simplify weigh_search() function

[nominatim.git] / nominatim / db / async_connection.py

diff --git a/nominatim/db/async_connection.py b/nominatim/db/async_connection.py
index c5d6872bf0790abfaa10f7b07d2567ba0913663d..07767e48ad8934c5dc831c16e9c0040e9a3a6d01 100644 (file)
--- a/nominatim/db/async_connection.py
+++ b/nominatim/db/async_connection.py
@@ -1,11 +1,16 @@
 # SPDX-License-Identifier: GPL-2.0-only
 #
 # SPDX-License-Identifier: GPL-2.0-only
 #

-# This file is part of Nominatim.
-# Copyright (C) 2021 by the Nominatim developer community.
+# This file is part of Nominatim. (https://nominatim.org)
+#
+# Copyright (C) 2022 by the Nominatim developer community.

 # For a full list of authors see the git log.
 # For a full list of authors see the git log.

-""" Database helper functions for the indexer.
+""" Non-blocking database connections.

 """
 """

+from typing import Callable, Any, Optional, Iterator, Sequence

 import logging
 import logging

+import select
+import time
+

 import psycopg2
 from psycopg2.extras import wait_select
 
 import psycopg2
 from psycopg2.extras import wait_select
 


@@ -14,9 +19,11 @@ from psycopg2.extras import wait_select
 try:
     import psycopg2.errors # pylint: disable=no-name-in-module,import-error
     __has_psycopg2_errors__ = True
 try:
     import psycopg2.errors # pylint: disable=no-name-in-module,import-error
     __has_psycopg2_errors__ = True

-except ModuleNotFoundError:
+except ImportError:

     __has_psycopg2_errors__ = False
 
     __has_psycopg2_errors__ = False
 

+from nominatim.typing import T_cursor, Query
+

 LOG = logging.getLogger()
 
 class DeadlockHandler:
 LOG = logging.getLogger()
 
 class DeadlockHandler:


@@ -25,22 +32,27 @@ class DeadlockHandler:
         normally.
     """
 
         normally.
     """
 

-    def __init__(self, handler):
+    def __init__(self, handler: Callable[[], None], ignore_sql_errors: bool = False) -> None:

         self.handler = handler
         self.handler = handler

+        self.ignore_sql_errors = ignore_sql_errors

 
 

-    def __enter__(self):
-        pass
+    def __enter__(self) -> 'DeadlockHandler':
+        return self

 
 

-    def __exit__(self, exc_type, exc_value, traceback):
+    def __exit__(self, exc_type: Any, exc_value: Any, traceback: Any) -> bool:

         if __has_psycopg2_errors__:
             if exc_type == psycopg2.errors.DeadlockDetected: # pylint: disable=E1101
                 self.handler()
                 return True
         if __has_psycopg2_errors__:
             if exc_type == psycopg2.errors.DeadlockDetected: # pylint: disable=E1101
                 self.handler()
                 return True

-        else:
-            if exc_type == psycopg2.extensions.TransactionRollbackError:
-                if exc_value.pgcode == '40P01':
-                    self.handler()
-                    return True
+        elif exc_type == psycopg2.extensions.TransactionRollbackError \
+             and exc_value.pgcode == '40P01':
+            self.handler()
+            return True
+
+        if self.ignore_sql_errors and isinstance(exc_value, psycopg2.Error):
+            LOG.info("SQL error ignored: %s", exc_value)
+            return True
+

         return False
 
 
         return False
 
 


@@ -48,25 +60,31 @@ class DBConnection:
     """ A single non-blocking database connection.
     """
 
     """ A single non-blocking database connection.
     """
 

-    def __init__(self, dsn):
-        self.current_query = None
-        self.current_params = None
+    def __init__(self, dsn: str,
+                 cursor_factory: Optional[Callable[..., T_cursor]] = None,
+                 ignore_sql_errors: bool = False) -> None:

         self.dsn = dsn
 
         self.dsn = dsn
 

-        self.conn = None
-        self.cursor = None
-        self.connect()
+        self.current_query: Optional[Query] = None
+        self.current_params: Optional[Sequence[Any]] = None
+        self.ignore_sql_errors = ignore_sql_errors
+
+        self.conn: Optional['psycopg2._psycopg.connection'] = None
+        self.cursor: Optional['psycopg2._psycopg.cursor'] = None
+        self.connect(cursor_factory=cursor_factory)

 
 

-    def close(self):
+    def close(self) -> None:

         """ Close all open connections. Does not wait for pending requests.
         """
         if self.conn is not None:
         """ Close all open connections. Does not wait for pending requests.
         """
         if self.conn is not None:

-            self.cursor.close()
+            if self.cursor is not None:
+                self.cursor.close()
+                self.cursor = None

             self.conn.close()
 
         self.conn = None
 
             self.conn.close()
 
         self.conn = None
 

-    def connect(self):
+    def connect(self, cursor_factory: Optional[Callable[..., T_cursor]] = None) -> None:

         """ (Re)connect to the database. Creates an asynchronous connection
             with JIT and parallel processing disabled. If a connection was
             already open, it is closed and a new connection established.
         """ (Re)connect to the database. Creates an asynchronous connection
             with JIT and parallel processing disabled. If a connection was
             already open, it is closed and a new connection established.


@@ -76,10 +94,14 @@ class DBConnection:
 
         # Use a dict to hand in the parameters because async is a reserved
         # word in Python3.
 
         # Use a dict to hand in the parameters because async is a reserved
         # word in Python3.

-        self.conn = psycopg2.connect(**{'dsn' : self.dsn, 'async' : True})
+        self.conn = psycopg2.connect(**{'dsn': self.dsn, 'async': True}) # type: ignore
+        assert self.conn

         self.wait()
 
         self.wait()
 

-        self.cursor = self.conn.cursor()
+        if cursor_factory is not None:
+            self.cursor = self.conn.cursor(cursor_factory=cursor_factory)
+        else:
+            self.cursor = self.conn.cursor()

         # Disable JIT and parallel workers as they are known to cause problems.
         # Update pg_settings instead of using SET because it does not yield
         # errors on older versions of Postgres where the settings are not
         # Disable JIT and parallel workers as they are known to cause problems.
         # Update pg_settings instead of using SET because it does not yield
         # errors on older versions of Postgres where the settings are not


@@ -90,44 +112,125 @@ class DBConnection:
                    WHERE name = 'max_parallel_workers_per_gather';""")
         self.wait()
 
                    WHERE name = 'max_parallel_workers_per_gather';""")
         self.wait()
 

-    def _deadlock_handler(self):
+    def _deadlock_handler(self) -> None:

         LOG.info("Deadlock detected (params = %s), retry.", str(self.current_params))
         LOG.info("Deadlock detected (params = %s), retry.", str(self.current_params))

+        assert self.cursor is not None
+        assert self.current_query is not None
+        assert self.current_params is not None
+

         self.cursor.execute(self.current_query, self.current_params)
 
         self.cursor.execute(self.current_query, self.current_params)
 

-    def wait(self):
+    def wait(self) -> None:

         """ Block until any pending operation is done.
         """
         while True:
         """ Block until any pending operation is done.
         """
         while True:

-            with DeadlockHandler(self._deadlock_handler):
+            with DeadlockHandler(self._deadlock_handler, self.ignore_sql_errors):

                 wait_select(self.conn)
                 self.current_query = None
                 return
 
                 wait_select(self.conn)
                 self.current_query = None
                 return
 

-    def perform(self, sql, args=None):
+    def perform(self, sql: Query, args: Optional[Sequence[Any]] = None) -> None:

         """ Send SQL query to the server. Returns immediately without
             blocking.
         """
         """ Send SQL query to the server. Returns immediately without
             blocking.
         """

+        assert self.cursor is not None

         self.current_query = sql
         self.current_params = args
         self.cursor.execute(sql, args)
 
         self.current_query = sql
         self.current_params = args
         self.cursor.execute(sql, args)
 

-    def fileno(self):
+    def fileno(self) -> int:

         """ File descriptor to wait for. (Makes this class select()able.)
         """
         """ File descriptor to wait for. (Makes this class select()able.)
         """

+        assert self.conn is not None

         return self.conn.fileno()
 
         return self.conn.fileno()
 

-    def is_done(self):
+    def is_done(self) -> bool:

         """ Check if the connection is available for a new query.
 
             Also checks if the previous query has run into a deadlock.
             If so, then the previous query is repeated.
         """
         """ Check if the connection is available for a new query.
 
             Also checks if the previous query has run into a deadlock.
             If so, then the previous query is repeated.
         """

+        assert self.conn is not None
+

         if self.current_query is None:
             return True
 
         if self.current_query is None:
             return True
 

-        with DeadlockHandler(self._deadlock_handler):
+        with DeadlockHandler(self._deadlock_handler, self.ignore_sql_errors):

             if self.conn.poll() == psycopg2.extensions.POLL_OK:
                 self.current_query = None
                 return True
 
         return False
             if self.conn.poll() == psycopg2.extensions.POLL_OK:
                 self.current_query = None
                 return True
 
         return False

+
+
+class WorkerPool:
+    """ A pool of asynchronous database connections.
+
+        The pool may be used as a context manager.
+    """
+    REOPEN_CONNECTIONS_AFTER = 100000
+
+    def __init__(self, dsn: str, pool_size: int, ignore_sql_errors: bool = False) -> None:
+        self.threads = [DBConnection(dsn, ignore_sql_errors=ignore_sql_errors)
+                        for _ in range(pool_size)]
+        self.free_workers = self._yield_free_worker()
+        self.wait_time = 0.0
+
+
+    def finish_all(self) -> None:
+        """ Wait for all connection to finish.
+        """
+        for thread in self.threads:
+            while not thread.is_done():
+                thread.wait()
+
+        self.free_workers = self._yield_free_worker()
+
+    def close(self) -> None:
+        """ Close all connections and clear the pool.
+        """
+        for thread in self.threads:
+            thread.close()
+        self.threads = []
+        self.free_workers = iter([])
+
+
+    def next_free_worker(self) -> DBConnection:
+        """ Get the next free connection.
+        """
+        return next(self.free_workers)
+
+
+    def _yield_free_worker(self) -> Iterator[DBConnection]:
+        ready = self.threads
+        command_stat = 0
+        while True:
+            for thread in ready:
+                if thread.is_done():
+                    command_stat += 1
+                    yield thread
+
+            if command_stat > self.REOPEN_CONNECTIONS_AFTER:
+                self._reconnect_threads()
+                ready = self.threads
+                command_stat = 0
+            else:
+                tstart = time.time()
+                _, ready, _ = select.select([], self.threads, [])
+                self.wait_time += time.time() - tstart
+
+
+    def _reconnect_threads(self) -> None:
+        for thread in self.threads:
+            while not thread.is_done():
+                thread.wait()
+            thread.connect()
+
+
+    def __enter__(self) -> 'WorkerPool':
+        return self
+
+
+    def __exit__(self, exc_type: Any, exc_value: Any, traceback: Any) -> None:
+        self.finish_all()
+        self.close()