This method was first seen in 045713ee24,
and subsequently reimplemented in
fb2325e358.
According to @jeremy, this is okay to remove. He thinks it was added
because at the time we didn't have much transaction state to keep track
of, and he viewed it as a hack for us to track it internally, thinking
it was better to ask the connection for the transaction state.
Over the years we have added more and more state to track, a lot of
which is impossible to ask the connection for. So it seems that this is
just a relic of the passed and we will just track the state internally
only.
This reverts commit c24c885209.
Here's the explanation I just sent to @tenderlove:
Hey,
I've been thinking about about the transaction memory leak thing that we
were discussing.
Example code:
post = nil
Post.transaction do
N.times { post = Post.create }
end
Post.transaction is going to create a real transaction and there will
also be a (savepoint) transaction inside each Post.create.
In an idea world, we'd like all but the last Post instance to be GC'd,
and for the last Post instance to receive its after_commit callback when
Post.transaction returns.
I can't see how this can work using your solution where the Post itself
holds a reference to the transaction it is in; when Post.transaction
returns, control does not switch to any of Post's instance methods, so
it can't trigger the callbacks itself.
What we really want is for the transaction itself to hold weak
references to the objects within the transaction. So those objects can
be GC'd, but if they are not GC'd then the transaction can iterate them
and execute their callbacks.
I've looked into WeakRef implementations that are available. On 1.9.3,
the stdlib weakref library is broken and we shouldn't use it.
There is a better implementation here:
https://github.com/bdurand/ref/blob/master/lib/ref/weak_reference/pure_ruby.rb
We could use that, either by pulling in the gem or just copying the code
in, but it still suffers from the limitation that it uses ObjectSpace
finalizers.
In my testing, this finalizers make GC quite expensive:
https://gist.github.com/3722432
Ruby 2.0 will have a native WeakRef implementation (via
ObjectSpace::WeakMap), hence won't be reliant on finalizers:
http://bugs.ruby-lang.org/issues/4168
So the ultimate solution will be for everyone to use Ruby 2.0, and for
us to just use ObjectSpace::WeakMap.
In the meantime, we have basically 3 options:
The first is to leave it as it is.
The second is to use a finalizer-based weakref implementation and take
the GC perf hit.
The final option is to store object ids rather than the actual objects.
Then use ObjectSpace._id2ref to deference the objects at the end of the
transaction, if they exist. This won't stop memory use growing within
the transaction, but it'll grow more slowly.
I benchmarked the performance of _id2ref this if the object does or does
not exist: https://gist.github.com/3722550
If it does exist it seems decent, but it's hugely more expensive if it
doesn't, probably because we have to do the rescue nil.
Probably most of the time the objects will exist. However the point of
doing this optimisation is to allow people to create a large number of
objects inside a transaction and have them be GC'd. So for that use
case, we'd be replacing one problem with another. I'm not sure which of
the two problems is worse.
My feeling is that we should just leave this for now and come back to it
when Ruby 2.0 is out.
I'm going to revert your commit because I can't see how it solves this.
Hope you don't mind... if I've misunderstood then let me know!
Jon
Having column related schema dumper code in the AbstractAdapter. The
code remains the same, but by placing it in the AbstractAdapter, we can
then overwrite it with Adapter specific methods that will help with
Adapter specific data types.
The goal of moving this code here is to create a new migration key for
PostgreSQL's array type. Since any datatype can be an array, the goal is
to have ':array => true' as a migration option, turning the datatype
into an array. I've implemented this in postgres_ext, the syntax is
shown here: https://github.com/dockyard/postgres_ext#arrays
Adds array migration support
Adds array_test.rb outlining the test cases for array data type
Adds pg_array_parser to Gemfile for testing
Adds pg_array_parser to postgresql_adapter (unused in this commit)
Adds schema dump support for arrays
Adds postgres array type casting support
Updates changelog, adds note for inet and cidr support, which I forgot to add before
Removing debugger, Adds pg_array_parser to JRuby platform
Removes pg_array_parser requirement, creates ArrayParser module used by
PostgreSQLAdapter
It's further work on CSRF after 245941101b.
The :null_session CSRF protection method provide an empty session during
request processing but doesn't reset it completely (as :reset_session
does).
ActiveSupport::Deprecation is now a class rather than a module. You can
get instance of ActiveSupport::Deprecation calling #instance method.
ActiveSupport::Deprecation.instance
But when you need to get new object od ActiveSupport::Deprecation you
need to just call #new.
@instance = ActiveSupport::Deprecation.new
Since you can create a new object, you can change the version and the
name of the library where the deprecator concerned.
ActiveSupport::Deprecation.new('2.0', 'MyGem')
If you need use another deprecator instance you can select it in the
options of deprecate method.
deprecate :method, :deprecator => deprecator_instance
Documentation has been updated.
Users of other SCM's can now generate rails
apps that will add the "empty" directories to source control,
but will not have a useless .gitignore or mis-named .gitkeep
files.
* Change `rails new` and `rails plugin new` generators to name
the `.gitkeep` as `.keep` in a more SCM-agnostic way.
* Change `--skip-git` option to only skip the `.gitignore` file
and still generate the `.keep` files.
* Add `--skip-keeps` option to skip the `.keep` files.
It closes#2800.
In some circumstances engine was Arel::Table.engine which for separate
reasons was an ActiveRecord::Model::DeprecationProxy, which caused a
deprecation warning.
In any case, we want the actual model class here, since we want to use
it to infer information about associations.
Rafael Mendonça França