From f4039c65a99dc18149d62beab1bbfc4fdb96af7a Mon Sep 17 00:00:00 2001
From: Kirill Bulatov <kirill@neon.tech>
Date: Tue, 31 Jan 2023 15:13:40 +0200
Subject: [PATCH] (De)Serialize Lsn and Key in LayerInfo in human-readable
 format

---
 libs/pageserver_api/src/models.rs | 34 +++++++++++++++++++++++++------
 pageserver/src/keyspace.rs        |  4 ++--
 2 files changed, 30 insertions(+), 8 deletions(-)

diff --git a/libs/pageserver_api/src/models.rs b/libs/pageserver_api/src/models.rs
index b4f08f2923..a0deba2eaf 100644
--- a/libs/pageserver_api/src/models.rs
+++ b/libs/pageserver_api/src/models.rs
@@ -3,6 +3,7 @@ use std::{
     fmt,
     num::{NonZeroU64, NonZeroUsize},
     ops::Range,
+    str::FromStr,
 };
 
 use byteorder::{BigEndian, ByteOrder, ReadBytesExt, BE};
@@ -237,28 +238,45 @@ pub struct LayerMapInfo {
     pub historic_layers: BTreeSet<HistoricLayerInfo>,
 }
 
+#[serde_as]
 #[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Copy, Clone, Serialize, Deserialize)]
 #[serde(tag = "kind")]
 pub enum InMemoryLayerInfo {
-    Open { lsn_start: Lsn },
-    Frozen { lsn_start: Lsn, lsn_end: Lsn },
+    Open {
+        #[serde_as(as = "DisplayFromStr")]
+        lsn_start: Lsn,
+    },
+    Frozen {
+        #[serde_as(as = "DisplayFromStr")]
+        lsn_start: Lsn,
+        #[serde_as(as = "DisplayFromStr")]
+        lsn_end: Lsn,
+    },
 }
 
+#[serde_as]
 #[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Clone, Serialize, Deserialize)]
 #[serde(tag = "kind")]
 pub enum HistoricLayerInfo {
     Delta {
         layer_file_name: String,
+        #[serde_as(as = "DisplayFromStr")]
         key_start: Key,
+        #[serde_as(as = "DisplayFromStr")]
         key_end: Key,
+        #[serde_as(as = "DisplayFromStr")]
         lsn_start: Lsn,
+        #[serde_as(as = "DisplayFromStr")]
         lsn_end: Lsn,
         remote: bool,
     },
     Image {
         layer_file_name: String,
+        #[serde_as(as = "DisplayFromStr")]
         key_start: Key,
+        #[serde_as(as = "DisplayFromStr")]
         key_end: Key,
+        #[serde_as(as = "DisplayFromStr")]
         lsn_start: Lsn,
         remote: bool,
     },
@@ -625,10 +643,6 @@ pub fn key_range_size(key_range: &Range<Key>) -> u32 {
     }
 }
 
-pub fn singleton_range(key: Key) -> Range<Key> {
-    key..key.next()
-}
-
 impl fmt::Display for Key {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(
@@ -639,6 +653,14 @@ impl fmt::Display for Key {
     }
 }
 
+impl FromStr for Key {
+    type Err = anyhow::Error;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        Self::from_hex(s)
+    }
+}
+
 impl Key {
     pub const MIN: Key = Key {
         field1: u8::MIN,
diff --git a/pageserver/src/keyspace.rs b/pageserver/src/keyspace.rs
index 2d68b48d15..2d402bf7cd 100644
--- a/pageserver/src/keyspace.rs
+++ b/pageserver/src/keyspace.rs
@@ -1,4 +1,4 @@
-use pageserver_api::models::{key_range_size, singleton_range, Key};
+use pageserver_api::models::{key_range_size, Key};
 use postgres_ffi::BLCKSZ;
 use std::ops::Range;
 
@@ -102,7 +102,7 @@ impl KeySpaceAccum {
     }
 
     pub fn add_key(&mut self, key: Key) {
-        self.add_range(singleton_range(key))
+        self.add_range(key..key.next())
     }
 
     pub fn add_range(&mut self, range: Range<Key>) {