chromium/third_party/mediapipe/src/mediapipe/framework/graph_service.h

// Copyright 2019 The MediaPipe Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#ifndef MEDIAPIPE_FRAMEWORK_GRAPH_SERVICE_H_
#define MEDIAPIPE_FRAMEWORK_GRAPH_SERVICE_H_

#include <memory>
#include <type_traits>
#include <utility>

#include "absl/log/absl_check.h"
#include "absl/strings/str_cat.h"
#include "mediapipe/framework/packet.h"
#include "mediapipe/framework/port/status.h"

namespace mediapipe {

// The GraphService API can be used to define extensions to a graph's execution
// environment. These are, essentially, graph-level singletons, and are
// available to all calculators in the graph (and in any subgraphs) without
// requiring a manual connection.
//
// IMPORTANT: this is an experimental API. Get in touch with the MediaPipe team
// if you want to use it. In most cases, you should use a side packet instead.

class GraphServiceBase { … };

// A global constant to refer a service:
// - Requesting `CalculatorContract::UseService` from calculator
// - Accessing `Calculator/SubgraphContext::Service`from calculator/subgraph
// - Setting before graph initialization `CalculatorGraph::SetServiceObject`
//
// NOTE: In headers, define your graph service reference safely as following:
// `inline constexpr GraphService<YourService> kYourService("YourService");`
//
template <typename T>
class GraphService final : public GraphServiceBase { … };

template <typename T>
class ServiceBinding { … };

}  // namespace mediapipe

#endif  // MEDIAPIPE_FRAMEWORK_GRAPH_SERVICE_H_