Crate triomphe

source ·
Expand description

Fork of Arc. This has the following advantages over std::sync::Arc:

  • triomphe::Arc doesn’t support weak references: we save space by excluding the weak reference count, and we don’t do extra read-modify-update operations to handle the possibility of weak references.
  • triomphe::UniqueArc allows one to construct a temporarily-mutable Arc which can be converted to a regular triomphe::Arc later
  • triomphe::OffsetArc can be used transparently from C++ code and is compatible with (and can be converted to/from) triomphe::Arc
  • triomphe::ArcBorrow is functionally similar to &triomphe::Arc<T>, however in memory it’s simply &T. This makes it more flexible for FFI; the source of the borrow need not be an Arc pinned on the stack (and can instead be a pointer from C++, or an OffsetArc). Additionally, this helps avoid pointer-chasing.
  • triomphe::Arc has can be constructed for dynamically-sized types via from_header_and_iter
  • triomphe::ThinArc provides thin-pointer Arcs to dynamically sized types
  • triomphe::ArcUnion is union of two triomphe:Arcs which fits inside one word of memory


  • An atomically reference counted shared pointer
  • A “borrowed Arc”. This is a pointer to a T that is known to have been allocated within an Arc.
  • A tagged union that can represent Arc<A> or Arc<B> while only consuming a single word. The type is also NonNull, and thus can be stored in an Option without increasing size.
  • Structure to allow Arc-managing some fixed-sized data and a variably-sized slice in a single allocation.
  • Header data with an inline length. Consumers that use HeaderWithLength as the Header type in HeaderSlice can take advantage of ThinArc.
  • An Arc, except it holds a pointer to the T instead of to the entire ArcInner.
  • A “thin” Arc containing dynamically sized data
  • An Arc that is known to be uniquely owned