storage: remove Display bound on Engine trait

src/storage/bitcask.rs

@@ -95,12 +95,6 @@ impl BitCask {
  }
 }
 
-impl std::fmt::Display for BitCask {
- fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
- write!(f, "bitcask")
- }
-}
-
 impl Engine for BitCask {
  type ScanIterator<'a> = ScanIterator<'a>;
 
@@ -150,7 +144,7 @@ impl Engine for BitCask {
  let live_disk_size = size + 8 * keys; // account for length prefixes
  let garbage_disk_size = total_disk_size - live_disk_size;
  Ok(Status {
- name: self.to_string(),
+ name: "bitcask".to_string(),
  keys,
  size,
  total_disk_size,

src/storage/engine.rs

@@ -9,7 +9,7 @@ use serde::{Deserialize, Serialize};
 /// Only supports single-threaded use since all methods (including reads) take a
 /// mutable reference -- serialized access can't be avoided anyway, since both
 /// Raft execution and file access is serial.
-pub trait Engine: std::fmt::Display + Send {
+pub trait Engine: Send {
  /// The iterator returned by scan().
  type ScanIterator<'a>: ScanIterator + 'a
  where
@@ -101,13 +101,6 @@ pub mod test {
  Set { key: Vec<u8>, value: Vec<u8> },
  }
 
- impl<E: Engine> std::fmt::Display for Emit<E> {
- fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
- // Just dispatch to the inner engine.
- self.inner.fmt(f)
- }
- }
-
  impl<E: Engine> Emit<E> {
  pub fn new(inner: E, tx: Sender<Operation>) -> Self {
  Self { inner, tx }

src/storage/memory.rs

@@ -14,12 +14,6 @@ impl Memory {
  }
 }
 
-impl std::fmt::Display for Memory {
- fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
- write!(f, "memory")
- }
-}
-
 impl Engine for Memory {
  type ScanIterator<'a> = ScanIterator<'a>;
 
@@ -54,7 +48,7 @@ impl Engine for Memory {
 
  fn status(&mut self) -> Result<Status> {
  Ok(Status {
- name: self.to_string(),
+ name: "memory".to_string(),
  keys: self.data.len() as u64,
  size: self.data.iter().fold(0, |size, (k, v)| size + k.len() as u64 + v.len() as u64),
  total_disk_size: 0,