jcouyang

The Promise All Problem

in case of processing a very large array e.g. Promise.all(A_VERY_LARGE_ARRAY_OF_XHR_PROMISE)

which would probably blow you browser memory by trying to send all requests at the same time

solution is limit the concurrent of requests, and wrap promise in thunk

Promise.allConcurrent(2)([()=>fetch('BLAH1'), ()=>fetch('BLAH2'),...()=>fetch('BLAHN')])

jcouyang

还记得 Haskell Curry吗，

多巧啊, 人家姓 Curry 名 Haskell, 难怪 Haskell 语言会自动柯里化, 呵呵. 但是不奇怪吗, 为什么要柯里化呢. 为什么如此重要导致 Haskell 会默认自动柯里化所有函数, 不就是返回一个部分配置好的函数吗.

我们来看一个 Haskell 的代码.

max 3 4
(max 3) 4

jcouyang

require "nokogiri"
require "open-uri"
url = "https://github.com/#{params['username']}"
document = Nokogiri::HTML(open(url))
contrib_boxes = document.css('svg.js-calendar-graph-svg')[0]
contrib_boxes['xmlns']="http://www.w3.org/2000/svg"
width = (params['width']||54*13-2).to_i
height = (params['height']||89).to_i
contrib_boxes.css('text').remove
contrib_boxes['width']=(width+11).to_s+'px'

jcouyang

Prepaire

• USB disk 格式化成ext2/3格式, with gparted in linux. 根据官方wiki, 最新的v24已经 不用jffs了, 目前的dd-wrt目录结构是这样的:

/tmp ## mounted on the RAM drive of dd-wrt
/jffs  ## builti-in flash, 已经disable
/mnt ## used for rw drive

jcouyang

settings.startToShowEmoji = 3;
settings.tabsMRUOrder = false;
settings.tabsThreshold = 4;

api.mapkey(';oc', 'Org Capture', function() {
  location.href='org-protocol://capture?' + 
    new URLSearchParams({
        template: 'x',
        url: window.location.href,
        title: document.title,

jcouyang

Keybase proof

I hereby claim:

• I am jcouyang on github.
• I am oyanglulu (https://keybase.io/oyanglulu) on keybase.
• I have a public key ASDd7C_jnHrfyZ-hv7yEPxWFSwbOCfYOX_oqoujJ55JeXwo

To claim this, I am signing this object:

jcouyang

<keymap version="1" name="Emacs copy" parent="macOS For All">
  <action id="$Copy">
    <keyboard-shortcut first-keystroke="alt c" />
  </action>
  <action id="$Cut">
    <keyboard-shortcut first-keystroke="shift delete" />
  </action>
  <action id="$Delete">
    <keyboard-shortcut first-keystroke="delete" />
    <keyboard-shortcut first-keystroke="ctrl d" />

jcouyang

本文基本上这为两篇文章的翻译和整合 -- Scalable networking And Why are event-driven server so great

OPPC模型瓶颈

传统服务器模型如Apache为每一个请求生成一个子进程。当用户连接到服务器的一个子进程就产生，并处理连接。每个连接获得一个单独的线程和子进程。当用户请求数据返回时，子进程开始等待数据库操作返回。如果此时另一个用户也请求返回数据，这时就产生了阻塞。

这种模式在非常小的工作负荷是表现良好，当请求的数量变得太大是服务器会压力过于巨大。 当Apache达到进程的最大数量，所有进程都变得缓慢。每个请求都有自己的线程，如果服务代码使用PHP编写时，每个进程所需要的内存量是相当大的[1]。

fork()操作延时

jcouyang

I'm a Emacs user and as you may know there is a awesome mode called gist.el, and since then, I found that it's completely my Evernote replacement. Why replace Evernote with gist?

• code snippet (very significant reason)
• Version Control, gist actually is a git repo, so you have all the commit history.
• Social, fork, star, and comment as well.
• I have emacs open all the time my machine is on. no reason open another app for note taking.
• annoying Evernote text editor without emacs like shotcut.
• Github Flavored Markdown(with emoji), or even org-mode and reStructuredText support.

But since there are not so many Emacsers, I create a Atom package glist which do the exact thing as gist.el for Atom.io. as atom support markdown instant preview, note taking with gist is even better.

jcouyang

; 当要打开一个symbolink的时候，如果symbollink到一个被git（或者其他vc）管理的文件时，emacs老问
; Symbolic link to Git-controlled source file; follow link? (y or n)
; 配置下这个变量就好了

(setq vc-follow-symlinks nil)

; nil 表示 不要问，no
; ask 表示每次都问
; t  表示follow