From: Jeremy Kemper <jeremy@...>
Date: 2009-11-09T09:51:14+09:00
Subject: Re: [ANN] called_from 0.1.0 released

This is probably the most common usage of Kernel#caller. You've made
it more useful and much faster -- great extension!

jeremy

On Sun, Nov 8, 2009 at 3:25 PM, makoto kuwata <kwatch@gmail.com> wrote:
> I releaded called_from 0.1.0.
> http://github.com/kwatch/called_from
>
> Kernel#caller() is very useful, but very slow.
> 'called_from' solves this problem.
>
>
> About
> -----
>
> 'called_from' provides called_from() global function
> which gets filename and line number of caller.
>
> In short:
>
>    require 'called_from'
>    filename, linenum, function = called_from(1)
>
> is equivarent to:
>
>    caller(1)[0] =~ /:(\d+)( in `(.*)')?/
>    filename, linenum, function = $`, $1, $2
>
> But called_from() is much faster than caller()[0].
>
>
>
> Example
> -------
>
>    require 'called_from'
>
>    ##
>    ## report not only what sql is queried but also from where query()
> is called.
>    ## (this is very convenient for development and debugging)
>    ## in such examle, speed of called_from() is very important.
>    ##
>    def query(sql)
>      filename, linenum, function = called_from()
>      log.debug("#{Time.now}: #{sql} (called from #{filename}:#
> {linenum})")
>      return connection.query(sql)
>    end
>
>    ##
>    ## if cache data is older than template file's timestamp,
>    ## refresh cache data.
>    ## it is very important that called_from() is much faster than
> caller()[0]
>    ## because speed is necessary for caching.
>    ##
>    def cache_helper(cache_key)
>      ## check template file's timestamp
>      template_filename, linenum, function = called_from()
>      timestamp = File.mtime(template_filename)
>      ## if cache data is newer than template's timestamp, return data
>      data = @cache.get(cache_key, :timestamp=>timestamp)
>      return data if data
>      ## if cache data is older than template's timestamp, refresh it
>      data = yield()
>      @cache.set(cache_key, data)
>      return data
>    end
>
>
>
> Benchmark
> ---------
>
> Here is an example result of benchmark on Merb application.
> This shows that called_from() is more than 30 times faster than caller
> ()[0].
>
>
>    *** n=100000
>                                 user     system      total
> real
>    caller()[0]              7.920000   0.400000   8.320000
> (  8.985343)
>    caller()[0]   (*1)       8.590000   0.420000   9.010000
> (  9.804065)
>    called_from()            0.240000   0.010000   0.250000
> (  0.257151)
>    called_from() (*2)       0.250000   0.000000   0.250000
> (  0.268603)
>
>
>    (*1) retrieve filename and line number using pattern match (=~ /:
> (\d+)/)
>    (*2) retrieve filename and line number
>
>
>
> Installation
> ------------
>
>    $ sudo gem install called_from
>
> Or
>
>    $ tar xzf called_from_X.X.X.tar.gz
>    $ cd called_from_X.X.X/
>    $ ruby setup.rb config
>    $ ruby setup.rb setup
>    $ sudo ruby setup.rb install
>
> Notice: called_from is implemented in both C-extention and pure Ruby.
> C-extention is available on UNIX-like OS and Ruby 1.8.x.
>
>
> --
> regards,
> makoto kuwata
>
>