port replication initialisation to Python

nominatim/db/status.py

@@ -0,0 +1,50 @@
+"""
+Access and helper functions for the status table.
+"""
+import datetime as dt
+import logging
+import re
+
+from ..tools.exec_utils import get_url
+
+LOG = logging.getLogger()
+
+def compute_database_date(conn):
+    """ Determine the date of the database from the newest object in the
+        data base.
+    """
+    # First, find the node with the highest ID in the database
+    with conn.cursor() as cur:
+        osmid = cur.scalar("SELECT max(osm_id) FROM place WHERE osm_type='N'")
+
+        if osmid is None:
+            LOG.fatal("No data found in the database.")
+            raise RuntimeError("No data found in the database.")
+
+    LOG.info("Using node id %d for timestamp lookup", osmid)
+    # Get the node from the API to find the timestamp when it was created.
+    node_url = 'https://www.openstreetmap.org/api/0.6/node/{}/1'.format(osmid)
+    data = get_url(node_url)
+
+    match = re.search(r'timestamp="((\d{4})-(\d{2})-(\d{2})T(\d{2}):(\d{2}):(\d{2}))Z"', data)
+
+    if match is None:
+        LOG.fatal("The node data downloaded from the API does not contain valid data.\n"
+                  "URL used: %s", node_url)
+        raise RuntimeError("Bad API data.")
+
+    LOG.debug("Found timestamp %s", match[1])
+
+    return dt.datetime.fromisoformat(match[1]).replace(tzinfo=dt.timezone.utc)
+
+
+def set_status(conn, date, seq=None, indexed=True):
+    """ Replace the current status with the given status.
+    """
+    assert date.tzinfo == dt.timezone.utc
+    with conn.cursor() as cur:
+        cur.execute("TRUNCATE TABLE import_status")
+        cur.execute("""INSERT INTO import_status (lastimportdate, sequence_id, indexed)
+                       VALUES (%s, %s, %s)""", (date, seq, indexed))
+
+    conn.commit()