In the rails/rails CI build for Ruby master we found that some tests
were failing due to inspect on a frozen object being incorrect.
An object's instance variable count was incorrect when frozen causing
the object's inspect to not splat out the object.
This fixes the issue and adds a test for inspecting frozen objects.
Co-Authored-By: Jemma Issroff <jemmaissroff@gmail.com>
Co-Authored-By: Aaron Patterson <tenderlove@ruby-lang.org>
Before d594a5a8bd, we were only
asserting that the value on an ivar_get was ractor_sharable if the
object was a T_OBJECT and also ractor shareable. We should still
be doing this check only if the object is a T_OBJECT and ractor
shareable
RARRAY_PTR when called with a transient array detransients the array
before returning its pointer which allocates in the heap.
Because RARRAY_PTR was being used during compaction (when re-embedding
arrays that have moved between size pools) this introduces the
possibility that we can hit a malloc threshold, triggering GC, while in
the middle of compaction.
We should avoid this by using safer functions to get hold of the
pointer. Since we know that the array is not embedded here, we can use
ARY_HEAP_PTR and ARY_EMBED_PTR directly
Loading Bundler beforehand was actually replacing ENV with a backup of
the pre-Bundler environment through `Bundler::EnvironmentPreserver`. I
think that was making a bug in `ENV.replace` not bite our tests, because
Bundler includes proper patches to workaround that issue. So this commit
also includes these patches in RubyGems tests.
8e079149b9
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Please update your editor config, and use misc/expand_tabs.rb in the pre-commit hook.
Object Shapes is used for accessing instance variables and representing the
"frozenness" of objects. Object instances have a "shape" and the shape
represents some attributes of the object (currently which instance variables are
set and the "frozenness"). Shapes form a tree data structure, and when a new
instance variable is set on an object, that object "transitions" to a new shape
in the shape tree. Each shape has an ID that is used for caching. The shape
structure is independent of class, so objects of different types can have the
same shape.
For example:
```ruby
class Foo
def initialize
# Starts with shape id 0
@a = 1 # transitions to shape id 1
@b = 1 # transitions to shape id 2
end
end
class Bar
def initialize
# Starts with shape id 0
@a = 1 # transitions to shape id 1
@b = 1 # transitions to shape id 2
end
end
foo = Foo.new # `foo` has shape id 2
bar = Bar.new # `bar` has shape id 2
```
Both `foo` and `bar` instances have the same shape because they both set
instance variables of the same name in the same order.
This technique can help to improve inline cache hits as well as generate more
efficient machine code in JIT compilers.
This commit also adds some methods for debugging shapes on objects. See
`RubyVM::Shape` for more details.
For more context on Object Shapes, see [Feature: #18776]
Co-Authored-By: Aaron Patterson <tenderlove@ruby-lang.org>
Co-Authored-By: Eileen M. Uchitelle <eileencodes@gmail.com>
Co-Authored-By: John Hawthorn <john@hawthorn.email>
