<!--
    Licensed to the Apache Software Foundation (ASF) under one
    or more contributor license agreements.  See the NOTICE file
    distributed with this work for additional information
    regarding copyright ownership.  The ASF licenses this file
    to you 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.
-->

This directory contains an example of a Python pipeline that uses Rust DoFns to perform some of the string processing in wordcount. This is performed using [PyO3](https://pyo3.rs/v0.27.2/) to produce bindings for the Rust code, managed using the [maturin](https://github.com/PyO3/maturin) python package.

This example should be built and run in a Python virtual environment with Apache Beam and maturin installed. The `requirements.txt` file in this directory can be used to install the version of maturin used when the example was created.

To build the Rust code, run the following from the wordcount_rust directory:

```bash
cd ./word_processing
maturin develop
```

This will compile the Rust code and build a Python package linked to it in the current environment. The resulting package can be imported as a Python module called `word_processing`.

To execute wordcount locally using the direct runner, execute the following from the wordcount_rust directory within the same virtual environment:

```bash
python wordcount_rust.py --runner DirectRunner --input "*" --output counts.txt
```

To execute wordcount using the Dataflow runner, the tarball of the PyO3 Rust package must be provided to GCP. This is done by building the tarball then providing it as an `extra_package` argument. The tarball can be built using the following command from the wordcount_rust directory:

```bash
cd ./word_processing
python -m build --sdist
```
This places the tarball in `./word_processing/dist` as `word_processing-0.1.0.tar.gz`. Job submission to Dataflow from the `wordcount_rust` directory then looks like the following:

```bash
python wordcount_rust.py --runner DataflowRunner --input gs://apache-beam-samples/shakespeare/*.txt --output gs://<YOUR_BUCKET>/wordcount_rust/counts.txt --project <YOUR_PROJECT> --region <YOUR_REGION> --extra_package ./word_processing/dist/word_processing-0.1.0.tar.gz
```

The job will then execute on Dataflow, installing the Rust package during worker setup. Wordcount will then execute and produce a counts.txt file in the specified output bucket.