From feae5f716f5883b9372cf2733fafd29224475955 Mon Sep 17 00:00:00 2001
From: John Spray <john@neon.tech>
Date: Tue, 7 Nov 2023 15:48:55 +0000
Subject: [PATCH] pageserver: carry a ShardIdentity in LocationConf

---
 libs/pageserver_api/src/models.rs |  3 +++
 pageserver/src/tenant/config.rs   | 24 +++++++++++++++++++++++-
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/libs/pageserver_api/src/models.rs b/libs/pageserver_api/src/models.rs
index cb99dc0a55..4587f790fc 100644
--- a/libs/pageserver_api/src/models.rs
+++ b/libs/pageserver_api/src/models.rs
@@ -259,6 +259,9 @@ pub struct LocationConfigSecondary {
 /// for use in external-facing APIs.
 #[derive(Serialize, Deserialize, Debug)]
 pub struct LocationConfig {
+    pub shard_number: u8,
+    pub shard_count: u8,
+    pub shard_stripe_size: u32,
     pub mode: LocationConfigMode,
     /// If attaching, in what generation?
     #[serde(default)]
diff --git a/pageserver/src/tenant/config.rs b/pageserver/src/tenant/config.rs
index 5f8c7f6c59..9e8ab3a083 100644
--- a/pageserver/src/tenant/config.rs
+++ b/pageserver/src/tenant/config.rs
@@ -10,6 +10,7 @@
 //!
 use anyhow::Context;
 use pageserver_api::models;
+use pageserver_api::shard::{ShardCount, ShardIdentity, ShardNumber, ShardStripeSize};
 use serde::{Deserialize, Serialize};
 use std::num::NonZeroU64;
 use std::time::Duration;
@@ -85,6 +86,11 @@ pub(crate) enum LocationMode {
 /// but have distinct LocationConf.
 #[derive(Clone, PartialEq, Eq, Serialize, Deserialize)]
 pub(crate) struct LocationConf {
+    /// Detailed identity of this TenantShard.  The shard number and count usually
+    /// appear in the keys of maps containing tenants, but it is convenient to also
+    /// store it here.
+    pub(crate) shard: ShardIdentity,
+
     /// The location-specific part of the configuration, describes the operating
     /// mode of this pageserver for this tenant.
     pub(crate) mode: LocationMode,
@@ -156,6 +162,7 @@ impl LocationConf {
     /// possible state.  This function should eventually be removed.
     pub(crate) fn attached_single(tenant_conf: TenantConfOpt, generation: Generation) -> Self {
         Self {
+            shard: ShardIdentity::none(),
             mode: LocationMode::Attached(AttachedLocationConfig {
                 generation,
                 attach_mode: AttachmentMode::Single,
@@ -226,7 +233,21 @@ impl LocationConf {
             }
         };
 
-        Ok(Self { mode, tenant_conf })
+        let shard = if conf.shard_count == 0 {
+            ShardIdentity::none()
+        } else {
+            ShardIdentity::new(
+                ShardNumber(conf.shard_number),
+                ShardCount(conf.shard_count),
+                ShardStripeSize(conf.shard_stripe_size),
+            )
+        };
+
+        Ok(Self {
+            shard,
+            mode,
+            tenant_conf,
+        })
     }
 }
 
@@ -236,6 +257,7 @@ impl Default for LocationConf {
     // => tech debt since https://github.com/neondatabase/neon/issues/1555
     fn default() -> Self {
         Self {
+            shard: ShardIdentity::none(),
             mode: LocationMode::Attached(AttachedLocationConfig {
                 generation: Generation::none(),
                 attach_mode: AttachmentMode::Single,