rfc #23: Prevent Pony users from creating "silent failure" scenarios …

…with their network code.

TCPConnectionNotify, UDPNotify and TCPListenNotify will all, by default, silently eat
connection failures.

examples/echo/echo.pony

@@ -51,3 +51,6 @@ class Server is TCPConnectionNotify
 
   fun ref closed(conn: TCPConnection ref) =>
     _out.print("server closed")
+
+  fun ref connect_failed(conn: TCPConnection ref) =>
+    _out.print("connect failed")

examples/net/server.pony

@@ -22,3 +22,6 @@ class ServerSide is TCPConnectionNotify
 
   fun ref closed(conn: TCPConnection ref) =>
     _env.out.print("server closed")
+
+  fun ref connect_failed(conn: TCPConnection ref) =>
+    _env.out.print("connect failed")

packages/net/_test.pony

@@ -214,7 +214,7 @@ class _TestTCPExpectNotify is TCPConnectionNotify
     _send(conn, "hi there")
 
   fun ref connect_failed(conn: TCPConnection ref) =>
-    _h.fail_action("client connect")
+    _h.fail_action("client connect failed")
 
   fun ref connected(conn: TCPConnection ref) =>
     _h.complete_action("client connect")
@@ -295,7 +295,7 @@ class _TestTCPWritevNotifyClient is TCPConnectionNotify
     conn.writev(recover ["hello"; ", hello"] end)
 
   fun ref connect_failed(conn: TCPConnection ref) =>
-    _h.fail_action("client connect")
+    _h.fail_action("client connect failed")
 
 class _TestTCPWritevNotifyServer is TCPConnectionNotify
   let _h: TestHelper
@@ -318,6 +318,9 @@ class _TestTCPWritevNotifyServer is TCPConnectionNotify
     end
     true
 
+  fun ref connect_failed(conn: TCPConnection ref) =>
+    _h.fail_action("sender connect failed")
+
 class iso _TestTCPMute is UnitTest
   """
   Test that the `mute` behavior stops us from reading incoming data. The
@@ -370,6 +373,10 @@ class _TestTCPMuteReceiveNotify is TCPConnectionNotify
     _h.complete(false)
     true
 
+  fun ref connect_failed(conn: TCPConnection ref) =>
+    _h.fail_action("receiver connect failed")
+
+
 class _TestTCPMuteSendNotify is TCPConnectionNotify
   """
   Notifier that sends data back when it receives any. Used in conjunction with
@@ -388,7 +395,7 @@ class _TestTCPMuteSendNotify is TCPConnectionNotify
     _h.complete_action("sender connected")
 
   fun ref connect_failed(conn: TCPConnection ref) =>
-    _h.fail_action("sender connected")
+    _h.fail_action("sender connect failed")
 
    fun ref received(conn: TCPConnection ref, data: Array[U8] val,
     times: USize): Bool
@@ -448,6 +455,10 @@ class _TestTCPUnmuteReceiveNotify is TCPConnectionNotify
     _h.complete(true)
     true
 
+  fun ref connect_failed(conn: TCPConnection ref) =>
+    _h.fail_action("receiver connect failed")
+
+
 class iso _TestTCPThrottle is UnitTest
   """
   Test that when we experience backpressure when sending that the `throttled`
@@ -493,6 +504,9 @@ class _TestTCPThrottleReceiveNotify is TCPConnectionNotify
     _h.complete_action("receiver asks for data")
     _h.dispose_when_done(conn)
 
+  fun ref connect_failed(conn: TCPConnection ref) =>
+    _h.fail_action("receiver connect failed")
+
 class _TestTCPThrottleSendNotify is TCPConnectionNotify
   """
   Notifier that sends data back when it receives any. Used in conjunction with
@@ -512,7 +526,7 @@ class _TestTCPThrottleSendNotify is TCPConnectionNotify
     _h.complete_action("sender connected")
 
   fun ref connect_failed(conn: TCPConnection ref) =>
-    _h.fail_action("sender connected")
+    _h.fail_action("sender connect failed")
 
   fun ref received(conn: TCPConnection ref, data: Array[U8] val,
     times: USize): Bool

packages/net/http/_server_conn_handler.pony

@@ -92,3 +92,9 @@ class _ServerConnHandler is TCPConnectionNotify
     try
       (_session as _ServerConnection).cancel(Payload.request())
     end
+
+  fun ref connect_failed(conn: TCPConnection ref) =>
+    """
+    The connect has failed. TODO: is it a case for server-side?
+    """
+    None

packages/net/tcp_connection.pony

@@ -36,6 +36,9 @@ actor TCPConnection
       _out.print("GOT:" + String.from_array(consume data))
       conn.close()
 
+    fun ref connect_failed(conn: TCPConnection ref) =>
+      None
+
   actor Main
     new create(env: Env) =>
       try
@@ -84,6 +87,9 @@ actor TCPConnection
     fun ref unthrottled(connection: TCPConnection ref) =>
       _coordinator.unthrottled(this)
 
+    fun ref connect_failed(conn: TCPConnection ref) =>
+      None
+
   actor Coordinator
     var _senders: List[Any tag] = _senders.create()
 
@@ -116,18 +122,21 @@ actor TCPConnection
         ""
       end
 
-  fun ref sentv(conn: TCPConnection ref, data: ByteSeqIter): ByteSeqIter =>
-    if not _throttled then
-      data
-    else
-      Array[String]
-    end
+    fun ref sentv(conn: TCPConnection ref, data: ByteSeqIter): ByteSeqIter =>
+      if not _throttled then
+        data
+      else
+        Array[String]
+      end
 
     fun ref throttled(connection: TCPConnection ref) =>
       _throttled = true
 
     fun ref unthrottled(connection: TCPConnection ref) =>
       _throttled = false
+
+    fun ref connect_failed(conn: TCPConnection ref) =>
+      None
   ```
 
   In general, unless you have a very specific use case, we strongly advise that

packages/net/tcp_connection_notify.pony

@@ -26,12 +26,19 @@ interface TCPConnectionNotify
     """
     None
 
-  fun ref connect_failed(conn: TCPConnection ref) =>
+  fun ref connect_failed(conn: TCPConnection ref)
     """
     Called when we have failed to connect to all possible addresses for the
     server. At this point, the connection will never be established.
+
+    It is expected to implement proper error handling. You need to opt in to
+    ignoring errors, which can be implemented like this:
+
+    ```
+    fun ref connect_failed(conn: TCPConnection ref) =>
+      None
+    ```
     """
-    None
 
   fun ref auth_failed(conn: TCPConnection ref) =>
     """

packages/net/tcp_listen_notify.pony

@@ -11,11 +11,18 @@ interface TCPListenNotify
     """
     None
 
-  fun ref not_listening(listen: TCPListener ref) =>
+  fun ref not_listening(listen: TCPListener ref)
     """
     Called if it wasn't possible to bind the listener to an address.
+
+    It is expected to implement proper error handling. You need to opt in to
+    ignoring errors, which can be implemented like this:
+
+    ```
+    fun ref not_listening(listen: TCPListener ref) =>
+      None
+    ```
     """
-    None
 
   fun ref closed(listen: TCPListener ref) =>
     """

packages/net/tcp_listener.pony

@@ -14,6 +14,9 @@ actor TCPListener
     fun ref received(conn: TCPConnection ref, data: Array[U8] iso): Bool =>
       conn.write(String.from_array(consume data))
       true
+    fun ref connect_failed(conn: TCPConnection ref) =>
+      None
+
 
   class MyTCPListenNotify is TCPListenNotify
     fun ref connected(listen: TCPListener ref): TCPConnectionNotify iso^ =>
@@ -38,7 +41,7 @@ actor TCPListener
   var _max_size: USize
 
   new create(auth: TCPListenerAuth, notify: TCPListenNotify iso,
-    host: String = "", service: String = "0", limit: USize = 0,
+    host: String = "", service: String = "0", limit: USize = 0, 
     init_size: USize = 64, max_size: USize = 16384)
   =>
     """
@@ -54,7 +57,7 @@ actor TCPListener
     _notify_listening()
 
   new ip4(auth: TCPListenerAuth, notify: TCPListenNotify iso,
-    host: String = "", service: String = "0", limit: USize = 0,
+    host: String = "", service: String = "0", limit: USize = 0, 
     init_size: USize = 64, max_size: USize = 16384)
   =>
     """
@@ -70,7 +73,7 @@ actor TCPListener
     _notify_listening()
 
   new ip6(auth: TCPListenerAuth, notify: TCPListenNotify iso,
-    host: String = "", service: String = "0", limit: USize = 0,
+    host: String = "", service: String = "0", limit: USize = 0, 
     init_size: USize = 64, max_size: USize = 16384)
   =>
     """

packages/net/udp_notify.pony

@@ -11,11 +11,18 @@ interface UDPNotify
     """
     None
 
-  fun ref not_listening(sock: UDPSocket ref) =>
+  fun ref not_listening(sock: UDPSocket ref)
     """
     Called if it wasn't possible to bind the socket to an address.
+
+    It is expected to implement proper error handling. You need to opt in to
+    ignoring errors, which can be implemented like this:
+
+    ```
+    fun ref not_listening(sock: UDPSocket ref) =>
+      None
+    ```
     """
-    None
 
   fun ref received(sock: UDPSocket ref, data: Array[U8] iso, from: NetAddress)
   =>

packages/net/udp_socket.pony

@@ -22,6 +22,9 @@ actor UDPSocket
     =>
       sock.write(consume data, from)
 
+    fun ref not_listening(sock: UDPSocket ref) =>
+      None
+
   actor Main
     new create(env: Env) =>
       try
@@ -47,6 +50,8 @@ actor UDPSocket
     =>
       _out.print("GOT:" + String.from_array(consume data))
       sock.dispose()
+    fun ref not_listening(sock: UDPSocket ref) =>
+      None
 
   actor Main
     new create(env: Env) =>