compute_ctl: Rearrange startup code (#11007)

Move most of the code to compute.rs, so that all the major startup steps
are visible in one place. You can now get a pretty good picture of what
happens in the latency-critical path at compute startup by reading
ComputeNode::start_compute().

This also clarifies the error handling in start_compute. Previously, the
start_postgres function sometimes returned an Err, and sometimes Ok but
with the compute status already set to Failed. Now the start_compute
function always returns Err on failure, and it's the caller's
responsibility to change the compute status to Failed. Separately from
that, it returns a handle to the Postgres process via a `&mut` reference
if it had already started Postgres (i.e. on success, or if the failure
happens after launching the Postgres process).

---------

Co-authored-by: Alexey Kondratov <kondratov.aleksey@gmail.com>

compute_tools/src/http/routes/configure.rs

@@ -22,7 +22,7 @@ pub(in crate::http) async fn configure(
     State(compute): State<Arc<ComputeNode>>,
     request: Json<ConfigurationRequest>,
 ) -> Response {
-    if !compute.live_config_allowed {
+    if !compute.params.live_config_allowed {
         return JsonResponse::error(
             StatusCode::PRECONDITION_FAILED,
             "live configuration is not allowed for this compute node".to_string(),

compute_tools/src/http/routes/extension_server.rs

@@ -18,11 +18,11 @@ pub(in crate::http) struct ExtensionServerParams {
 /// Download a remote extension.
 pub(in crate::http) async fn download_extension(
     Path(filename): Path<String>,
-    params: Query<ExtensionServerParams>,
+    ext_server_params: Query<ExtensionServerParams>,
     State(compute): State<Arc<ComputeNode>>,
 ) -> Response {
     // Don't even try to download extensions if no remote storage is configured
-    if compute.ext_remote_storage.is_none() {
+    if compute.params.ext_remote_storage.is_none() {
         return JsonResponse::error(
             StatusCode::PRECONDITION_FAILED,
             "remote storage is not configured",
@@ -46,9 +46,9 @@ pub(in crate::http) async fn download_extension(
 
         remote_extensions.get_ext(
             &filename,
-            params.is_library,
-            &compute.build_tag,
-            &compute.pgversion,
+            ext_server_params.is_library,
+            &compute.params.build_tag,
+            &compute.params.pgversion,
         )
     };