Added logging for MultiDBClients (#3896)

* Added logging for MultiDBClients

* Codestyle changes

* Codestyle changes

Author: vladvildanov

docs/multi_database.rst docs/geographic_failover.rstdocs/multi_database.rst renamed to docs/geographic_failover.rst

@@ -1,4 +1,4 @@
-Multi-database client (Active-Active)
+Client-side geographic failover (Active-Active)
 =====================================
 
 The multi-database client allows your application to connect to multiple Redis databases, which are typically replicas of each other.

redis/asyncio/multidb/client.py

@@ -23,7 +23,7 @@
 class MultiDBClient(AsyncRedisModuleCommands, AsyncCoreCommands):
     """
     Client that operates on multiple logical Redis databases.
-    Should be used in Active-Active database setups.
+    Should be used in Client-side geographic failover database setups.
     """
 
     def __init__(self, config: MultiDbConfig):
@@ -299,7 +299,7 @@ async def _check_databases_health(
                 unhealthy_db = result.database
                 unhealthy_db.circuit.state = CBState.OPEN
 
-                logger.exception(
+                logger.debug(
                     "Health check failed, due to exception",
                     exc_info=result.original_exception,
                 )
@@ -337,8 +337,14 @@ def _on_circuit_state_change_callback(
             return
 
         if old_state == CBState.CLOSED and new_state == CBState.OPEN:
+            logger.error(
+                f"Database {circuit.database} is unreachable. Failover has been initiated."
+            )
             loop.call_later(DEFAULT_GRACE_PERIOD, _half_open_circuit, circuit)
 
+        if old_state != CBState.CLOSED and new_state == CBState.CLOSED:
+            logger.info(f"Database {circuit.database} is reachable again.")
+
     async def aclose(self):
         if self.command_executor.active_database:
             await self.command_executor.active_database.client.aclose()

redis/asyncio/multidb/database.py

@@ -67,3 +67,6 @@ def circuit(self) -> CircuitBreaker:
     @circuit.setter
     def circuit(self, circuit: CircuitBreaker):
         self._cb = circuit
+
+    def __repr__(self):
+        return f"Database(client={self.client}, weight={self.weight})"

redis/multidb/client.py

@@ -24,7 +24,7 @@
 class MultiDBClient(RedisModuleCommands, CoreCommands):
     """
     Client that operates on multiple logical Redis databases.
-    Should be used in Active-Active database setups.
+    Should be used in Client-side geographic failover database setups.
     """
 
     def __init__(self, config: MultiDbConfig):
@@ -276,6 +276,11 @@ def _check_databases_health(self, on_error: Callable[[Exception], None] = None):
                         unhealthy_db = e.database
                         unhealthy_db.circuit.state = CBState.OPEN
 
+                        logger.debug(
+                            "Health check failed, due to exception",
+                            exc_info=e.original_exception,
+                        )
+
                         if on_error:
                             on_error(e.original_exception)
             except TimeoutError:
@@ -291,10 +296,17 @@ def _on_circuit_state_change_callback(
             return
 
         if old_state == CBState.CLOSED and new_state == CBState.OPEN:
+            logger.error(
+                f"Database {circuit.database} is unreachable. Failover has been initiated."
+            )
+
             self._bg_scheduler.run_once(
                 DEFAULT_GRACE_PERIOD, _half_open_circuit, circuit
             )
 
+        if old_state != CBState.CLOSED and new_state == CBState.CLOSED:
+            logger.info(f"Database {circuit.database} is reachable again.")
+
     def close(self):
         """
         Closes the client and all its resources.

redis/multidb/database.py

@@ -128,3 +128,6 @@ def circuit(self) -> CircuitBreaker:
     @circuit.setter
     def circuit(self, circuit: CircuitBreaker):
         self._cb = circuit
+
+    def __repr__(self):
+        return f"Database(client={self.client}, weight={self.weight})"