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Advanced Distributed System Design Course - Udi Dahan

Notes by Craig Phillips

Fallacies of Distributed Computing

• There are 11 fallacies of Distributed Computing:
  1. The network is reliable
  2. Latency isn’t a problem
  3. Bandwidth isn’t a problem
  4. The network is secure

5. The topology won’t change

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Filling an array or slice with a repeated pattern

Looking for an efficient pure GO approach to copy repeating patterns into a slice, for a toy project, I ran a few tests and discovered a neat approach to significantly improve performance. For the toy project, I am using this to fill a background buffer with a specific RGB color pattern, so improving this performance significantly improved my acheivable framerate.

All the test were run with a buffer of 73437 bytes, allocated as follows

var bigSlice = make([]byte, 73437, 73437)

Fill the slice with the value 65 by looping through each element and setting the value

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for num in chain(range(12_300, 40_944),
                 range(44_000, 64_207)):

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import string
info = [eval(f"('{a}', string.{a})") for a in dir(string) if not a.startswith("_")]
for elem in info:
    print(elem)

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# https://stackoverflow.com/questions/57340713/how-do-i-un-shuffle-a-list-back-to-its-original-form

import random

def getperm(l):
    random.seed(101)
    perm = list(range(len(l)))
    random.shuffle(perm)
    return perm

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sudo rm /etc/apt/preferences.d/nosnap.pref
sudo apt update
sudo apt install snapd

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package main

import (
	"bytes"
	"crypto/aes"
	"crypto/cipher"
	"encoding/hex"
	"fmt"
)

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import cv2

cap = cv2.VideoCapture(0)

# Capture frame
ret, frame = cap.read()
if ret:
	cv2.imwrite('image.jpg', frame)

cap.release()

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#include <memory>
#include <iostream>

class objectA {
public:
   ~objectA() {
      std::cout << "A";
   }
};

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set session transaction isolation level read comitted; - сразу данные видны в текущей сессии из другой сессии

start transaction;

...

commit;


set session transaction isolation level repeatable read; - данные не видны в текущей сессии из другой сессии