RUST-838 Improve bson::DateTime now() performance (#260)

This also completes RUST-841

Author: pymongo

src/datetime.rs

@@ -70,7 +70,7 @@ impl crate::DateTime {
 
     /// Returns a [`DateTime`] which corresponds to the current date and time.
     pub fn now() -> DateTime {
-        Self::from_chrono(Utc::now())
+        Self::from_system_time(SystemTime::now())
     }
 
     #[cfg(not(feature = "chrono-0_4"))]

src/oid.rs

@@ -163,7 +163,7 @@ impl ObjectId {
     }
 
     /// Returns the raw byte representation of an ObjectId.
-    pub fn bytes(&self) -> [u8; 12] {
+    pub const fn bytes(&self) -> [u8; 12] {
         self.id
     }
 

src/ser/error.rs

@@ -14,7 +14,7 @@ pub enum Error {
     /// A key could not be serialized to a BSON string.
     InvalidDocumentKey(Bson),
 
-    /// A general error that ocurred during serialization.
+    /// A general error that occurred during serialization.
     /// See: https://docs.rs/serde/1.0.110/serde/ser/trait.Error.html#tymethod.custom
     #[non_exhaustive]
     SerializationError {