partitioner: unpub Partitioner(Hasher) trait and impls

We do not expect users to implement their own Partitioners nor use their
methods. Therefore, `Partitioner` trait and its implementors,
`Murmur3Partitioner` and `CDCPartitioner`, are made `pub(crate)`.
Same with `PartitionerHasher` trait and its implementors.

Author: wprzytula

scylla/src/routing/partitioner.rs

@@ -49,9 +49,8 @@ impl Partitioner for PartitionerName {
     }
 }
 
-// TODO: make this back `pub(crate)` in this PR.
 #[allow(clippy::upper_case_acronyms)]
-pub enum PartitionerHasherAny {
+pub(crate) enum PartitionerHasherAny {
     Murmur3(Murmur3PartitionerHasher),
     CDC(CDCPartitionerHasher),
 }
@@ -77,11 +76,12 @@ impl PartitionerHasher for PartitionerHasherAny {
 /// The Partitioners' design is based on std::hash design: `Partitioner`
 /// corresponds to `HasherBuilder`, and `PartitionerHasher` to `Hasher`.
 /// See their documentation for more details.
-pub trait Partitioner {
+pub(crate) trait Partitioner {
     type Hasher: PartitionerHasher;
 
     fn build_hasher(&self) -> Self::Hasher;
 
+    #[allow(unused)] // Currently, no public API uses this.
     fn hash_one(&self, data: &[u8]) -> Token {
         let mut hasher = self.build_hasher();
         hasher.write(data);
@@ -94,12 +94,12 @@ pub trait Partitioner {
 /// Instances of this trait are created by a `Partitioner` and are stateful.
 /// At any point, one can call `finish()` and a `Token` will be computed
 /// based on values that has been fed so far.
-pub trait PartitionerHasher {
+pub(crate) trait PartitionerHasher {
     fn write(&mut self, pk_part: &[u8]);
     fn finish(&self) -> Token;
 }
 
-pub struct Murmur3Partitioner;
+pub(crate) struct Murmur3Partitioner;
 
 impl Partitioner for Murmur3Partitioner {
     type Hasher = Murmur3PartitionerHasher;
@@ -114,7 +114,7 @@ impl Partitioner for Murmur3Partitioner {
     }
 }
 
-pub struct Murmur3PartitionerHasher {
+pub(crate) struct Murmur3PartitionerHasher {
     total_len: usize,
     buf: [u8; Self::BUF_CAPACITY],
     h1: Wrapping<i64>,
@@ -280,9 +280,9 @@ enum CDCPartitionerHasherState {
     Computed(Token),
 }
 
-pub struct CDCPartitioner;
+pub(crate) struct CDCPartitioner;
 
-pub struct CDCPartitionerHasher {
+pub(crate) struct CDCPartitionerHasher {
     state: CDCPartitionerHasherState,
 }