raiden: perform health checks and enable WebRTC

The health checks are done whenever

- a channel is opened
- a message is about to be sent
- the transport is started

Fixes raiden-network#7151.

raiden/blockchain/events.py

@@ -1,6 +1,6 @@
 import time
 from dataclasses import dataclass
-from typing import Tuple
+from typing import Callable, Tuple
 
 import structlog
 from eth_utils import to_canonical_address, to_checksum_address
@@ -294,6 +294,8 @@ def __init__(
             contract_manager
         )
 
+        self._listeners: List[Callable] = []
+
     def fetch_logs_in_batch(self, target_block_number: BlockNumber) -> Optional[PollResult]:
         """Poll the smart contract events for a limited number of blocks to
         avoid read timeouts (issue #3558).
@@ -562,6 +564,9 @@ def _query_and_track(
                 )
                 result.extend(decoded_events)
 
+                for listener in self._listeners:
+                    listener(decoded_events)
+
                 # Go through the results and create the child filters, if necessary.
                 event_filter = new_filters_from_events(decoded_events)
 
@@ -575,6 +580,14 @@ def _query_and_track(
 
         return result, max_request_duration
 
-    def uninstall_all_event_listeners(self) -> None:
+    def stop(self) -> None:
         with self._filters_lock:
             self._address_to_abi = {}
+
+        del self._listeners[:]
+
+    def register_listener(self, listener: Callable) -> None:
+        self._listeners.append(listener)
+
+    def unregister_listener(self, listener: Callable) -> None:
+        self._listeners.remove(listener)

raiden/network/transport/matrix/transport.py

@@ -389,6 +389,8 @@ def __init__(self, config: MatrixTransportConfig, environment: Environment) -> N
         self._config = config
         self._environment = environment
         self._raiden_service: Optional["RaidenService"] = None
+        # the addresses for which we're currently trying to initialize WebRTC channels
+        self._web_rtc_channel_inits: Set[Address] = set()
 
         if config.server == MATRIX_AUTO_SELECT_SERVER:
             homeserver_candidates = config.available_servers
@@ -569,6 +571,15 @@ def start(  # type: ignore
 
         self._schedule_new_greenlet(self._set_presence, UserPresence.ONLINE)
 
+        chain_state = views.state_from_raiden(raiden_service)
+        for neighbour in views.all_neighbour_nodes(chain_state):
+            self.health_check_web_rtc(neighbour)
+
+    def health_check_web_rtc(self, partner: Address) -> None:
+        if not self._web_rtc_manager.has_ready_channel(partner):
+            # TODO: initialize WebRTC for the partner address
+            pass
+
     def _set_presence(self, state: UserPresence) -> None:
         waiting_period = randint(SET_PRESENCE_INTERVAL // 4, SET_PRESENCE_INTERVAL)
         gevent.wait(  # pylint: disable=gevent-disable-wait
@@ -1158,6 +1169,8 @@ def _send_raw(
     ) -> None:
         assert self._raiden_service is not None, "_raiden_service not set"
 
+        self.health_check_web_rtc(receiver_address)
+
         user_ids: Set[UserID] = set()
         if self._web_rtc_manager.has_ready_channel(receiver_address):
             communication_medium = CommunicationMedium.WEB_RTC
@@ -1201,8 +1214,7 @@ def _send_raw(
             return
 
     def _maybe_initialize_web_rtc(self, address: Address) -> None:
-
-        if self._stop_event.ready():
+        if self._stop_event.ready() or address in self._web_rtc_channel_inits:
             return
 
         assert self._raiden_service is not None, "_raiden_service not set"
@@ -1216,7 +1228,11 @@ def _maybe_initialize_web_rtc(self, address: Address) -> None:
                 partner_address=to_checksum_address(address),
             )
             # initiate web rtc handling
-            self._schedule_new_greenlet(self._initialize_web_rtc, address)
+            self._web_rtc_channel_inits.add(address)
+            try:
+                self._schedule_new_greenlet(self._initialize_web_rtc, address)
+            finally:
+                self._web_rtc_channel_inits.remove(address)
 
     def _initialize_web_rtc(self, partner_address: Address) -> None:
         assert self._raiden_service is not None, "_raiden_service not set"

raiden/raiden_service.py

@@ -21,7 +21,7 @@
 from raiden.api.python import RaidenAPI
 from raiden.api.rest import APIServer, RestAPI
 from raiden.blockchain.decode import blockchainevent_to_statechange
-from raiden.blockchain.events import BlockchainEvents
+from raiden.blockchain.events import BlockchainEvents, DecodedEvent
 from raiden.blockchain.filters import RaidenContractFilter
 from raiden.constants import (
     ABSENT_SECRET,
@@ -132,6 +132,7 @@
     typecheck,
 )
 from raiden.utils.upgrades import UpgradeManager
+from raiden_contracts.constants import ChannelEvent
 from raiden_contracts.contract_manager import ContractManager
 
 log = structlog.get_logger(__name__)
@@ -526,7 +527,7 @@ def stop(self) -> None:
         assert (
             self.blockchain_events
         ), f"The blockchain_events has to be set by the start. node:{self!r}"
-        self.blockchain_events.uninstall_all_event_listeners()
+        self.blockchain_events.stop()
 
         # Close storage DB to release internal DB lock
         assert (
@@ -774,6 +775,7 @@ def _synchronize_with_blockchain(self) -> None:
             block_batch_size_config=self.config.blockchain.block_batch_size_config,
             node_address=self.address,
         )
+        blockchain_events.register_listener(self._blockchain_event_listener)
 
         self.last_log_block = last_block_number
         self.last_log_time = time.monotonic()
@@ -790,6 +792,17 @@ def _synchronize_with_blockchain(self) -> None:
 
         self.alarm.register_callback(self._best_effort_synchronize)
 
+    def _blockchain_event_listener(self, events: List[DecodedEvent]) -> None:
+        for event in events:
+            args = event.event_data["args"]
+            if event.event_data["event"] == ChannelEvent.OPENED:
+                other = (
+                    args["participant1"]
+                    if args["participant1"] != self.address
+                    else args["participant2"]
+                )
+                self.transport.health_check_web_rtc(other)
+
     def _start_alarm_task(self) -> None:
         """Start the alarm task.