nominatim/api/core.py

   1 # SPDX-License-Identifier: GPL-2.0-only
   2 #
   3 # This file is part of Nominatim. (https://nominatim.org)
   4 #
   5 # Copyright (C) 2023 by the Nominatim developer community.
   6 # For a full list of authors see the git log.
   7 """
   8 Implementation of classes for API access via libraries.
   9 """
  10 from typing import Mapping, Optional, Any, AsyncIterator
  11 import asyncio
  12 import contextlib
  13 from pathlib import Path
  14
  15 import sqlalchemy as sa
  16 import sqlalchemy.ext.asyncio as sa_asyncio
  17 import asyncpg
  18
  19 from nominatim.db.sqlalchemy_schema import SearchTables
  20 from nominatim.config import Configuration
  21 from nominatim.api.status import get_status, StatusResult
  22 from nominatim.api.connection import SearchConnection
  23
  24 class NominatimAPIAsync:
  25     """ API loader asynchornous version.
  26     """
  27     def __init__(self, project_dir: Path,
  28                  environ: Optional[Mapping[str, str]] = None) -> None:
  29         self.config = Configuration(project_dir, environ)
  30         self.server_version = 0
  31
  32         self._engine_lock = asyncio.Lock()
  33         self._engine: Optional[sa_asyncio.AsyncEngine] = None
  34         self._tables: Optional[SearchTables] = None
  35
  36
  37     async def setup_database(self) -> None:
  38         """ Set up the engine and connection parameters.
  39
  40             This function will be implicitly called when the database is
  41             accessed for the first time. You may also call it explicitly to
  42             avoid that the first call is delayed by the setup.
  43         """
  44         async with self._engine_lock:
  45             if self._engine:
  46                 return
  47
  48             dsn = self.config.get_database_params()
  49
  50             dburl = sa.engine.URL.create(
  51                        'postgresql+asyncpg',
  52                        database=dsn.get('dbname'),
  53                        username=dsn.get('user'), password=dsn.get('password'),
  54                        host=dsn.get('host'), port=int(dsn['port']) if 'port' in dsn else None,
  55                        query={k: v for k, v in dsn.items()
  56                               if k not in ('user', 'password', 'dbname', 'host', 'port')})
  57             engine = sa_asyncio.create_async_engine(
  58                              dburl, future=True,
  59                              connect_args={'server_settings': {
  60                                 'DateStyle': 'sql,european',
  61                                 'max_parallel_workers_per_gather': '0'
  62                              }})
  63
  64             try:
  65                 async with engine.begin() as conn:
  66                     result = await conn.scalar(sa.text('SHOW server_version_num'))
  67                     self.server_version = int(result)
  68             except asyncpg.PostgresError:
  69                 self.server_version = 0
  70
  71             if self.server_version >= 110000:
  72                 @sa.event.listens_for(engine.sync_engine, "connect")
  73                 def _on_connect(dbapi_con: Any, _: Any) -> None:
  74                     cursor = dbapi_con.cursor()
  75                     cursor.execute("SET jit_above_cost TO '-1'")
  76                 # Make sure that all connections get the new settings
  77                 await self.close()
  78
  79             self._tables = SearchTables(sa.MetaData(), engine.name) # pylint: disable=no-member
  80             self._engine = engine
  81
  82
  83     async def close(self) -> None:
  84         """ Close all active connections to the database. The NominatimAPIAsync
  85             object remains usable after closing. If a new API functions is
  86             called, new connections are created.
  87         """
  88         if self._engine is not None:
  89             await self._engine.dispose()
  90
  91
  92     @contextlib.asynccontextmanager
  93     async def begin(self) -> AsyncIterator[SearchConnection]:
  94         """ Create a new connection with automatic transaction handling.
  95
  96             This function may be used to get low-level access to the database.
  97             Refer to the documentation of SQLAlchemy for details how to use
  98             the connection object.
  99         """
 100         if self._engine is None:
 101             await self.setup_database()
 102
 103         assert self._engine is not None
 104         assert self._tables is not None
 105
 106         async with self._engine.begin() as conn:
 107             yield SearchConnection(conn, self._tables)
 108
 109
 110     async def status(self) -> StatusResult:
 111         """ Return the status of the database.
 112         """
 113         try:
 114             async with self.begin() as conn:
 115                 status = await get_status(conn)
 116         except asyncpg.PostgresError:
 117             return StatusResult(700, 'Database connection failed')
 118
 119         return status
 120
 121
 122 class NominatimAPI:
 123     """ API loader, synchronous version.
 124     """
 125
 126     def __init__(self, project_dir: Path,
 127                  environ: Optional[Mapping[str, str]] = None) -> None:
 128         self._loop = asyncio.new_event_loop()
 129         self._async_api = NominatimAPIAsync(project_dir, environ)
 130
 131
 132     def close(self) -> None:
 133         """ Close all active connections to the database. The NominatimAPIAsync
 134             object remains usable after closing. If a new API functions is
 135             called, new connections are created.
 136         """
 137         self._loop.run_until_complete(self._async_api.close())
 138         self._loop.close()
 139
 140
 141     def status(self) -> StatusResult:
 142         """ Return the status of the database.
 143         """
 144         return self._loop.run_until_complete(self._async_api.status())