Upgrade to Pro
— share decks privately, control downloads, hide ads and more …
Speaker Deck
Features
Speaker Deck
PRO
Sign in
Sign up for free
Search
Search
Knee-Deep Into P2P: A Tale of Fail (non-Elixir)
Search
Fernando Mendes
March 07, 2018
Programming
0
170
Knee-Deep Into P2P: A Tale of Fail (non-Elixir)
The slides for my talk at Lambda Days 2018 (
www.lambdadays.org/lambdadays2018
)
Fernando Mendes
March 07, 2018
Tweet
Share
More Decks by Fernando Mendes
See All by Fernando Mendes
you. and the morals of technology
fribmendes
1
130
Knee-Deep Into P2P: A Tale of Fail (PWL Porto)
fribmendes
0
57
Knee-Deep Into P2P: A Tale of Fail (ElixirConf EU 2018 version)
fribmendes
0
150
A Look Into Bloom Filters
fribmendes
0
400
Bloom Filters: A Look Into Ruby
fribmendes
0
110
Programming WTF: HTML & CSS
fribmendes
4
150
Ruby: A (pointless) Workshop
fribmendes
1
160
Elixir: A Talk For College Students
fribmendes
0
160
Riding Rails
fribmendes
0
100
Other Decks in Programming
See All in Programming
FormFlow - Build Stunning Multistep Forms
yceruto
1
190
データベースコネクションプール(DBCP)の変遷と理解
fujikawa8
1
270
すべてのコンテキストを、 ユーザー価値に変える
applism118
2
410
社内での開発コミュニティ活動とモジュラーモノリス標準化事例のご紹介/xPalette and Introduction of Modular monolith standardization
m4maruyama
1
130
Javaに鉄道指向プログラミング (Railway Oriented Pro gramming) のエッセンスを取り入れる/Bringing the Essence of Railway-Oriented Programming to Java
cocet33000
2
580
Datadog RUM 本番導入までの道
shinter61
1
310
コードの90%をAIが書く世界で何が待っているのか / What awaits us in a world where 90% of the code is written by AI
rkaga
41
28k
ドメインモデリングにおける抽象の役割、tagless-finalによるDSL構築、そして型安全な最適化
knih
11
1.9k
Create a website using Spatial Web
akkeylab
0
290
Webの外へ飛び出せ NativePHPが切り拓くPHPの未来
takuyakatsusa
1
170
WindowInsetsだってテストしたい
ryunen344
1
190
Railsアプリケーションと パフォーマンスチューニング ー 秒間5万リクエストの モバイルオーダーシステムを支える事例 ー Rubyセミナー 大阪
falcon8823
1
530
Featured
See All Featured
Mobile First: as difficult as doing things right
swwweet
223
9.7k
The Straight Up "How To Draw Better" Workshop
denniskardys
233
140k
jQuery: Nuts, Bolts and Bling
dougneiner
63
7.8k
Code Review Best Practice
trishagee
68
18k
Product Roadmaps are Hard
iamctodd
PRO
53
11k
Helping Users Find Their Own Way: Creating Modern Search Experiences
danielanewman
29
2.7k
Visualizing Your Data: Incorporating Mongo into Loggly Infrastructure
mongodb
46
9.6k
Site-Speed That Sticks
csswizardry
10
650
The World Runs on Bad Software
bkeepers
PRO
69
11k
Done Done
chrislema
184
16k
Typedesign – Prime Four
hannesfritz
42
2.7k
CSS Pre-Processors: Stylus, Less & Sass
bermonpainter
357
30k
Transcript
Knee-Deep Into P2P A Tale of Fail @fribmendes
Knee-Deep Into P2P A Tale of Fail @fribmendes
“This is SOOO boring…” - me, circa last year or
smth
None
None
None
“This is SOOO boring…” - me, 10 months ago
None
None
None
None
None
“ ” - me, whenever I get to play with
distributed systems
None
I don’t know how to smart office
I know how to web development
I know how to web development … what now?
None
Step 1: receive new connections
Step 1: receive new connections Step 2: accept and send
messages
Step 1: receive new connections Step 2: accept and send
messages Step 3: do a bunch of Steps 1 and 2
Step 1: receive new connections
None
defmodule Gossip.Server do def listen(pid, port) do {:ok, server_socket} =
:gen_tcp.listen(port, @socket_opts) accept_loop(pid, server_socket) end defp accept_loop(pid, server_socket) do {:ok, client} = :gen_tcp.accept(server_socket) :inet.setopts(client, [active: true]) :gen_tcp.controlling_process(client, pid) Gossip.accept(pid, client) accept_loop(pid, server_socket) end end
defmodule Gossip.Server do def listen(pid, port) do {:ok, server_socket} =
:gen_tcp.listen(port, @socket_opts) accept_loop(pid, server_socket) end defp accept_loop(pid, server_socket) do {:ok, client} = :gen_tcp.accept(server_socket) :inet.setopts(client, [active: true]) :gen_tcp.controlling_process(client, pid) Gossip.accept(pid, client) accept_loop(pid, server_socket) end end
Step 1: receive new connections Step 2: accept and send
messages
None
defmodule Gossip.Worker do def recv_loop(pid, socket) do continue = receive
do {:tcp, _port, msg} -> Gossip.recv(pid, msg) true {:tcp_closed, port} -> :gen_tcp.close(port) Gossip.disconnect(pid, self()) false {:send, msg} -> :gen_tcp.send(socket, msg) true end continue and recv_loop(pid, socket) end end
defmodule Gossip.Worker do def recv_loop(pid, socket) do continue = receive
do {:tcp, _port, msg} -> Gossip.recv(pid, msg) true {:tcp_closed, port} -> :gen_tcp.close(port) Gossip.disconnect(pid, self()) false {:send, msg} -> :gen_tcp.send(socket, msg) true end continue and recv_loop(pid, socket) end end
Step 1: receive new connections Step 2: accept and send
messages Step 3: do a bunch of Steps 1 and 2
Raspberry Pi #1 Raspberry Pi #2
None
None
“Does it scale?”
None
Time to copy off the internet find a creative solution
None
g
Gnutella
Gnutella
Gnutella
Gnutella
Gnutella
g (gnutella2)
Gnutella
G2/Gnutella2
G2/Gnutella2
G2/Gnutella2
G2/Gnutella2
None
None
None
None
None
HyParView
None
None
None
None
None
None
Plumtrees
Optimal number of messages
But you can’t afford to lose nodes
None
None
None
None
None
None
None
None
None
None
“Aha! It works on my computer!”
“Great but we need something to show”
“Great but we need something to show” (aka Raspberry Pi
time)
“Sure. Seems legit…” — @iampfac
“Wait. He works here!?” — @naps62
“Hey, I can borrow™ someone else’s code”
None
None
None
you shall not pass!
Solution: stick everything on Raspberry Pi’s
Things running on one Raspberry Pi
Things running on one Raspberry Pi ✓BEAM
Things running on one Raspberry Pi ✓BEAM ✓thebox (sensors)
Things running on one Raspberry Pi ✓BEAM ✓thebox (sensors) ✓Phoenix
app
Things running on one Raspberry Pi ✓BEAM (x2) ✓thebox (sensors)
✓Phoenix app
Things running on one Raspberry Pi ✓BEAM (x2) ✓thebox (sensors)
✓Phoenix app ✓Postgres
Things running on one Raspberry Pi ✓BEAM (x2) ✓thebox (sensors)
✓Phoenix app ✓Postgres ✓Cassandra
Things running on one Raspberry Pi ✓BEAM (x2) ✓thebox (sensors)
✓Phoenix app ✓Postgres ✓Cassandra it works!
None
None
@antenna = Satellite::Antenna.new(host, port) @antenna.on(“data") do |data| if data.avg_temp >
25 slack.send_msg(“people, it's too hot") end end @antenna.on("lights") do |payload, data| payload == "on" ? turn_lights_on : turn_lights_off end @antenna.watch
“Looking good! Everything’s working!”
None
State of each node:
State of each node: • Last sensor readings
State of each node: • Last sensor readings • Network
map (MAC-IP)
State of each node: • Last sensor readings • Network
map (MAC-IP) • Target values
State of each node: • Last sensor readings • Network
map (MAC-IP) • Target values
None
How do we handle concurrency?
None
None
No database locks. No transactions. You’re on your own, kiddo.
Vector Clocks
None
None
None
None
None
None
None
Shared state and why it sucks
Vector = (1, 0) Vector = (0, 1)
CAP Theorem
CAP Theorem “you’re a programmer. you can’t have nice things.”
consistency availability partitioning
consistency availability partitioning
Eventual Consistency
CRDTs
Operation-Based CRDT
Operation-Based CRDT commutative but not idempotent update exactly once
no CRDTs
no CRDTs
no CRDTs
no CRDTs
Op-based CRDTs
Op-based CRDTs
Op-based CRDTs
Op-based CRDTs
State-Based CRDT
State-Based CRDT commutative and idempotent heavier on the network
State-based CRDTs
State-based CRDTs
State-based CRDTs
State-based CRDTs
None
None
None
None
None
None
None
Wrapping up
System resources matter
System resources matter your algorithms should account for them
There are models. Use them.
Distributed System Checklist
Distributed System Checklist •Is the number of processes known or
finite?
Distributed System Checklist •Is the number of processes known or
finite? •Is there a global notion of time?
Distributed System Checklist •Is the number of processes known or
finite? •Is there a global notion of time? •Is the network reliable?
Distributed System Checklist •Is the number of processes known or
finite? •Is there a global notion of time? •Is the network reliable? •Is there full connectivity?
Distributed System Checklist •Is the number of processes known or
finite? •Is there a global notion of time? •Is the network reliable? •Is there full connectivity? •What happens when a process crashes?
It really doesn’t change that much
CRDTs aren’t a golden hammer
Reinventing the wheel is stupid
None
Knee-Deep Into P2P A Tale of Fail @fribmendes