Merge 2025-04-09 main commit 'e7502a3d637932a59ee502ababb1df3d0e3bca26' into yuchen/direct-io-delta-image-layer-write

pageserver/src/http/openapi_spec.yml

@@ -212,6 +212,12 @@ paths:
               schema:
                 type: string
                 format: date-time
+        "412":
+          description: No timestamp is found for given LSN, e.g. if there had been no commits till LSN
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/PreconditionFailedError"
 
   /v1/tenant/{tenant_id}/timeline/{timeline_id}/get_lsn_by_timestamp:
     parameters:

pageserver/src/http/routes.rs

@@ -989,7 +989,7 @@ async fn get_lsn_by_timestamp_handler(
     if !tenant_shard_id.is_shard_zero() {
         // Requires SLRU contents, which are only stored on shard zero
         return Err(ApiError::BadRequest(anyhow!(
-            "Size calculations are only available on shard zero"
+            "Lsn calculations by timestamp are only available on shard zero"
         )));
     }
 
@@ -1064,7 +1064,7 @@ async fn get_timestamp_of_lsn_handler(
     if !tenant_shard_id.is_shard_zero() {
         // Requires SLRU contents, which are only stored on shard zero
         return Err(ApiError::BadRequest(anyhow!(
-            "Size calculations are only available on shard zero"
+            "Timestamp calculations by lsn are only available on shard zero"
         )));
     }
 
@@ -1090,8 +1090,8 @@ async fn get_timestamp_of_lsn_handler(
             .to_string();
             json_response(StatusCode::OK, time)
         }
-        None => Err(ApiError::NotFound(
-            anyhow::anyhow!("Timestamp for lsn {} not found", lsn).into(),
+        None => Err(ApiError::PreconditionFailed(
+            format!("Timestamp for lsn {} not found", lsn).into(),
         )),
     }
 }

pageserver/src/pgdatadir_mapping.rs

@@ -691,7 +691,7 @@ impl Timeline {
         Ok(buf.get_u32_le())
     }
 
-    /// Get size of an SLRU segment
+    /// Does the slru segment exist?
     pub(crate) async fn get_slru_segment_exists(
         &self,
         kind: SlruKind,
@@ -844,9 +844,9 @@ impl Timeline {
         .await
     }
 
-    /// Obtain the possible timestamp range for the given lsn.
+    /// Obtain the timestamp for the given lsn.
     ///
-    /// If the lsn has no timestamps, returns None. returns `(min, max, median)` if it has timestamps.
+    /// If the lsn has no timestamps (e.g. no commits), returns None.
     pub(crate) async fn get_timestamp_for_lsn(
         &self,
         probe_lsn: Lsn,