pageserver: refactor creation API (add ShardParams)

libs/pageserver_api/src/models.rs

@@ -18,7 +18,10 @@ use utils::{
     lsn::Lsn,
 };
 
-use crate::{reltag::RelTag, shard::TenantShardId};
+use crate::{
+    reltag::RelTag,
+    shard::{ShardCount, ShardStripeSize, TenantShardId},
+};
 use anyhow::bail;
 use bytes::{Buf, BufMut, Bytes, BytesMut};
 
@@ -188,6 +191,31 @@ pub struct TimelineCreateRequest {
     pub pg_version: Option<u32>,
 }
 
+/// Parameters that apply to all shards in a tenant.  Used during tenant creation.
+#[derive(Serialize, Deserialize, Debug)]
+#[serde(deny_unknown_fields)]
+pub struct ShardParameters {
+    pub count: ShardCount,
+    #[serde(default)]
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub stripe_size: Option<ShardStripeSize>,
+}
+
+impl ShardParameters {
+    fn is_unsharded(&self) -> bool {
+        self.count == ShardCount(0)
+    }
+}
+
+impl Default for ShardParameters {
+    fn default() -> Self {
+        Self {
+            count: ShardCount(0),
+            stripe_size: None,
+        }
+    }
+}
+
 #[derive(Serialize, Deserialize, Debug)]
 #[serde(deny_unknown_fields)]
 pub struct TenantCreateRequest {
@@ -195,6 +223,12 @@ pub struct TenantCreateRequest {
     #[serde(default)]
     #[serde(skip_serializing_if = "Option::is_none")]
     pub generation: Option<u32>,
+
+    // If omitted, create a single shard with TenantShardId::unsharded()
+    #[serde(default)]
+    #[serde(skip_serializing_if = "ShardParameters::is_unsharded")]
+    pub shard_parameters: ShardParameters,
+
     #[serde(flatten)]
     pub config: TenantConfig, // as we have a flattened field, we should reject all unknown fields in it
 }

libs/pageserver_api/src/shard.rs

@@ -1,6 +1,9 @@
 use std::{ops::RangeInclusive, str::FromStr};
 
-use crate::key::{is_rel_block_key, Key};
+use crate::{
+    key::{is_rel_block_key, Key},
+    models::ShardParameters,
+};
 use hex::FromHex;
 use serde::{Deserialize, Serialize};
 use thiserror;
@@ -403,6 +406,17 @@ impl ShardIdentity {
         }
     }
 
+    /// For use when creating ShardIdentity instances for new shards, where a creation request
+    /// specifies the ShardParameters that apply to all shards.
+    pub fn from_params(number: ShardNumber, params: &ShardParameters) -> Self {
+        Self {
+            number,
+            count: params.count,
+            layout: LAYOUT_V1,
+            stripe_size: params.stripe_size.unwrap_or(DEFAULT_STRIPE_SIZE),
+        }
+    }
+
     fn is_broken(&self) -> bool {
         self.layout == LAYOUT_BROKEN
     }