add a timeout for DB queries

nominatim/api/connection.py

@@ -9,6 +9,7 @@ Extended SQLAlchemy connection class that also includes access to the schema.
 """
 from typing import cast, Any, Mapping, Sequence, Union, Dict, Optional, Set, \
                    Awaitable, Callable, TypeVar
+import asyncio
 
 import sqlalchemy as sa
 from sqlalchemy.ext.asyncio import AsyncConnection
@@ -34,6 +35,14 @@ class SearchConnection:
         self.t = tables # pylint: disable=invalid-name
         self._property_cache = properties
         self._classtables: Optional[Set[str]] = None
+        self.query_timeout: Optional[int] = None
+
+
+    def set_query_timeout(self, timeout: Optional[int]) -> None:
+        """ Set the timeout after which a query over this connection
+            is cancelled.
+        """
+        self.query_timeout = timeout
 
 
     async def scalar(self, sql: sa.sql.base.Executable,
@@ -42,7 +51,8 @@ class SearchConnection:
         """ Execute a 'scalar()' query on the connection.
         """
         log().sql(self.connection, sql, params)
-        return await self.connection.scalar(sql, params)
+        async with asyncio.timeout(self.query_timeout):
+            return await self.connection.scalar(sql, params)
 
 
     async def execute(self, sql: 'sa.Executable',
@@ -51,7 +61,8 @@ class SearchConnection:
         """ Execute a 'execute()' query on the connection.
         """
         log().sql(self.connection, sql, params)
-        return await self.connection.execute(sql, params)
+        async with asyncio.timeout(self.query_timeout):
+            return await self.connection.execute(sql, params)
 
 
     async def get_property(self, name: str, cached: bool = True) -> str:

nominatim/api/core.py

@@ -36,6 +36,8 @@ class NominatimAPIAsync:
                  environ: Optional[Mapping[str, str]] = None,
                  loop: Optional[asyncio.AbstractEventLoop] = None) -> None:
         self.config = Configuration(project_dir, environ)
+        self.query_timeout = self.config.get_int('QUERY_TIMEOUT') \
+                             if self.config.QUERY_TIMEOUT else None
         self.server_version = 0
 
         if sys.version_info >= (3, 10):
@@ -128,6 +130,7 @@ class NominatimAPIAsync:
         """
         try:
             async with self.begin() as conn:
+                conn.set_query_timeout(self.query_timeout)
                 status = await get_status(conn)
         except (PGCORE_ERROR, sa.exc.OperationalError):
             return StatusResult(700, 'Database connection failed')
@@ -142,6 +145,7 @@ class NominatimAPIAsync:
         """
         details = ntyp.LookupDetails.from_kwargs(params)
         async with self.begin() as conn:
+            conn.set_query_timeout(self.query_timeout)
             if details.keywords:
                 await make_query_analyzer(conn)
             return await get_detailed_place(conn, place, details)
@@ -154,6 +158,7 @@ class NominatimAPIAsync:
         """
         details = ntyp.LookupDetails.from_kwargs(params)
         async with self.begin() as conn:
+            conn.set_query_timeout(self.query_timeout)
             if details.keywords:
                 await make_query_analyzer(conn)
             return SearchResults(filter(None,
@@ -173,6 +178,7 @@ class NominatimAPIAsync:
 
         details = ntyp.ReverseDetails.from_kwargs(params)
         async with self.begin() as conn:
+            conn.set_query_timeout(self.query_timeout)
             if details.keywords:
                 await make_query_analyzer(conn)
             geocoder = ReverseGeocoder(conn, details)
@@ -187,6 +193,7 @@ class NominatimAPIAsync:
             raise UsageError('Nothing to search for.')
 
         async with self.begin() as conn:
+            conn.set_query_timeout(self.query_timeout)
             geocoder = ForwardGeocoder(conn, ntyp.SearchDetails.from_kwargs(params))
             phrases = [Phrase(PhraseType.NONE, p.strip()) for p in query.split(',')]
             return await geocoder.lookup(phrases)
@@ -204,6 +211,7 @@ class NominatimAPIAsync:
         """ Find an address using structured search.
         """
         async with self.begin() as conn:
+            conn.set_query_timeout(self.query_timeout)
             details = ntyp.SearchDetails.from_kwargs(params)
 
             phrases: List[Phrase] = []
@@ -260,6 +268,7 @@ class NominatimAPIAsync:
 
         details = ntyp.SearchDetails.from_kwargs(params)
         async with self.begin() as conn:
+            conn.set_query_timeout(self.query_timeout)
             if near_query:
                 phrases = [Phrase(PhraseType.NONE, p) for p in near_query.split(',')]
             else:

settings/env.defaults

@@ -214,6 +214,10 @@ NOMINATIM_SERVE_LEGACY_URLS=yes
 # of connections _per worker_.
 NOMINATIM_API_POOL_SIZE=10
 
+# Timeout is seconds after which a single query to the database is cancelled.
+# When empty, then timeouts are disabled.
+NOMINATIM_QUERY_TIMEOUT=60
+
 # Search elements just within countries
 # If, despite not finding a point within the static grid of countries, it
 # finds a geometry of a region, do not return the geometry. Return "Unable