diff options
Diffstat (limited to 'src/bytes.rs')
| -rw-r--r-- | src/bytes.rs | 36 |
1 files changed, 32 insertions, 4 deletions
diff --git a/src/bytes.rs b/src/bytes.rs index fa43d3a..0404a72 100644 --- a/src/bytes.rs +++ b/src/bytes.rs @@ -32,7 +32,7 @@ use crate::Buf; /// All `Bytes` implementations must fulfill the following requirements: /// - They are cheaply cloneable and thereby shareable between an unlimited amount /// of components, for example by modifying a reference count. -/// - Instances can be sliced to refer to a subset of the the original buffer. +/// - Instances can be sliced to refer to a subset of the original buffer. /// /// ``` /// use bytes::Bytes; @@ -71,7 +71,7 @@ use crate::Buf; /// /// For `Bytes` implementations which point to a reference counted shared storage /// (e.g. an `Arc<[u8]>`), sharing will be implemented by increasing the -/// the reference count. +/// reference count. /// /// Due to this mechanism, multiple `Bytes` instances may point to the same /// shared memory region. @@ -807,8 +807,36 @@ impl From<&'static str> for Bytes { impl From<Vec<u8>> for Bytes { fn from(vec: Vec<u8>) -> Bytes { - let slice = vec.into_boxed_slice(); - slice.into() + let mut vec = vec; + let ptr = vec.as_mut_ptr(); + let len = vec.len(); + let cap = vec.capacity(); + + // Avoid an extra allocation if possible. + if len == cap { + return Bytes::from(vec.into_boxed_slice()); + } + + let shared = Box::new(Shared { + buf: ptr, + cap, + ref_cnt: AtomicUsize::new(1), + }); + mem::forget(vec); + + let shared = Box::into_raw(shared); + // The pointer should be aligned, so this assert should + // always succeed. + debug_assert!( + 0 == (shared as usize & KIND_MASK), + "internal: Box<Shared> should have an aligned pointer", + ); + Bytes { + ptr, + len, + data: AtomicPtr::new(shared as _), + vtable: &SHARED_VTABLE, + } } } |