blob: 414583bbd723046f390ba706b3e3ed26c44d5e6e [file] [log] [blame]
// 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.
#include <string>
#include <utility>
#include "base/bind.h"
#include "base/callback.h"
#include "base/macros.h"
#include "base/memory/ptr_util.h"
#include "mojo/public/cpp/bindings/binding.h"
#include "mojo/public/cpp/bindings/connection_error_callback.h"
#include "mojo/public/cpp/bindings/interface_ptr.h"
#include "mojo/public/cpp/bindings/interface_request.h"
#include "mojo/public/cpp/bindings/message.h"
namespace mojo {
template <typename BindingType>
struct BindingSetTraits;
template <typename Interface, typename ImplRefTraits>
struct BindingSetTraits<Binding<Interface, ImplRefTraits>> {
using ProxyType = InterfacePtr<Interface>;
using RequestType = InterfaceRequest<Interface>;
using BindingType = Binding<Interface, ImplRefTraits>;
using ImplPointerType = typename BindingType::ImplPointerType;
static RequestType MakeRequest(ProxyType* proxy) {
return mojo::MakeRequest(proxy);
using BindingId = size_t;
template <typename ContextType>
struct BindingSetContextTraits {
using Type = ContextType;
static constexpr bool SupportsContext() { return true; }
template <>
struct BindingSetContextTraits<void> {
// NOTE: This choice of Type only matters insofar as it affects the size of
// the |context_| field of a BindingSetBase::Entry with void context. The
// context value is never used in this case.
using Type = bool;
static constexpr bool SupportsContext() { return false; }
// Generic definition used for BindingSet and AssociatedBindingSet to own a
// collection of bindings which point to the same implementation.
// If |ContextType| is non-void, then every added binding must include a context
// value of that type, and |dispatch_context()| will return that value during
// the extent of any message dispatch targeting that specific binding.
template <typename Interface, typename BindingType, typename ContextType>
class BindingSetBase {
using ContextTraits = BindingSetContextTraits<ContextType>;
using Context = typename ContextTraits::Type;
using PreDispatchCallback = base::Callback<void(const Context&)>;
using Traits = BindingSetTraits<BindingType>;
using ProxyType = typename Traits::ProxyType;
using RequestType = typename Traits::RequestType;
using ImplPointerType = typename Traits::ImplPointerType;
BindingSetBase() : weak_ptr_factory_(this) {}
void set_connection_error_handler(base::RepeatingClosure error_handler) {
error_handler_ = std::move(error_handler);
void set_connection_error_with_reason_handler(
RepeatingConnectionErrorWithReasonCallback error_handler) {
error_with_reason_handler_ = std::move(error_handler);
// Sets a callback to be invoked immediately before dispatching any message or
// error received by any of the bindings in the set. This may only be used
// with a non-void |ContextType|.
void set_pre_dispatch_handler(const PreDispatchCallback& handler) {
"Pre-dispatch handler usage requires non-void context type.");
pre_dispatch_handler_ = handler;
// Adds a new binding to the set which binds |request| to |impl| with no
// additional context.
BindingId AddBinding(ImplPointerType impl, RequestType request) {
"Context value required for non-void context type.");
return AddBindingImpl(std::move(impl), std::move(request), false);
// Adds a new binding associated with |context|.
BindingId AddBinding(ImplPointerType impl,
RequestType request,
Context context) {
"Context value unsupported for void context type.");
return AddBindingImpl(std::move(impl), std::move(request),
// Removes a binding from the set. Note that this is safe to call even if the
// binding corresponding to |id| has already been removed.
// Returns |true| if the binding was removed and |false| if it didn't exist.
bool RemoveBinding(BindingId id) {
auto it = bindings_.find(id);
if (it == bindings_.end())
return false;
return true;
// Swaps the interface implementation with a different one, to allow tests
// to modify behavior.
// Returns the existing interface implementation to the caller.
ImplPointerType SwapImplForTesting(BindingId id, ImplPointerType new_impl) {
auto it = bindings_.find(id);
if (it == bindings_.end())
return nullptr;
return it->second->SwapImplForTesting(new_impl);
void CloseAllBindings() { bindings_.clear(); }
bool empty() const { return bindings_.empty(); }
size_t size() const { return bindings_.size(); }
// Implementations may call this when processing a dispatched message or
// error. During the extent of message or error dispatch, this will return the
// context associated with the specific binding which received the message or
// error. Use AddBinding() to associated a context with a specific binding.
const Context& dispatch_context() const {
"dispatch_context() requires non-void context type.");
return *dispatch_context_;
// Implementations may call this when processing a dispatched message or
// error. During the extent of message or error dispatch, this will return the
// BindingId of the specific binding which received the message or error.
BindingId dispatch_binding() const {
return dispatch_binding_;
// Reports the currently dispatching Message as bad and closes the binding the
// message was received from. Note that this is only legal to call from
// directly within the stack frame of a message dispatch. If you need to do
// asynchronous work before you can determine the legitimacy of a message, use
// GetBadMessageCallback() and retain its result until you're ready to invoke
// or discard it.
void ReportBadMessage(const std::string& error) {
// Acquires a callback which may be run to report the currently dispatching
// Message as bad and close the binding the message was received from. Note
// that this is only legal to call from directly within the stack frame of a
// message dispatch, but the returned callback may be called exactly once any
// time thereafter as long as the binding set itself hasn't been destroyed yet
// to report the message as bad. This may only be called once per message.
// The returned callback must be called on the BindingSet's own sequence.
ReportBadMessageCallback GetBadMessageCallback() {
return base::BindOnce(
[](ReportBadMessageCallback error_callback,
base::WeakPtr<BindingSetBase> binding_set, BindingId binding_id,
const std::string& error) {
if (binding_set)
mojo::GetBadMessageCallback(), weak_ptr_factory_.GetWeakPtr(),
void FlushForTesting() {
is_flushing_ = true;
for (auto& binding : bindings_)
if (binding.second)
is_flushing_ = false;
// Clean up any bindings that were destroyed.
for (auto it = bindings_.begin(); it != bindings_.end();) {
if (!it->second)
it = bindings_.erase(it);
friend class Entry;
class Entry {
Entry(ImplPointerType impl,
RequestType request,
BindingSetBase* binding_set,
BindingId binding_id,
Context context)
: binding_(std::move(impl), std::move(request)),
context_(std::move(context)) {
base::BindOnce(&Entry::OnConnectionError, base::Unretained(this)));
void FlushForTesting() { binding_.FlushForTesting(); }
ImplPointerType SwapImplForTesting(ImplPointerType new_impl) {
return binding_.SwapImplForTesting(new_impl);
class DispatchFilter : public MessageReceiver {
explicit DispatchFilter(Entry* entry) : entry_(entry) {}
~DispatchFilter() override {}
// MessageReceiver:
bool Accept(Message* message) override {
return true;
Entry* entry_;
void WillDispatch() {
binding_set_->SetDispatchContext(&context_, binding_id_);
void OnConnectionError(uint32_t custom_reason,
const std::string& description) {
binding_set_->OnConnectionError(binding_id_, custom_reason, description);
BindingType binding_;
BindingSetBase* const binding_set_;
const BindingId binding_id_;
Context const context_;
void SetDispatchContext(const Context* context, BindingId binding_id) {
dispatch_context_ = context;
dispatch_binding_ = binding_id;
if (!pre_dispatch_handler_.is_null())
BindingId AddBindingImpl(ImplPointerType impl,
RequestType request,
Context context) {
BindingId id = next_binding_id_++;
DCHECK_GE(next_binding_id_, 0u);
auto entry = std::make_unique<Entry>(std::move(impl), std::move(request),
this, id, std::move(context));
bindings_.insert(std::make_pair(id, std::move(entry)));
return id;
void OnConnectionError(BindingId id,
uint32_t custom_reason,
const std::string& description) {
auto it = bindings_.find(id);
DCHECK(it != bindings_.end());
// We keep the Entry alive throughout error dispatch.
std::unique_ptr<Entry> entry = std::move(it->second);
if (!is_flushing_)
if (error_handler_) {
} else if (error_with_reason_handler_) {
error_with_reason_handler_.Run(custom_reason, description);
base::RepeatingClosure error_handler_;
RepeatingConnectionErrorWithReasonCallback error_with_reason_handler_;
PreDispatchCallback pre_dispatch_handler_;
BindingId next_binding_id_ = 0;
std::map<BindingId, std::unique_ptr<Entry>> bindings_;
bool is_flushing_ = false;
const Context* dispatch_context_ = nullptr;
BindingId dispatch_binding_;
base::WeakPtrFactory<BindingSetBase> weak_ptr_factory_;
template <typename Interface, typename ContextType = void>
using BindingSet = BindingSetBase<Interface, Binding<Interface>, ContextType>;
} // namespace mojo