From 2a7dc8eabbbf7e81643abf4c3a4f9066ef3d74a5 Mon Sep 17 00:00:00 2001
From: Harun Zengin <h.zengin@sonnen.de>
Date: Fri, 19 Apr 2024 17:29:27 +0200
Subject: [PATCH] Catch :noproc errors on cluster pools (#365)

Co-authored-by: Andrea Leopardi <an.leopardi@gmail.com>
---
 lib/xandra/cluster.ex            | 18 +++++++++--
 lib/xandra/connection_error.ex   |  7 +++++
 test/integration/errors_test.exs | 53 ++++++++++++++++++++++++++++++++
 3 files changed, 76 insertions(+), 2 deletions(-)

diff --git a/lib/xandra/cluster.ex b/lib/xandra/cluster.ex
index c66f00db..ac025ee9 100644
--- a/lib/xandra/cluster.ex
+++ b/lib/xandra/cluster.ex
@@ -433,7 +433,14 @@ defmodule Xandra.Cluster do
     with_conn_and_retrying(
       cluster,
       options,
-      &Xandra.execute(&1, batch, options_without_retry_strategy)
+      fn conn ->
+        try do
+          Xandra.execute(conn, batch, options_without_retry_strategy)
+        catch
+          :exit, {:noproc, _} ->
+            {:error, ConnectionError.new("execute", {:cluster, :pool_closed})}
+        end
+      end
     )
   end
 
@@ -455,7 +462,14 @@ defmodule Xandra.Cluster do
     with_conn_and_retrying(
       cluster,
       options,
-      &Xandra.execute(&1, query, params, options_without_retry_strategy)
+      fn conn ->
+        try do
+          Xandra.execute(conn, query, params, options_without_retry_strategy)
+        catch
+          :exit, {:noproc, _} ->
+            {:error, ConnectionError.new("execute", {:cluster, :pool_closed})}
+        end
+      end
     )
   end
 
diff --git a/lib/xandra/connection_error.ex b/lib/xandra/connection_error.ex
index 3dafbb8d..89ea959d 100644
--- a/lib/xandra/connection_error.ex
+++ b/lib/xandra/connection_error.ex
@@ -92,6 +92,13 @@ defmodule Xandra.ConnectionError do
     "not connected to any of the nodes"
   end
 
+  defp format_reason({:cluster, :pool_closed}) do
+    """
+    the Xandra pool is closed, probably because the network connection dropped right after
+    Xandra.Cluster.Pool.checkout/0
+    """
+  end
+
   defp format_reason(reason) do
     case :inet.format_error(reason) do
       ~c"unknown POSIX error" -> inspect(reason)
diff --git a/test/integration/errors_test.exs b/test/integration/errors_test.exs
index f0b1241c..e2bc224e 100644
--- a/test/integration/errors_test.exs
+++ b/test/integration/errors_test.exs
@@ -2,6 +2,9 @@ defmodule ErrorsTest do
   use XandraTest.IntegrationCase, async: true
 
   alias Xandra.Error
+  alias Xandra.Cluster
+  alias Xandra.Cluster.Host
+  alias Xandra.ConnectionError
 
   test "each possible error", %{conn: conn} do
     assert {:error, reason} = Xandra.execute(conn, "")
@@ -45,4 +48,54 @@ defmodule ErrorsTest do
     assert_raise Error, fn -> Xandra.prepare!(conn, "") end
     assert_raise Error, fn -> Xandra.execute!(conn, "USE unknown") end
   end
+
+  describe "on Xandra.Cluster level" do
+    defmodule Xandra.Cluster.PoolMock do
+      @behaviour :gen_statem
+
+      def child_spec(opts) do
+        %{
+          id: __MODULE__,
+          start: {__MODULE__, :start_link, [opts]},
+          type: :worker,
+          restart: :permanent
+        }
+      end
+
+      def start_link([]) do
+        :gen_statem.start_link(__MODULE__, :no_args, [])
+      end
+
+      def checkout(pid) do
+        :gen_statem.call(pid, :checkout)
+      end
+
+      @impl true
+      def init(:no_args) do
+        {dead_pid, ref} = spawn_monitor(fn -> :ok end)
+
+        receive do
+          {:DOWN, ^ref, _, _, _} -> :ok
+        end
+
+        {:ok, :waiting, [{dead_pid, %Host{}}]}
+      end
+
+      @impl true
+      def callback_mode do
+        :state_functions
+      end
+
+      def waiting({:call, from}, :checkout, data) do
+        {:keep_state_and_data, {:reply, from, {:ok, data}}}
+      end
+    end
+
+    test "noproc errors are caught" do
+      {:ok, cluster} = start_supervised(Xandra.Cluster.PoolMock)
+
+      assert {:error, %ConnectionError{action: "execute", reason: {:cluster, :pool_closed}}} =
+               Cluster.execute(cluster, "select * from system.peers")
+    end
+  end
 end