开发者 (6) - 码厩

#58 转载：正则表达式历史

开发者正则表达式 2021-12-19

正则表达式在我们日常的软件开发过程中被广泛使用，例如编写 Nginx 配置文件、在 Linux 与 macOS 下查找文件，然而不同软件不同操作系统对于正则的应用有着不一样的行为，主要原因是正则表达式演进过程中，出现 POSIX 与 PCRE 派系之分。

#57 程序员的 10 个习惯

开发者 2021-12-08

公众号四猿外的文章《这 10 个程序员的好习惯，让我变强了》，很有同感，这里总结一下：

要看官方文档，网上的资料鱼龙混杂
开发者的可靠性：自测没有问题了再交付
日志设计合理，保证调试时，有恰当的信息来定位问题
精通 Git
优先功能实现，别急着优化
过早优化是魔鬼，应该根据实际运行的情况来优化
先做明确的需求，不确定或者模糊的需求先往后放
积极主动：发现问题，提出方案，解决问题
开发时间评估，保证有冗余时间，以处理可能的意外
学习编程主要靠上手写代码，不要光看文档
英语。不需要很好，能看懂英文文档就行

#56 Susam Pal：Curl 计时

开发者 Curl 2021-11-28

Here is a command I use often while measuring why an HTTP request is taking too long:

curl -L -w "time_namelookup: %{time_namelookup}
time_connect: %{time_connect}
time_appconnect: %{time_appconnect}
time_pretransfer: %{time_pretransfer}
time_redirect: %{time_redirect}
time_starttransfer: %{time_starttransfer}
time_total: %{time_total}
" https://example.com/

Here is the same command written as a one-liner, so that I can copy it easily from this page with a triple-click whenever I need it in future:

curl -L -w "time_namelookup: %{time_namelookup}\ntime_connect: %{time_connect}\ntime_appconnect: %{time_appconnect}\ntime_pretransfer: %{time_pretransfer}\ntime_redirect: %{time_redirect}\ntime_starttransfer: %{time_starttransfer}\ntime_total: %{time_total}\n" https://example.com/

Here is how the output of the above command typically looks:

$ curl -L -w "namelookup: %{time_namelookup}\nconnect: %{time_connect}\nappconnect: %{time_appconnect}\npretransfer: %{time_pretransfer}\nstarttransfer: %{time_starttransfer}\ntotal: %{time_total}\n" https://example.com/
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
...
</html>
time_namelookup: 0.001403
time_connect: 0.245464
time_appconnect: 0.757656
time_pretransfer: 0.757823
time_redirect: 0.000000
time_starttransfer: 0.982111
time_total: 0.982326

In the output above, I have omitted most of the HTML output and replaced the omitted part with ellipsis for the sake of brevity.

The list below provides a description of each number in the output above. This information is picked straight from the manual page of curl 7.20.0. Here are the details:

time_namelookup: The time, in seconds, it took from the start until the name resolving was completed.
time_connect: The time, in seconds, it took from the start until the TCP connect to the remote host (or proxy) was completed.
time_appconnect: The time, in seconds, it took from the start until the SSL/SSH/etc connect/handshake to the remote host was completed. (Added in 7.19.0)
time_pretransfer: The time, in seconds, it took from the start until the file transfer was just about to begin. This includes all pre-transfer commands and negotiations that are specific to the particular protocol(s) involved.
time_redirect: The time, in seconds, it took for all redirection steps include name lookup, connect, pretransfer and transfer before the final transaction was started. time_redirect shows the complete execution time for multiple redirections. (Added in 7.12.3)
time_starttransfer: The time, in seconds, it took from the start until the first byte was just about to be transferred. This includes time_pretransfer and also the time the server needed to calculate the result.
time_total: The total time, in seconds, that the full operation lasted. The time will be displayed with millisecond resolution.

An important thing worth noting here is that the difference in the numbers for time_appconnect and time_connect time tells us how much time is spent in SSL/TLS handshake. For a cleartext connection without SSL/TLS, this number is reported as zero. Here is an example output that demonstrates this:

$ curl -L -w "time_namelookup: %{time_namelookup}\ntime_connect: %{time_connect}\ntime_appconnect: %{time_appconnect}\ntime_pretransfer: %{time_pretransfer}\ntime_redirect: %{time_redirect}\ntime_starttransfer: %{time_starttransfer}\ntime_total: %{time_total}\n" http://example.com/
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
...
</html>
time_namelookup: 0.001507
time_connect: 0.247032
time_appconnect: 0.000000
time_pretransfer: 0.247122
time_redirect: 0.000000
time_starttransfer: 0.512645
time_total: 0.512853

Also note that time_redirect is zero in both outputs above. That is because no redirection occurs while visiting example.com. Here is another example that shows how the output looks when a redirection occurs:

$ curl -L -w "time_namelookup: %{time_namelookup}\ntime_connect: %{time_connect}\ntime_appconnect: %{time_appconnect}\ntime_pretransfer: %{time_pretransfer}\ntime_redirect: %{time_redirect}\ntime_starttransfer: %{time_starttransfer}\ntime_total: %{time_total}\n" https://susam.in/blog
<!DOCTYPE HTML>
<html>
...
</html>
time_namelookup: 0.001886
time_connect: 0.152445
time_appconnect: 0.465326
time_pretransfer: 0.465413
time_redirect: 0.614289
time_starttransfer: 0.763997
time_total: 0.765413

When faced with a potential latency issue in web services, this is often one of the first commands I run several times from multiple clients because the results form this command help to get a quick sense of the layer that might be responsible for the latency issue.

#55 语言代码

开发者 2021-11-21

语言指包括语言的字符集以及有关的货币符号，日期格式等。为了区分不通的语言，人们设计了一些语言代码相关的标准来。
作为开发，只要涉及多语言，都一定会接触到语言代码。在各种不通的技术、语言框架中，这些代码并没有非常统一，比如简体中文，我见过 zh, zh_CN, zh-Hans, chs, zh_chs 几种不同的表示。

#54 如何推送消息给手机

开发者移动端推送 2021-11-20

我没有做过移动端开发，我突然想到，如果我们要给手机端推送消息，会有些什么办法。
想来想去只有短信是最容易实现的，而且效果可以接受。

#53 常用工具汇总

开发者开发工具在线服务 2021-11-18

编辑器

VSCode
JetBrains 全家桶

SSH

putty
下载地址：https://www.chiark.greenend.org.uk/~sgtatham/putty/latest.html
https://github.com/larryli/PuTTY/releases
https://en.wikipedia.org/wiki/PuTTY
PuTTY User Manual

数据库 GUI

HeidiSQL
下载地址：https://www.heidisql.com/download.php
DBeaver
社区版下载地址：https://github.com/dbeaver/dbeaver/releases
商业版提供两周的免费试用。
SQLiteBrowser
安装：sudo apt install -y sqlitebrowser
下载地址：https://github.com/sqlitebrowser/sqlitebrowser/releases

Redis GUI

AnotherReidsDesktopManager
下载地址：https://github.com/qishibo/AnotherRedisDesktopManager/releases

虚拟化与容器

VirtualBox
Vagrant
Docker

编程相关

gitg
Beyond Compare 可以一直试用
Meld Linux 下的简化版 Beyond Compare

其他

WireShark
FileZilla
Typora
Honkit
坚果云 Linux / Windows 均有相应的客户端
下载地址：https://www.jianguoyun.com/s/downloads
KeePassXC
下载地址：https://github.com/keepassxreboot/keepassxc/releases
Everything
下载地址：https://www.voidtools.com/zh-cn/
v2ray
- Windows: 2dust/v2rayN
- Android: 2dust/v2rayNG
- 跨平台（Qt）: Shadowsocks-NET/Qv2ray

在线服务

https://picwish.cn

#52 最近工作的一次总结

个人工作开发者 2021-11-13

最近两周开发了一个功能，其实质就是做个数据统计，没啥好说的。
我是在没有产品设计的前提下开始工作，产品的设计反倒有一点依赖我所能提供的数据。
而且，和以往自己写功能逻辑不通的是，我这次只管提供数据和方案，业务逻辑的实现由别人来做。
工作过程中遇到了一些问题，这里做个总结（复盘）。

#51 我的开发机器

个人开发者 2021-10-24

Notebook
我的主力开发环境是大概 14 年 4 月在 DELL 官方 (dell.com) 买的一台 Inspiron 14R (5437) 笔记本。
PS: 这台笔记本原本是我老婆办公用, 用了将近五年之后, 于 2019 年 1 月在换了一台小米 Air 13.3, 然后我就有笔记本了...到现在我也用了两年多了。