This new ActiveRecord configuration option allows you to easily
pinpoint what line of application code is triggering SQL queries in the
development log by appending below each SQL statement log the line of
Ruby code that triggered it.

It’s useful with N+1 issues, and to locate stray queries.

By default this new option ignores Rails and Ruby code in order to
surface only callers from your application Ruby code or your gems.

It is enabled on newly generated Rails 5.2 applications and can be
enabled on existing Rails applications:

```ruby
Rails.application.configure do
  # ...
  config.active_record.verbose_query_logs = true
end
```

The `rails app:upgrade` task will also add it to
`config/development.rb`.

This feature purposely avoids coupling with
ActiveSupport::BacktraceCleaner since ActiveRecord can be used without
ActiveRecord. This decision can be reverted in the future to allow more
configurable backtraces (the exclusion of gem callers for example).

This reverts commit 3420a145, reversing
changes made to afb66a5a.

Addresses #29021

Address #29021

Since Ruby 2.5.0-dev does not return decimal value when it is 0.
This change has been made at Ruby 2.5.0-dev between `(2017-05-05 trunk 58572)`
and `(2017-05-07 trunk 58586)`, likely Revision 58586.

This fix has been tested with these Ruby versions:

* ruby 2.5.0dev (2017-05-15 trunk 58733) [x86_64-linux]
* ruby 2.4.1p111 (2017-03-22 revision 58053) [x86_64-linux]
* ruby 2.3.4p301 (2017-03-30 revision 58214) [x86_64-linux]
* ruby 2.2.7p470 (2017-03-28 revision 58194) [x86_64-linux]

[Yasuo Honda & Ryuta Kamizono]

Just use one `Event` class. Reduces duplication, makes the tests easier
to read. It might seem like each tests needs a different kind of Struct,
since we make a new one for each test case.

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

If an attribute was of the binary type, and also was a Hash, it would
previously not be logged, and instead raise an error saying that
`bytesize` was not defined for the `attribute.value` (a `Hash`).

Now, as is done on 4-2-stable, the attribute's database value is
`bytesize`d, and then logged out to the terminal.

Reproduction script:

```ruby
require 'active_record'
require 'minitest/autorun'
require 'logger'

ActiveRecord::Base.establish_connection(adapter: 'sqlite3', database: ':memory:')
ActiveRecord::Base.logger = Logger.new(STDOUT)

ActiveRecord::Schema.define do
  create_table :posts, force: true do |t|
    t.binary :preferences
  end
end

class Post < ActiveRecord::Base
  serialize :preferences
end

class BugTest < Minitest::Test
  def test_24955
    Post.create!(preferences: {a: 1})

    assert_equal 1, Post.count
  end
end
```

- Improves coloring for statements like:

    # Become WHITE
    SELECT * FROM (
        SELECT * FROM mytable FOR UPDATE
    ) ss WHERE col1 = 5;
    LOCK TABLE table_name IN ACCESS EXCLUSIVE MODE;

    # Becomes RED
    ROLLBACK

- Reinstates the coloration of the `payload[:name]`.
  Instead of simple alternating colors, adds meaning:
  - `MAGENTA` for `"SQL"` or `blank?` payload names
  - `CYAN` for Model Load/Exists

- Introduces specs for sql coloration.
- Introduces specs for payload name coloration.

GH#20885

`bound_attributes` is now used universally across the board, removing
the need for the conversion layer. These changes are mostly mechanical,
with the exception of the log subscriber. Additional, we had to
implement `hash` on the attribute objects, so they could be used as a
key for query caching.

There's very little value in logging "<NULL binary data>" instead of
just "nil". I'd like to remove the column from the equation entirely,
and this case is preventing us from doing so.

We can conditional define the tests depending on the adapter or
connection.

Lets keep the skip for fail tests that need to be fixed.

If I have a query that produces sql
`WHERE "users"."name" = 'a         b'` then in the log all the
whitespace is being squeezed. So the sql that is printed in the
log is `WHERE "users"."name" = 'a b'`.

This can be confusing. This commit fixes it by ensuring that
whitespace is not squeezed.

fixes #10982

Some tests were raising the following error:

    Could not log "sql.active_record" event. NoMethodError: undefined method
    `type' for nil:NilClass`

Due to the way binds were being logged, the column info was considered
always present, but that is not true for some of the tests listed in the
issue.

Closes #8806.

The number of sql statement logged depends on each database adapter
implementation.
Also, this test does not depends on how many sql statement executed.

Mysql2 doesn't support binds, which means no binds payload is set when
logging, so the logic to render binary data differently here doesn't work.

Introduced in 99d142a9.

They tend to be large and not very useful in the log.

On reflection, it seems like a bit of a weird method to have on
ActiveRecord::Base, and it shouldn't be needed most of the time anyway.

Previously it returned an Array.

If you want an array, call e.g. `Post.to_a` rather than `Post.all`. This
is more explicit.

In most cases this should not break existing code, since
Relations use method_missing to delegate unknown methods to #to_a
anyway.

Refactor Active Record test connection setup. Please see the RUNNING_UNIT_TESTS file for details, but essentially you can now configure things in test/config.yml. You can also run tests directly via the command line, e.g. ruby path/to/test.rb (no rake needed, uses default db connection from test/config.yml). This will help us fix the CI by enabling us to isolate the different Rails versions to different databases.

Disable IdentityMap in log tests, it's not important and when running tests rake task it logs more messages in the tested buffer.
Signed-off-by: NJosé Valim <jose.valim@gmail.com>

* AS::Notifications#instrument should not measure anything, it is not its responsibility;

* Adding another argument to AS::Notifications#instrument API needs to be properly discussed;

Signed-off-by: NJosé Valim <jose.valim@gmail.com>