ public:
+  // Configuration used by CreateAssociatedInterface(). Please see the comments
+  // of that method for more details.
+  enum AssociatedInterfaceConfig { WILL_PASS_PTR, WILL_PASS_REQUEST };
+
+  AssociatedGroup();
+  AssociatedGroup(const AssociatedGroup& other);
+
+  ~AssociatedGroup();
+
+  AssociatedGroup& operator=(const AssociatedGroup& other);
+
+  // |config| indicates whether |ptr_info| or |request| will be sent to the
+  // remote side of the message pipe.
+  //
+  // NOTE: If |config| is |WILL_PASS_REQUEST|, you will want to bind |ptr_info|
+  // to a local AssociatedInterfacePtr to make calls. However, there is one
+  // restriction: the pointer should NOT be used to make calls before |request|
+  // is sent. Violating that will cause the message pipe to be closed. On the
+  // other hand, as soon as |request| is sent, the pointer is usable. There is
+  // no need to wait until |request| is bound to an implementation at the remote
+  // side.
+  template <typename T>
+  void CreateAssociatedInterface(AssociatedInterfaceConfig config,
+                                 AssociatedInterfacePtrInfo<T>* ptr_info,
+                                 AssociatedInterfaceRequest<T>* request) {
+    internal::ScopedInterfaceEndpointHandle local;
+    internal::ScopedInterfaceEndpointHandle remote;
+    CreateEndpointHandlePair(&local, &remote);
+
+    if (!local.is_valid() || !remote.is_valid()) {
+      *ptr_info = AssociatedInterfacePtrInfo<T>();
+      *request = AssociatedInterfaceRequest<T>();
+      return;
+    }
+
+    if (config == WILL_PASS_PTR) {
+      internal::AssociatedInterfacePtrInfoHelper::SetHandle(ptr_info,
+                                                            remote.Pass());
+      // The implementation is local, therefore set the version according to
+      // the interface definition that this code is built against.
+      ptr_info->set_version(T::Version_);
+      internal::AssociatedInterfaceRequestHelper::SetHandle(request,
+                                                            local.Pass());
+    } else {
+      internal::AssociatedInterfacePtrInfoHelper::SetHandle(ptr_info,
+                                                            local.Pass());
+      // The implementation is remote, we don't know about its actual version
+      // yet.
+      ptr_info->set_version(0u);
+      internal::AssociatedInterfaceRequestHelper::SetHandle(request,
+                                                            remote.Pass());
+    }
+  }
+
+ private:
+  friend class internal::MultiplexRouter;
+
+  void CreateEndpointHandlePair(
+      internal::ScopedInterfaceEndpointHandle* local_endpoint,
+      internal::ScopedInterfaceEndpointHandle* remote_endpoint);
+
+  scoped_refptr<internal::MultiplexRouter> router_;
+};
+
+}  // namespace mojo
+
+#endif  // MOJO_PUBLIC_CPP_BINDINGS_ASSOCIATED_GROUP_H_