| /* | |
| * This program is free software: you can redistribute it and/or modify | |
| * it under the terms of the GNU General Public License as published by | |
| * the Free Software Foundation, either version 3 of the License, or | |
| * (at your option) any later version. | |
| */ | |
| #include <arpa/inet.h> | |
| #include <linux/if_packet.h> | |
| #include <stdio.h> |
The idea is to provide a database as a service to end users in such a way that no one except the user herself can access the data, not even the hosting provider or the database administrator.
L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns
Compress 1K bytes with Zippy ............. 3,000 ns = 3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns = 20 µs
SSD random read ........................ 150,000 ns = 150 µs
Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs
| Latency Comparison Numbers (~2012) | |
| ---------------------------------- | |
| L1 cache reference 0.5 ns | |
| Branch mispredict 5 ns | |
| L2 cache reference 7 ns 14x L1 cache | |
| Mutex lock/unlock 25 ns | |
| Main memory reference 100 ns 20x L2 cache, 200x L1 cache | |
| Compress 1K bytes with Zippy 3,000 ns 3 us | |
| Send 1K bytes over 1 Gbps network 10,000 ns 10 us | |
| Read 4K randomly from SSD* 150,000 ns 150 us ~1GB/sec SSD |
| require 'fiddle' | |
| require 'minitest/autorun' | |
| class RubyVM | |
| class InstructionSequence | |
| address = Fiddle::Handle::DEFAULT['rb_iseq_load'] | |
| func = Fiddle::Function.new(address, [Fiddle::TYPE_VOIDP] * 3, Fiddle::TYPE_VOIDP) | |
| define_singleton_method(:load) do |data, parent = nil, opt = nil| | |
| func.call(Fiddle.dlwrap(data), parent, opt).to_value |
Install Dependencies
npm install --save jquery popper.js tether bootstrap@4.0.0-beta font-awesome // popper.js for bootstrap 4 dependencyCopy font-awesome fonts to assets/static/fonts folder
cp -r assets/node_modules/font-awesome/fonts to assets/static
| defmodule HttpRequester do | |
| use GenServer | |
| def start_link(_) do | |
| GenServer.start_link(__MODULE__, nil, []) | |
| end | |
| def fetch(server, url) do | |
| # Don't use cast: http://blog.elixirsips.com/2014/07/16/errata-dont-use-cast-in-a-poolboy-transaction/ | |
| timeout_ms = 10_000 |
These are the Kickstarter Engineering and Data role definitions for both teams.
| # LVDB - LLOOGG Memory DB | |
| # Copyriht (C) 2009 Salvatore Sanfilippo <antirez@gmail.com> | |
| # All Rights Reserved | |
| # TODO | |
| # - cron with cleanup of timedout clients, automatic dump | |
| # - the dump should use array startsearch to write it line by line | |
| # and may just use gets to read element by element and load the whole state. | |
| # - 'help','stopserver','saveandstopserver','save','load','reset','keys' commands. | |
| # - ttl with milliseconds resolution 'ttl a 1000'. Check ttl in dump! |
Disclaimer: This piece is written anonymously. The names of a few particular companies are mentioned, but as common examples only.
This is a short write-up on things that I wish I'd known and considered before joining a private company (aka startup, aka unicorn in some cases). I'm not trying to make the case that you should never join a private company, but the power imbalance between founder and employee is extreme, and that potential candidates would