Merb_piece_cache 0.1.0 released

Ruby
1

I releaded merb_piece_cache 0.1.0.

About

merb_piece_cache is a Merb plug-in to cache html fragments.
You can eliminate database access with this plugin.

Currently only file-base cache store is provided.
(Memory-base cache store may be provided in future.)

Install

### install gem
$ sudo gem install merb_helpers_monkey
## add 'dependency "merb_piece_cache"'
$ vi config/dependencies.rb

This plugin requires ‘called_from’ library.
If you install this plugin manually, don’t forget to install
‘called_from’.

Example

  • [controller] delay database access by if_not_cached() helper.
  • [template] specify cache area by cache_with() helper.

controller:

def index
  ## @user is necessary every time
  @user = User.current()
  ## @members is necessary only when cache is refreshed
  ## (block parameter is called only when cache is expired or not

found)
if_not_cached {|cache_key|
@members = Members.all(:order=>[:created_at])
}
render
end

template:

<!-- rendered every time (because never cached) -->
<% if @user %>
  Hello <%=h @user %>!
<% else %>
  <a href="/login">Login</a>
<% end %>

<!-- rendered only when cache is expired or not found -->
<% lifetime = 5*60  # sec, default is nil(=infinity) %>
<% cache_with("members", lifetime) do %>
  <ul>
  <% for member in @members %>
    <li><%=h @member.name %></li>
  <% end %>
  <ul>
<% end %>

Reference

Merb_piece_cache plugin provides the following helpers.

  • if_not_cached() {|cache_key| … }
    Register block as callback object which is called when fragment
    cache is re-generated (In other words, block parameter is called
    only when cache is re-generated).
    Block paramter can receive cache_key as 1st argument so that
    you can switch data processing according to cache_key.

  • piece_cache(cache_key, lifetime=nil) { … }
    When cache is found and not expired, then add cache data into
    view.
    Otherwise, call block to re-generate cache data and cache it.
    (Notice that block parameter is called only when cache is re-
    generated.)
    It is able to specify cache lifetime. For example, if you specify
    lifetime=5*60, cache data will be expired after 5 minutes.

  • cache_with(cache_key, lifetime=nil) { … }
    Alias of piece_cache().
    You can re-define this helper to extend cache behaviour.

Configuration

You can configure merb_piece_cache plugin in your environment file.
(config/environments/{production,development,test}.rb).
For example, add the followings into your ‘development.rb’:

Merb::Plugins.config[:merb_piece_cache] = {
  ## show cached area in template (convenient for debug!)
  :show_area => true,
  ## directory to place cache files (default: "MERB_ROOT/tmp/

cache")
:root_dir => “/var/tmp”,
}

Tips

  • You can prepare different data in if_not_exist() according to
    cache_key.

    def index
  if_not_cached {|cache_key|
    case cache_key
    when /^post\/(\d+)$/
      @post = BlogPost.get($1)
    when /^post\/(\d+)/comments$/
      @comments = BlogComment.all(:post_id=>$1)
    end
  }
  render
end

  • piece_cache() (and also cache_with()) checks template timestamp.
    If cache data is older than template timestamp, then cache data will
    be
    re-generated.

License

MIT License