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Runner

Lutra runner interface is an abstraction of the execution target of Lutra programs. It defines functions to pass a program from the caller to the callee, provide program inputs and return outputs.

Sequence diagram of the runner interface

Sequence diagram of the runner interface.

All data passed trough the interface is encoded in Lutra binary format.

Interface

Trimmed down for brevity, this the the interface (found in lutra-runner crate):

/// Ability to execute a Lutra program.
trait Run {
    /// Prepares a program for execution and returns a handle, which can be
    /// used with [Run::execute].
    fn prepare(
        &self,
        program: rr::Program,
    ) -> Result<Self::Prepared, Self::Error>;

    /// Execute a prepared program.
    /// Program's format must match the format supported by this runner.
    fn execute(
        &self,
        program: &Self::Prepared,
        input: &[u8],
    ) -> Result<vec::Vec<u8>, Self::Error>;

    /// Return static interface of this runner as Lutra source code.
    ///
    /// Runners can provide implementations for functions that are not part of
    /// standard library. This function returns definitions of these functions as
    /// Lutra source code.
    ///
    /// For example: interpreter can provide `fs::read_parquet(...)`
    /// and PostgreSQL runner can provide `sql::from(...)`.
    fn pull_schema(&self) -> Result<string::String, Self::Error>;
}