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Now we have a 'dummy_impl' module that has a fake GC implementation. Maybe someday we should actually implement a real nop gc, like Java is adding. Right now the only doc-test we have is for `safepoint!` but at least that works :)
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,131 @@ | ||
| //! Dummy collector implementation for testing | ||
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| use crate::{ | ||
| Trace, TraceImmutable, GcVisitor, NullTrace, CollectorId, | ||
| GcSafe, GcSystem, GcContext, | ||
| }; | ||
| use std::ptr::NonNull; | ||
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| /// Fake a [Gc] that points to the specified value | ||
| /// | ||
| /// This will never actually be collected | ||
| /// and will always be valid | ||
| pub fn gc<'gc, T: GcSafe + 'static>(ptr: &'static T) -> Gc<'gc, T> { | ||
| unsafe { | ||
| Gc::from_raw( | ||
| DummyCollectorId { _priv: () }, | ||
| NonNull::from(ptr) | ||
| ) | ||
| } | ||
| } | ||
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| /// Allocate a [(fake) Gc](Gc) that points to the specified | ||
| /// value and leak it. | ||
| /// | ||
| /// Since collection is unimplemented, | ||
| /// this intentionally leaks memory. | ||
| pub fn leaked<'gc, T: GcSafe + 'static>(value: T) -> Gc<'gc, T> { | ||
| gc(Box::leak(Box::new(value))) | ||
| } | ||
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| /// An fake [garbage collected pointer](::zerogc::Gc) | ||
| /// that uses the dummy collector system | ||
| /// | ||
| /// This never actually collects any garbage | ||
| pub type Gc<'gc, T> = crate::Gc<'gc, T, DummyCollectorId>; | ||
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| /// A dummy implementation of [crate::GcSystem] | ||
| /// which is useful for testing | ||
| /// | ||
| /// This just blindly allocates memory and doesn't | ||
| /// actually do any collection. | ||
| pub struct DummyContext { | ||
| _priv: () | ||
| } | ||
| unsafe impl GcContext for DummyContext { | ||
| type System = DummySystem; | ||
| type Id = DummyCollectorId; | ||
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| unsafe fn basic_safepoint<T: Trace>(&mut self, _value: &mut &mut T) { | ||
| // safepoints are a nop since there is nothing to track | ||
| } | ||
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| unsafe fn freeze(&mut self) { | ||
| unimplemented!() | ||
| } | ||
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| unsafe fn unfreeze(&mut self) { | ||
| unimplemented!() | ||
| } | ||
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| unsafe fn recurse_context<T, F, R>(&self, value: &mut &mut T, func: F) -> R | ||
| where T: Trace, F: for<'gc> FnOnce(&'gc mut Self, &'gc mut T) -> R { | ||
| // safepoints are a nop since there is nothing to track | ||
| let mut child = DummyContext { _priv: () }; | ||
| func(&mut child, &mut *value) | ||
| } | ||
| } | ||
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| /// A dummy implementation of [::zerogc::GcSystem] | ||
| /// which is useful for testing | ||
| /// | ||
| /// All methods panic and this should never be used | ||
| /// in actual code. | ||
| #[derive(Default)] | ||
| pub struct DummySystem { | ||
| _priv: () | ||
| } | ||
| impl DummySystem { | ||
| /// Create a new fake system for testing | ||
| pub fn new() -> Self { | ||
| DummySystem::default() | ||
| } | ||
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| /// Create a [DummyContext] | ||
| /// | ||
| /// There are few restrictions on this | ||
| /// because it doesn't actually do anything | ||
| pub fn new_context(&self) -> DummyContext { | ||
| DummyContext { | ||
| _priv: () | ||
| } | ||
| } | ||
| } | ||
| unsafe impl GcSystem for DummySystem { | ||
| type Id = DummyCollectorId; | ||
| type Context = DummyContext; | ||
| } | ||
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| /// The id for a [dummy gc pointer](Gc) | ||
| #[derive(Copy, Clone, Debug, Eq, PartialEq)] | ||
| pub struct DummyCollectorId { | ||
| _priv: () | ||
| } | ||
| unsafe impl Trace for DummyCollectorId { | ||
| const NEEDS_TRACE: bool = false; | ||
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| fn visit<V: GcVisitor>(&mut self, _visitor: &mut V) -> Result<(), <V as GcVisitor>::Err> { | ||
| Ok(()) | ||
| } | ||
| } | ||
| unsafe impl TraceImmutable for DummyCollectorId { | ||
| fn visit_immutable<V: GcVisitor>(&self, _visitor: &mut V) -> Result<(), V::Err> { | ||
| Ok(()) | ||
| } | ||
| } | ||
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| unsafe impl NullTrace for DummyCollectorId {} | ||
| unsafe impl CollectorId for DummyCollectorId { | ||
| type System = DummySystem; | ||
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| unsafe fn gc_write_barrier<'gc, T, V>( | ||
| _owner: &Gc<'gc, T>, | ||
| _value: &Gc<'gc, V>, | ||
| _field_offset: usize | ||
| ) where T: GcSafe + ?Sized + 'gc, V: GcSafe + ?Sized + 'gc {} | ||
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| unsafe fn assume_valid_system(&self) -> &Self::System { | ||
| unimplemented!() | ||
| } | ||
| } |
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