Account DB and Container DB

DB

Database code for Swift

swift.common.db.BROKER_TIMEOUT = 25

Timeout for trying to connect to a DB

swift.common.db.DB_PREALLOCATION = False

Whether calls will be made to preallocate disk space for database files.

exception swift.common.db.DatabaseAlreadyExists(path)

Bases: sqlite3.DatabaseError

More friendly error messages for DB Errors.

class swift.common.db.DatabaseBroker(db_file, timeout=25, logger=None, account=None, container=None, pending_timeout=None, stale_reads_ok=False, skip_commits=False)

Bases: object

Encapsulates working with a database.

property db_file
delete_db(timestamp)

Mark the DB as deleted

Parameters

timestamp – internalized delete timestamp

empty()

Check if the broker abstraction contains any undeleted records.

get()

Use with the “with” statement; returns a database connection.

get_device_path()
get_info()
get_items_since(start, count)

Get a list of objects in the database between start and end.

Parameters
  • start – start ROWID

  • count – number to get

Returns

list of objects between start and end

get_max_row(table=None)
get_raw_metadata()
get_replication_info()

Get information about the DB required for replication.

Returns

dict containing keys from get_info plus max_row and metadata

Note:: get_info’s <db_contains_type>_count is translated to just

“count” and metadata is the raw string.

get_sync(id, incoming=True)

Gets the most recent sync point for a server from the sync table.

Parameters
  • id – remote ID to get the sync_point for

  • incoming – if True, get the last incoming sync, otherwise get the last outgoing sync

Returns

the sync point, or -1 if the id doesn’t exist.

get_syncs(incoming=True)

Get a serialized copy of the sync table.

Parameters

incoming – if True, get the last incoming sync, otherwise get the last outgoing sync

Returns

list of {‘remote_id’, ‘sync_point’}

initialize(put_timestamp=None, storage_policy_index=None)

Create the DB

The storage_policy_index is passed through to the subclass’s _initialize method. It is ignored by AccountBroker.

Parameters
  • put_timestamp – internalized timestamp of initial PUT request

  • storage_policy_index – only required for containers

is_deleted()

Check if the DB is considered to be deleted.

Returns

True if the DB is considered to be deleted, False otherwise

is_reclaimable(now, reclaim_age)

Check if the broker abstraction is empty, and has been marked deleted for at least a reclaim age.

lock()

Use with the “with” statement; locks a database.

make_tuple_for_pickle(record)

Turn this db record dict into the format this service uses for pending pickles.

maybe_get(conn)
merge_items(item_list, source=None)

Save :param:item_list to the database.

merge_syncs(sync_points, incoming=True)

Merge a list of sync points with the incoming sync table.

Parameters
  • sync_points – list of sync points where a sync point is a dict of {‘sync_point’, ‘remote_id’}

  • incoming – if True, get the last incoming sync, otherwise get the last outgoing sync

merge_timestamps(created_at, put_timestamp, delete_timestamp)

Used in replication to handle updating timestamps.

Parameters
  • created_at – create timestamp

  • put_timestamp – put timestamp

  • delete_timestamp – delete timestamp

property metadata

Returns the metadata dict for the database. The metadata dict values are tuples of (value, timestamp) where the timestamp indicates when that key was set to that value.

newid(remote_id)

Re-id the database. This should be called after an rsync.

Parameters

remote_id – the ID of the remote database being rsynced in

possibly_quarantine(exc_type, exc_value, exc_traceback)

Checks the exception info to see if it indicates a quarantine situation (malformed or corrupted database). If not, the original exception will be reraised. If so, the database will be quarantined and a new sqlite3.DatabaseError will be raised indicating the action taken.

put_record(record)

Put a record into the DB. If the DB has an associated pending file with space then the record is appended to that file and a commit to the DB is deferred. If the DB is in-memory or its pending file is full then the record will be committed immediately.

Parameters

record – a record to be added to the DB.

Raises
  • DatabaseConnectionError – if the DB file does not exist or if skip_commits is True.

  • LockTimeout – if a timeout occurs while waiting to take a lock to write to the pending file.

quarantine(reason)

The database will be quarantined and a sqlite3.DatabaseError will be raised indicating the action taken.

reclaim(age_timestamp, sync_timestamp)

Delete reclaimable rows and metadata from the db.

By default this method will delete rows from the db_contains_type table that are marked deleted and whose created_at timestamp is < age_timestamp, and deletes rows from incoming_sync and outgoing_sync where the updated_at timestamp is < sync_timestamp. In addition, this calls the _reclaim_metadata() method.

Subclasses may reclaim other items by overriding _reclaim().

Parameters
  • age_timestamp – max created_at timestamp of object rows to delete

  • sync_timestamp – max update_at timestamp of sync rows to delete

update_metadata(metadata_updates, validate_metadata=False)

Updates the metadata dict for the database. The metadata dict values are tuples of (value, timestamp) where the timestamp indicates when that key was set to that value. Key/values will only be overwritten if the timestamp is newer. To delete a key, set its value to (‘’, timestamp). These empty keys will eventually be removed by reclaim()

update_put_timestamp(timestamp)

Update the put_timestamp. Only modifies it if it is greater than the current timestamp.

Parameters

timestamp – internalized put timestamp

update_status_changed_at(timestamp)

Update the status_changed_at field in the stat table. Only modifies status_changed_at if the timestamp is greater than the current status_changed_at timestamp.

Parameters

timestamp – internalized timestamp

updated_timeout(new_timeout)

Use with “with” statement; updates timeout within the block.

static validate_metadata(metadata)

Validates that metadata falls within acceptable limits.

Parameters

metadata – to be validated

Raises

HTTPBadRequest – if MAX_META_COUNT or MAX_META_OVERALL_SIZE is exceeded, or if metadata contains non-UTF-8 data

exception swift.common.db.DatabaseConnectionError(path, msg, timeout=0)

Bases: sqlite3.DatabaseError

More friendly error messages for DB Errors.

class swift.common.db.GreenDBConnection(database, timeout=None, *args, **kwargs)

Bases: sqlite3.Connection

SQLite DB Connection handler that plays well with eventlet.

commit()

Commit the current transaction.

cursor(cls=None)

Return a cursor for the connection.

class swift.common.db.GreenDBCursor(*args, **kwargs)

Bases: sqlite3.Cursor

SQLite Cursor handler that plays well with eventlet.

execute(*args, **kwargs)

Executes a SQL statement.

swift.common.db.PICKLE_PROTOCOL = 2

Pickle protocol to use

swift.common.db.chexor(old, name, timestamp)

Each entry in the account and container databases is XORed by the 128-bit hash on insert or delete. This serves as a rolling, order-independent hash of the contents. (check + XOR)

Parameters
  • old – hex representation of the current DB hash

  • name – name of the object or container being inserted

  • timestamp – internalized timestamp of the new record

Returns

a hex representation of the new hash value

swift.common.db.dict_factory(crs, row)

This should only be used when you need a real dict, i.e. when you’re going to serialize the results.

swift.common.db.get_db_connection(path, timeout=30, okay_to_create=False)

Returns a properly configured SQLite database connection.

Parameters
  • path – path to DB

  • timeout – timeout for connection

  • okay_to_create – if True, create the DB if it doesn’t exist

Returns

DB connection object

swift.common.db.native_str_keys(metadata)
swift.common.db.utf8encode(*args)
swift.common.db.zero_like(count)

We’ve cargo culted our consumers to be tolerant of various expressions of zero in our databases for backwards compatibility with less disciplined producers.

DB replicator

class swift.common.db_replicator.ReplConnection(node, partition, hash_, logger)

Bases: swift.common.bufferedhttp.BufferedHTTPConnection

Helper to simplify REPLICATEing to a remote server.

replicate(*args)

Make an HTTP REPLICATE request

Parameters

args – list of json-encodable objects

Returns

bufferedhttp response object

class swift.common.db_replicator.Replicator(conf, logger=None)

Bases: swift.common.daemon.Daemon

Implements the logic for directing db replication.

cleanup_post_replicate(broker, orig_info, responses)

Cleanup non primary database from disk if needed.

Parameters
  • broker – the broker for the database we’re replicating

  • orig_info – snapshot of the broker replication info dict taken before replication

  • responses – a list of boolean success values for each replication request to other nodes

Return success

returns False if deletion of the database was attempted but unsuccessful, otherwise returns True.

delete_db(broker)
extract_device(object_file)

Extract the device name from an object path. Returns “UNKNOWN” if the path could not be extracted successfully for some reason.

Parameters

object_file – the path to a database file.

report_up_to_date(full_info)
roundrobin_datadirs(dirs)
run_forever(*args, **kwargs)

Replicate dbs under the given root in an infinite loop.

run_once(*args, **kwargs)

Run a replication pass once.

class swift.common.db_replicator.ReplicatorRpc(root, datadir, broker_class, mount_check=True, logger=None)

Bases: object

Handle Replication RPC calls. TODO(redbo): document please :)

complete_rsync(drive, db_file, args)
debug_timing(name)
dispatch(replicate_args, args)
merge_items(broker, args)
merge_syncs(broker, args)
rsync_then_merge(drive, db_file, args)
sync(broker, args)
swift.common.db_replicator.looks_like_partition(dir_name)

True if the directory name is a valid partition number, False otherwise.

swift.common.db_replicator.quarantine_db(object_file, server_type)

In the case that a corrupt file is found, move it to a quarantined area to allow replication to fix it.

Parameters
  • object_file – path to corrupt file

  • server_type – type of file that is corrupt (‘container’ or ‘account’)

swift.common.db_replicator.roundrobin_datadirs(datadirs)

Generator to walk the data dirs in a round robin manner, evenly hitting each device on the system, and yielding any .db files found (in their proper places). The partitions within each data dir are walked randomly, however.

Parameters

datadirs – a list of tuples of (path, context, partition_filter) to walk. The context may be any object; the context is not used by this function but is included with each yielded tuple.

Returns

A generator of (partition, path_to_db_file, context)