add serde support to Lsn type

A serialized Lsn and a serialized u64 should be identical.

zenith_utils/Cargo.toml

@@ -5,11 +5,10 @@ authors = ["Eric Seppanen <eric@zenith.tech>"]
 edition = "2018"
 
 [dependencies]
-serde = "1.0"
+serde = { version = "1.0", features = ["derive"] }
 bincode = "1.3"
 thiserror = "1.0"
 
 [dev-dependencies]
-serde = { version = "1.0", features = ["derive"] }
 hex-literal = "0.3"
 bytes = "1.0"

zenith_utils/src/lsn.rs

@@ -1,5 +1,6 @@
 #![warn(missing_docs)]
 
+use serde::{Deserialize, Serialize};
 use std::fmt;
 use std::ops::{Add, AddAssign};
 use std::path::Path;
@@ -10,7 +11,8 @@ use std::sync::atomic::{AtomicU64, Ordering};
 pub const XLOG_BLCKSZ: u32 = 8192;
 
 /// A Postgres LSN (Log Sequence Number), also known as an XLogRecPtr
-#[derive(Clone, Copy, Eq, Ord, PartialEq, PartialOrd)]
+#[derive(Clone, Copy, Eq, Ord, PartialEq, PartialOrd, Serialize, Deserialize)]
+#[serde(transparent)]
 pub struct Lsn(pub u64);
 
 /// We tried to parse an LSN from a string, but failed