Skip to content

fix: Reconnect on a closed connection when checked out #304

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
jrogov wants to merge 1 commit into
base: master
Choose a base branch
from
+68 −8
Open

fix: Reconnect on a closed connection when checked out #304

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
76 changes: 68 additions & 8 deletions lib/ch/connection.ex
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,8 @@ defmodule Ch.Connection do

@user_agent "ch/" <> Mix.Project.config()[:version]

@server_display_name_key :server_display_name

@typep conn :: HTTP.t()

@impl true
Expand All @@ -25,6 +27,12 @@ defmodule Ch.Connection do
|> maybe_put_private(:username, opts[:username])
|> maybe_put_private(:password, opts[:password])
|> maybe_put_private(:settings, opts[:settings])
|> HTTP.put_private(:reconnect_opts, %{
scheme: scheme,
address: address,
port: port,
mint_opts: mint_opts
})

handshake = Query.build("select 1, version()")
params = DBConnection.Query.encode(handshake, _params = [], _opts = [])
Expand Down Expand Up @@ -364,19 +372,23 @@ defmodule Ch.Connection do
| {:error, Error.t(), conn}
| {:disconnect, Mint.Types.error(), conn}
defp request(conn, method, path, headers, body, opts) do
with {:ok, conn, _ref} <- send_request(conn, method, path, headers, body) do
receive_full_response(conn, timeout(conn, opts))
end
with_retry_if_stale_connection(conn, fn conn ->
with {:ok, conn, _ref} <- send_request(conn, method, path, headers, body) do
receive_full_response(conn, timeout(conn, opts))
end
end)
end

@spec request_chunked(conn, binary, binary, Mint.Types.headers(), Enumerable.t(), Keyword.t()) ::
{:ok, conn, [response]}
| {:error, Error.t(), conn}
| {:disconnect, Mint.Types.error(), conn}
def request_chunked(conn, method, path, headers, stream, opts) do
with {:ok, conn, ref} <- send_request(conn, method, path, headers, :stream),
{:ok, conn} <- stream_body(conn, ref, stream),
do: receive_full_response(conn, timeout(conn, opts))
with_retry_if_stale_connection(conn, fn conn ->
with {:ok, conn, ref} <- send_request(conn, method, path, headers, :stream),
{:ok, conn} <- stream_body(conn, ref, stream),
do: receive_full_response(conn, timeout(conn, opts))
end)
Comment on lines 386 to +391
Copy link
Copy Markdown
Author

@jrogov jrogov Apr 10, 2026

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I'm pretty sure we should not do this on request_chunked when stream-writing the data, as it would mean that we could write duplicated data. Just wanted to check if that's correct.

If that's so, let me know, and I'll remove this part

Copy link
Copy Markdown
Collaborator

@ruslandoga ruslandoga Apr 10, 2026 •
edited
Loading

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

as it would mean that we could write duplicated data

I think since it's an ongoing HTTP request, if the connection gets closed for it, ClickHouse would drop all received data, at least for non-async inserts. But I haven't actually checked that. So it might be that we don't gain anything from reconnecting since we need to start sending the stream anew anyway.

Copy link
Copy Markdown
Collaborator

@ruslandoga ruslandoga Apr 10, 2026 •
edited
Loading

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Also request_chunked should probably be removed (I'll open a PR), I added it because I didn't know at the time about ability to do Stream.into/2 with DBConnection.

DBConnection.run(ch, fn conn ->
  File.stream!("demo.csv", 512_000)
  |> Stream.into(Ch.stream(conn, "insert into demo format CSV"))
  |> Stream.run()
end)

But the issue would remain, do we reconnect in those scenarios or not.

end

@spec stream_body(conn, Mint.Types.request_ref(), Enumerable.t()) ::
Expand Down Expand Up @@ -405,6 +417,56 @@ defmodule Ch.Connection do
end
end

defp with_retry_if_stale_connection(conn, fun) do
case fun.(conn) do
{:disconnect, reason, conn} ->
if reconnectable_error?(reason) do
case reconnect(conn) do
{:ok, new_conn} ->
fun.(new_conn)

{:error, reason} ->
{:disconnect, reason, conn}
end
else
{:disconnect, reason, conn}
end

other ->
other
end
end

defp reconnectable_error?(%Mint.TransportError{reason: :closed}), do: true
defp reconnectable_error?(%Mint.TransportError{reason: :econnreset}), do: true
defp reconnectable_error?(_), do: false

@spec reconnect(conn) :: {:ok, conn} | {:error, Mint.Types.error()}
defp reconnect(conn) do
%{scheme: scheme, address: address, port: port, mint_opts: mint_opts} =
HTTP.get_private(conn, :reconnect_opts)

{:ok, _closed_conn} = HTTP.close(conn)

case HTTP.connect(scheme, address, port, mint_opts) do
{:ok, new_conn} ->
new_conn =
new_conn
|> HTTP.put_private(:timeout, HTTP.get_private(conn, :timeout))
|> maybe_put_private(:database, HTTP.get_private(conn, :database))
|> maybe_put_private(:username, HTTP.get_private(conn, :username))
|> maybe_put_private(:password, HTTP.get_private(conn, :password))
|> maybe_put_private(:settings, HTTP.get_private(conn, :settings))
|> HTTP.put_private(:reconnect_opts, HTTP.get_private(conn, :reconnect_opts))
|> maybe_put_private(@server_display_name_key, HTTP.get_private(conn, @server_display_name_key))

{:ok, new_conn}

{:error, _reason} = error ->
error
end
end

@spec receive_full_response(conn, timeout) ::
{:ok, conn, [response]}
| {:error, Error.t(), conn}
Expand Down Expand Up @@ -499,8 +561,6 @@ defmodule Ch.Connection do
"/?" <> URI.encode_query(settings ++ query_params)
end

@server_display_name_key :server_display_name

@spec ensure_same_server(conn, Mint.Types.headers()) :: conn
defp ensure_same_server(conn, headers) do
expected_name = HTTP.get_private(conn, @server_display_name_key)
Expand Down
Loading