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Development documentation

This documentation provides guidance on developer workflows for working with the code in this repository.

Code organization

This repository is split up into two main modules:

  1. src/client
  2. src/job_attachments

The src/client organization is laid out below.

For more information on job attachments, see here.

src/client/api

This submodule contains utilities to call boto3 in a standardized way using an aws profile configured for AWS Deadline Cloud, helpers for working with the AWS Deadline Cloud monitor login/logout, and objects representing AWS Deadline Cloud resources.

src/client/cli

This submodule contains entry points for the CLI applications provided by the library.

src/client/config

This submodule contains an interface to the machine-specific AWS Deadline Cloud configuration, specifically settings stored in ~/.deadline/*

src/client/ui

This submodule contains Qt GUIs, based on PySide(2/6), for common controls and widgets used in interactive submitters, and to display the status of various AWS Deadline Cloud resources.

src/client/job_bundle

This submodule contains code related to the history of job submissions performed on the workstation. Its initial functionality is to create job bundle directories in a standardized manner.

Build / Test / Release

Build the package.

hatch build

Run tests

hatch run test

Run integration tests

hatch run integ:test

Run linting

hatch run lint

Run formating

hatch run fmt

Run tests for all supported Python versions.

hatch run all:test

Qt and Calling AWS (including AWS Deadline Cloud) APIs

TL;DR Never call an AWS API from the main Qt event loop. Always run it in a separate thread, and use a Signal/Slot to send the result back to GUI widget that needs an update. The code in the separate thread should watch a boolean flag indicating whether to abandon its work.

AWS APIs, while often quick, can be very slow sometimes. When calling to a distant region, they can consistently have very high latency.

In Qt, event handling happens in the process's main thread that is running an event loop. If code performs a slow operation, such as calling an AWS API, that blocks all interactivity with the GUI.

We can maintain GUI interactivity by running these slow operations in a separate thread. If the separate thread, however, directly modifies the GUI, this can produce crashes or undefined behavior. Therefore, the only way the results of these operations should be consumed is by emitting a Qt Signal from the thread, and consuming it in the Widget.

Another detail is that threads need to finish running before the process can exit. If an operation in a thread continues indefinitely, this will block program exit, so it should watch for a signal from the application.

If interacting with the GUI can start multiple background threads, you should also track which is the latest, so the code only applies the result of the newest operation.

See deadline_config_dialog.py for some examples that do all of the above. Here's some code that was edited to show how it fits together:

class MyCustomWidget(QWidget):
   # Signals for the widget to receive from the thread
   background_exception = Signal(str, BaseException)
   update = Signal(int, BackgroundResult)

   def __init__(self, ...):
      # Save information about the thread
      self.__refresh_thread = None
      self.__refresh_id = 0

      # Set this to True when exiting
      self.canceled = False

      # Connect the Signals to handler functions that run on the main thread
      self.update.connect(self.handle_update)
      self.background_exception.connect(self.handle_background_exception)

    def closeEvent(self, event):
      # Tell background threads when the widget closes
      self.canceled = True
      event.accept()

   def handle_background_exception(self, e: BaseException):
      # Handle the error
      QMessageBox.warning(...)

   def handle_update(self, refresh_id: int, result: BackgroundResult):
      # Apply the refresh if it's still for the latest call
      if refresh_id == self.__refresh_id:
         # Do something with result
         self.result_widget.set_message(result)

    def start_the_refresh(self):
        # This function starts the thread to run in the background

        # Update the GUI state to reflect the update
        self.result_widget.set_refreshing_status(True)

        self.__refresh_id += 1
        self.__refresh_thread = threading.Thread(
            target=self._refresh_thread_function,
            name=f"AWS Deadline Cloud Refresh Thread",
            args=(self.__refresh_id,),
        )
        self.__refresh_thread.start()

   def _refresh_thread_function(self, refresh_id: int):
      # This function is for the background thread
      try:
         # Call the slow operations
         result = boto3_client.potentially_expensive_api(...)
         # Only emit the result if it isn't canceled
         if not self.canceled:
            self.update.emit(refresh_id, result)
      except BaseException as e:
         # Use multiple signals for different meanings, such as handling errors.
         if not self.canceled:
            self.background_exception.emit(f"Background thread error", e)

We recommend you set up your runtimes via mise.

Running Docker-based Unit Tests

  • Some of the unit tests in this package require a docker environment to run. These tests are marked with @pytest.mark.docker. In order to execute these tests, please run the run_sudo_tests.sh script located in the scripts directory. For detailed instructions, please refer to scripts/README.md.
  • If you make changes to the download or asset_sync modules, it's highly recommended to run and ensure these tests pass.