DNM verbose WAL ingest logging

pageserver/src/pgdatadir_mapping.rs

@@ -1288,9 +1288,11 @@ impl<'a> DatadirModification<'a> {
         self.pending_nblocks = 0;
 
         for (key, value) in self.pending_updates.drain() {
+            tracing::debug!("commit: put {} @ {}", key, lsn);
             writer.put(key, lsn, &value, ctx).await?;
         }
         for key_range in self.pending_deletions.drain(..) {
+            tracing::debug!("commit: delete {:?} @ {}", key_range, lsn);
             writer.delete(key_range, lsn).await?;
         }
 
@@ -1303,6 +1305,10 @@ impl<'a> DatadirModification<'a> {
         Ok(())
     }
 
+    pub fn is_no_op(&self) -> bool {
+        self.pending_updates.is_empty() && self.pending_deletions.is_empty()
+    }
+
     // Internal helper functions to batch the modifications
 
     async fn get(&self, key: Key, ctx: &RequestContext) -> Result<Bytes, PageReconstructError> {