Maximilian Antoni mantoni

Configure Synology NAS as Git Server

Instructions for setting up a git server on a Synology NAS with Diskstation. Specifically, I am using a DS414 with DSM 5.0.

Set Up User and Folder

Create user gituser via Diskstation interface (with File Station and WebDAV privilages)
Add new shared folder called git (located at /volume1/git) with read/write access for gituser and admin. This folder will hold all the repos.
Install Git Server package via Diskstation

Approximating the median of a Stream via stochastic averaging

Often it is useful to have access to the median value for fields of a data stream since they are more robust with respect to outliers. The median is defined as the value of a dataset such that, when sorted, 50% of the data is smaller than the value and 50% of the data is larger then the value. Ordinarily this is difficult to calculate on a stream because it requires the collection and sorting of all data.

The median of a data stream can be approximated with a technique called stochastic averaging. To approximate the median value of a data stream one could use the following approach:

Given the current estimate of the median M. If the next observed value in the stream is larger than M, increase the current estimate by r (= the learning rate). If it is smaller, decrease the estimate by r. When M is close to the median, it increases as often as it decreases, and therefore it stabilizes.

This approach was taken from the book "Real-time Analytics -

Running statistics with Redis and Lua

This is an example for computing running statistics with Lua backed by a hash in Redis. We support counting, average (with and without exponential smoothing), stddev, variance, min, max, sum of observed values. An example for approximating a running median can be found here: https://gist.github.com/thomasdarimont/fff68191d45a001b2d84

Data structure

We use a hash for storing various statistic value under the key "stats_value" in redis. Note: If you need a specific alpha value for smoothing the average, then set the desired alpha -> e.g. alpha 0.7. If alpha is 0.0 then no smoothing is applied.

Multipart MIME Email Guide

This is a guide on how to send a properly formatted multipart email. Multipart email strings are MIME encoded, raw text email templates. This method of structuring an email allows for multiple versions of the same email to support different email clients.

// Example Multipart Email:
From: [email protected]
To: [email protected]
Subject: Multipart Email Example
Content-Type: multipart/alternative; boundary="boundary-string"

	const reg = new RegExp("([^?=&]+)(=([^&]*))?", "g")

	function qs (uri) {
	const obj = {}
	uri = uri.replace(/^.*\?/, '')
	uri.replace(reg, map)
	return obj

	function map (a0, a1, a2, a3) {
	obj[decodeURIComponent(a1)] = decodeURIComponent(a3)