ruby benchmark

Benchmarking Makes it Better
<br />require 'benchmark'<br /><br />#The bm method provides basic interface to the benchmark method. It takes an optional label_width argument. Each method tested can have a label specified.<br /><br />n = 5_000_000<br />Benchmark.bm(15) do |x|<br /> x.report("for loop:") { for i in 1..n; a = "1"; end }<br /> x.report("times:") { n.times do ; a = "1"; end }<br /> x.report("upto:") { 1.upto(n) do ; a = "1"; end }<br />end<br /><br /><br /># Model<br />Project.benchmark("Creating project") do<br /> project = Project.create("name" => "stuff")<br /> project.create_manager("name" => "David")<br /> project.milestones << Milestone.find(:all)<br />end<br /><br /># Controller<br />def process_projects<br /> self.class.benchmark("Processing projects") do<br /> Project.process(params[:project_ids])<br /> Project.update_cached_projects<br /> end<br />end<br /><br /># View<br /><% benchmark("Showing projects partial") do %><br /> <%= render :partial => @projects %><br /><% end %><br />

X-Sendfile

mod_xsendfile
Reference : Advanced Rails p121

The X-Sendfile protocol is a very simple standard, first introduced in the Lighttpd
web server, which directs the web server to send a file from the filesystem to the client
rather than a response generated by the application server.

X-Sendfile uses the X-Sendfile HTTPheader pointing to the server’s path to the file
to send, in conjunction with the other standard HTTPheaders. A typical response
using X-Sendfile would look something like this:
X-Sendfile: /home/rails/sample_application/private/secret_codes_69843.zip<br />Content-Type: application/octet-stream<br />Content-Disposition: attachment; file="secret_codes.zip"<br />Content-Length: 654685<br />Assuming the web server is properly

From Rails, you can set the response headers by modifying the response.headers
hash:<br />response.headers['X-Sendfile'] = file_path<br />response.headers['Content-Type'] = 'application/octet-stream'<br />response.headers['Content-Disposition'] = "attachment; file=\"#{file_name}\""<br />response.headers['Content-Length'] = File.size(file_path)

delegate

Rails delegate method

<br />class User < ActiveRecord::Base <br /> belongs_to :customer <br />end <br /><br />class Customer < ActiveRecord::Base <br /> has_one :user <br /> delegate :name, :name=, :email, :email=, :to => :user <br />end<br />
那個 :to => :user 其實是由customer object 再去找 user 的 instance method
所以其實可以在 overwirte 掉做其他的處理

Metric Fu

Metric Fu railscast
ASCIIcast Metric Fu
About metric_fu 1.1.4
flog_file error
test_helper error

apache 設定

一些apache 設定 Etags and expire gzip compression
Speed up your Apache/Passenger Rails app in 2min
<br /><[ifmodule mod_expires.c]><br /> <[FilesMatch "\.(ico|pdf|flv|jpg|jpeg|png|gif|js|css|swf)?d{10}"]><br /> ExpiresActive on<br /> ExpiresDefault "access plus 1 year"<br /> <[/filesmatch]><br /><[/ifmodule]><br /> <br />FileETag MTime Size<br /> <br /><[VirtualHost *:8888]><br /> ServerAdmin lake@here.com<br /> ServerName lake.com<br /> DocumentRoot /home/lake/deploy/current/public<br /> <br /> # gzip html, css and js<br /> AddOutputFilterByType DEFLATE text/html text/css application/x-javascript application/javascript<br /> <br /> RewriteEngine On<br /> <br /> RewriteCond %{HTTP_HOST} algostars\.com\.tw [NC]<br /> RewriteRule ^/(.*) http://www.algostars.com/$1 [L,R]<br /> <br /><[/VirtualHost]><br />

capistrano, fast_remote_cache

fast_remote_cache

37signals 用hard link 取代 copy 的方式

因為有需要一直用新的branch 更新, cache_copy 有需要一直變換其svn repository

所以需要overwrite 一下 fast_remote_cache 的一些 methods
#lib/capistrano/recipes/deploy/strategy<br />/fast_remote_cache.rb<br /><br /> def deploy!<br /> prepare!<br /> copy_repository_cache<br /> end<br /><br /> def prepare!<br /> switch_repository_cache<br /> update_repository_cache<br /> end<br /><br /> private<br /><br /> def switch_repository_cache<br /> logger.trace "switching the cached checkout on all servers"<br /> command = "if [ -d #{repository_cache} ]; then " +<br /> "#{source.switch(repository, repository_cache)}; " +<br /> "fi"<br /> scm_run(command)<br /> end<br /><br />require 'capistrano/recipes/deploy/scm/subversion'<br />class Capistrano::Deploy::SCM::Subversion<br /> def switch(url,destination)<br /> logger.trace "switch #{destination} to #{url}"<br /> scm :switch, arguments, verbose, authentication, url, destination<br /> end<br />end<br /><br />

ssh 免打密碼自動登入 memo

from here
在 自己電腦 Client 端
<br />[root@ ~]# ssh-keygen -t dsa<br />Generating public/private dsa key pair.<br />Enter file in which to save the key (/root/.ssh/id_dsa): <br />Enter passphrase (empty for no passphrase):<br />Enter same passphrase again:<br />Your identification has been saved in /root/.ssh/id_dsa.<br />Your public key has been saved in /root/.ssh/id_dsa.pub.<br />The key fingerprint is:<br />ad:85:bddb5:ddr:a544c:fc:ef:57:dd:4b:ef:a9:8a:db root@~<br /><br />[root@ ~]# cd /root/.ssh/id_dsa<br />id_dsa id_dsa.pub <br />[root@ ~]# scp /root/.ssh/id_dsa.pub root@192.168.188.199:/root/.ssh/ <br />

server 端<br />cd .ssh<br />cat ./id_rsa.pub >> authorized_keys<br />

capistrano 指令順序

* executing `deploy:update'<br /> #** transaction: start<br /> * executing `deploy:update_code'<br />...<br /> #* executing "if [ -d /home/goadmin/algo_test/shared/cached-copy ]; then svn update -q --username goadmin --password goadmin1234 --no-auth-cache -r11562 /home/goadmin/algo_test/shared/cached-copy; else svn checkout -q --username goadmin --password goadmin1234 --no-auth-cache -r11562 svn://svn.icetech.com.tw/algostars_web /home/goadmin/algo_test/shared/cached-copy; fi"<br /><br /> #executing "cp -RPp /home/goadmin/algo_test/shared/cached-copy /home/goadmin/algo_test/releases/20090715082138 && (echo 11562 > /home/goadmin/algo_test/releases/20090715082138/REVISION)"<br /><br /><br /> * executing `deploy:finalize_update'<br /> #* executing "chmod -R g+w /home/goadmin/algo_test/releases/20090715082138"<br /><br /> #* executing "rm -rf /home/goadmin/algo_test/releases/20090715082138/log /home/goadmin/algo_test/releases/20090715082138/public/system /home/goadmin/algo_test/releases/20090715082138/tmp/pids &&\\\n mkdir -p /home/goadmin/algo_test/releases/20090715082138/public &&\\\n mkdir -p /home/goadmin/algo_test/releases/20090715082138/tmp &&\\\n ln -s /home/goadmin/algo_test/shared/log /home/goadmin/algo_test/releases/20090715082138/log &&\\\n ln -s /home/goadmin/algo_test/shared/system /home/goadmin/algo_test/releases/20090715082138/public/system &&\\\n ln -s /home/goadmin/algo_test/shared/pids /home/goadmin/algo_test/releases/20090715082138/tmp/pids"<br /><br /><br /> #triggering after callbacks for `deploy:update_code'<br /> * executing `algo:symlink'<br /><br /> * executing `deploy:symlink'<br /> #* executing "rm -f /home/goadmin/algo_test/current && ln -s /home/goadmin/algo_test/releases/20090715082138 /home/goadmin/algo_test/current"<br />

Understanding_Deployment_Strategies, deploy_via

Understanding Deployment Strategies

Deployment strategies are just ways for capistrano to get your code onto your target servers, ready to rock and roll

Deploy Strategy :checkout 就是checkout 新的# Example Command as run by Capistrano on your target server <br />[host1.example.com]# svn checkout svn+ssh://test.example.com/repository/trunk /u/apps/example/releases/20081008215259/<br />

Deploy Strategy :copy 有時候 你的target server 可能因為被防火牆擋了 就是拿不到svn, 就只好用這個, 把本地的東西copy 過去
#The copy strategy is for those who struggle with a firewall or network problems stopping their deploy target servers not being able to access their SCM repository. <br /><br />set :copy_strategy, :export<br /><br />set :copy_cache, true<br />set :copy_cache, "/tmp/caches/myapp"<br /><br />set :copy_exclude, [".git/*", ".svn/*"]<br />set :copy_compression, :gzip # Also valid are :zip and :bz2<br />

Deploy Strategy :export 就是用export 拿code, 用export 拿code 不會有svn control
#In this case, your code is deployed to the server by capistrano issuing an "export" command; which for those unfamiliar extracts a copy of the HEAD, minus the .svn metadata directories - rendering this an "exported" copy, rather than a working, versioned copy.<br /># Example Command as run by Capistrano on your target server <br />[host1.example.com]# svn export svn+ssh://test.example.com/repository/trunk /u/apps/example/releases/20081008215259/<br />

Deploy Strategy :remote_cache, 把code 弄在cache copy 底下, 然後對其做svn update, 然後再把該份code 弄到新的release 去
#Remote cache works by using a working copy of your code stored in a 'cache' on the target server(s) to speed up deployment. <br /><br /># Example Settings<br />set :deploy_to, /u/apps/example<br />set :deploy_via, :remote_cache<br />set :copy_exclude, [".svn", ".DS_Store"] #設定不要弄進release 的<br />set :repository, svn+ssh://test.example.com/repository/trunk<br /><br /># Example truncated, capistrano does something clever to decide whether to create this repository cache, or just sync it<br />#先做svn update<br />[host1.example.com]# svn update /u/apps/example/shared/cached-copy<br /><br /># Then *ONE* of the following, depending whether or not you specified :copy_exclude<br />#下面二選一, 看有沒有用 :copy_exclude 而定<br />[host1.example.com]# rsync -rp --exclude=".svn" --exclude=".DS_Store" /u/apps/example/shared/cached-copy/* /u/apps/example/releases/20081008215259<br />[host1.example.com]# cp -RPp /u/apps/example/shared/cached-copy/ /u/apps/example/releases/20081008215259<br /><br />

capistrano deploy.rb 設定 註解

Capistrano deploy.rb文件的記錄

# 在redhat 內核中不需要sudo 方式運行。 <br /> set :use_sudo, false # Do not use sudo ro run command. <br /><br /> set :domain, 'www.firebirds.com'<br /> set :application, 'ruby_on_rails'<br /> set :user, 'root' # connect to server use this variable. # 連接app服務器,並執行命令 <br /><br /> set :repository, "svn://172.10.12.8/www/ror/trunk"<br /><br /> set :port, 8888 # connect server use ssh with this port# ssh連接app服務器的端口號. <br /><br /> set :deploy_to, "/var/www/ror" # deploy to server location <br /><br /> # set :scm, :subversion <br /> set :scm_username, 'xxx'<br /><br /> set :scm_password, proc{Capistrano::CLI.password_prompt('SVN pass:')} # 在出現SVN pass: 時輸入svn密碼. # 在第一次用過後，svn shell會記住此密碼，下次可不用。 <br /><br /> role :app, "172.10.12.8"<br /> role :web, "172.10.12.8"<br /> role :db, "172.10.12.8", :primary => true<br /><br /> # app, web, db 都 在同一台機器上如下即可 <br /> #server "172.10.12.8", :app, :web, :db, :primary => true <br /> set :deploy_via, :export # 在服務器上連接到源碼庫裡去更新 <br /> # set :deploy_via, :copy # 在本地打包上傳至服務器 <br /><br /> set :runner, user # excute command with the front of user defined. <br /><br /> # Does not look like you are using the fastcgi processes that reaper is <br /> # designed to restart in the setup you described. In your cap script set <br /> # them to false. EG set :spinner, "false". See the manual for details. <br /> set :spinner, "false" # 使用fascgi 的話，把此行註釋 <br /><br /> #after 'deploy', 'deploy:cleanup' # hock after deploy <br /> #after 'deploy:migrations', 'deploy:cleanup' # hock after deploy:migrations<br />

content_tag_for, div_for

content_tag_for, div_for
<br /> <% content_tag_for(:tr, @person) do %><br /> <td><%=h @person.first_name %></td><br /> <td><%=h @person.last_name %></td><br /> <% end %><br />#產生<br /><tr id="person_123" class="person">....</tr><br /><br /><br />#If you require the HTML id attribute to have a prefix, you can specify it: <br /> <% content_tag_for(:tr, @person, :foo) do %><br />#產生<br /><tr id="foo_person_123" class="person">...<br /><br /><br /><% content_tag_for(:li, @person, :class => "bar") %>...<br />#產生<br /> <li id="person_123" class="person bar">...<br /><br /><br /><br /><% div_for(@person, :class => "foo") do %><br /> <%=h @person.name %><br /><% end %><br />#產生<br /><div id="person_123" class="person foo"> Joe Bloggs </div><br />

action cache, cahce_path, to_proc

Action Caching
Symbol#to_proc
caches_action :index, :cache_path => :index_cache_path.to_proc<br /><br />#...<br /><br />private<br /><br />def index_cache_path<br /> if admin?<br /> '/admin/products'<br /> else<br /> '/public/products'<br /> end<br />end<br /><br />

ActionController::Caching::Actions
<br /> class ListsController < ApplicationController<br /> before_filter :authenticate, :except => :public<br /> caches_page :public<br /> caches_action :index, :if => Proc.new { |c| !c.request.format.json? } # cache if is not a JSON request<br /> caches_action :show, :cache_path => { :project => 1 }, :expires_in => 1.hour<br /> caches_action :feed, :cache_path => Proc.new { |controller|<br /> controller.params[:user_id] ?<br /> controller.send(:user_list_url, controller.params[:user_id], controller.params[:id]) :<br /> controller.send(:list_url, controller.params[:id]) }<br /> end<br />

Action caching 內部是用 fragment caching 和 around filter 來實做
Action caching internally uses the fragment caching and an around filter to do the job. The fragment cache is named according to both the current host and the path. So a page that is accessed at http://david.somewhere.com/lists/show/1 will result in a fragment named "david.somewhere.com/lists/show/1". This allows the cacher to differentiate between "david.somewhere.com/lists/" and "jamis.somewhere.com/lists/" — which is a helpful way of assisting the subdomain-as-account-key pattern.

不同的url 就是不同的request, cache 也是不同的
Different representations of the same resource, e.g. http://david.somewhere.com/lists and http://david.somewhere.com/lists.xml are treated like separate requests and so are cached separately. Keep in mind when expiring an action cache that :action => 'lists' is not the same as :action => 'list', :format => :xml.

可以讓你自己控制cache_path, 就算是相同的request 也可以利用block 做些判斷生出不同的path, 當你用了block 你可以利用他拿到 controller instance
You can set modify the default action cache path by passing a :cache_path option. This will be passed directly to ActionCachePath.path_for. This is handy for actions with multiple possible routes that should be cached differently. If a block is given, it is called with the current controller instance.

也有 if, unless 來讓你丟block 進去做判斷
And you can also use :if (or :unless) to pass a Proc that specifies when the action should be cached.

如果你把layout 設成false, 你可以只存content, 你可以利用這樣來動態改變layout
If you pass :layout => false, it will only cache your action content. It is useful when your layout has dynamic information.

def to_proc<br /> proc { |obj, *args| obj.send(self, *args) }<br /> end<br />

Apache , virtualhost

Host websites on your local machine using Apache websever
VirtualHost Examples
<br />#FILE: /etc/apache2/sites-available/websiteA<br />NameVirtualHost websiteA:80<br /><br /><[virtualhost websiteA:80]><br />ServerAdmin ravi@localhost<br />ServerName websiteA<br />DocumentRoot /var/www/websiteA/<br /><directory><br />Options FollowSymLinks<br />AllowOverride None<br /><[/directory]><br /><[directory /var/www/websiteA/]><br />Options Indexes FollowSymLinks MultiViews<br />AllowOverride None<br />Order allow,deny<br />allow from all<br />...<br /><[/directory]><br />...<br />...<br /><[/virtualhost]> <br />

ServerName indicates the name (or alias) with which your site has to be recognised. Usually a webserver will be hosting multiple sites with different domain names on the same machine. At such times, the webserver distinguishes between different websites through the ServerName directive.
you will be giving it your domain name say like www.mysite.com or something.

The DocumentRoot option denotes which files to be served when the server name is entered in the web browser. This usually points to the place where you have stored your website files.

javascript encode, decode AND JSON in JavaScript

JSON in JavaScript
encode,decode,escape,unescape
encodeURI
decodeURI
encodeURIComponent
decodeURIComponent
<br />//json like string to object<br />var myObject = eval('(' + myJSONtext + ')');<br /><br />//json object to string<br />var myJSONText = JSON.stringify(myObject, function (key, value) {<br /> return value;<br />});<br />
<br /> #URL-encode a string. <br /> url_encoded_string = CGI::escape("'Stop!' said Fred") <br />