// Copyright 2023 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_STREAM_HANDLER_MUX_INPUT_STREAM_HANDLER_H_
#define MEDIAPIPE_FRAMEWORK_STREAM_HANDLER_MUX_INPUT_STREAM_HANDLER_H_
#include <memory>
#include <utility>
#include "absl/synchronization/mutex.h"
#include "mediapipe/framework/calculator_context_manager.h"
#include "mediapipe/framework/calculator_framework.h"
#include "mediapipe/framework/collection_item_id.h"
#include "mediapipe/framework/input_stream_handler.h"
namespace mediapipe {
// Implementation of the input stream handler for the MuxCalculator.
//
// One of the input streams is the control stream; all the other input streams
// are data streams. To make MuxInputStreamHandler work properly, the tag of the
// input streams must obey the following rules:
// Let N be the number of input streams. Data streams must use tag "INPUT" with
// index 0, ..., N - 2; the control stream must use tag "SELECT".
//
// The control stream carries packets of type 'int'. The 'int' value in a
// control stream packet must be a valid index in the range 0, ..., N - 2 and
// select the data stream at that index. The selected data stream must have a
// packet with the same timestamp as the control stream packet.
//
// When the control stream is done, GetNodeReadiness() returns
// NodeReadiness::kReadyForClose.
//
// TODO: pass the input stream tags to the MuxInputStreamHandler
// constructor so that it can refer to input streams by tag. See b/30125118.
class MuxInputStreamHandler : public InputStreamHandler {
public:
MuxInputStreamHandler() = delete;
MuxInputStreamHandler(std::shared_ptr<tool::TagMap> tag_map,
CalculatorContextManager* cc_manager,
const MediaPipeOptions& options,
bool calculator_run_in_parallel)
: InputStreamHandler(std::move(tag_map), cc_manager, options,
calculator_run_in_parallel) {}
private:
CollectionItemId GetControlStreamId() const;
void RemoveOutdatedDataPackets(Timestamp timestamp);
protected:
// In MuxInputStreamHandler, a node is "ready" if:
// - the control stream is done (need to call Close() in this case), or
// - we have received the packets on the control stream and the selected data
// stream at the next timestamp.
NodeReadiness GetNodeReadiness(Timestamp* min_stream_timestamp) override;
// Only invoked when associated GetNodeReadiness() returned kReadyForProcess.
void FillInputSet(Timestamp input_timestamp,
InputStreamShardSet* input_set) override;
private:
// Must be acquired when manipulating the control and data streams to ensure
// we have a consistent view of the two streams.
absl::Mutex input_streams_mutex_;
};
} // namespace mediapipe
#endif // MEDIAPIPE_FRAMEWORK_STREAM_HANDLER_MUX_INPUT_STREAM_HANDLER_H_
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