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https://github.com/tahoe-lafs/tahoe-lafs.git
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67 lines
2.1 KiB
Python
67 lines
2.1 KiB
Python
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import os, sys
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import sqlite3
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from sqlite3 import IntegrityError
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[IntegrityError]
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class DBError(Exception):
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pass
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def get_db(dbfile, stderr=sys.stderr,
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create_version=(None, None), updaters={}, just_create=False, dbname="db",
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journal_mode=None, synchronous=None):
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"""Open or create the given db file. The parent directory must exist.
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create_version=(SCHEMA, VERNUM), and SCHEMA must have a 'version' table.
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Updaters is a {newver: commands} mapping, where e.g. updaters[2] is used
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to get from ver=1 to ver=2. Returns a (sqlite3,db) tuple, or raises
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DBError.
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"""
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must_create = not os.path.exists(dbfile)
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try:
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db = sqlite3.connect(dbfile)
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except (EnvironmentError, sqlite3.OperationalError), e:
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raise DBError("Unable to create/open %s file %s: %s" % (dbname, dbfile, e))
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schema, target_version = create_version
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c = db.cursor()
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# Enabling foreign keys allows stricter integrity checking.
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# The default is unspecified according to <http://www.sqlite.org/foreignkeys.html#fk_enable>.
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c.execute("PRAGMA foreign_keys = ON;")
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if journal_mode is not None:
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c.execute("PRAGMA journal_mode = %s;" % (journal_mode,))
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if synchronous is not None:
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c.execute("PRAGMA synchronous = %s;" % (synchronous,))
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if must_create:
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c.executescript(schema)
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c.execute("INSERT INTO version (version) VALUES (?)", (target_version,))
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db.commit()
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try:
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c.execute("SELECT version FROM version")
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version = c.fetchone()[0]
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except sqlite3.DatabaseError, e:
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# this indicates that the file is not a compatible database format.
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# Perhaps it was created with an old version, or it might be junk.
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raise DBError("%s file is unusable: %s" % (dbname, e))
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if just_create: # for tests
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return (sqlite3, db)
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while version < target_version and version+1 in updaters:
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c.executescript(updaters[version+1])
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db.commit()
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version = version+1
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if version != target_version:
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raise DBError("Unable to handle %s version %s" % (dbname, version))
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return (sqlite3, db)
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