lbarasti’s gists

lbarasti / des.cr

Last active January 20, 2021 16:44

Playing with queues and Discrete-Event Simulations in Crystal

	require "statistics"
	require "tablo"
	extend Statistics::Distributions

	# Launches a DES that will halt once the simulation's time exceeds `max_t`
	def simulate(nodes : Array(Node), max_t : Int32)
	t = 0_f64

	loop do
	next_node = nodes.map { \|a\| {a, a.next(t) \|\| Float64::MAX} }

lbarasti / normal_distribution.cr

Last active May 4, 2020 14:13

Sampling random variables and plotting histograms in Crystal

	require "statistics"
	require "ishi"
	require "tablo"

	include Statistics::Distributions

	# Turns a named tuple into tabular representation
	def table(data : NamedTuple)
	Tablo::Table.new(data.map { \|k, v\| [k, v] }, header_frequency: nil) { \|t\|
	t.add_column("coefficient") { \|n\| n[0] }

lbarasti / select_heartbeat.cr

Created May 2, 2020 23:37

select use case 5: Heartbeats

	def log(msg)
	puts "#{Fiber.current.name}: #{msg}"
	end

	record Heartbeat, id : UInt64 = Fiber.current.object_id
	Diagnostic = Channel(Heartbeat).new

	diagnostic_enabled = true # tweak this value

	if diagnostic_enabled

lbarasti / select_pipeline.cr

Created May 2, 2020 23:43

select use case 4: dealing with back-pressure

	def producer(name : String, &generator : -> T) forall T
	Channel(T).new.tap { \|ch\|
	spawn(name: name) do
	loop do
	ch.send generator.call
	end
	end
	}
	end

lbarasti / select_with_timeout.cr

Last active May 2, 2020 23:49

select use case 3: timeout on async calls

	def log(msg)
	puts "#{Fiber.current.name}: #{msg}"
	end

	Cache = Hash(Symbol, Float64?).new

	def get_stock_price_async(sym : Symbol) : Channel(Float64)
	Channel(Float64).new.tap { \|ch\|
	spawn do
	sleep rand

lbarasti / select_send_receive.cr

Created May 2, 2020 23:50

use case 2: mixing send and receive

	def producer(name : String, &generator : -> T) forall T
	Channel(T).new.tap { \|ch\|
	spawn(name: name) do
	loop do
	ch.send generator.call
	end
	end
	}
	end

lbarasti / select_terminate.cr

Created May 2, 2020 23:54

select use case 1: graceful termination

	def producer(name : String, &generator : -> T) forall T
	Channel(T).new.tap { \|ch\|
	spawn(name: name) do
	loop do
	ch.send generator.call
	end
	end
	}
	end

lbarasti / launch.json

Created July 14, 2020 09:30

VS code config for Crystal projects - includes tasks to run and debug the current file

	{
	"version": "0.2.0",
	"configurations": [
	{
	"type": "lldb",
	"request": "launch",
	"name": "crystal: debug current file",
	"preLaunchTask": "crystal: build current file (debug)",
	"program": "${workspaceFolder}/bin/${fileBasenameNoExtension}",
	"args": [],

lbarasti / components.rb

Created January 27, 2021 21:51

Source code for https://lbarasti.com/post/ruby_ractor

	def source(generator, target:, name: nil)
	Ractor.new(generator, target, name: name) do \|generator, target\|
	loop do
	target.send generator.next
	end
	end
	end

	def buffer
	Ractor.new do

lbarasti / cve_records.cr

Created September 14, 2021 14:41

	require "json"

	# https://csrc.nist.gov/schema/nvd/feed/1.1/nvd_cve_feed_json_1.1.schema
	record CVE_Response, resultsPerPage : Int32, startIndex : Int32,
	totalResults : Int32, result : CVE_Result do
	include JSON::Serializable
	end

	record CVE_Result, cve_data_type : String, cve_data_format : String,
	cve_data_version : String, cve_data_numberOfCVEs : String?,

Lorenzo Barasti lbarasti