Feature: Add LightNode and MessageCache

A LightNode can synchronize on a subset, or domain, of aleph.im messages. It relies on the MessageCache, which manages a message database with peewee.

.gitignore

@@ -10,6 +10,7 @@
 *.pot
 __pycache__/*
 .cache/*
+cache/**/*
 .*.swp
 */.ipynb_checkpoints/*
 

setup.cfg

@@ -82,6 +82,7 @@ testing =
     substrate-interface
     py-sr25519-bindings
     ledgereth==0.9.0
+    peewee
 mqtt =
     aiomqtt<=0.1.3
     certifi
@@ -107,6 +108,8 @@ ledger =
     ledgereth==0.9.0
 docs =
     sphinxcontrib-plantuml
+cache =
+    peewee
 
 [options.entry_points]
 # Add here console scripts like:

src/aleph/sdk/__init__.py

@@ -1,6 +1,6 @@
 from pkg_resources import DistributionNotFound, get_distribution
 
-from aleph.sdk.client import AlephHttpClient, AuthenticatedAlephHttpClient
+from aleph.sdk.client import AlephHttpClient, AuthenticatedAlephHttpClient, LightNode
 
 try:
     # Change here if project is renamed and does not equal the package name
@@ -11,4 +11,4 @@
 finally:
     del get_distribution, DistributionNotFound
 
-__all__ = ["AlephHttpClient", "AuthenticatedAlephHttpClient"]
+__all__ = ["AlephHttpClient", "AuthenticatedAlephHttpClient", "LightNode"]

src/aleph/sdk/client/__init__.py

@@ -1,10 +1,14 @@
 from .abstract import AlephClient, AuthenticatedAlephClient
 from .authenticated_http import AuthenticatedAlephHttpClient
 from .http import AlephHttpClient
+from .light_node import LightNode
+from .message_cache import MessageCache
 
 __all__ = [
     "AlephClient",
     "AuthenticatedAlephClient",
     "AlephHttpClient",
     "AuthenticatedAlephHttpClient",
+    "MessageCache",
+    "LightNode",
 ]

src/aleph/sdk/client/http.py

@@ -6,6 +6,7 @@
 import aiohttp
 from aleph_message import parse_message
 from aleph_message.models import AlephMessage, ItemHash, ItemType
+from aleph_message.status import MessageStatus
 from pydantic import ValidationError
 
 from ..conf import settings
@@ -171,6 +172,8 @@ async def download_file_to_buffer(
                     )
                 else:
                     raise FileTooLarge(f"The file from {file_hash} is too large")
+            else:
+                response.raise_for_status()
 
     async def download_file_ipfs_to_buffer(
         self,
@@ -314,6 +317,13 @@ async def get_message(
                 )
         return message
 
+    async def get_message_status(self, item_hash: str) -> MessageStatus:
+        async with self.http_session.get(
+            f"/api/v0/messages/{item_hash}"
+        ) as resp:
+            resp.raise_for_status()
+            return MessageStatus((await resp.json())["status"])
+
     async def watch_messages(
         self,
         message_filter: Optional[MessageFilter] = None,