Merge pull request #13 from wowica/reconnect-ondisconnect

improve reconnections

README.md

@@ -9,7 +9,7 @@ An Elixir client for [Ogmios](https://github.com/CardanoSolutions/ogmios).
 Mini-Protocols supported by this library:
 
 - [x] Chain Synchronization
-- [ ] State Query (partially supported)
+- [x] State Query (partially supported)
 - [ ] Mempool Monitoring
 - [ ] Tx Submission
 

lib/xogmios/chain_sync.ex

@@ -7,6 +7,10 @@ defmodule Xogmios.ChainSync do
 
   @callback handle_block(map(), any()) ::
               {:ok, :next_block, map()} | {:ok, map()} | {:ok, :close, map()}
+  @callback handle_connect(map()) ::
+              {:ok, map()}
+  @callback handle_disconnect(String.t(), map()) ::
+              {:ok, map()} | {:reconnect, non_neg_integer(), map()}
 
   # The keepalive option is used to maintain the connection active.
   # This is important because proxies might close idle connections after a few seconds.
@@ -15,7 +19,10 @@ defmodule Xogmios.ChainSync do
   def start_link(client, opts) do
     {url, opts} = Keyword.pop(opts, :url)
     initial_state = Keyword.merge(opts, handler: client)
-    :websocket_client.start_link(url, client, initial_state, keepalive: @keepalive_in_ms)
+
+    :websocket_client.start_link({:local, client}, url, client, initial_state,
+      keepalive: @keepalive_in_ms
+    )
   end
 
   defmacro __using__(_opts) do
@@ -26,6 +33,10 @@ defmodule Xogmios.ChainSync do
 
       require Logger
 
+      def handle_connect(state), do: {:ok, state}
+      def handle_disconnect(_reason, state), do: {:ok, state}
+      defoverridable handle_connect: 1, handle_disconnect: 2
+
       def handle_message(%{"id" => "start"} = message, state) do
         %{
           "method" => "nextBlock",

lib/xogmios/chain_sync/connection.ex

@@ -6,13 +6,16 @@ defmodule Xogmios.ChainSync.Connection do
 
   alias Xogmios.ChainSync.Messages
 
+  require Logger
+
   defmacro __using__(_opts) do
     quote do
       @behaviour :websocket_client
 
       require Logger
 
       @name __MODULE__
+      @reconnect_interval 5_000
 
       def child_spec(opts) do
         %{
@@ -38,12 +41,25 @@ defmodule Xogmios.ChainSync.Connection do
       def onconnect(_arg, state) do
         start_message = Messages.next_block_start()
         :websocket_client.cast(self(), {:text, start_message})
-        {:ok, state}
+
+        case state.handler.handle_connect(state) do
+          {:ok, new_state} ->
+            {:ok, new_state}
+
+          _ ->
+            {:ok, state}
+        end
       end
 
       @impl true
-      def ondisconnect(_reason, state) do
-        {:ok, state}
+      def ondisconnect(reason, state) do
+        case state.handler.handle_disconnect(reason, state) do
+          {:ok, state} ->
+            {:ok, state}
+
+          {:reconnect, reconnect_interval_in_ms, new_state} ->
+            {:reconnect, reconnect_interval_in_ms, new_state}
+        end
       end
 
       @impl true