Add diagnostic logging to shard setup and repo facet initialization

Summary:
TW task tsp_global/mononoke/mononoke_git_server/59 had 9 shards stuck in Setup
state for 1+ hour with no errors logged. Investigation revealed that
repo_factory.build() uses futures::try_join! to build ~30 facets concurrently —
all must complete for build() to return. SQL-backed facets have 10s query timeouts
but non-SQL facets (blobstore fetches, Scribe subscriptions) have no timeout. A
single stuck facet blocks the entire build() and keeps the shard in InProgress
state indefinitely with no diagnostic output.

This diff adds start/finish logging to pinpoint which facet is stuck:
- Setup task: logs completion time and success/failure
- WBC: logs after create_subscription and after coordinator spawn
- Preloaded commit graph: adds blobstore_key to Started/Finished logs for repo identification
- Suspect facets in repo_factory: start/finish logging for bonsai_tag_mapping,
  git_ref_content_mapping, commit_graph, cgdm_changeset_divider, hook_manager

Reviewed By: RajivTS

Differential Revision: D102354775

fbshipit-source-id: f075dee72d31aa989910abcd2be69bda56b363fd

Author: Prashant Pal

eden/mononoke/cmdlib/sharding/src/facebook.rs

@@ -133,10 +133,24 @@ impl RepoSetupProcess {
             setup_handle: runtime_handle.spawn({
                 let repo_shard = repo_shard.clone();
                 async move {
-                    // Create guard that will decrement counter on drop
                     let _guard = ConcurrentSetupGuard::new(fb);
-
-                    setup_job.setup(&repo_shard).await
+                    let start = time::Instant::now();
+                    let result = setup_job.setup(&repo_shard).await;
+                    let elapsed_s = start.elapsed().as_secs_f64();
+                    match &result {
+                        Ok(_) => info!(
+                            shard = %repo_shard,
+                            elapsed_s,
+                            "Setup for shard completed"
+                        ),
+                        Err(e) => error!(
+                            shard = %repo_shard,
+                            elapsed_s,
+                            error = %format!("{:#}", e),
+                            "Setup for shard failed"
+                        ),
+                    }
+                    result
                 }
             }),
             shard,

eden/mononoke/repo_attributes/bookmarks/warm_bookmarks_cache/src/lib.rs

@@ -648,6 +648,10 @@ impl WarmBookmarksCache {
             .create_subscription(ctx, Freshness::MaybeStale)
             .await
             .context("Error creating bookmarks subscription")?;
+        tracing::debug!(
+            repo = %repo_identity.name(),
+            "WBC: bookmarks subscription created successfully"
+        );
 
         let bookmarks_to_watch = init_bookmarks(
             ctx,
@@ -678,6 +682,11 @@ impl WarmBookmarksCache {
             notify_sync_complete.clone(),
         );
 
+        tracing::debug!(
+            repo = %repo_identity.name(),
+            "WBC: Bookmarks Coordinator Spawned"
+        );
+
         Ok(Self {
             bookmarks: bookmarks_to_watch,
             terminate: Some(sender),

eden/mononoke/repo_attributes/commit_graph/preloaded_commit_graph_storage/src/lib.rs

@@ -310,7 +310,7 @@ impl Loader<PreloadedEdges> for PreloadedEdgesLoader {
         mononoke::spawn_task({
             cloned!(self.ctx, self.blobstore_without_cache, self.blobstore_key);
             async move {
-                info!("Started preloading commit graph");
+                info!(blobstore_key = %blobstore_key, "Started preloading commit graph");
                 let maybe_bytes = blobstore_without_cache.get(&ctx, &blobstore_key).await?;
                 match maybe_bytes {
                     Some(bytes) => {
@@ -319,6 +319,7 @@ impl Loader<PreloadedEdges> for PreloadedEdgesLoader {
                             tokio::task::spawn_blocking(move || deserialize_preloaded_edges(bytes))
                                 .await??;
                         info!(
+                            blobstore_key = %blobstore_key,
                             "Finished preloading commit graph ({} changesets)",
                             preloaded_edges.cs_id_to_edges.len()
                         );