ruby - Is there one Rack app instance per HTTP request? -

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i'm building facebook app called lovers, using sinatra app on heroku. it's running on ruby 1.9.2 on heroku's bamboo-mri-1.9.2 stack.

it's modular sinatra app, , in lovers source code, i'm giving each instance of sinatra app (lovers::application) instance of facebook::application:

require 'sinatra/base'  class lovers::application < sinatra::base   attr_reader :facebook    def initialize(app=nil)     @facebook = facebook::application.new(       lovers::conf.fb_app_id,       lovers::conf.fb_app_secret,       lovers::conf.fb_canvas_name)     super(app)   end   # ... end

that way, can lovers.application.facebook access facebook::application instance anywhere within lovers module, lovers::user.

does make sense, or should have instances of lovers::application (if there's ever more one) share same facebook::application instance, i.e., lovers.facebook. that's we're doing redis: lovers.redis, makes sense me. guess i'm leaning toward changing latter, want make sure before change it. think?

finally, there 1 instance of lovers::application per http request?

update:

i read on heroku dynos. apparently, each dyno (process) runs instance of lovers::application. so, after reading sharing global variable among processes, think means if define class variable @@hit_count in lovers::application class, have different values depending on dyno receives request, assuming increment @@hit_count every time home page requested, i.e.:

  @@hit_count = 0    "/"     @@hit_count += 1   end

"finally, there 1 instance of lovers::application per http request?"

there's 1 instance per process/dyno.

"it have different values depending on dyno receives request, assuming increment @@hit_count every time home page requested"

yes, if need global state have keep state outside of process/dyno. there many different ways this, , choose depend on details of app , traffic levels. if don't lot of traffic can simple keeping in database. can atomic increments in postgres or mysql hit_count. however, approach may become bottleneck if have lot of traffic.


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