yang-wei

https://zookeeper.apache.org/doc/current/zookeeperProgrammers.html#sc_ZooKeeperAccessControl

digest uses a username:password string to generate MD5 hash which is then used as an ACL ID identity. Authentication is done by sending the username:password in clear text. When used in the ACL the expression will be the username:base64 encoded SHA1 password digest.

echo -n user1:12345 | openssl dgst -binary -sha1 | openssl base64
+owfoSBn/am19roBPzR1/MfCblE=

yang-wei

### Keybase proof

I hereby claim:

  * I am yang-wei on github.
  * I am yangwei (https://keybase.io/yangwei) on keybase.
  * I have a public key ASBjO6K0Dd_Bdqv617XxyzK2xvYVgCWvwaluoe0WHo1tIwo

To claim this, I am signing this object:

yang-wei

https://www.youtube.com/watch?v=TMuno5RZNeE

Encapsulation ?

• OO weaken encapsulation by introducing private, public, protected

Inheritance ?

• why Java doesn't have inheritance ? Diamond problem

Polymorphism

• https://medium.com/@shanikae/polymorphism-explained-simply-7294c8deeef7

yang-wei

Playing with MySQL

Read Committed

• prevent dirty write

  • row level locks

• prevent dirty read

  • row level locks could be use but not performant
  • write new value and remember old value at the same time. return old value while transaction is not done

yang-wei

system wide

> cat /proc/sys/fs/file-max
13032310

> cat /proc/sys/fs/file-nr
25696   0       13032310

yang-wei

trait RedisCluster {
  def connect: Throwable \/ StatefulRedisClusterConnection[String, String]
}

class RedisClusterWithLettuce(host: String, port: Int) extends RedisCluster {

  private val client = RedisClusterWithLettuce.build(host, port)

  def connect: Throwable \/ StatefulRedisClusterConnection[String, String] = {
    \/.fromTryCatchNonFatal {

yang-wei

```
❯ redis-cli -c -h localhost -p 6379
localhost:6379> cluster nodes
2f7fd4b118aec5f0d0b10a16006815098ae89e9c 192.168.48.2:6379@16379 myself,master - 0 1604830164000 1 connected 0-5460
10f1bbb2e194af0fd389253742f1cdd312dc0556 192.168.48.2:6384@16384 slave f53b0c7e1fffee2b20e7c8886075f545c50f1e9b 0 1604830165755 6 connected
ef35b6133ec1be37e8989ac4c9b3ebecf75cd612 192.168.48.2:6383@16383 slave dbb28f3dd2fa0462e7bac0ee3aef1ef9a59a1ba3 0 1604830167000 5 connected
dbb28f3dd2fa0462e7bac0ee3aef1ef9a59a1ba3 192.168.48.2:6380@16380 master - 0 1604830166271 2 connected 5461-10922
f53b0c7e1fffee2b20e7c8886075f545c50f1e9b 192.168.48.2:6381@16381 master - 0 1604830167299 3 connected 10923-16383
eeb51c67dbf497953c1fe30b7ffb7aaeabe0dc27 192.168.48.2:6382@16382 slave 2f7fd4b118aec5f0d0b10a16006815098ae89e9c 0 1604830166000 4 connected
```

yang-wei

➜  admin git:(master) phpbrew --version
phpbrew - 1.23.1
cliframework core: 2.5.4
➜  admin git:(master) php -v
PHP 5.6.30 (cli) (built: Aug  7 2018 17:48:36)
Copyright (c) 1997-2016 The PHP Group
Zend Engine v2.6.0, Copyright (c) 1998-2016 Zend Technologies
➜  admin git:(master) which php
/Users/l-wei/.phpbrew/php/php-5.6.30/bin/php

yang-wei

go run server.go

curl

curl -v -H 'Content-Type: multipart/form-data' -F "uploadfile=@./sample_video.mp4" -k http://localhost:8080/upload

yang-wei

<?php

class Helper {
  /**
   * Break up process for function with first large array parameter into multiple time and merge
   * Can be useful when thing are slow querying database or requesting api with large size of array at once
   */
  public static function chunkify(callable $fn, array $fnFirstParam = [], $chunkSize=1000, ...$fnRestParams) {
    $result = [];
    foreach (array_chunk($fnFirstParam, $chunkSize) as $chunk) {