Nominatim/nominatim/tools/replication.py
2022-04-07 17:58:04 +02:00

149 lines
4.6 KiB
Python

# SPDX-License-Identifier: GPL-2.0-only
#
# 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.
"""
Functions for updating a database from a replication source.
"""
from contextlib import contextmanager
import datetime as dt
from enum import Enum
import logging
import time
from nominatim.db import status
from nominatim.tools.exec_utils import run_osm2pgsql
from nominatim.errors import UsageError
try:
from osmium.replication.server import ReplicationServer
from osmium import WriteHandler
except ImportError as exc:
logging.getLogger().fatal("pyosmium not installed. Replication functions not available.\n"
"To install pyosmium via pip: pip3 install osmium")
raise UsageError("replication tools not available") from exc
LOG = logging.getLogger()
def init_replication(conn, base_url):
""" Set up replication for the server at the given base URL.
"""
LOG.info("Using replication source: %s", base_url)
date = status.compute_database_date(conn)
# margin of error to make sure we get all data
date -= dt.timedelta(hours=3)
repl = ReplicationServer(base_url)
seq = repl.timestamp_to_sequence(date)
if seq is None:
LOG.fatal("Cannot reach the configured replication service '%s'.\n"
"Does the URL point to a directory containing OSM update data?",
base_url)
raise UsageError("Failed to reach replication service")
status.set_status(conn, date=date, seq=seq)
LOG.warning("Updates initialised at sequence %s (%s)", seq, date)
def check_for_updates(conn, base_url):
""" Check if new data is available from the replication service at the
given base URL.
"""
_, seq, _ = status.get_status(conn)
if seq is None:
LOG.error("Replication not set up. "
"Please run 'nominatim replication --init' first.")
return 254
state = ReplicationServer(base_url).get_state_info()
if state is None:
LOG.error("Cannot get state for URL %s.", base_url)
return 253
if state.sequence <= seq:
LOG.warning("Database is up to date.")
return 2
LOG.warning("New data available (%i => %i).", seq, state.sequence)
return 0
class UpdateState(Enum):
""" Possible states after an update has run.
"""
UP_TO_DATE = 0
MORE_PENDING = 2
NO_CHANGES = 3
def update(conn, options):
""" Update database from the next batch of data. Returns the state of
updates according to `UpdateState`.
"""
startdate, startseq, indexed = status.get_status(conn)
if startseq is None:
LOG.error("Replication not set up. "
"Please run 'nominatim replication --init' first.")
raise UsageError("Replication not set up.")
if not indexed and options['indexed_only']:
LOG.info("Skipping update. There is data that needs indexing.")
return UpdateState.MORE_PENDING
last_since_update = dt.datetime.now(dt.timezone.utc) - startdate
update_interval = dt.timedelta(seconds=options['update_interval'])
if last_since_update < update_interval:
duration = (update_interval - last_since_update).seconds
LOG.warning("Sleeping for %s sec before next update.", duration)
time.sleep(duration)
if options['import_file'].exists():
options['import_file'].unlink()
# Read updates into file.
with _make_replication_server(options['base_url']) as repl:
outhandler = WriteHandler(str(options['import_file']))
endseq = repl.apply_diffs(outhandler, startseq + 1,
max_size=options['max_diff_size'] * 1024)
outhandler.close()
if endseq is None:
return UpdateState.NO_CHANGES
# Consume updates with osm2pgsql.
options['append'] = True
options['disable_jit'] = conn.server_version_tuple() >= (11, 0)
run_osm2pgsql(options)
# Write the current status to the file
endstate = repl.get_state_info(endseq)
status.set_status(conn, endstate.timestamp if endstate else None,
seq=endseq, indexed=False)
return UpdateState.UP_TO_DATE
def _make_replication_server(url):
""" Returns a ReplicationServer in form of a context manager.
Creates a light wrapper around older versions of pyosmium that did
not support the context manager interface.
"""
if hasattr(ReplicationServer, '__enter__'):
return ReplicationServer(url)
@contextmanager
def get_cm():
yield ReplicationServer(url)
return get_cm()