Class InputContext

• Defined in File io_context.hpp

Derived Type

• public holoscan::gxf::GXFInputContext (Class GXFInputContext)

class InputContext

Class to hold the input context.

This class provides the interface to receive the input data from the operator.

Subclassed by holoscan::gxf::GXFInputContext

Public Functions

inline InputContext(ExecutionContext *execution_context, Operator *op, std::unordered_map<std::string, std::unique_ptr<IOSpec>> &inputs)

Construct a new InputContext object.

Parameters

• execution_context – The pointer to the execution context.

• op – The pointer to the operator that this context is associated with.

• inputs – The references to the map of the input specs.

inline InputContext(ExecutionContext *execution_context, Operator *op)

Construct a new InputContext object.

inputs for the InputContext will be set to op->spec()->inputs()

Parameters

• execution_context – The pointer to GXF execution runtime

• op – The pointer to the operator that this context is associated with.

inline ExecutionContext *execution_context() const

Get pointer to the execution context.

Returns

The pointer to the execution context.

inline Operator *op() const

Return the operator that this context is associated with.

Returns

The pointer to the operator.

inline std::unordered_map<std::string, std::unique_ptr<IOSpec>> &inputs() const

Return the reference to the map of the input specs.

Returns

The reference to the map of the input specs.

inline bool empty(const char *name = nullptr)

Return whether the input port has any data.

For parameters with std::vector<IOSpec*> type, if all the inputs are empty, it will return true. Otherwise, it will return false.

Parameters

name – The name of the input port to check.

Returns

True, if it has no data, otherwise false.

template<typename DataT>
inline holoscan::expected<DataT, holoscan::RuntimeError> receive(const char *name = nullptr)

Receive a message from the input port with the given name.

If the operator has a single input port, the name of the input port can be omitted.

If the input port with the given name and type (DataT) is available, it will return the data from the input port. Otherwise, it will return an object of the holoscan::unexpected class which will contain the error message. The error message can be access by calling the what() method of the holoscan::unexpected object.

Example:

Copy

Copied!

            

            
class PingRxOp : public holoscan::ops::GXFOperator {
 public:
  HOLOSCAN_OPERATOR_FORWARD_ARGS_SUPER(PingRxOp, holoscan::ops::GXFOperator)

  PingRxOp() = default;

  void setup(OperatorSpec& spec) override {
    spec.input<std::shared_ptr<ValueData>>("in");
  }

  void compute(InputContext& op_input, OutputContext&, ExecutionContext&) override {
    auto value = op_input.receive<std::shared_ptr<ValueData>>("in");
    if (value.has_value()) {
      HOLOSCAN_LOG_INFO("Message received (value: {})", value->data());
    }
  }
};
        

Template Parameters

DataT – The type of the data to receive.

Parameters

name – The name of the input port to receive the data from.

Returns

The received data.

Protected Functions

inline virtual bool empty_impl(const char *name = nullptr)

The implementation of the empty method.

Parameters

name – The name of the input port

Returns

True if the input port is empty or by default. Otherwise, false.

inline virtual std::any receive_impl(const char *name = nullptr, bool no_error_message = false)

The implementation of the receive method.

Depending on the type of the data, this method receives a message from the input port with the given name.

Parameters

• name – The name of the input port.

• no_error_message – Whether to print an error message when the input port is not found.

Returns

The data received from the input port.

Protected Attributes

ExecutionContext *execution_context_ = nullptr

The execution context that is associated with.

Operator *op_ = nullptr

The operator that this context is associated with.

std::unordered_map<std::string, std::unique_ptr<IOSpec>> &inputs_

The inputs.