Merge pull request #13 from mardiros/features/dependency-injection-in…

…stanciation

Refactor to isolate dependencies per transaction

src/messagebus/domain/model/message.py

@@ -6,7 +6,7 @@
 """
 
 from datetime import datetime
-from typing import Any, Generic
+from typing import Any, Generic, TypeVar
 from uuid import UUID
 
 from lastuuid import uuid7
@@ -69,3 +69,6 @@ class GenericEvent(Message[TMetadata]):
 """Command that use the default metadata."""
 Event = GenericEvent[Metadata]
 """Event that use the default metadata."""
+
+
+TMessage = TypeVar("TMessage", bound=Message[Any])

src/messagebus/service/_async/dependency.py

@@ -0,0 +1,39 @@
+from collections.abc import Mapping, Sequence
+from typing import Any, Generic
+
+from messagebus.domain.model.message import TMessage
+from messagebus.service._async.unit_of_work import TAsyncUow
+from messagebus.typing import AsyncMessageHandler, P
+
+
+class AsyncDependency:
+    """Describe an async dependency"""
+
+    async def on_after_commit(self) -> None:
+        """Method called when the unit of work transaction is has been commited."""
+
+    async def on_after_rollback(self) -> None:
+        """Method called when the unit of work transaction is has been rolled back."""
+
+
+class AsyncMessageHook(Generic[TMessage, TAsyncUow, P]):
+    callback: AsyncMessageHandler[TMessage, "TAsyncUow", P]
+    dependencies: Sequence[str]
+
+    def __init__(
+        self,
+        callback: AsyncMessageHandler[TMessage, "TAsyncUow", P],
+        dependencies: Sequence[str],
+    ) -> None:
+        self.callback = callback
+        self.dependencies = dependencies
+
+    async def __call__(
+        self,
+        msg: TMessage,
+        uow: "TAsyncUow",
+        dependencies: Mapping[str, AsyncDependency],
+    ) -> Any:
+        deps = {k: dependencies[k] for k in self.dependencies}
+        resp = await self.callback(msg, uow, **deps)  # type: ignore
+        return resp

src/messagebus/service/_async/registry.py

@@ -7,15 +7,24 @@
 import inspect
 import logging
 from collections import defaultdict
-from functools import partial
+from collections.abc import Mapping
 from typing import Any, Generic, cast
 
 import venusian  # type: ignore
 
 from messagebus.domain.model import GenericCommand, GenericEvent, Message
-from messagebus.typing import AsyncMessageHandler, P, TAsyncUow, TMessage
-
-from .unit_of_work import AsyncUnitOfWorkTransaction, TRepositories
+from messagebus.domain.model.message import TMessage
+from messagebus.service._async.dependency import (
+    AsyncDependency,
+    AsyncMessageHandler,
+    AsyncMessageHook,
+    P,
+)
+from messagebus.service._async.unit_of_work import (
+    AsyncUnitOfWorkTransaction,
+    TAsyncUow,
+    TRepositories,
+)
 
 log = logging.getLogger(__name__)
 VENUSIAN_CATEGORY = "messagebus"
@@ -55,38 +64,38 @@ class AsyncMessageBus(Generic[TRepositories]):
 
     def __init__(self, **dependencies: Any) -> None:
         self.commands_registry: dict[
-            type[GenericCommand[Any]],
-            AsyncMessageHandler[GenericCommand[Any], Any, ...],
+            type[GenericCommand[Any]], AsyncMessageHook[Any, Any, Any]
         ] = {}
         self.events_registry: dict[
-            type[GenericEvent[Any]],
-            list[AsyncMessageHandler[GenericEvent[Any], Any, ...]],
+            type[GenericEvent[Any]], list[AsyncMessageHook[Any, Any, Any]]
         ] = defaultdict(list)
-        self.depencencies = dependencies or {}
+        self.dependencies = cast(
+            Mapping[str, type[AsyncDependency]], dependencies or {}
+        )
 
     def add_listener(
         self, msg_type: type[Message[Any]], callback: AsyncMessageHandler[Any, Any, P]
     ) -> None:
         signature = inspect.signature(callback)
-        kwargs = {}
+        dependencies: list[str] = []
         for idx, key in enumerate(signature.parameters):
             if idx >= 2:
-                if key not in self.depencencies:
+                if key not in self.dependencies:
                     raise ConfigurationError(
                         f"Missing dependency in message bus: {key} for command "
                         f"type {msg_type.__name__}, listener: {callback.__name__}"
                     )
-                kwargs[key] = self.depencencies[key]
-        if kwargs:
-            callback = partial(callback, **kwargs)  # type: ignore
+                dependencies.append(key)
+
+        msghook = AsyncMessageHook(callback, dependencies)
         if issubclass(msg_type, GenericCommand):
             if msg_type in self.commands_registry:
                 raise ConfigurationError(
                     f"{msg_type} command has been registered twice"
                 )
-            self.commands_registry[msg_type] = callback
+            self.commands_registry[msg_type] = msghook
         elif issubclass(msg_type, GenericEvent):
-            self.events_registry[msg_type].append(callback)
+            self.events_registry[msg_type].append(msghook)
         else:
             raise ConfigurationError(
                 f"Invalid usage of the listen decorator: "
@@ -101,12 +110,13 @@ def remove_listener(
                 raise ConfigurationError(f"{msg_type} command has not been registered")
             del self.commands_registry[msg_type]
         elif issubclass(msg_type, GenericEvent):
-            try:
-                self.events_registry[msg_type].remove(callback)
-            except ValueError as exc:
-                raise ConfigurationError(
-                    f"{msg_type} event has not been registered"
-                ) from exc
+            msg_hooks = [
+                v for v in self.events_registry[msg_type] if v.callback == callback
+            ]
+            if msg_hooks:
+                self.events_registry[msg_type].remove(msg_hooks[0])
+            else:
+                raise ConfigurationError(f"{msg_type} event has not been registered")
         else:
             raise ConfigurationError(
                 f"Invalid usage of the listen decorator: "
@@ -120,6 +130,7 @@ async def handle(
         Notify listener of that event registered with `messagebus.add_listener`.
         Return the first event from the command.
         """
+        dependencies = {k: uow.add_listener(v()) for k, v in self.dependencies.items()}
         queue = [message]
         idx = 0
         ret = None
@@ -130,14 +141,14 @@ async def handle(
             msg_type = type(message)
             if msg_type in self.commands_registry:
                 cmdret = await self.commands_registry[msg_type](  # type: ignore
-                    cast(GenericCommand[Any], message), uow
+                    cast(GenericCommand[Any], message), uow, dependencies
                 )
                 if idx == 0:
                     ret = cmdret
                 queue.extend(uow.uow.collect_new_events())
             elif msg_type in self.events_registry:
-                for callback in self.events_registry[msg_type]:  # type: ignore
-                    await callback(cast(GenericEvent[Any], message), uow)
+                for msghook in self.events_registry[msg_type]:  # type: ignore
+                    await msghook(cast(GenericEvent[Any], message), uow, dependencies)
                     queue.extend(uow.uow.collect_new_events())
             await uow.eventstore.add(message)
             idx += 1

src/messagebus/service/_async/unit_of_work.py

@@ -6,9 +6,12 @@
 import enum
 from collections.abc import Iterator
 from types import TracebackType
-from typing import Any, Generic, TypeVar
+from typing import TYPE_CHECKING, Any, Generic, TypeVar
 
 from messagebus.domain.model import Message
+
+if TYPE_CHECKING:
+    from messagebus.service._async.dependency import AsyncDependency
 from messagebus.service._async.repository import (
     AsyncAbstractRepository,
     AsyncEventstoreAbstractRepository,
@@ -39,6 +42,7 @@ class AsyncUnitOfWorkTransaction(Generic[TRepositories]):
     def __init__(self, uow: AsyncAbstractUnitOfWork[TRepositories]) -> None:
         self.status = TransactionStatus.running
         self.uow = uow
+        self._hooks: list[Any] = []
 
     def __getattr__(self, name: str) -> TRepositories:
         return getattr(self.uow, name)
@@ -47,15 +51,29 @@ def __getattr__(self, name: str) -> TRepositories:
     def eventstore(self) -> AsyncEventstoreAbstractRepository:
         return self.uow.eventstore
 
+    def add_listener(self, listener: AsyncDependency) -> AsyncDependency:
+        self._hooks.append(listener)
+        return listener
+
+    async def _on_after_commit(self) -> None:
+        for val in self._hooks:
+            await val.on_after_commit()
+
+    async def _on_after_rollback(self) -> None:
+        for val in self._hooks:
+            await val.on_after_rollback()
+
     async def commit(self) -> None:
         if self.status != TransactionStatus.running:
             raise TransactionError(f"Transaction already closed ({self.status.value}).")
         await self.uow.commit()
         self.status = TransactionStatus.committed
+        await self._on_after_commit()
 
     async def rollback(self) -> None:
         await self.uow.rollback()
         self.status = TransactionStatus.rolledback
+        await self._on_after_rollback()
 
     async def __aenter__(self) -> AsyncUnitOfWorkTransaction[TRepositories]:
         if self.status != TransactionStatus.running:
@@ -130,3 +148,6 @@ async def commit(self) -> None:
     @abc.abstractmethod
     async def rollback(self) -> None:
         """Rollback the transation."""
+
+
+TAsyncUow = TypeVar("TAsyncUow", bound=AsyncAbstractUnitOfWork[Any])

src/messagebus/service/_sync/dependency.py

@@ -0,0 +1,39 @@
+from collections.abc import Mapping, Sequence
+from typing import Any, Generic
+
+from messagebus.domain.model.message import TMessage
+from messagebus.service._sync.unit_of_work import TSyncUow
+from messagebus.typing import P, SyncMessageHandler
+
+
+class SyncDependency:
+    """Describe an async dependency"""
+
+    def on_after_commit(self) -> None:
+        """Method called when the unit of work transaction is has been commited."""
+
+    def on_after_rollback(self) -> None:
+        """Method called when the unit of work transaction is has been rolled back."""
+
+
+class SyncMessageHook(Generic[TMessage, TSyncUow, P]):
+    callback: SyncMessageHandler[TMessage, "TSyncUow", P]
+    dependencies: Sequence[str]
+
+    def __init__(
+        self,
+        callback: SyncMessageHandler[TMessage, "TSyncUow", P],
+        dependencies: Sequence[str],
+    ) -> None:
+        self.callback = callback
+        self.dependencies = dependencies
+
+    def __call__(
+        self,
+        msg: TMessage,
+        uow: "TSyncUow",
+        dependencies: Mapping[str, SyncDependency],
+    ) -> Any:
+        deps = {k: dependencies[k] for k in self.dependencies}
+        resp = self.callback(msg, uow, **deps)  # type: ignore
+        return resp