Add a simple API for fetching a list of entries from the cache, where
any missing entries are computed by a supplied block.

autosave_association issue that occurs when table has unique index (resubmission)

Use faster Array.new instead of []*padding

This reverts commit 09751fdc, reversing
changes made to 6a5ab08d.

This change caused a failure in
actionpack/test/abstract/callbacks_test.rb.

MiniTest 4.7.3 detects the presence of SIGINFO and stores the answer in
a constant.

It seems that MiniTest 4.7.4 changes this, and instead relies on an
info_signal method being implemented on the runner object.

In ActiveSupport::Testing::Isolation, we use ProxyTestResult to stand in
for the runner object. This object implements `method_missing`, and as
such its #info_signal method has a truthy return value. This results in
MiniTest trying to install the SIGINFO handler on platforms where
SIGINFO does not exists.

To fix, I am simply defining an explicit ProxyTestResult#info_signal
method.

test_mysql_integer_not_null_defaults in test/cases/defaults_test.rb was
failing. This test relies on the connection being in strict mode. By
default a new connection is not in strict mode, but Active Record
automatically places it in strict mode.

ActiveSchemaTest overwrites the connection's #execute method in order to
prevent SQL statements from actually being executed. One of the
operations which is performed in ActiveSchema test is a #recreate_database.

Since 2088bf27, recreate_database on
mysql or mysql2 will trigger a reconnect.

Due to the implementation of the hacking of #execute in
ActiveSchemaTest, this reconnect would take place, but the connection
would *not* be placed in strict mode because #execute had been
overridden to prevent SQL queries hitting the database.

Therefore, after ActiveSchemaTest, the connection would no longer be in
strict mode, causing test_mysql_integer_not_null_defaults to fail.

I don't think that the way that ActiveSchemaTest is implemented is
particularly nice or clean, but I have taken steps to make its hacks
more isolated - it now create a separate connection object which is
thrown away after the test, and the hacks are applied on the singleton
class of this object.

Restore ActiveRecord connection to original environment after rake:db:test:prepare task.

Improving the performance of callbacks

callbacks in the CallbackChain, so you don't have to iterate over all
callbacks when checking for duplicates.

Benchmark results when the tests in
activerecord/test/cases/associations_test.rb were run with and without
the change:

== On master (when scanning all of the callbacks):

 ---------------------------------------------------------
  %   cumulative   self              self     total
 time   seconds   seconds    calls  ms/call  ms/call  name
 ---------------------------------------------------------

  1.85     9.26      0.82    18412     0.04     0.05
ActiveSupport::Callbacks::Callback#matches?
  1.22    12.32      0.54    18412     0.03     0.08
ActiveSupport::Callbacks::Callback#duplicates?
  0.93    14.61      0.41    19600     0.02     0.21
ActiveSupport::Callbacks::CallbackChain#remove_duplicates

Finished tests in 1.217065s, 30.4010 tests/s, 53.4072 assertions/s.
 ---------------------------------------------------------

== On my branch (when using a hash to check callback duplication):

 ---------------------------------------------------------
  %   cumulative   self              self     total
 time   seconds   seconds    calls  ms/call  ms/call  name
 ---------------------------------------------------------
  0.15    29.63      0.06     1188     0.05     0.72
ActiveSupport::Callbacks::CallbackChain#handle_duplicates
  0.00    40.50      0.00       84     0.00     0.12
ActiveSupport::Callbacks::Callback#matches?
  0.00    40.50      0.00       84     0.00     0.12
ActiveSupport::Callbacks::Callback#duplicates?
  0.00    40.50      0.00       91     0.00     0.22
ActiveSupport::Callbacks::CallbackChain#scan_and_remove_duplicates

Finished tests in 1.117757s, 33.1020 tests/s, 58.1522 assertions/s.
 ---------------------------------------------------------

Add parameter :sslcompression to PostgreSQL adapter.

It is new in PostgreSQL-9.2 .

Add styling to h1 for default rescue layout

Refactoring the creation of TestTasks to remove code duplication.

Add test for `AR::Base#to_param`

According to the doc of `AR::Base#to_param`(
https://github.com/rails/rails/blob/04cda1848cb847c2bdad0bfc12160dc8d554
7775/activerecord/lib/active_record/integration.rb#L18 ), it returns
`nil` if the record is not persisted.

Fix typo in test

Fixes Dependency bug in Active Support

fixes bug introduced by  #3329
These are the conditions necessary to reproduce the bug:
- For an association, autosave => true.
- An association record is being destroyed
- A new association record is being created.
- There is a unique index one of the association's fields.
- The record being created has the same value as the record being
destroyed on the indexed field.

Before, the deletion of records was postponed until after all
insertions/saves.  Therefore the new record with the identical value in
the indexed field caused a non-unique value error to be thrown at the database
level.

With this fix, the deletions happen first, before the insertions/saves.
Therefore the record with the duplicate value is gone from the database
before the new record is created, thereby avoiding the non-uniuqe value
error.

DateTime defined in date.rb

Extract tests code out from AR's base_test.rb to integration_test.rb

`AR::Base#to_param` and `AR::Base#cache_key` is defined at
active_record/integration.rb, so tests for those methods should be at
integration_test.rb

Convert ActiveModel to 1.9 hash syntax.

I also attempted to fix other styleguide violations such as
{ a: :b } over {a: :b} and foo(b: 'bar') over foo( b: 'bar' ).

Handle aliased attributes in AR::Relation

Introduced in 09ac1776.

Use constant for encoding

When using symbol keys, ActiveRecord will now translate aliased attribute names to the actual column name used in the database:

With the model

  class Topic
    alias_attribute :heading, :title
  end

The call

  Topic.where(heading: 'The First Topic')

should yield the same result as

  Topic.where(title: 'The First Topic')

This also applies to ActiveRecord::Relation::Calculations calls such as `Model.sum(:aliased)` and `Model.pluck(:aliased)`.

This will not work with SQL fragment strings like `Model.sum('DISTINCT aliased')`.

Github #7839

*Godfrey Chan*

Allow override of PostgreSQL UUID primary key default

without this, it's not possible to use UUID primary keys without uuid-ossp installed and activated

Make railties version match RAILS_VERSION

Remove varargs from `Object#in?`