Remove create_col from ClientDB trait

lighthouse/db/disk_db.rs

@@ -55,15 +55,7 @@ impl DiskDB {
             db,
         }
     }
-}
 
-impl From<RocksError> for DBError {
-    fn from(e: RocksError) -> Self {
-        Self { message: e.to_string() }
-    }
-}
-
-impl ClientDB for DiskDB {
     /// Create a RocksDB column family. Corresponds to the
     /// `create_cf()` function on the RocksDB API.
     fn create_col(&mut self, col: &str)
@@ -75,6 +67,15 @@ impl ClientDB for DiskDB {
         }
     }
 
+}
+
+impl From<RocksError> for DBError {
+    fn from(e: RocksError) -> Self {
+        Self { message: e.to_string() }
+    }
+}
+
+impl ClientDB for DiskDB {
     /// Get the value for some key on some column.
     ///
     /// Corresponds to the `get_cf()` method on the RocksDB API.

lighthouse/db/memory_db.rs

@@ -45,12 +45,6 @@ impl MemoryDB {
 }
 
 impl ClientDB for MemoryDB {
-    fn create_col(&mut self, col: &str)
-        -> Result<(), DBError>
-    {
-        Ok(())      // This field is not used. Will remove from trait.
-    }
-
     /// Get the value of some key from the database. Returns `None` if the key does not exist.
     fn get(&self, col: &str, key: &[u8])
         -> Result<Option<DBValue>, DBError>

lighthouse/db/traits.rs

@@ -18,9 +18,6 @@ impl DBError {
 /// program to use a persistent on-disk database during production,
 /// but use a transient database during tests.
 pub trait ClientDB: Sync + Send {
-    fn create_col(&mut self, col: &str)
-        -> Result<(), DBError>;
-
     fn get(&self, col: &str, key: &[u8])
         -> Result<Option<DBValue>, DBError>;