Implement Write Barrier and dsize for FFI::FunctionType #1001
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| // IMPORTANT: WB_PROTECTED objects must only use the RB_OBJ_WRITE() | ||
| // macro to update VALUE references, as to trigger write barriers. |
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I was asked to add this comment when I added write barriers in the protobuf gem, and I think it's a good idea as it might remind future contributors.
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| static size_t | ||
| fntype_memsize(const void *data) |
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I think I accounted for all held data, but worst case these function don't have to be 100% accurate.
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A FunctionInfo can have a closurePool associated for all closures that are created in relation to this FunctionInfo. I'll add at least the management data of the ClosurePool to the size.
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Sounds good, I'll have a look at it.
We canalso report the size of the pool divided by the number of refs to it, I've done that in msgpack-ruby.
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| function_type = FFI::FunctionType.new(:int, []) | ||
| size = ObjectSpace.memsize_of(function_type) | ||
| expect(size).to be > base_size |
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The size can vary on platforms etc, so I usually use this pattern to ensure the function report something, but not assert a precise size.
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spec/ffi/function_type_spec.rb
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| require File.expand_path(File.join(File.dirname(__FILE__), "spec_helper")) | ||
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| describe FFI::FunctionType, skip: RUBY_PLATFORM == "java" do |
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The java ext doesn't define this class, I suppose that's why it wasn't tested. But I think these specs are worth it for the MRI implementation.
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Yes, FunctionInfo is just an internal class not exposed through the API.
Write barrier protected objects are allowed to be promoted to the old generation, which means they only get marked on major GC. The downside is that the RB_BJ_WRITE macro MUST be used to set references, otherwise the referenced object may be garbaged collected. This commit also implement a `dsize` function so that these instance report a more relevant size in various memory profilers.
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Ok, it's now 🟢 , moving on to the next one. |
Ref: #991
Write barrier protected objects are allowed to be promoted to the old generation, which means they only get marked on major GC.
The downside is that the RB_BJ_WRITE macro MUST be used to set references, otherwise the referenced object may be garbaged collected.
This commit also implement a
dsizefunction so that these instance report a more relevant size in various memory profilers.