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Remove Deref and DerefMut implementations from WeakFlowRef.

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By definition of a weak pointer, these implementations cannot be safe.
This commit is contained in:
Ms2ger 2015-06-27 18:09:14 +02:00
parent 8892f8175d
commit b37d9cc173
2 changed files with 13 additions and 22 deletions
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2
components/layout/flow.rs
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@ -1393,7 +1393,7 @@ impl ContainingBlockLink {
panic!("Link to containing block not established; perhaps you forgot to call \ panic!("Link to containing block not established; perhaps you forgot to call \
`set_absolute_descendants`?") `set_absolute_descendants`?")
} }
Some(ref mut link) => link.generated_containing_block_size(for_flow), Some(ref link) => link.upgrade().unwrap().generated_containing_block_size(for_flow),
} }
} }
} }

33
components/layout/flow_ref.rs
View file

@ -10,7 +10,7 @@
#![allow(unsafe_code)] #![allow(unsafe_code)]
use flow::Flow; use flow::{Flow, BaseFlow};
use flow; use flow;
use std::mem; use std::mem;
@ -133,11 +133,19 @@ impl Clone for FlowRef {
} }
} }
fn base<'a>(r: &WeakFlowRef) -> &'a BaseFlow {
let data = r.object.data;
debug_assert!(!data.is_null());
unsafe {
mem::transmute::<*mut (), &'a BaseFlow>(data)
}
}
impl WeakFlowRef { impl WeakFlowRef {
/// Upgrades a WeakFlowRef to a FlowRef. /// Upgrades a WeakFlowRef to a FlowRef.
pub fn upgrade(&self) -> Option<FlowRef> { pub fn upgrade(&self) -> Option<FlowRef> {
unsafe { unsafe {
let object = flow::base(&**self); let object = base(self);
// We use a CAS loop to increment the strong count instead of a // We use a CAS loop to increment the strong count instead of a
// fetch_add because once the count hits 0 is must never be above // fetch_add because once the count hits 0 is must never be above
// 0. // 0.
@ -153,27 +161,10 @@ impl WeakFlowRef {
} }
} }
impl<'a> Deref for WeakFlowRef {
type Target = Flow + 'a;
fn deref(&self) -> &(Flow + 'a) {
unsafe {
mem::transmute_copy::<raw::TraitObject, &(Flow + 'a)>(&self.object)
}
}
}
impl DerefMut for WeakFlowRef {
fn deref_mut<'a>(&mut self) -> &mut (Flow + 'a) {
unsafe {
mem::transmute_copy::<raw::TraitObject, &mut (Flow + 'a)>(&self.object)
}
}
}
impl Clone for WeakFlowRef { impl Clone for WeakFlowRef {
fn clone(&self) -> WeakFlowRef { fn clone(&self) -> WeakFlowRef {
unsafe { unsafe {
flow::base(&**self).weak_ref_count().fetch_add(1, Ordering::Relaxed); base(self).weak_ref_count().fetch_add(1, Ordering::Relaxed);
} }
WeakFlowRef { object: self. object } WeakFlowRef { object: self. object }
} }
@ -187,7 +178,7 @@ impl Drop for WeakFlowRef {
return return
} }
if flow::base(&**self).weak_ref_count().fetch_sub(1, Ordering::Release) == 1 { if base(self).weak_ref_count().fetch_sub(1, Ordering::Release) == 1 {
atomic::fence(Ordering::Acquire); atomic::fence(Ordering::Acquire);
// This dance deallocates the Box<Flow> without running its // This dance deallocates the Box<Flow> without running its