Put the repo name in these errors

lib/db_connection/holder.ex

@@ -135,25 +135,43 @@ defmodule DBConnection.Holder do
       :ets.lookup(holder, :conn)
     rescue
       ArgumentError ->
-        msg = "connection is closed because of an error, disconnect or timeout"
+        msg =
+          maybe_prefix_repo(
+            "connection is closed because of an error, disconnect or timeout",
+            opts
+          )
+
         {:disconnect, DBConnection.ConnectionError.exception(msg), _state = :unused}
     else
       [conn(lock: conn_lock)] when conn_lock != lock ->
-        raise "an outdated connection has been given to DBConnection on #{fun}/#{length(args) + 2}"
+        raise maybe_prefix_repo(
+                "an outdated connection has been given to DBConnection on #{fun}/#{length(args) + 2}",
+                opts,
+                ":"
+              )
 
       [conn(status: :error)] ->
-        msg = "connection is closed because of an error, disconnect or timeout"
+        msg =
+          maybe_prefix_repo(
+            "connection is closed because of an error, disconnect or timeout",
+            opts
+          )
+
         {:disconnect, DBConnection.ConnectionError.exception(msg), _state = :unused}
 
       [conn(status: :aborted)] when type != :cleanup ->
-        msg = "transaction rolling back"
+        msg = maybe_prefix_repo("transaction rolling back", opts)
         {:disconnect, DBConnection.ConnectionError.exception(msg), _state = :unused}
 
       [conn(module: module, state: state)] ->
         holder_apply(holder, module, fun, args ++ [opts, state])
     end
   end
 
+  defp maybe_prefix_repo(msg, opts, separator \\ "") do
+    if opts[:repo], do: "#{inspect(opts[:repo])} " <> separator <> msg, else: msg
+  end
+
   ## Pool state helpers API (invoked by callers)
 
   @spec put_state(pool_ref :: any, term) :: :ok

lib/db_connection/ownership/manager.ex

@@ -107,7 +107,8 @@ defmodule DBConnection.Ownership.Manager do
        mode: mode,
        mode_ref: nil,
        ets: ets,
-       log: log
+       log: log,
+       repo: pool_opts[:repo]
      }}
   end
 
@@ -223,7 +224,7 @@ defmodule DBConnection.Ownership.Manager do
         {:noreply, state}
 
       :not_found when mode == :manual ->
-        not_found(from, mode)
+        not_found(from, mode, state.repo)
         {:noreply, state}
 
       :not_found ->
@@ -393,10 +394,12 @@ defmodule DBConnection.Ownership.Manager do
     caller
   end
 
-  defp not_found({pid, _} = from, mode) do
+  defp not_found({pid, _} = from, mode, repo) do
     msg = """
     cannot find ownership process for #{Util.inspect_pid(pid)}
-    using mode #{inspect(mode)}.
+    using mode #{inspect(mode)} on repo #{inspect(repo)}.
+    (Note that a connection's mode reverts to :manual if its owner
+    terminates.)
 
     When using ownership, you must manage connections in one
     of the four ways: