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ruby--ruby/test/fiddle/test_pinned.rb
Aaron Patterson 307388ea19 [ruby/fiddle] Add a "pinning" reference (#44)
* Add a "pinning" reference

A `Fiddle::Pinned` objects will prevent the objects they point to from
moving.  This is useful in the case where you need to pass a reference
to a C extension that keeps the address in a global and needs the
address to be stable.

For example:

```ruby
class Foo
  A = "hi" # this is an embedded string

  some_c_function A # A might move!
end
```

If `A` moves, then the underlying string buffer may also move.
`Fiddle::Pinned` will prevent the object from moving:

```ruby
class Foo
  A = "hi" # this is an embedded string

  A_pinner = Fiddle::Pinned.new(A) # :nodoc:

  some_c_function A # A can't move because of `Fiddle::Pinned`
end
```

This is a similar strategy to what Graal uses:

  https://www.graalvm.org/sdk/javadoc/org/graalvm/nativeimage/PinnedObject.html#getObject--

* rename global to match exception name

* Introduce generic Fiddle::Error and rearrange error classes

Fiddle::Error is the generic exception base class for Fiddle exceptions.
This commit introduces the class and rearranges Fiddle exceptions to
inherit from it.

https://github.com/ruby/fiddle/commit/ac52d00223
2020-11-18 09:05:13 +09:00

27 lines
534 B
Ruby

# frozen_string_literal: true
begin
require_relative 'helper'
rescue LoadError
end
module Fiddle
class TestPinned < Fiddle::TestCase
def test_pin_object
x = Object.new
pinner = Pinned.new x
assert_same x, pinner.ref
end
def test_clear
pinner = Pinned.new Object.new
refute pinner.cleared?
pinner.clear
assert pinner.cleared?
ex = assert_raise(Fiddle::ClearedReferenceError) do
pinner.ref
end
assert_match "called on", ex.message
end
end
end