jm + via:jgc   6

Details of the Cloudflare outage on July 2, 2019
Great writeup from jgc. Worth noting some important lessons:

* config changes should be rolled out carefully and gradually, just like code;

* particularly regexps, which are effectively code anyway;

* emergency-use rollback systems need to work, of course!;

* having emergency-only systems is a risk, too, since infrequently-used code paths are likely to atrophy and break without anyone noticing (as nsheridan said);

* /.*/ in a regexp is pretty much always bad news, and would have been worth a linter to catch before commit.
cloudflare  outages  regex  postmortems  regexps  deployment  rollback  via:jgc 
5 weeks ago by jm
Will the madness never end? Komodia SSL certificates are EVERYWHERE
I think that at this point it is safe to assume that any SSL interception product sold by Komodia or based on the Komodia SDK is going to be using the same method. What does this mean? Well, this means that those dodgy certificates aren’t limited to Lenovo laptops sold over a specific date range. It means that anyone who has come into contact with a Komodia product, or who has had some sort of Parental Control software installed on their computer should probably check to see if they are affected.
komodia  via:jgc  ssl  lenovo  parental-control  censorware  mitm 
february 2015 by jm
cloudflare/lua-aho-corasick
A nice Lua/C++ implementation of Aho-Corasick for fast string matching against multiple patterns (via JGC). This uses an interesting technique to get better performance by compacting the data structure into a single buffer, to avoid following pointers all over RAM and busting the cache.
optimization  speed  performance  aho-corasick  tries  string-matching  strings  algorithms  lua  c++  via:jgc 
august 2014 by jm
How the search for flight AF447 used Bayesian inference
Via jgc, the search for the downed Air France flight was optimized using this technique:

'Metron’s approach to this search planning problem is rooted in classical Bayesian inference,
which allows organization of available data with associated uncertainties and computation of the
Probability Distribution Function (PDF) for target location given these data. In following this
approach, the first step was to gather the available information about the location of the impact site
of the aircraft. This information was sometimes contradictory and filled with ambiguities and
uncertainties. Using a Bayesian approach we organized this material into consistent scenarios,
quantified the uncertainties with probability distributions, weighted the relative likelihood of each
scenario, and performed a simulation to produce a prior PDF for the location of the wreck.'
metron  bayes  bayesian-inference  machine-learning  statistics  via:jgc  air-france  disasters  probability  inference  searching 
march 2014 by jm
Computer History Museum: MacPaint and QuickDraw source code
wow, great snapshot of computing history here. just wish the code was not locked away in a ZIP, and instead hyperlinked for readability. Also a working link would be nice too (via jgc)
via:jgc  apple  code  history  mac  source  bill-atkinson  macpaint  pascal  quickdraw  graphics  from delicious
july 2010 by jm

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