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Matt Jones 5e024070ab Fix connection leak when a thread checks in additional connections.
The code in `ConnectionPool#release` assumed that a single thread only
ever holds a single connection, and thus that releasing a connection
only requires the owning thread_id.

There is a trivial counterexample to this assumption: code that checks
out additional connections from the pool in the same thread. For
instance:

    connection_1 = ActiveRecord::Base.connection
    connection_2 = ActiveRecord::Base.connection_pool.checkout
    ActiveRecord::Base.connection_pool.checkin(connection_2)
    connection_3 = ActiveRecord::Base.connection

At this point, connection_1 has been removed from the
`@reserved_connections` hash, causing a NEW connection to be returned as
connection_3 and the loss of any tracking info on connection_1. As long
as the thread in this example lives, connection_1 will be inaccessible
and un-reapable. If this block of code runs more times than the size of
the connection pool in a single thread, every subsequent connection
attempt will timeout, as all of the available connections have been
leaked.

Reverts parts of 9e457a8654 and
essentially all of 4367d2f05c
2014-12-23 09:54:52 -05:00
actionmailer Merge pull request #17896 from GBH/globbing_route_mailer_preview 2014-12-08 15:10:47 -02:00
actionpack Merge branch 'master' of github.com:rails/docrails 2014-12-20 14:26:21 +00:00
actionview Better tests for AV::RecordIdentifier 2014-12-23 01:59:25 +01:00
activejob Add 'require' for Hash#with_indifferent_access 2014-12-21 21:03:16 +09:00
activemodel Don't calculate all in-place changes to determine if attribute_changed? 2014-12-22 14:55:58 -07:00
activerecord Fix connection leak when a thread checks in additional connections. 2014-12-23 09:54:52 -05:00
activesupport Fix syntax error with RDoc directive, 2014-12-20 14:52:26 -08:00
ci Pass symbol as an argument instead of a block 2014-11-29 11:53:24 +01:00
guides Do not use line breaks on notes [ci skip] 2014-12-22 15:25:32 -02:00
railties Add test missed by a03ea684ef 2014-12-22 14:05:35 -07:00
tasks activejob needs to be built before actionmailer 2014-12-19 16:12:32 -08:00
tools minor docs change [ci skip] 2014-11-03 12:37:39 +05:30
.gitignore Updated link to to GitHub article about ignoring files [ci skip] 2013-05-05 20:33:24 +05:30
.travis.yml Enable Travis CI container-mode 2014-12-18 18:09:58 -02:00
.yardopts
CONTRIBUTING.md Follow-up to #16097 [ci skip] 2014-07-18 12:29:54 +02:00
Gemfile Use arel master 2014-11-29 16:11:57 -07:00
install.rb Added activejob to install.rb 2014-08-12 15:37:18 +03:00
load_paths.rb
rails.gemspec Bump ruby version to 2.1.0 in rails.gemspec too. 2014-11-29 18:45:47 +02:00
RAILS_VERSION Start Rails 5 development 🎉 2014-11-28 15:00:06 -02:00
Rakefile Remove activejob integration tests 2014-08-12 10:07:21 +00:00
README.md Remove bullet 2014-12-21 16:28:25 -04:00
RELEASING_RAILS.rdoc Rephrase this from 3f38762 [ci skip] 2014-12-14 20:11:11 -05:00
version.rb Start Rails 5 development 🎉 2014-11-28 15:00:06 -02:00

Welcome to Rails

Rails is a web-application framework that includes everything needed to create database-backed web applications according to the Model-View-Controller (MVC) pattern.

Understanding the MVC pattern is key to understanding Rails. MVC divides your application into three layers, each with a specific responsibility.

The Model layer represents your domain model (such as Account, Product, Person, Post, etc.) and encapsulates the business logic that is specific to your application. In Rails, database-backed model classes are derived from ActiveRecord::Base. Active Record allows you to present the data from database rows as objects and embellish these data objects with business logic methods. You can read more about Active Record in its README. Although most Rails models are backed by a database, models can also be ordinary Ruby classes, or Ruby classes that implement a set of interfaces as provided by the Active Model module. You can read more about Active Model in its README.

The Controller layer is responsible for handling incoming HTTP requests and providing a suitable response. Usually this means returning HTML, but Rails controllers can also generate XML, JSON, PDFs, mobile-specific views, and more. Controllers load and manipulate models, and render view templates in order to generate the appropriate HTTP response. In Rails, incoming requests are routed by Action Dispatch to an appropriate controller, and controller classes are derived from ActionController::Base. Action Dispatch and Action Controller are bundled together in Action Pack. You can read more about Action Pack in its README.

The View layer is composed of "templates" that are responsible for providing appropriate representations of your application's resources. Templates can come in a variety of formats, but most view templates are HTML with embedded Ruby code (ERB files). Views are typically rendered to generate a controller response, or to generate the body of an email. In Rails, View generation is handled by Action View. You can read more about Action View in its README.

Active Record, Action Pack, and Action View can each be used independently outside Rails. In addition to them, Rails also comes with Action Mailer (README), a library to generate and send emails; Active Job (README), a framework for declaring jobs and making them run on a variety of queueing backends; and Active Support (README), a collection of utility classes and standard library extensions that are useful for Rails, and may also be used independently outside Rails.

Getting Started

  1. Install Rails at the command prompt if you haven't yet:

     gem install rails
    
  2. At the command prompt, create a new Rails application:

     rails new myapp
    

    where "myapp" is the application name.

  3. Change directory to myapp and start the web server:

     cd myapp
     rails server
    

    Run with --help or -h for options.

  4. Using a browser, go to http://localhost:3000 and you'll see: "Welcome aboard: You're riding Ruby on Rails!"

  5. Follow the guidelines to start developing your application. You may find the following resources handy:

Contributing

We encourage you to contribute to Ruby on Rails! Please check out the Contributing to Ruby on Rails guide for guidelines about how to proceed. Join us!

Code Status

Build Status

License

Ruby on Rails is released under the MIT License.