From 8d8bc304c1220ab371b28ecdfe249b2a5f828e8f Mon Sep 17 00:00:00 2001
From: Eric Seppanen <eric@zenith.tech>
Date: Fri, 7 May 2021 12:34:31 -0700
Subject: [PATCH] work around NodeId endian issues

Instead of playing games during serialize/deserialize, just treat
NodeId::term as an 8-byte array instead of a u64.
---
 Cargo.lock                   |  1 +
 walkeeper/Cargo.toml         |  1 +
 walkeeper/src/wal_service.rs | 30 +++++++-----------------------
 3 files changed, 9 insertions(+), 23 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 2df732e815..e59adeb4b1 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2238,6 +2238,7 @@ dependencies = [
  "crc32c",
  "daemonize",
  "fs2",
+ "hex",
  "lazy_static",
  "log",
  "pageserver",
diff --git a/walkeeper/Cargo.toml b/walkeeper/Cargo.toml
index 2e58ad0dd0..878ce491aa 100644
--- a/walkeeper/Cargo.toml
+++ b/walkeeper/Cargo.toml
@@ -30,6 +30,7 @@ crc32c = "0.6.0"
 parse_duration = "2.1.1"
 walkdir = "2"
 serde = { version = "1.0", features = ["derive"] }
+hex = "0.4.3"
 
 # FIXME: 'pageserver' is needed for ZTimelineId. Refactor
 pageserver = { path = "../pageserver" }
diff --git a/walkeeper/src/wal_service.rs b/walkeeper/src/wal_service.rs
index 5f2fcd92be..8d790634ac 100644
--- a/walkeeper/src/wal_service.rs
+++ b/walkeeper/src/wal_service.rs
@@ -78,9 +78,7 @@ fn read_into(r: &mut impl Read, buf: &mut BytesMut) -> io::Result<usize> {
 #[derive(Debug, Clone, Copy, Ord, PartialOrd, PartialEq, Eq, Serialize, Deserialize)]
 struct NodeId {
     uuid: u128,
-    #[serde(serialize_with = "serialize_u64_flip_endian")]
-    #[serde(deserialize_with = "deserialize_u64_flip_endian")]
-    term: u64,
+    term: [u8; 8],
 }
 
 #[repr(C)]
@@ -236,23 +234,6 @@ fn parse_hex_str(s: &str) -> Result<u64> {
     }
 }
 
-// For use with serde's `serialize_with` attribute
-fn serialize_u64_flip_endian<S>(x: &u64, s: S) -> std::result::Result<S::Ok, S::Error>
-where
-    S: serde::Serializer,
-{
-    s.serialize_u64(u64::from_be(*x))
-}
-
-// For use with serde's `deserialize_with` attribute
-fn deserialize_u64_flip_endian<'de, D>(deserializer: D) -> std::result::Result<u64, D::Error>
-where
-    D: serde::de::Deserializer<'de>,
-{
-    let x: u64 = serde::de::Deserialize::deserialize(deserializer)?;
-    Ok(u64::from_be(x))
-}
-
 impl SafeKeeperInfo {
     fn new() -> SafeKeeperInfo {
         SafeKeeperInfo {
@@ -262,7 +243,10 @@ impl SafeKeeperInfo {
             server: ServerInfo {
                 protocol_version: SK_PROTOCOL_VERSION, /* proxy-safekeeper protocol version */
                 pg_version: UNKNOWN_SERVER_VERSION,    /* Postgres server version */
-                node_id: NodeId { term: 0, uuid: 0 },
+                node_id: NodeId {
+                    term: [0; 8],
+                    uuid: 0,
+                },
                 system_id: 0, /* Postgres system identifier */
                 timeline_id: ZTimelineId::from([0u8; 16]),
                 wal_end: 0,
@@ -588,8 +572,8 @@ impl Connection {
             self.send()?;
             io_error!(
                 "Reject connection attempt with term {} because my term is {}",
-                prop.node_id.term,
-                my_info.server.node_id.term
+                hex::encode(prop.node_id.term),
+                hex::encode(my_info.server.node_id.term)
             );
         }
         my_info.server.node_id = prop.node_id;