DB import: skip invalid SWHIDs during import

This makes DB import much more rosbut, at the price of ~15% performance
impact (which is still very much bearable, in light of recent DB import
improvements).  If needed, this cost can be mitigated in the future by
pipelining SWHID validation with SQLite insertion, using either a thread or
asyncio.

Closes T2813

swh/scanner/db.py

@@ -11,7 +11,9 @@ SWHIDs can be added directly from an input file.
 """
 
 from io import TextIOWrapper
+import logging
 from pathlib import Path
+import re
 import sqlite3
 from typing import Iterable
 
@@ -19,6 +21,10 @@ from swh.core.utils import grouper
 
 from .exceptions import DBError
 
+# XXX copied and simplified from swh.model.identifiers (WIP), replace this in favor of
+# swh.model.identifiers.SWHID_RE when it is landed there
+SWHID_RE = re.compile("^swh:1:(ori|snp|rel|rev|dir|cnt):[0-9a-f]{40}$")
+
 
 class Db:
     """Local database interface"""
@@ -45,6 +51,17 @@ class Db:
                 [(swhid_chunk,) for swhid_chunk in swhids_chunk],
             )
 
+    @staticmethod
+    def iter_swhids(lines: Iterable[str]) -> Iterable[str]:
+        lineno = 0
+        for line in lines:
+            lineno += 1
+            swhid = line.rstrip()
+            if SWHID_RE.match(swhid):
+                yield swhid
+            else:
+                logging.error("ignoring invalid SWHID on line %d: %s", lineno, swhid)
+
     def create_from(
         self, input_file: TextIOWrapper, chunk_size: int, cur: sqlite3.Cursor
     ):
@@ -53,7 +70,7 @@ class Db:
             self.create_table(cur)
             cur.execute("PRAGMA synchronous = OFF")
             cur.execute("PRAGMA journal_mode = OFF")
-            self.add((line.rstrip() for line in input_file), chunk_size, cur)
+            self.add(self.iter_swhids(input_file), chunk_size, cur)
             cur.close()
             self.conn.commit()
         except sqlite3.Error as e: