Merge pull request #366 from goodboy/dereg_on_oserror

Make `find_actor()` delete stale sockaddr entries from registrar on `OSError`

tests/test_discovery.py

@@ -1,7 +1,7 @@
-"""
+'''
-Discovery subsys.
+Discovery subsystem via a "registrar" actor scenarios.
 
-"""
+'''
 import os
 import signal
 import platform
@@ -163,7 +163,10 @@ async def unpack_reg(
     else:
         msg = await actor_or_portal.run_from_ns('self', 'get_registry')
 
-    return {tuple(key.split('.')): val for key, val in msg.items()}
+    return {
+        tuple(key.split('.')): val
+        for key, val in msg.items()
+    }
 
 
 async def spawn_and_check_registry(
@@ -356,20 +359,24 @@ async def close_chans_before_nursery(
             try:
                 get_reg = partial(unpack_reg, aportal)
 
-                async with tractor.open_nursery() as tn:
+                async with tractor.open_nursery() as an:
-                    portal1 = await tn.start_actor(
+                    portal1 = await an.start_actor(
-                        name='consumer1', enable_modules=[__name__])
+                        name='consumer1',
-                    portal2 = await tn.start_actor(
+                        enable_modules=[__name__],
-                        'consumer2', enable_modules=[__name__])
+                    )
+                    portal2 = await an.start_actor(
+                        'consumer2',
+                        enable_modules=[__name__],
+                    )
 
-                    # TODO: compact this back as was in last commit once
+                    async with (
-                    # 3.9+, see https://github.com/goodboy/tractor/issues/207
+                        portal1.open_stream_from(
-                    async with portal1.open_stream_from(
                             stream_forever
-                    ) as agen1:
+                        ) as agen1,
-                        async with portal2.open_stream_from(
+                        portal2.open_stream_from(
                             stream_forever
-                        ) as agen2:
+                        ) as agen2,
+                    ):
                             async with (
                                 collapse_eg(),
                                 trio.open_nursery() as tn,
@@ -392,6 +399,7 @@ async def close_chans_before_nursery(
                                     # also kill off channels cuz why not
                                     await agen1.aclose()
                                     await agen2.aclose()
+
             finally:
                 with trio.CancelScope(shield=True):
                     await trio.sleep(1)
@@ -427,7 +435,7 @@ def test_close_channel_explicit(
 
 
 @pytest.mark.parametrize('use_signal', [False, True])
-def test_close_channel_explicit_remote_arbiter(
+def test_close_channel_explicit_remote_registrar(
     daemon: subprocess.Popen,
     start_method: str,
     use_signal: bool,
@@ -448,3 +456,65 @@ def test_close_channel_explicit_remote_arbiter(
                 remote_arbiter=True,
             ),
         )
+
+
+@tractor.context
+async def kill_transport(
+    ctx: tractor.Context,
+) -> None:
+
+    await ctx.started()
+    actor: tractor.Actor = tractor.current_actor()
+    actor.ipc_server.cancel()
+    await trio.sleep_forever()
+
+
+
+# @pytest.mark.parametrize('use_signal', [False, True])
+def test_stale_entry_is_deleted(
+    debug_mode: bool,
+    daemon: subprocess.Popen,
+    start_method: str,
+    reg_addr: tuple,
+):
+    '''
+    Ensure that when a stale entry is detected in the registrar's
+    table that the `find_actor()` API takes care of deleting the
+    stale entry and not delivering a bad portal.
+
+    '''
+    async def main():
+
+        name: str = 'transport_fails_actor'
+        _reg_ptl: tractor.Portal
+        an: tractor.ActorNursery
+        async with (
+            tractor.open_nursery(
+                debug_mode=debug_mode,
+                registry_addrs=[reg_addr],
+            ) as an,
+            tractor.get_registry(reg_addr) as _reg_ptl,
+        ):
+            ptl: tractor.Portal = await an.start_actor(
+                name,
+                enable_modules=[__name__],
+            )
+            async with ptl.open_context(
+                kill_transport,
+            ) as (first, ctx):
+                async with tractor.find_actor(
+                    name,
+                    registry_addrs=[reg_addr],
+                ) as maybe_portal:
+                    # because the transitive
+                    # `._discovery.maybe_open_portal()` call should
+                    # fail and implicitly call `.delete_addr()`
+                    assert maybe_portal is None
+                    registry: dict = await unpack_reg(_reg_ptl)
+                    assert ptl.chan.aid.uid not in registry
+
+                # should fail since we knocked out the IPC tpt XD
+                await ptl.cancel_actor()
+                await an.cancel()
+
+    trio.run(main)

tractor/_discovery.py

@@ -153,21 +153,27 @@ async def query_actor(
     regaddr: UnwrappedAddress|None = None,
 
 ) -> AsyncGenerator[
-    UnwrappedAddress|None,
+    tuple[UnwrappedAddress|None, Portal|LocalPortal|None],
     None,
 ]:
     '''
     Lookup a transport address (by actor name) via querying a registrar
     listening @ `regaddr`.
 
-    Returns the transport protocol (socket) address or `None` if no
+    Yields a `tuple` of `(addr, reg_portal)` where,
-    entry under that name exists.
+    - `addr` is the transport protocol (socket) address or `None` if
+      no entry under that name exists,
+    - `reg_portal` is the `Portal` (or `LocalPortal` when the
+      current actor is the registrar) used for the lookup (or
+      `None` when the peer was found locally via
+      `get_peer_by_name()`).
 
     '''
     actor: Actor = current_actor()
     if (
         name == 'registrar'
-        and actor.is_registrar
+        and
+        actor.is_registrar
     ):
         raise RuntimeError(
             'The current actor IS the registry!?'
@@ -175,10 +181,10 @@ async def query_actor(
 
     maybe_peers: list[Channel]|None = get_peer_by_name(name)
     if maybe_peers:
-        yield maybe_peers[0].raddr
+        yield maybe_peers[0].raddr, None
         return
 
-    reg_portal: Portal
+    reg_portal: Portal|LocalPortal
     regaddr: Address = wrap_address(regaddr) or actor.reg_addrs[0]
     async with get_registry(regaddr) as reg_portal:
         # TODO: return portals to all available actors - for now
@@ -188,8 +194,7 @@ async def query_actor(
             'find_actor',
             name=name,
         )
-        yield addr
+        yield addr, reg_portal
-
 
 @acm
 async def maybe_open_portal(
@@ -204,14 +209,48 @@ async def maybe_open_portal(
     async with query_actor(
         name=name,
         regaddr=addr,
-    ) as addr:
+    ) as (addr, reg_portal):
-        pass
+        if not addr:
+            yield None
+            return
 
-    if addr:
+        try:
             async with _connect_chan(addr) as chan:
                 async with open_portal(chan) as portal:
                     yield portal
+
+        # most likely we were unable to connect the
+        # transport and there is likely a stale entry in
+        # the registry actor's table, thus we need to
+        # instruct it to clear that stale entry and then
+        # more silently (pretend there was no reason but
+        # to) indicate that the target actor can't be
+        # contacted at that addr.
+        except OSError:
+            # NOTE: ensure we delete the stale entry
+            # from the registrar actor when available.
+            if reg_portal is not None:
+                uid: tuple[str, str]|None = await reg_portal.run_from_ns(
+                    'self',
+                    'delete_addr',
+                    addr=addr,
+                )
+                if uid:
+                    log.warning(
+                        f'Deleted stale registry entry !\n'
+                        f'addr: {addr!r}\n'
+                        f'uid: {uid!r}\n'
+                    )
                 else:
+                    log.warning(
+                        f'No registry entry found for addr: {addr!r}'
+                    )
+            else:
+                log.warning(
+                    f'Connection to {addr!r} failed'
+                    f' and no registry portal available'
+                    f' to delete stale entry.'
+                )
             yield None
 
 
@@ -280,7 +319,7 @@ async def find_actor(
         if not any(portals):
             if raise_on_none:
                 raise RuntimeError(
-                    f'No actor "{name}" found registered @ {registry_addrs}'
+                    f'No actor {name!r} found registered @ {registry_addrs!r}'
                 )
             yield None
             return

tractor/_runtime.py

@@ -68,6 +68,7 @@ import textwrap
 from types import ModuleType
 import warnings
 
+from bidict import bidict
 import trio
 from trio._core import _run as trio_runtime
 from trio import (
@@ -1920,10 +1921,10 @@ class Arbiter(Actor):
         **kwargs,
     ) -> None:
 
-        self._registry: dict[
+        self._registry: bidict[
             tuple[str, str],
             UnwrappedAddress,
-        ] = {}
+        ] = bidict({})
         self._waiters: dict[
             str,
             # either an event to sync to receiving an actor uid (which
@@ -2012,7 +2013,13 @@ class Arbiter(Actor):
             # should never be 0-dynamic-os-alloc
             await debug.pause()
 
-        self._registry[uid] = addr
+        # XXX NOTE, value must also be hashable AND since
+        # `._registry` is a `bidict` values must be unique; use
+        # `.forceput()` to replace any prior (stale) entries
+        # that might map a different uid to the same addr (e.g.
+        # after an unclean shutdown or actor-restart reusing
+        # the same address).
+        self._registry.forceput(uid, tuple(addr))
 
         # pop and signal all waiter events
         events = self._waiters.pop(name, [])
@@ -2029,4 +2036,29 @@ class Arbiter(Actor):
         uid = (str(uid[0]), str(uid[1]))
         entry: tuple = self._registry.pop(uid, None)
         if entry is None:
-            log.warning(f'Request to de-register {uid} failed?')
+            log.warning(
+                f'Request to de-register {uid!r} failed?'
+            )
+
+    async def delete_addr(
+        self,
+        addr: tuple[str, int|str]|list[str|int],
+    ) -> tuple[str, str]|None:
+        # NOTE: `addr` arrives as a `list` over IPC
+        # (msgpack deserializes tuples -> lists) so
+        # coerce to `tuple` for the bidict hash lookup.
+        uid: tuple[str, str]|None = self._registry.inverse.pop(
+            tuple(addr),
+            None,
+        )
+        if uid:
+            report: str = 'Deleting registry-entry for,\n'
+        else:
+            report: str = 'No registry entry for,\n'
+
+        log.warning(
+            report
+            +
+            f'{addr!r}@{uid!r}'
+        )
+        return uid