Mojo C++ bindings: InterfacePtr<T> and Binding<T> use MultiplexRouter when T passes associated inte…

mojo/public/cpp/bindings/lib/interface_ptr_state.h

+// Copyright 2014 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_LIB_INTERFACE_PTR_STATE_H_
+#define MOJO_PUBLIC_CPP_BINDINGS_LIB_INTERFACE_PTR_STATE_H_
+
+#include <algorithm>  // For |std::swap()|.
+
+#include "base/logging.h"
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "mojo/public/cpp/bindings/associated_group.h"
+#include "mojo/public/cpp/bindings/callback.h"
+#include "mojo/public/cpp/bindings/interface_ptr_info.h"
+#include "mojo/public/cpp/bindings/lib/control_message_proxy.h"
+#include "mojo/public/cpp/bindings/lib/filter_chain.h"
+#include "mojo/public/cpp/bindings/lib/interface_endpoint_client.h"
+#include "mojo/public/cpp/bindings/lib/interface_id.h"
+#include "mojo/public/cpp/bindings/lib/message_header_validator.h"
+#include "mojo/public/cpp/bindings/lib/multiplex_router.h"
+#include "mojo/public/cpp/bindings/lib/router.h"
+#include "mojo/public/cpp/bindings/lib/scoped_interface_endpoint_handle.h"
+
+struct MojoAsyncWaiter;
+
+namespace mojo {
+namespace internal {
+
+template <typename Interface, bool use_multiplex_router>
+class InterfacePtrState;
+
+// Uses a single-threaded, dedicated router. If |Interface| doesn't have any
+// methods to pass associated interface pointers or requests, there won't be
+// multiple interfaces running on the underlying message pipe. In that case, we
+// can use this specialization to reduce cost.
+template <typename Interface>
+class InterfacePtrState<Interface, false> {
+ public:
+  InterfacePtrState()
+      : proxy_(nullptr), router_(nullptr), waiter_(nullptr), version_(0u) {}
+
+  ~InterfacePtrState() {
+    // Destruction order matters here. We delete |proxy_| first, even though
+    // |router_| may have a reference to it, so that destructors for any request
+    // callbacks still pending can interact with the InterfacePtr.
+    delete proxy_;
+    delete router_;
+  }
+
+  Interface* instance() {
+    ConfigureProxyIfNecessary();
+
+    // This will be null if the object is not bound.
+    return proxy_;
+  }
+
+  uint32_t version() const { return version_; }
+
+  void QueryVersion(const Callback<void(uint32_t)>& callback) {
+    ConfigureProxyIfNecessary();
+
+    // It is safe to capture |this| because the callback won't be run after this
+    // object goes away.
+    auto callback_wrapper = [this, callback](uint32_t version) {
+      this->version_ = version;
+      callback.Run(version);
+    };
+
+    // Do a static cast in case the interface contains methods with the same
+    // name.
+    static_cast<ControlMessageProxy*>(proxy_)->QueryVersion(callback_wrapper);
+  }
+
+  void RequireVersion(uint32_t version) {
+    ConfigureProxyIfNecessary();
+
+    if (version <= version_)
+      return;
+
+    version_ = version;
+    // Do a static cast in case the interface contains methods with the same
+    // name.
+    static_cast<ControlMessageProxy*>(proxy_)->RequireVersion(version);
+  }
+
+  void Swap(InterfacePtrState* other) {
+    using std::swap;
+    swap(other->proxy_, proxy_);
+    swap(other->router_, router_);
+    handle_.swap(other->handle_);
+    swap(other->waiter_, waiter_);
+    swap(other->version_, version_);
+  }
+
+  void Bind(InterfacePtrInfo<Interface> info, const MojoAsyncWaiter* waiter) {
+    DCHECK(!proxy_);
+    DCHECK(!router_);
+    DCHECK(!handle_.is_valid());
+    DCHECK(!waiter_);
+    DCHECK_EQ(0u, version_);
+    DCHECK(info.is_valid());
+
+    handle_ = info.PassHandle();
+    waiter_ = waiter;
+    version_ = info.version();
+  }
+
+  bool WaitForIncomingResponse() {
+    ConfigureProxyIfNecessary();
+
+    DCHECK(router_);
+    return router_->WaitForIncomingMessage(MOJO_DEADLINE_INDEFINITE);
+  }
+
+  // After this method is called, the object is in an invalid state and
+  // shouldn't be reused.
+  InterfacePtrInfo<Interface> PassInterface() {
+    return InterfacePtrInfo<Interface>(
+        router_ ? router_->PassMessagePipe() : handle_.Pass(), version_);
+  }
+
+  bool is_bound() const { return handle_.is_valid() || router_; }
+
+  bool encountered_error() const {
+    return router_ ? router_->encountered_error() : false;
+  }
+
+  void set_connection_error_handler(const Closure& error_handler) {
+    ConfigureProxyIfNecessary();
+
+    DCHECK(router_);
+    router_->set_connection_error_handler(error_handler);
+  }
+
+  // Returns true if bound and awaiting a response to a message.
+  bool has_pending_callbacks() const {
+    return router_ && router_->has_pending_responders();
+  }
+
+  AssociatedGroup* associated_group() { return nullptr; }
+
+  void EnableTestingMode() {
+    ConfigureProxyIfNecessary();
+    router_->EnableTestingMode();
+  }
+
+ private:
+  using Proxy = typename Interface::Proxy_;
+
+  void ConfigureProxyIfNecessary() {
+    // The proxy has been configured.
+    if (proxy_) {
+      DCHECK(router_);
+      return;
+    }
+    // The object hasn't been bound.
+    if (!waiter_) {
+      DCHECK(!handle_.is_valid());
+      return;
+    }
+
+    FilterChain filters;
+    filters.Append<MessageHeaderValidator>();
+    filters.Append<typename Interface::ResponseValidator_>();
+
+    router_ = new Router(handle_.Pass(), filters.Pass(), waiter_);
+    waiter_ = nullptr;
+
+    proxy_ = new Proxy(router_);
+  }
+
+  Proxy* proxy_;
+  Router* router_;
+
+  // |proxy_| and |router_| are not initialized until read/write with the
+  // message pipe handle is needed. |handle_| and |waiter_| are valid between
+  // the Bind() call and the initialization of |proxy_| and |router_|.
+  ScopedMessagePipeHandle handle_;
+  const MojoAsyncWaiter* waiter_;
+
+  uint32_t version_;
+
+  DISALLOW_COPY_AND_ASSIGN(InterfacePtrState);
+};
+
+// Uses a multiplexing router. If |Interface| has methods to pass associated
+// interface pointers or requests, this specialization should be used.
+template <typename Interface>
+class InterfacePtrState<Interface, true> {
+ public:
+  InterfacePtrState() : waiter_(nullptr), version_(0u) {}
+
+  ~InterfacePtrState() {
+    endpoint_client_.reset();
+    proxy_.reset();
+    if (router_)
+      router_->CloseMessagePipe();
+  }
+
+  Interface* instance() {
+    ConfigureProxyIfNecessary();
+
+    // This will be null if the object is not bound.
+    return proxy_.get();
+  }
+
+  uint32_t version() const { return version_; }
+
+  void QueryVersion(const Callback<void(uint32_t)>& callback) {
+    ConfigureProxyIfNecessary();
+
+    // It is safe to capture |this| because the callback won't be run after this
+    // object goes away.
+    auto callback_wrapper = [this, callback](uint32_t version) {
+      this->version_ = version;
+      callback.Run(version);
+    };
+
+    // Do a static cast in case the interface contains methods with the same
+    // name.
+    static_cast<ControlMessageProxy*>(proxy_.get())
+        ->QueryVersion(callback_wrapper);
+  }
+
+  void RequireVersion(uint32_t version) {
+    ConfigureProxyIfNecessary();
+
+    if (version <= version_)
+      return;
+
+    version_ = version;
+    // Do a static cast in case the interface contains methods with the same
+    // name.
+    static_cast<ControlMessageProxy*>(proxy_.get())->RequireVersion(version);
+  }
+
+  void Swap(InterfacePtrState* other) {
+    using std::swap;
+    swap(other->router_, router_);
+    swap(other->endpoint_client_, endpoint_client_);
+    swap(other->proxy_, proxy_);
+    handle_.swap(other->handle_);
+    swap(other->waiter_, waiter_);
+    swap(other->version_, version_);
+  }
+
+  void Bind(InterfacePtrInfo<Interface> info, const MojoAsyncWaiter* waiter) {
+    DCHECK(!router_);
+    DCHECK(!endpoint_client_);
+    DCHECK(!proxy_);
+    DCHECK(!handle_.is_valid());
+    DCHECK(!waiter_);
+    DCHECK_EQ(0u, version_);
+    DCHECK(info.is_valid());
+
+    handle_ = info.PassHandle();
+    waiter_ = waiter;
+    version_ = info.version();
+  }
+
+  // After this method is called, the object is in an invalid state and
+  // shouldn't be reused.
+  InterfacePtrInfo<Interface> PassInterface() {
+    endpoint_client_.reset();
+    proxy_.reset();
+    return InterfacePtrInfo<Interface>(
+        router_ ? router_->PassMessagePipe() : handle_.Pass(), version_);
+  }
+
+  bool is_bound() const { return handle_.is_valid() || endpoint_client_; }
+
+  bool encountered_error() const {
+    return endpoint_client_ ? endpoint_client_->encountered_error() : false;
+  }
+
+  void set_connection_error_handler(const Closure& error_handler) {
+    ConfigureProxyIfNecessary();
+
+    DCHECK(endpoint_client_);
+    endpoint_client_->set_connection_error_handler(error_handler);
+  }
+
+  // Returns true if bound and awaiting a response to a message.
+  bool has_pending_callbacks() const {
+    return endpoint_client_ && endpoint_client_->has_pending_responders();
+  }
+
+  AssociatedGroup* associated_group() {
+    ConfigureProxyIfNecessary();
+    return endpoint_client_->associated_group();
+  }
+
+  void EnableTestingMode() {
+    ConfigureProxyIfNecessary();
+    router_->EnableTestingMode();
+  }
+
+  // Intentionally not defined:
+  // bool WaitForIncomingResponse();
+
+ private:
+  using Proxy = typename Interface::Proxy_;
+
+  void ConfigureProxyIfNecessary() {
+    // The proxy has been configured.
+    if (proxy_) {
+      DCHECK(router_);
+      DCHECK(endpoint_client_);
+      return;
+    }
+    // The object hasn't been bound.
+    if (!waiter_) {
+      DCHECK(!handle_.is_valid());
+      return;
+    }
+
+    router_ = new MultiplexRouter(true, handle_.Pass(), waiter_);
+    endpoint_client_.reset(new InterfaceEndpointClient(
+        router_->CreateLocalEndpointHandle(kMasterInterfaceId), nullptr,
+        make_scoped_ptr(new typename Interface::ResponseValidator_())));
+    proxy_.reset(new Proxy(endpoint_client_.get(), endpoint_client_->router()));
+
+    waiter_ = nullptr;
+  }
+
+  scoped_refptr<MultiplexRouter> router_;
+
+  scoped_ptr<InterfaceEndpointClient> endpoint_client_;
+  scoped_ptr<Proxy> proxy_;
+
+  // |router_| (as well as other members above) is not initialized until
+  // read/write with the message pipe handle is needed. |handle_| and |waiter_|
+  // are valid between the Bind() call and the initialization of |router_|.
+  ScopedMessagePipeHandle handle_;
+  const MojoAsyncWaiter* waiter_;
+
+  uint32_t version_;
+
+  DISALLOW_COPY_AND_ASSIGN(InterfacePtrState);
+};
+
+}  // namespace internal
+}  // namespace mojo
+
+#endif  // MOJO_PUBLIC_CPP_BINDINGS_LIB_INTERFACE_PTR_STATE_H_