All indentation was normalized by rubocop auto-correct at 80e66cc4.
But comments was still kept absolute position. This commit aligns
comments with method definitions for consistency.

Style/SpaceBeforeBlockBraces
Style/SpaceInsideBlockBraces
Style/SpaceInsideHashLiteralBraces

Fix all violations in the repository.

The current code base is not uniform. After some discussion,
we have chosen to go with double quotes by default.

Using locals will cause layouts to be cached multiple times in the
template cache.  This commit removes locals from consideration when
looking up the layout.

Object#inspect recursively inspects instance variables, exposing all
internal state, including sensitive internal cache objects. Override
Cache#inspect to give a high-level summary that never interferes with
concurrent cache writes.

`OptimizedFileSystemResolver` (which most Rails apps use), but did not
implement the feature on the more generic `PathResolver`, which is often
used in tests etc.

Fixes #23881

1. Conceptually revert #20276

   The feature was implemented for the `responders` gem. In the end,
   they did not need that feature, and have found a better fix (see
   plataformatec/responders#131).

   `ImplicitRender` is the place where Rails specifies our default
   policies for the case where the user did not explicitly tell us
   what to render, essentially describing a set of heuristics. If
   the gem (or the user) knows exactly what they want, they could
   just perform the correct `render` to avoid falling through to
   here, as `responders` did (the user called `respond_with`).

   Reverting the patch allows us to avoid exploding the complexity
   and defining “the fallback for a fallback” policies.

2. `respond_to` and templates are considered exhaustive enumerations

   If the user specified a list of formats/variants in a `respond_to`
   block, anything that is not explicitly included should result
   in an `UnknownFormat` error (which is then caught upstream to
   mean “406 Not Acceptable” by default). This is already how it
   works before this commit.

   Same goes for templates – if the user defined a set of templates
   (usually in the file system), that set is now considered exhaustive,
   which means that “missing” templates are considered `UnknownFormat`
   errors (406).

3. To keep API endpoints simple, the implicit render behavior for
   actions with no templates defined at all (regardless of formats,
   locales, variants, etc) are defaulted to “204 No Content”. This
   is a strictly narrower version of the feature landed in #19036 and
   #19377.

4. To avoid confusion when interacting in the browser, these actions
   will raise an `UnknownFormat` error for “interactive” requests
   instead. (The precise definition of “interactive” requests might
   change – the spirit here is to give helpful messages and avoid
   confusions.)

Closes #20666, #23062, #23077, #23564

[Godfrey Chan, Jon Moss, Kasper Timm Hansen, Mike Clark, Matthew Draper]

CVE-2016-0752

The thread_safe gem is being deprecated and all its code has been merged
into the concurrent-ruby gem. The new class, Concurrent::Map, is exactly
the same as its predecessor except for fixes to two bugs discovered
during the merge.

I wrote a utility that helps find areas where you could optimize your program using a frozen string instead of a string literal, it's called [let_it_go](https://github.com/schneems/let_it_go). After going through the output and adding `.freeze` I was able to eliminate the creation of 1,114 string objects on EVERY request to [codetriage](codetriage.com). How does this impact execution?

To look at memory:

```ruby
require 'get_process_mem'

mem = GetProcessMem.new
GC.start
GC.disable
1_114.times { " " }
before = mem.mb

after = mem.mb
GC.enable
puts "Diff: #{after - before} mb"

```

Creating 1,114 string objects results in `Diff: 0.03125 mb` of RAM allocated on every request. Or 1mb every 32 requests.

To look at raw speed:

```ruby
require 'benchmark/ips'

number_of_objects_reduced = 1_114

Benchmark.ips do |x|
  x.report("freeze")    { number_of_objects_reduced.times { " ".freeze } }
  x.report("no-freeze") { number_of_objects_reduced.times { " " } }
end
```

We get the results

```
Calculating -------------------------------------
              freeze     1.428k i/100ms
           no-freeze   609.000  i/100ms
-------------------------------------------------
              freeze     14.363k (± 8.5%) i/s -     71.400k
           no-freeze      6.084k (± 8.1%) i/s -     30.450k
```

Now we can do some maths:

```ruby
ips = 6_226k # iterations / 1 second
call_time_before = 1.0 / ips # seconds per iteration 

ips = 15_254 # iterations / 1 second
call_time_after = 1.0 / ips # seconds per iteration 

diff = call_time_before - call_time_after

number_of_objects_reduced * diff * 100

# => 0.4530373333993266 miliseconds saved per request
```

So we're shaving off 1 second of execution time for every 220 requests. 

Is this going to be an insane speed boost to any Rails app: nope. Should we merge it: yep. 

p.s. If you know of a method call that doesn't modify a string input such as [String#gsub](https://github.com/schneems/let_it_go/blob/b0e2da69f0cca87ab581022baa43291cdf48638c/lib/let_it_go/core_ext/string.rb#L37) please [give me a pull request to the appropriate file](https://github.com/schneems/let_it_go/blob/b0e2da69f0cca87ab581022baa43291cdf48638c/lib/let_it_go/core_ext/string.rb#L37), or open an issue in LetItGo so we can track and freeze more strings. 

Keep those strings Frozen

![](https://www.dropbox.com/s/z4dj9fdsv213r4v/let-it-go.gif?dl=1)

Just saw these in passing while reading this file.

Colons are not metacharacters.

Now that we only support Ruby 2.2+ we don't need this conditional
anymore

These requires were added only to change deprecation message

Files without a template handler in their extension will be rended
using the raw handler instead of ERB.

If someone copies the docs into their app they'll find it simply doesn't
work because the locale pattern doesn't have the same logic. This makes
the doc examples work exactly as written.

[ci skip]

The current style for warning messages without newlines uses
concatenation of string literals with manual trailing spaces
where needed.

Heredocs have better readability, and with `squish` we can still
produce a single line.

This is a similar use case to the one that motivated defining
`strip_heredoc`, heredocs are super clean.

I didn't want to do this, FNM_EXTGLOB is defined on 2.1.x, but Dir.glob
returns the wrong value on Ruby less than 2.2.0.  Checking for a
case-insensitive FS seems too hard, so just check Ruby version  Checking
for a case-insensitive FS seems too hard, so just check Ruby version.

this is due to:

  https://bugs.ruby-lang.org/issues/5994

By default, variants in the templates will be picked up if a variant is set
and there's a match. The format will be:

  app/views/projects/show.html.erb
  app/views/projects/show.html+tablet.erb
  app/views/projects/show.html+phone.erb

If request.variant = :tablet is set, we'll automatically be rendering the
html+tablet template.

In the controller, we can also tailer to the variants with this syntax:

  class ProjectsController < ActionController::Base
    def show
      respond_to do |format|
        format.html do |html|
          @stars = @project.stars

          html.tablet { @notifications = @project.notifications }
          html.phone  { @chat_heads    = @project.chat_heads }
        end

        format.js
        format.atom
      end
    end
  end

The variant itself is nil by default, but can be set in before filters, like
so:

  class ApplicationController < ActionController::Base
    before_action do
      if request.user_agent =~ /iPad/
        request.variant = :tablet
      end
    end
  end

This is modeled loosely on custom mime types, but it's specifically not
intended to be used together. If you're going to make a custom mime type,
you don't need a variant. Variants are for variations on a single mime
types.

Summary of the changes:
 * Add thread_safe gem.
 * Use thread safe cache for digestor caching.
 * Replace manual synchronization with ThreadSafe::Cache in Relation::Delegation.
 * Replace @attribute_method_matchers_cache Hash with ThreadSafe::Cache.
 * Use TS::Cache to avoid the synchronisation overhead on listener retrieval.
 * Replace synchronisation with TS::Cache usage.
 * Use a preallocated array for performance/memory reasons.
 * Update the controllers cache to the new AS::Dependencies::ClassCache API.
   The original @controllers cache no longer makes much sense after @tenderlove's
   changes in 7b6bfe84 and f345e238.
 * Use TS::Cache in the connection pool to avoid locking overhead.
 * Use TS::Cache in ConnectionHandler.