kryndex / flight_review

web application for flight log analysis & review

Flight Review

This is a web application for flight log analysis. It allows users to upload ULog flight logs, and analyze them through the browser.

It uses the bokeh library for plotting and the Tornado Web Server.

Flight Review is deployed on https://review.px4.io.

Installation and Setup

• clone the repository
• use python3
• pip3 install bokeh jinja2 pyulog simplekml (at least version 0.12.6 of bokeh is required)
• sudo apt-get install sqlite3
• configure web server config (this can be skipped for a local installation): create a file config_user.ini and copy and adjust the sections and values from config_default.ini that should be overridden.
• ./setup_db.py to initialize the database. This script can also be used to upgrade the DB tables, for instance when new entries are added (it automatically detects that).

Usage

For local usage, the server can be started directly with a log file name, without having to upload it first:

./serve.py -f <file.ulg>

The plot_app directory contains a bokeh server application for plotting. It can be run stand-alone with bokeh serve --show plot_app (or with cd plot_app; bokeh serve --show main.py, to start without the html template).

The whole web application is run with the serve.py script. Run ./serve.py -h for further details.

Interactive Usage

The plotting can also be used interative using a Jupyter Notebook. It requires python knowledge, but provides full control over what and how to plot with immediate feedback.

• pip3 install jupyter
• Start the notebook: jupyter notebook
• open the testing_notebook.ipynb file

Implementation

The web site is structured around a bokeh application in plot_app (plot_app/configured_plots.py contains all the configured plots). This application also handles the statistics page, as it contains bokeh plots as well. The other pages (upload, browse, ...) are implemented as tornado handlers in tornado_handlers.py.

Tornado uses a single-threaded event loop. This means all operations should be non-blocking (see also http://www.tornadoweb.org/en/stable/guide/async.html). (This is currently not the case for sending emails).

Reading ULog files is expensive and thus should be avoided if not really necessary. There are two mechanisms helping with that:

• Loaded ULog files are kept in RAM using an LRU cache with configurable size (when using the helper method). This works from different requests and sessions and from all source contexts.
• There's a LogsGenerated DB table, which contains extracted data from ULog for faster access.

Caching

In addition to in-memory caching there is also some on-disk caching: KML files are stored on disk. Also the parameters and airframes are cached and downloaded every 24 hours. It is safe to delete these files (but not the cache directory).

Notes about python imports

Bokeh uses dynamic code loading and the plot_app/main.py gets loaded on each session (page load) to isolate requests. This also means we cannot use relative imports. We have to use sys.path.append to include modules in plot_app from the root directory (Eg tornado_handlers.py). Then to make sure the same module is only loaded once, we use import xy instead of import plot_app.xy. It's useful to look at print('\n'.join(sys.modules.keys())) to check this.

Contributing

Contributions are welcome! Just open a pull request with detailed description why the changes are needed, or open an issue for bugs, feature requests, etc...