add migration tool, needs more testing

misc/migrate_usage_db.py

@@ -0,0 +1,47 @@
+"""Migrate the usage data from the old bundled Transit Relay database.
+
+The magic-wormhole package used to include both servers (Rendezvous and
+Transit). "wormhole server" started both of these, and used the
+"relay.sqlite" database to store both immediate server state and long-term
+usage data.
+
+These were split out to their own packages: version 0.11 omitted the Transit
+Relay in favor of the new "magic-wormhole-transit-relay" distribution.
+
+This script reads the long-term Transit usage data from the pre-0.11
+wormhole-server relay.sqlite, and copies it into a new "usage.sqlite"
+database in the current directory.
+
+It will refuse to touch an existing "usage.sqlite" file.
+
+The resuting "usage.sqlite" should be passed into --usage-db=, e.g. "twist
+transitrelay --usage=.../PATH/TO/usage.sqlite".
+"""
+
+from __future__ import unicode_literals, print_function
+import sys
+from wormhole_transit_relay.database import open_existing_db, create_db
+
+source_fn = sys.argv[1]
+source_db = open_existing_db(source_fn)
+target_db = create_db("usage.sqlite")
+
+num_rows = 0
+for row in source_db.execute("SELECT * FROM `transit_usage`"
+                             " ORDER BY `started`").fetchall():
+    target_db.execute("INSERT INTO `usage`"
+                      " (`started`, `total_time`, `waiting_time`,"
+                      "  `total_bytes`, `result`)"
+                      " VALUES(?,?,?,?,?)",
+                      (row["started"], row["total_time"], row["waiting_time"],
+                       row["total_bytes"], row["result"]))
+    num_rows += 1
+target_db.execute("INSERT INTO `current`"
+                  " (`rebooted`, `updated`, `connected`, `waiting`,"
+                  "  `incomplete_bytes`)"
+                  " VALUES(?,?,?,?,?)",
+                  (0, 0, 0, 0, 0))
+target_db.commit()
+
+print("usage database migrated (%d rows) into 'usage.sqlite'" % num_rows)
+sys.exit(0)