re-privatize the Join trait

1 files changed, 9 insertions, 38 deletions

diff --git a/src/join.rs b/src/join.rs
index 60932db..2435bc6 100644
--- a/src/join.rs
+++ b/src/join.rs
@@ -8,47 +8,18 @@
 //! [`hash`] and [`Hasher::update`], always use `SerialJoin` internally.
 //!
 //! The `Join` trait is an almost exact copy of the [`rayon::join`] API, and
-//! `RayonJoin` is the only non-trivial implementation provided. The only
-//! difference between the function signature in the `Join` trait and the
-//! underlying one in Rayon, is that the trait method includes two length
-//! parameters. This gives an implementation the option of e.g. setting a
-//! subtree size threshold below which it keeps splits on the same thread.
-//! However, neither of the two provided implementations currently makes use of
-//! those parameters. Note that in Rayon, the very first `join` call is more
-//! expensive than subsequent calls, because it moves work from the calling
-//! thread into the thread pool. That makes a coarse-grained input length
-//! threshold in the caller more effective than a fine-grained subtree size
-//! threshold after the implementation has already started recursing.
+//! `RayonJoin` is the only non-trivial implementation. Previously this trait
+//! was public, but currently it's been re-privatized, as it's both 1) of no
+//! value to most callers and 2) a pretty big implementation detail to commit
+//! to.
 //!
-//! # Example
-//!
-//! ```
-//! // Hash a large input using multi-threading. Note that multi-threading
-//! // comes with some overhead, and it can actually hurt performance for small
-//! // inputs. The meaning of "small" varies, however, depending on the
-//! // platform and the number of threads. (On x86_64, the cutoff tends to be
-//! // around 128 KiB.) You should benchmark your own use case to see whether
-//! // multi-threading helps.
-//! # #[cfg(feature = "rayon")]
-//! # {
-//! # fn some_large_input() -> &'static [u8] { b"foo" }
-//! let input: &[u8] = some_large_input();
-//! let mut hasher = blake3::Hasher::new();
-//! hasher.update_with_join::<blake3::join::RayonJoin>(input);
-//! let hash = hasher.finalize();
-//! # }
-//! ```
-//!
-//! [`Hasher::update_with_join`]: ../struct.Hasher.html#method.update_with_join
-//! [`Hasher::update`]: ../struct.Hasher.html#method.update
-//! [`hash`]: ../fn.hash.html
 //! [`rayon::join`]: https://docs.rs/rayon/1.3.0/rayon/fn.join.html
 
 /// The trait that abstracts over single-threaded and multi-threaded recursion.
 ///
 /// See the [`join` module docs](index.html) for more details.
 pub trait Join {
-    fn join<A, B, RA, RB>(oper_a: A, oper_b: B, len_a: usize, len_b: usize) -> (RA, RB)
+    fn join<A, B, RA, RB>(oper_a: A, oper_b: B) -> (RA, RB)
     where
         A: FnOnce() -> RA + Send,
         B: FnOnce() -> RB + Send,
@@ -66,7 +37,7 @@ pub enum SerialJoin {}
 
 impl Join for SerialJoin {
     #[inline]
-    fn join<A, B, RA, RB>(oper_a: A, oper_b: B, _len_a: usize, _len_b: usize) -> (RA, RB)
+    fn join<A, B, RA, RB>(oper_a: A, oper_b: B) -> (RA, RB)
     where
         A: FnOnce() -> RA + Send,
         B: FnOnce() -> RB + Send,
@@ -88,7 +59,7 @@ pub enum RayonJoin {}
 #[cfg(feature = "rayon")]
 impl Join for RayonJoin {
     #[inline]
-    fn join<A, B, RA, RB>(oper_a: A, oper_b: B, _len_a: usize, _len_b: usize) -> (RA, RB)
+    fn join<A, B, RA, RB>(oper_a: A, oper_b: B) -> (RA, RB)
     where
         A: FnOnce() -> RA + Send,
         B: FnOnce() -> RB + Send,
@@ -107,7 +78,7 @@ mod test {
     fn test_serial_join() {
         let oper_a = || 1 + 1;
         let oper_b = || 2 + 2;
-        assert_eq!((2, 4), SerialJoin::join(oper_a, oper_b, 3, 4));
+        assert_eq!((2, 4), SerialJoin::join(oper_a, oper_b));
     }
 
     #[test]
@@ -115,6 +86,6 @@ mod test {
     fn test_rayon_join() {
         let oper_a = || 1 + 1;
         let oper_b = || 2 + 2;
-        assert_eq!((2, 4), RayonJoin::join(oper_a, oper_b, 3, 4));
+        assert_eq!((2, 4), RayonJoin::join(oper_a, oper_b));
     }
 }