From da511ac109d8418ad520dc562f89330b76c1e936 Mon Sep 17 00:00:00 2001
From: ruslandoga <67764432+ruslandoga@users.noreply.github.com>
Date: Mon, 11 Nov 2024 15:50:47 +0700
Subject: [PATCH 1/8] proxy info messages to the adapter

---
 lib/db_connection/connection.ex | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/lib/db_connection/connection.ex b/lib/db_connection/connection.ex
index ae5f911..f6934fd 100644
--- a/lib/db_connection/connection.ex
+++ b/lib/db_connection/connection.ex
@@ -330,12 +330,22 @@ defmodule DBConnection.Connection do
     handle_timeout(s)
   end
 
-  def handle_event(:info, msg, :no_state, %{mod: mod} = s) do
-    Logger.info(fn ->
-      [inspect(mod), ?\s, ?(, inspect(self()), ") missed message: " | inspect(msg)]
-    end)
+  def handle_event(:info, msg, :no_state, %{mod: mod, state: state} = s) do
+    if function_exported?(mod, :handle_info, 2) do
+      case apply(mod, :handle_info, [msg, state]) do
+        {:ok, state} ->
+          pool_update(state, s)
+
+        {:disconnect, err, state} ->
+          {:keep_state, %{s | state: state}, {:next_event, :internal, {:disconnect, {:log, err}}}}
+      end
+    else
+      Logger.info(fn ->
+        [inspect(mod), ?\s, ?(, inspect(self()), ") missed message: " | inspect(msg)]
+      end)
 
-    handle_timeout(s)
+      handle_timeout(s)
+    end
   end
 
   @doc false

From 00c6958bffa4ec17e5febbb9525c5e90f3e84ea5 Mon Sep 17 00:00:00 2001
From: ruslandoga <67764432+ruslandoga@users.noreply.github.com>
Date: Mon, 11 Nov 2024 15:57:42 +0700
Subject: [PATCH 2/8] add failing tests

---
 integration_test/cases/info_test.exs                     | 5 +++++
 integration_test/connection_pool/disconnect_all_test.exs | 2 ++
 2 files changed, 7 insertions(+)
 create mode 100644 integration_test/cases/info_test.exs

diff --git a/integration_test/cases/info_test.exs b/integration_test/cases/info_test.exs
new file mode 100644
index 0000000..1226c27
--- /dev/null
+++ b/integration_test/cases/info_test.exs
@@ -0,0 +1,5 @@
+defmodule TestInfo do
+  use ExUnit.Case, async: true
+
+  test "handle_info returns new state"
+end
diff --git a/integration_test/connection_pool/disconnect_all_test.exs b/integration_test/connection_pool/disconnect_all_test.exs
index d2698cd..1b639ef 100644
--- a/integration_test/connection_pool/disconnect_all_test.exs
+++ b/integration_test/connection_pool/disconnect_all_test.exs
@@ -80,4 +80,6 @@ defmodule TestPoolDisconnectAll do
              handle_execute: [_, _, _, :final_state1]
            ] = A.record(agent)
   end
+
+  test "disconnect on info"
 end

From ba7677aaaaece115f857dbdd149aa5c09f4ad07c Mon Sep 17 00:00:00 2001
From: ruslandoga <67764432+ruslandoga@users.noreply.github.com>
Date: Mon, 11 Nov 2024 16:08:02 +0700
Subject: [PATCH 3/8] update tcp_connection example

---
 .formatter.exs                                | 2 +-
 examples/tcp_connection/lib/tcp_connection.ex | 9 +++++++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/.formatter.exs b/.formatter.exs
index be68757..ab786a0 100644
--- a/.formatter.exs
+++ b/.formatter.exs
@@ -1,4 +1,4 @@
 # Used by "mix format"
 [
-  inputs: ["{mix,.formatter}.exs", "{config,lib,test,integration_test}/**/*.{ex,exs}"]
+  inputs: ["{mix,.formatter}.exs", "{config,lib,test,examples,integration_test}/**/*.{ex,exs}"]
 ]
diff --git a/examples/tcp_connection/lib/tcp_connection.ex b/examples/tcp_connection/lib/tcp_connection.ex
index efb6835..29a1704 100644
--- a/examples/tcp_connection/lib/tcp_connection.ex
+++ b/examples/tcp_connection/lib/tcp_connection.ex
@@ -64,6 +64,8 @@ defmodule TCPConnection do
 
     case :gen_tcp.connect(host, port, socket_opts, timeout) do
       {:ok, sock} ->
+        # Monitor the socket so we can react to it being closed. See handle_info/2.
+        _ref = :inet.monitor(sock)
         {:ok, {sock, <<>>}}
 
       {:error, reason} ->
@@ -143,6 +145,13 @@ defmodule TCPConnection do
     end
   end
 
+  # The handle_info callback is optional and can be removed if not needed.
+  # Here it is used to react to `:inet.monitor/1` messages which arrive
+  # when socket gets closed while the connection is idle.
+  def handle_info({:DOWN, _ref, _type, sock, _info}, {sock, _buffer} = s) do
+    {:disconnect, TCPConnection.Error.exception({:idle, :closed}), s}
+  end
+
   @impl true
   def handle_close(_, _, s) do
     {:ok, nil, s}

From 9fe84fce94608184a40ffe096254cd36eb2ffd0b Mon Sep 17 00:00:00 2001
From: ruslandoga <67764432+ruslandoga@users.noreply.github.com>
Date: Mon, 11 Nov 2024 18:17:58 +0700
Subject: [PATCH 4/8] add tests

---
 examples/tcp_connection/lib/tcp_connection.ex | 12 +++-
 integration_test/cases/info_test.exs          | 59 ++++++++++++++++++-
 .../connection_pool/disconnect_all_test.exs   |  2 -
 lib/db_connection/connection.ex               |  8 +--
 test/test_support.exs                         |  4 ++
 5 files changed, 75 insertions(+), 10 deletions(-)

diff --git a/examples/tcp_connection/lib/tcp_connection.ex b/examples/tcp_connection/lib/tcp_connection.ex
index 29a1704..ebc1b7b 100644
--- a/examples/tcp_connection/lib/tcp_connection.ex
+++ b/examples/tcp_connection/lib/tcp_connection.ex
@@ -148,8 +148,16 @@ defmodule TCPConnection do
   # The handle_info callback is optional and can be removed if not needed.
   # Here it is used to react to `:inet.monitor/1` messages which arrive
   # when socket gets closed while the connection is idle.
-  def handle_info({:DOWN, _ref, _type, sock, _info}, {sock, _buffer} = s) do
-    {:disconnect, TCPConnection.Error.exception({:idle, :closed}), s}
+  def handle_info({:DOWN, _ref, _type, sock, _info}, {sock, _buffer}) do
+    {:disconnect, TCPConnection.Error.exception({:idle, :closed})}
+  end
+
+  def handle_info(msg, state) do
+    Logger.info(fn ->
+      ["#{__MODULE__} (", inspect(self()), ") missed message: ", inspect(msg)]
+    end)
+
+    :ok
   end
 
   @impl true
diff --git a/integration_test/cases/info_test.exs b/integration_test/cases/info_test.exs
index 1226c27..5d815d5 100644
--- a/integration_test/cases/info_test.exs
+++ b/integration_test/cases/info_test.exs
@@ -1,5 +1,60 @@
-defmodule TestInfo do
+defmodule InfoTest do
   use ExUnit.Case, async: true
+  alias TestPool, as: P
+  alias TestAgent, as: A
 
-  test "handle_info returns new state"
+  test "handle_info handles message and moves on" do
+    stack = [
+      fn opts ->
+        send(opts[:parent], {:connected, self()})
+        {:ok, :state}
+      end,
+      :ok,
+      {:idle, :state},
+      {:idle, :state}
+    ]
+
+    {:ok, agent} = A.start_link(stack)
+    {:ok, pool} = P.start_link(agent: agent, parent: self())
+
+    assert_receive {:connected, conn}
+    send(conn, "some harmless message")
+    assert P.run(pool, fn _ -> :result end) == :result
+
+    assert [
+             connect: _,
+             handle_info: _,
+             handle_status: _,
+             handle_status: _
+           ] = A.record(agent)
+  end
+
+  test "handle_info can force disconnect" do
+    stack = [
+      fn opts ->
+        send(opts[:parent], {:connected, self()})
+        {:ok, :state}
+      end,
+      {:disconnect, :reason},
+      :ok,
+      fn opts ->
+        send(opts[:parent], :reconnected)
+        {:ok, :state}
+      end
+    ]
+
+    {:ok, agent} = A.start_link(stack)
+    P.start_link(agent: agent, parent: self())
+
+    assert_receive {:connected, conn}
+    send(conn, "some harmful message")
+    assert_receive :reconnected
+
+    assert [
+             connect: _,
+             handle_info: _,
+             disconnect: _,
+             connect: _
+           ] = A.record(agent)
+  end
 end
diff --git a/integration_test/connection_pool/disconnect_all_test.exs b/integration_test/connection_pool/disconnect_all_test.exs
index 1b639ef..d2698cd 100644
--- a/integration_test/connection_pool/disconnect_all_test.exs
+++ b/integration_test/connection_pool/disconnect_all_test.exs
@@ -80,6 +80,4 @@ defmodule TestPoolDisconnectAll do
              handle_execute: [_, _, _, :final_state1]
            ] = A.record(agent)
   end
-
-  test "disconnect on info"
 end
diff --git a/lib/db_connection/connection.ex b/lib/db_connection/connection.ex
index f6934fd..b1c120f 100644
--- a/lib/db_connection/connection.ex
+++ b/lib/db_connection/connection.ex
@@ -333,11 +333,11 @@ defmodule DBConnection.Connection do
   def handle_event(:info, msg, :no_state, %{mod: mod, state: state} = s) do
     if function_exported?(mod, :handle_info, 2) do
       case apply(mod, :handle_info, [msg, state]) do
-        {:ok, state} ->
-          pool_update(state, s)
+        :ok ->
+          handle_timeout(s)
 
-        {:disconnect, err, state} ->
-          {:keep_state, %{s | state: state}, {:next_event, :internal, {:disconnect, {:log, err}}}}
+        {:disconnect, err} ->
+          {:keep_state, s, {:next_event, :internal, {:disconnect, {:log, err}}}}
       end
     else
       Logger.info(fn ->
diff --git a/test/test_support.exs b/test/test_support.exs
index dcbe445..a63818d 100644
--- a/test/test_support.exs
+++ b/test/test_support.exs
@@ -150,6 +150,10 @@ defmodule TestConnection do
     TestAgent.eval(:handle_deallocate, [query, cursor, opts, state])
   end
 
+  def handle_info(message, state) do
+    TestAgent.eval(:handle_info, [message, state])
+  end
+
   defp put_agent_from_opts(opts) do
     Process.get(:agent) || Process.put(:agent, agent_from_opts(opts))
   end

From 595439a2574ad58f38e867881dfd06af12b9713e Mon Sep 17 00:00:00 2001
From: ruslandoga <67764432+ruslandoga@users.noreply.github.com>
Date: Mon, 11 Nov 2024 18:27:19 +0700
Subject: [PATCH 5/8] add another failing test

---
 integration_test/cases/info_test.exs | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/integration_test/cases/info_test.exs b/integration_test/cases/info_test.exs
index 5d815d5..ff5273e 100644
--- a/integration_test/cases/info_test.exs
+++ b/integration_test/cases/info_test.exs
@@ -57,4 +57,6 @@ defmodule InfoTest do
              connect: _
            ] = A.record(agent)
   end
+
+  test "handle_info's disconnect with connection checked out"
 end

From a3ece3c382fec7557494caf0ddcaf4717dca4c48 Mon Sep 17 00:00:00 2001
From: ruslandoga <67764432+ruslandoga@users.noreply.github.com>
Date: Mon, 11 Nov 2024 19:48:19 +0700
Subject: [PATCH 6/8] make test pass

---
 integration_test/cases/info_test.exs | 44 ++++++++++++++++++++++++++--
 1 file changed, 42 insertions(+), 2 deletions(-)

diff --git a/integration_test/cases/info_test.exs b/integration_test/cases/info_test.exs
index ff5273e..ee88121 100644
--- a/integration_test/cases/info_test.exs
+++ b/integration_test/cases/info_test.exs
@@ -1,7 +1,9 @@
 defmodule InfoTest do
   use ExUnit.Case, async: true
+
   alias TestPool, as: P
   alias TestAgent, as: A
+  alias TestQuery, as: Q
 
   test "handle_info handles message and moves on" do
     stack = [
@@ -47,7 +49,7 @@ defmodule InfoTest do
     P.start_link(agent: agent, parent: self())
 
     assert_receive {:connected, conn}
-    send(conn, "some harmful message")
+    send(conn, "some harmful message that casuses disconnect")
     assert_receive :reconnected
 
     assert [
@@ -58,5 +60,43 @@ defmodule InfoTest do
            ] = A.record(agent)
   end
 
-  test "handle_info's disconnect with connection checked out"
+  test "handle_info's disconnect while checked out client crashes is no-op" do
+    stack = [
+      fn _opts ->
+        {:ok, %{conn_pid: self()}}
+      end,
+      fn _query, _params, _opts, %{conn_pid: conn_pid} ->
+        send(
+          conn_pid,
+          "some harmful message that causes disconnect while conneciton is checked out"
+        )
+
+        # This waits for the info message to be processed in the connection.
+        :sys.get_state(conn_pid)
+        {:disconnect, :closed, :new_state}
+      end,
+      {:disconnect, :closed},
+      :ok,
+      fn opts ->
+        send(opts[:parent], :reconnected)
+        {:ok, :state}
+      end
+    ]
+
+    parent = self()
+
+    {:ok, agent} = A.start_link(stack)
+    {:ok, pool} = P.start_link(agent: agent, parent: parent)
+
+    assert {:error, :closed} = P.execute(pool, %Q{}, [:first])
+    assert_receive :reconnected
+
+    assert [
+             connect: _,
+             handle_execute: _,
+             handle_info: _,
+             disconnect: _,
+             connect: _
+           ] = A.record(agent)
+  end
 end

From a5cd7d7323fb4692393776afebf66c71ecf5064d Mon Sep 17 00:00:00 2001
From: ruslandoga <67764432+ruslandoga@users.noreply.github.com>
Date: Mon, 11 Nov 2024 19:57:40 +0700
Subject: [PATCH 7/8] cleanup

---
 integration_test/cases/info_test.exs | 26 ++++++++++++--------------
 1 file changed, 12 insertions(+), 14 deletions(-)

diff --git a/integration_test/cases/info_test.exs b/integration_test/cases/info_test.exs
index ee88121..dea3f6b 100644
--- a/integration_test/cases/info_test.exs
+++ b/integration_test/cases/info_test.exs
@@ -5,7 +5,7 @@ defmodule InfoTest do
   alias TestAgent, as: A
   alias TestQuery, as: Q
 
-  test "handle_info handles message and moves on" do
+  test "handle_info handles harmless message and moves on" do
     stack = [
       fn opts ->
         send(opts[:parent], {:connected, self()})
@@ -37,7 +37,7 @@ defmodule InfoTest do
         send(opts[:parent], {:connected, self()})
         {:ok, :state}
       end,
-      {:disconnect, :reason},
+      {:disconnect, RuntimeError.exception("TCP connection just closed")},
       :ok,
       fn opts ->
         send(opts[:parent], :reconnected)
@@ -49,7 +49,7 @@ defmodule InfoTest do
     P.start_link(agent: agent, parent: self())
 
     assert_receive {:connected, conn}
-    send(conn, "some harmful message that casuses disconnect")
+    send(conn, "monitor says TCP connection just closed")
     assert_receive :reconnected
 
     assert [
@@ -66,16 +66,14 @@ defmodule InfoTest do
         {:ok, %{conn_pid: self()}}
       end,
       fn _query, _params, _opts, %{conn_pid: conn_pid} ->
-        send(
-          conn_pid,
-          "some harmful message that causes disconnect while conneciton is checked out"
-        )
+        send(conn_pid, "monitor says TCP connection just closed")
 
-        # This waits for the info message to be processed in the connection.
+        # This waits for the info message to be processed.
         :sys.get_state(conn_pid)
-        {:disconnect, :closed, :new_state}
+
+        {:disconnect, RuntimeError.exception("TCP connection is closed"), :new_state}
       end,
-      {:disconnect, :closed},
+      {:disconnect, RuntimeError.exception("TCP connection just closed")},
       :ok,
       fn opts ->
         send(opts[:parent], :reconnected)
@@ -83,12 +81,12 @@ defmodule InfoTest do
       end
     ]
 
-    parent = self()
-
     {:ok, agent} = A.start_link(stack)
-    {:ok, pool} = P.start_link(agent: agent, parent: parent)
+    {:ok, pool} = P.start_link(agent: agent, parent: self())
+
+    assert {:error, %RuntimeError{message: "TCP connection is closed"}} =
+             P.execute(pool, %Q{}, [:first])
 
-    assert {:error, :closed} = P.execute(pool, %Q{}, [:first])
     assert_receive :reconnected
 
     assert [

From f4e74de89c491a1c0a1d264a634052b5af147818 Mon Sep 17 00:00:00 2001
From: ruslandoga <67764432+ruslandoga@users.noreply.github.com>
Date: Mon, 11 Nov 2024 19:58:41 +0700
Subject: [PATCH 8/8] cleanup x2

---
 integration_test/cases/info_test.exs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/integration_test/cases/info_test.exs b/integration_test/cases/info_test.exs
index dea3f6b..7d187c8 100644
--- a/integration_test/cases/info_test.exs
+++ b/integration_test/cases/info_test.exs
@@ -85,7 +85,7 @@ defmodule InfoTest do
     {:ok, pool} = P.start_link(agent: agent, parent: self())
 
     assert {:error, %RuntimeError{message: "TCP connection is closed"}} =
-             P.execute(pool, %Q{}, [:first])
+             P.execute(pool, %Q{}, [])
 
     assert_receive :reconnected