Stack Overflow notifier

The app notifies about new questions from Stack Overflow. It does that querying the Stack Overflow API: fetch a new question every minute and send a notification about new questions only.

The algorithm

Question IDs are incremental, that makes finding new questions an easy task. The notification algorithm uses two vectors and one u32 number containing the latest question ID that is stored between runs.

It is meant to be running in a loop and execute the following steps:

Get latest 10 questions of a particular tag
Save them into an vector of a freshly retrieved records
Copy new records (those IDs are greater than the latest question ID) into another vector of new questions
- if the latest question id equals to its initial value of u32::MAX (means it's the first run), no new questions would be collected
Go through the new questions and send notifications
Update the value of the latest question ID
Wait one minute before continuing the loop

Build

Make sure libssl-dev is installed

# for Ubuntu
sudo apt install libssl-dev

Run it from source with Rust installed

cargo run -- stackoverflow_question_tag

You have to specify a question tag for the questions you are interested in. For example, the tag can be rust.

See also the next section to run the app with an API key

Install and run

Being in the project's directory, run

cargo install --path .

By default, the binary goes to .cargo/bin/so_notifier in your home directory.

Run it as any other binary with the following command

~/.cargo/bin/so_notifier stackoverflow_question_tag

Also, don't forget to export the auth key if you want a decent API request limit (see The API and throttle).

# ~/.profile
export SO_NOTIFY_AUTH_KEY='<the key>'

Logging

The installed version uses syslog for logging. By default, the messages are going to /var/log/syslog. You can extract the messages using grep.

For example

grep so_notifier /var/log/syslog | tail

Logging to a separate file

On Linux:

Add the following line to /etc/rsyslog.conf:

local1.info /var/log/so_notifier.log

Restart the service

sudo service rsyslog restart

Autostart

An autostart has to be done after the window system starts, so use your window manager autostart facilities. Some sample instructions:

Gnome

Since the binary is placed in a hidden directory, you may need to copy the path from Install and run section.

For Gnome, go to the applications list, search for Startup Applications Preferences. Create a new startup entry and use an absolute path (this is important).

The API and throttle

The Stackexchange API applies number of throttles, so to use this app in full, follow these instructions:

Do not execute the same API query more often than once a minute. This app has one minute timeout hardcoded for now. You can increase it, but do not decrease.
By default, quota number is only 300 requests. That is enough to try, but not enough if you want the app to run for some significant time. To increase quota, you would need a Stackexchange application key. To obtain the key, register your application. You can set OAuth Domain to localhost, and Client Side OAuth Flow is not needed. Once it's registered, get Key from the page with the application credentials.

You can find all registered applications on Your Apps page.

denispeplin/so_notifier