Rewrite durable task lifecycle, gallery indexing and subscription publication

scripts/migrate_task_operations.py

@@ -0,0 +1,44 @@
+#!/usr/bin/env python3
+"""Explicit task-v2 schema migration. Default is read-only; --apply backs up first."""
+import argparse
+import datetime
+import json
+from pathlib import Path
+import sqlite3
+
+
+def migrate(database: Path, apply: bool = False) -> dict:
+    if not database.is_file():
+        raise ValueError("database must already exist")
+    with sqlite3.connect(database.resolve().as_uri() + ("?mode=rw" if apply else "?mode=ro"), uri=True) as db:
+        if not db.execute("pragma table_info(gallery)").fetchall():
+            raise ValueError("required table missing: gallery")
+        duplicates = db.execute("select count(*) from (select gid from gallery group by gid having count(*)>1)").fetchone()[0]
+        if duplicates:
+            raise ValueError("duplicate gallery gid; reconcile before migration")
+        present = bool(db.execute("pragma table_info(task_operation)").fetchall())
+        result = {"apply": apply, "create_operation_table": not present}
+        if not apply:
+            return result
+        stamp = datetime.datetime.now(datetime.timezone.utc).strftime("%Y%m%dT%H%M%S%fZ")
+        backup = database.with_name(database.name + ".before-task-v2." + stamp)
+        with sqlite3.connect(backup) as copy:
+            db.backup(copy)
+        backup.chmod(0o600)
+        sql = Path(__file__).with_name("migrate_task_operation_v2.sql").read_text()
+        try:
+            db.executescript("BEGIN IMMEDIATE;\n" + sql + "\nCOMMIT;")
+        except BaseException:
+            db.rollback()
+            raise
+        result["backup"] = str(backup)
+        result["operation_rows"] = db.execute("select count(*) from task_operation").fetchone()[0]
+        return result
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument("database", type=Path)
+    parser.add_argument("--apply", action="store_true")
+    arguments = parser.parse_args()
+    print(json.dumps(migrate(arguments.database, arguments.apply), ensure_ascii=False))