Add temporary FLAKE_DEBUG probe for stagings 404

app/controllers/runtime/stagings_controller.rb

@@ -33,7 +33,28 @@ def download_package(guid)
       raise ApiError.new_from_details('BlobstoreNotLocal') unless package_blobstore.local?
 
       package = PackageModel.find(guid:)
-      raise ApiError.new_from_details('NotFound', guid) if package.nil?
+      if package.nil?
+        # FLAKE_DEBUG: temporary instrumentation for the intermittent 404 on this
+        # endpoint (a just-created package un-findable by its own guid). Fires only
+        # on the nil path, so it is silent in normal operation. Captures, on the
+        # connection the SELECT actually used, whether the row is physically present
+        # (raw_match), how many package rows are visible at all (total_count), whether
+        # the surrounding transaction is still open (in_txn), and the identity of the
+        # db/connection/thread so a swap vs. the inserting side is detectable.
+        # Revert once CI has logged one occurrence. See the test-side counterpart in
+        # spec/unit/controllers/runtime/stagings_controller_spec.rb.
+        db = PackageModel.db
+        raw_match = db[:packages].where(guid:).count
+        total_count = db[:packages].count
+        conn_id = db.synchronize(&:object_id)
+        logger.error(
+          "FLAKE_DEBUG stagings-404 guid=#{guid} raw_match=#{raw_match} " \
+          "total_count=#{total_count} in_txn=#{db.in_transaction?} " \
+          "db_id=#{db.object_id} conn_id=#{conn_id} " \
+          "thread_id=#{Thread.current.object_id}"
+        )
+        raise ApiError.new_from_details('NotFound', guid)
+      end
 
       blob = package_blobstore.blob(guid)
       if blob.nil?

spec/unit/controllers/runtime/stagings_controller_spec.rb

@@ -262,7 +262,25 @@ module VCAP::CloudController
     describe 'GET /staging/packages/:guid' do
       let(:package) { create(:package_model) }
 
-      before { authorize(staging_user, staging_password) }
+      # FLAKE_DEBUG: temporary instrumentation for the intermittent 404 on this
+      # endpoint. Force the lazy `package` INSERT here and log the db/connection/
+      # thread identity of the INSERTING side, so the controller-side FLAKE_DEBUG
+      # line (app/controllers/runtime/stagings_controller.rb) has a baseline to
+      # compare against -- a connection or thread swap between insert and read is
+      # only conclusive with both sides logged. Revert together with the
+      # controller-side probe once CI has captured one occurrence.
+      before do
+        authorize(staging_user, staging_password)
+
+        db = VCAP::CloudController::PackageModel.db
+        guid = package.guid
+        conn_id = db.synchronize(&:object_id)
+        warn(
+          "FLAKE_DEBUG stagings-404-insert guid=#{guid} " \
+          "in_txn=#{db.in_transaction?} db_id=#{db.object_id} " \
+          "conn_id=#{conn_id} thread_id=#{Thread.current.object_id}"
+        )
+      end
 
       def create_test_blob
         tmpfile = Tempfile.new('staging-test-blob')