tools/fidl/fidlgen_llcpp/codegen/fragment_protocol_event_handler.tmpl

{{/*
// Copyright 2021 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
*/}}

{{- define "Protocol:EventHandler:WireMessagingHeader" }}
{{- EnsureNamespace "" }}
{{- IfdefFuchsia }}
template<>
class {{ .WireEventHandlerInterface }} {
public:
  {{ .WireEventHandlerInterface.Self }}() = default;
  virtual ~{{ .WireEventHandlerInterface.Self }}() = default;
  {{- range .Events -}}
    {{- .Docs }}
    virtual void {{ .Name }}({{ .WireEvent }}* event) = 0;
  {{- end }}
};

template<>
class {{ .WireAsyncEventHandler }}
    : public {{ .WireEventHandlerInterface }}, public ::fidl::internal::AsyncEventHandler {
 public:
  {{ .WireAsyncEventHandler.Self }}() = default;
  {{- range .Events -}}
    {{- .Docs }}
    void {{ .Name }}({{ .WireEvent }}* event) override {}
  {{- end }}
};

template<>
class {{ .WireSyncEventHandler }} : public {{ .WireEventHandlerInterface }} {
 public:
  {{ .WireSyncEventHandler.Self }}() = default;

  {{- range .Events }}
    {{- if .Transitional }}
      void {{ .Name }}({{ .WireEvent }}* event) override { got_transitional_ = true; }
    {{- end }}
  {{- end }}

  // Handle all possible events defined in this protocol.
  // Blocks to consume exactly one message from the channel, then call the corresponding virtual
  // method.
  ::fidl::Status HandleOneEvent(
      ::{{ .Transport.Namespace }}::UnownedClientEnd<{{ . }}> client_end);

 private:
  [[maybe_unused]]
  bool got_transitional_ = false;
};

template <>
class {{ .WireEventDispatcher }} final :
    public ::fidl::internal::IncomingEventDispatcher<{{ .WireAsyncEventHandler }}> {
 public:
  explicit {{ .WireEventDispatcher.Self }}({{ .WireAsyncEventHandler }}* event_handler)
      : IncomingEventDispatcher(event_handler) {}

 private:
  std::optional<::fidl::UnbindInfo> DispatchEvent(
      ::fidl::IncomingMessage& msg,
      ::fidl::internal::IncomingTransportContext transport_context) override;
};
{{- EndifFuchsia }}
{{- end }}



{{- define "Protocol:EventHandler:WireMessagingSource" }}
{{ EnsureNamespace "" }}
{{- IfdefFuchsia }}
{{ if .Transport.HasEvents }}
::fidl::Status {{ .WireSyncEventHandler.NoLeading }}::HandleOneEvent(
    ::{{ .Transport.Namespace }}::UnownedClientEnd<{{ . }}> client_end) {
  zx_status_t status = client_end.channel()->wait_one(ZX_CHANNEL_READABLE | ZX_CHANNEL_PEER_CLOSED,
                                                      ::zx::time::infinite(),
                                                      nullptr);
  if (status != ZX_OK) {
    return ::fidl::Status::TransportError(status, ::fidl::internal::kErrorWaitOneFailed);
  }
  constexpr uint32_t kHandleAllocSize = ([]() constexpr {
    uint32_t x = 0;
    {{- range .Events }}
    if (::fidl::TypeTraits<{{ .WireTransactionalEvent }}>::kMaxNumHandles >= x) {
      x = ::fidl::TypeTraits<{{ .WireTransactionalEvent }}>::kMaxNumHandles;
    }
    {{- end }}
    if (x > ZX_CHANNEL_MAX_MSG_HANDLES) {
      x = ZX_CHANNEL_MAX_MSG_HANDLES;
    }
    return x;
  })();
  static_assert(kHandleAllocSize <= ZX_CHANNEL_MAX_MSG_HANDLES);
  {{ .SyncEventAllocationV1.BackingBufferType }} read_storage;
  std::array<zx_handle_t, kHandleAllocSize> read_handles;
  // TODO(fxbug.dev/85734) Remove this channel-specific allocation.
  std::array<fidl_channel_handle_metadata_t, kHandleAllocSize> read_handle_metadata;
  ::fidl::IncomingMessage msg = ::fidl::MessageRead(
      zx::unowned_channel(client_end.handle()),
      read_storage.view(),
      read_handles.data(),
      read_handle_metadata.data(),
      kHandleAllocSize,
      ReadOptions{.discardable = true}
  );
  if (msg.status() == ZX_ERR_BUFFER_TOO_SMALL) {
    // Message size is unexpectedly larger than calculated.
    // This can only be due to a newer version of the protocol defining a new event,
    // whose size exceeds the maximum of known events in the current protocol.
    return ::fidl::Status::UnexpectedMessage(
        ZX_ERR_BUFFER_TOO_SMALL, ::fidl::internal::kErrorSyncEventBufferTooSmall);
  }
  if (!msg.ok()) {
    return msg;
  }
  fidl_message_header_t* hdr = msg.header();
  switch (hdr->ordinal) {
  {{- range .Events }}
    case {{ .OrdinalName }}: {
      ::fidl::unstable::DecodedMessage<{{ .WireTransactionalEvent }}> decoded{::std::move(msg)};
      if (!decoded.ok()) {
        return ::fidl::Status(decoded);
      }
      {{- if .ResponseArgs }}
      auto* primary = &decoded.PrimaryObject()->body;
      {{- else }}
      {{ .WireEvent }} empty_event;
      auto* primary = &empty_event;
      {{- end }}
      got_transitional_ = false;
      {{ .Name }}(primary);
      if (got_transitional_) {
        return ::fidl::Status::UnexpectedMessage(
            ZX_ERR_NOT_SUPPORTED, ::fidl::internal::kErrorSyncEventUnhandledTransitionalEvent);
      }
      return ::fidl::Status::Ok();
    }
  {{- end }}
    default: {
      return ::fidl::Status::UnknownOrdinal();
    }
  }
}

std::optional<::fidl::UnbindInfo>
{{ .WireEventDispatcher.NoLeading }}::DispatchEvent(
    ::fidl::IncomingMessage& msg,
    ::fidl::internal::IncomingTransportContext transport_context) {
  switch (msg.header()->ordinal) {
  {{- range .Events }}
    case {{ .OrdinalName }}:
    {
      ::fidl::unstable::DecodedMessage<{{ .WireTransactionalEvent }}> decoded{std::move(msg)};
      if (!decoded.ok()) {
        return ::fidl::UnbindInfo{decoded};
      }
      if (event_handler()) {
        {{- if .ResponseArgs }}
        auto* primary = &decoded.PrimaryObject()->body;
        {{- else }}
        {{ .WireEvent }} empty_event;
        auto* primary = &empty_event;
        {{- end }}
        event_handler()->{{ .Name }}(primary);
      }
      return std::nullopt;
    }
  {{- end }}
    default:
      break;
  }
  return ::fidl::UnbindInfo::UnknownOrdinal();
}

{{- else }}{{/* not .Transport.HasEvents */}}
::fidl::Status {{ .WireSyncEventHandler.NoLeading }}::HandleOneEvent(
    ::{{ .Transport.Namespace }}::UnownedClientEnd<{{ . }}> client_end) {
      ZX_PANIC("events not supported for transport '{{ .Transport.Name }}'");
}
std::optional<::fidl::UnbindInfo>
{{ .WireEventDispatcher.NoLeading }}::DispatchEvent(
    fidl::IncomingMessage& msg,
    internal::IncomingTransportContext transport_context) {
      ZX_PANIC("events not supported for transport '{{ .Transport.Name }}'");
}
{{- end }}
{{- EndifFuchsia }}
{{- end }}



{{- define "Protocol:EventHandler:NaturalMessagingHeader" }}
{{- EnsureNamespace "" }}
{{- IfdefFuchsia }}
template<>
class {{ .NaturalEventHandlerInterface }} {
 public:
  {{ .NaturalEventHandlerInterface.Self }}() = default;
  virtual ~{{ .NaturalEventHandlerInterface.Self }}() = default;
  {{- range .Events -}}
    {{- .Docs }}
    virtual void {{ .Name }}({{ .NaturalEvent }}&) = 0;
  {{- end }}
};

template<>
class {{ .NaturalAsyncEventHandler }}
    : public {{ .NaturalEventHandlerInterface }}, public ::fidl::internal::AsyncEventHandler {
 public:
  {{ .NaturalAsyncEventHandler.Self }}() = default;

  {{- range .Events -}}
    {{- .Docs }}
    void {{ .Name }}({{ .NaturalEvent }}&) override {}
  {{- end }}
};

template <>
class {{ .NaturalEventDispatcher }} final :
    public ::fidl::internal::IncomingEventDispatcher<{{ .NaturalAsyncEventHandler }}> {
 public:
  explicit {{ .NaturalEventDispatcher.Self }}({{ .NaturalAsyncEventHandler }}* event_handler)
      : IncomingEventDispatcher(event_handler) {}

 private:
  std::optional<::fidl::UnbindInfo> DispatchEvent(
      ::fidl::IncomingMessage& msg,
      internal::IncomingTransportContext transport_context) override;
};
{{- EndifFuchsia }}
{{- end }}



{{- define "Protocol:EventHandler:NaturalMessagingSource" }}
{{- EnsureNamespace "" }}
{{- IfdefFuchsia }}
std::optional<::fidl::UnbindInfo>
{{ .NaturalEventDispatcher.NoLeading }}::DispatchEvent(
    ::fidl::IncomingMessage& msg,
    ::fidl::internal::IncomingTransportContext transport_context) {
  {{- if .Events }}
  switch (msg.header()->ordinal) {
  {{- range .Events }}
    case {{ .OrdinalName }}:
    {
      ::fitx::result decoded = ::fidl::internal::DecodeTransactionalMessage
            {{- if .HasResponsePayload }}<{{ .ResponsePayload }}>{{ end -}}(std::move(msg));
      if (decoded.is_error()) {
        return ::fidl::UnbindInfo(decoded.error_value());
      }
      if (event_handler()) {
        {{ .NaturalEvent }} event
        {{- if .HasResponsePayload }}
            = {{ .NaturalEventConverter }}::FromDomainObject(std::move(decoded.value()))
        {{- end }};
        event_handler()->{{ .Name }}(event);
      }
      return std::nullopt;
    }
  {{- end }}
    default:
      break;
  }
  {{- end }}
  return ::fidl::UnbindInfo::UnknownOrdinal();
}

{{- EndifFuchsia }}
{{- end }}