desc
stringlengths
3
26.7k
decl
stringlengths
11
7.89k
bodies
stringlengths
8
553k
'Use Cassandra\'s native batch statement to apply mutations atomically. Args: mutations: A list of dictionaries representing mutations. txid: An integer specifying a transaction ID.'
def _normal_batch(self, mutations, txid):
self.logger.debug('Normal batch: {} mutations'.format(len(mutations))) batch = BatchStatement(consistency_level=ConsistencyLevel.QUORUM, retry_policy=BASIC_RETRIES) prepared_statements = {'insert': {}, 'delete': {}} for mutation in mutations: table = mutation['table'] if (table ...
'Apply mutations across tables. Args: mutations: A list of dictionaries representing mutations. txid: An integer specifying a transaction ID.'
def apply_mutations(self, mutations, txid):
prepared_statements = {'insert': {}, 'delete': {}} statements_and_params = [] for mutation in mutations: table = mutation['table'] if (table == 'group_updates'): key = mutation['key'] insert = '\n INSERT INTO group_updates ...
'Insert or delete multiple rows across tables in an atomic statement. Args: app: A string containing the application ID. mutations: A list of dictionaries representing mutations. entity_changes: A list of changes at the entity level. txn: A transaction ID handler. Raises: FailedBatch if a concurrent process modifies th...
def _large_batch(self, app, mutations, entity_changes, txn):
self.logger.debug('Large batch: transaction {}, {} mutations'.format(txn, len(mutations))) large_batch = LargeBatch(self.session, app, txn) try: large_batch.start() except FailedBatch as batch_error: raise AppScaleDBConnectionError(str(batch_error)) insert_item = '\n ...
'Insert or delete multiple rows across tables in an atomic statement. Args: app: A string containing the application ID. mutations: A list of dictionaries representing mutations. entity_changes: A list of changes at the entity level. txn: A transaction ID handler.'
def batch_mutate(self, app, mutations, entity_changes, txn):
size = batch_size(mutations) if (size > LARGE_BATCH_THRESHOLD): self._large_batch(app, mutations, entity_changes, txn) else: self._normal_batch(mutations, txn)
'Remove a set of rows corresponding to a set of keys. Args: table_name: Table to delete rows from row_keys: A list of keys to remove column_names: Not used Raises: TypeError: If an argument passed in was not of the expected type. AppScaleDBConnectionError: If the batch_delete could not be performed due to an error with...
def batch_delete(self, table_name, row_keys, column_names=()):
if (not isinstance(table_name, str)): raise TypeError('Expected a str') if (not isinstance(row_keys, list)): raise TypeError('Expected a list') row_keys_bytes = [bytearray(row_key) for row_key in row_keys] statement = 'DELETE FROM "{table}" WHERE {key} IN %s...
'Drops a given table (aka column family in Cassandra) Args: table_name: A string name of the table to drop Raises: TypeError: If an argument passed in was not of the expected type. AppScaleDBConnectionError: If the delete_table could not be performed due to an error with Cassandra.'
def delete_table(self, table_name):
if (not isinstance(table_name, str)): raise TypeError('Expected a str') statement = 'DROP TABLE IF EXISTS "{table}"'.format(table=table_name) query = SimpleStatement(statement, retry_policy=BASIC_RETRIES) try: self.session.execute(query) except dbconstants.TRANSIENT...
'Creates a table if it doesn\'t already exist. Args: table_name: The column family name column_names: Not used but here to match the interface Raises: TypeError: If an argument passed in was not of the expected type. AppScaleDBConnectionError: If the create_table could not be performed due to an error with Cassandra.'
def create_table(self, table_name, column_names):
if (not isinstance(table_name, str)): raise TypeError('Expected a str') if (not isinstance(column_names, list)): raise TypeError('Expected a list') statement = 'CREATE TABLE IF NOT EXISTS "{table}" ({key} blob,{column} text,{value} blob,PRIMARY KEY ...
'Gets a dense range ordered by keys. Returns an ordered list of a dictionary of [key:{column1:value1, column2:value2},...] or a list of keys if keys only. Args: table_name: Name of table to access column_names: Columns which get returned within the key range start_key: String for which the query starts at end_key: Stri...
def range_query(self, table_name, column_names, start_key, end_key, limit, offset=0, start_inclusive=True, end_inclusive=True, keys_only=False):
if (not isinstance(table_name, str)): raise TypeError('table_name must be a string') if (not isinstance(column_names, list)): raise TypeError('column_names must be a list') if (not isinstance(start_key, str)): raise TypeError('start_key must be a s...
'Retrieve a value from the datastore metadata table. Args: key: A string containing the key to fetch. Returns: A string containing the value or None if the key is not present.'
def get_metadata(self, key):
statement = '\n SELECT {value} FROM "{table}"\n WHERE {key} = %s\n AND {column} = %s\n '.format(value=ThriftColumn.VALUE, table=dbconstants.DATASTORE_METADATA_TABLE, key=ThriftColumn.KEY, column=ThriftColu...
'Set a datastore metadata value. Args: key: A string containing the key to set. value: A string containing the value to set.'
def set_metadata(self, key, value):
if (not isinstance(key, str)): raise TypeError('key should be a string') if (not isinstance(value, str)): raise TypeError('value should be a string') statement = '\n INSERT INTO "{table}" ({key}, {column}, {value})\n ...
'Gets the indices of the given application. Args: app_id: Name of the application. Returns: Returns a list of encoded entity_pb.CompositeIndex objects.'
def get_indices(self, app_id):
start_key = dbconstants.KEY_DELIMITER.join([app_id, 'index', '']) end_key = dbconstants.KEY_DELIMITER.join([app_id, 'index', dbconstants.TERMINATING_STRING]) result = self.range_query(dbconstants.METADATA_TABLE, dbconstants.METADATA_SCHEMA, start_key, end_key, dbconstants.MAX_NUMBER_OF_COMPOSITE_INDEXES, of...
'Checks whether or not the data layout can be used. Returns: A boolean.'
def valid_data_version(self):
try: version = self.get_metadata(VERSION_INFO_KEY) except cassandra.InvalidRequest: return False return ((version is not None) and (float(version) == EXPECTED_DATA_VERSION))
'Fetch the latest transaction IDs for each group. Args: groups: An interable containing encoded Reference objects. Returns: A set of integers specifying transaction IDs.'
def group_updates(self, groups):
futures = [] for group in groups: query = 'SELECT * FROM group_updates WHERE group=%s' futures.append(self.session.execute_async(query, [bytearray(group)])) updates = set() for future in futures: rows = future.result() try: result = rows[0] ...
'Persist transaction metadata. Args: app: A string containing an application ID. txid: An integer specifying the transaction ID. is_xg: A boolean specifying that the transaction is cross-group. in_progress: An iterable containing transaction IDs.'
def start_transaction(self, app, txid, is_xg, in_progress):
if in_progress: in_progress_bin = bytearray(struct.pack(('q' * len(in_progress)), *in_progress)) else: in_progress_bin = None insert = '\n INSERT INTO transactions (txid_hash, operation, namespace, path,\n ...
'Update transaction metadata with new put operations. Args: app: A string containing an application ID. txid: An integer specifying the transaction ID. entities: A list of entities that will be put upon commit.'
def put_entities_tx(self, app, txid, entities):
batch = BatchStatement(consistency_level=ConsistencyLevel.QUORUM, retry_policy=BASIC_RETRIES) insert = self.session.prepare('\n INSERT INTO transactions (txid_hash, operation, namespace, path, entity)\n VALUES (?, ?, ?, ?, ?)\n ...
'Update transaction metadata with new delete operations. Args: app: A string containing an application ID. txid: An integer specifying the transaction ID. entity_keys: A list of entity keys that will be deleted upon commit.'
def delete_entities_tx(self, app, txid, entity_keys):
batch = BatchStatement(consistency_level=ConsistencyLevel.QUORUM, retry_policy=BASIC_RETRIES) insert = self.session.prepare('\n INSERT INTO transactions (txid_hash, operation, namespace, path, entity)\n VALUES (?, ?, ?, ?, ?)\n ...
'Count the number of existing tasks associated with the transaction. Args: app: A string specifying an application ID. txid: An integer specifying a transaction ID. Returns: An integer specifying the number of existing tasks.'
def transactional_tasks_count(self, app, txid):
select = '\n SELECT count(*) FROM transactions\n WHERE txid_hash = %(txid_hash)s\n AND operation = %(operation)s\n ' parameters = {'txid_hash': tx_partition(app, txid), 'operation': TxnActions.ENQUEUE_...
'Add tasks to be enqueued upon the completion of a transaction. Args: app: A string specifying an application ID. txid: An integer specifying a transaction ID. tasks: A list of TaskQueueAddRequest objects.'
def add_transactional_tasks(self, app, txid, tasks):
batch = BatchStatement(consistency_level=ConsistencyLevel.QUORUM, retry_policy=BASIC_RETRIES) insert = self.session.prepare('\n INSERT INTO transactions (txid_hash, operation, namespace, path, task)\n VALUES (?, ?, ?, ?, ?)\n ...
'Keep track of which entity groups were read in a transaction. Args: app: A string specifying an application ID. txid: An integer specifying a transaction ID. group_keys: An iterable containing Reference objects.'
def record_reads(self, app, txid, group_keys):
batch = BatchStatement(consistency_level=ConsistencyLevel.QUORUM, retry_policy=BASIC_RETRIES) insert = self.session.prepare('\n INSERT INTO transactions (txid_hash, operation, namespace, path)\n VALUES (?, ?, ?, ?)\n ...
'Fetch transaction state. Args: app: A string specifying an application ID. txid: An integer specifying a transaction ID. Returns: A dictionary containing transaction state.'
def get_transaction_metadata(self, app, txid):
select = '\n SELECT namespace, operation, path, start_time, is_xg, in_progress,\n entity, task\n FROM transactions\n WHERE txid_hash = %(txid_hash)s\n ...
'Creates a new EntityIDAllocator object. Args: session: A cassandra-drivers session object. project: A string specifying a project ID.'
def __init__(self, session, project, scattered=False):
self.project = project self.session = session self.scattered = scattered if scattered: self.max_allowed = _MAX_SCATTERED_COUNTER else: self.max_allowed = _MAX_SEQUENTIAL_COUNTER
'Ensures an entry exists for a reservation. Args: retries: The number of times to retry the insert. Raises: AllocationFailed if the insert is tried too many times.'
def _ensure_entry(self, retries=5):
if (retries < 0): raise AppScaleDBConnectionError('Unable to create reserved_ids entry') logger.debug('Creating reserved_ids entry for {}'.format(self.project)) insert = SimpleStatement('\n INSERT INTO reserved_ids (project, scattered, la...
'Retrieves the last entity ID that was reserved. Returns: An integer specifying an entity ID.'
def _get_last_reserved(self):
get_reserved = SimpleStatement('\n SELECT last_reserved\n FROM reserved_ids\n WHERE project = %(project)s\n AND scattered = %(scattered)s\n ', consistency_level=ConsistencyLevel.SERIAL)...
'Retrieve the op_id that was last written during a reservation. Returns: A UUID4 containing the latest op_id.'
def _get_last_op_id(self):
get_op_id = SimpleStatement('\n SELECT op_id\n FROM reserved_ids\n WHERE project = %(project)s\n AND scattered = %(scattered)s\n ', consistency_level=ConsistencyLevel.SERIAL) parame...
'Update the last reserved value to allocate that block. Args: last_reserved: An integer specifying the last reserved value. new_reserved: An integer specifying the new reserved value. Raises: ReservationFailed if the update statement fails.'
def _set_reserved(self, last_reserved, new_reserved):
op_id = uuid.uuid4() set_reserved = SimpleStatement('\n UPDATE reserved_ids\n SET last_reserved = %(new_reserved)s,\n op_id = %(op_id)s\n WHERE project = %(project)s\n ...
'Reserve a block of IDs for this project. Args: size: The number of IDs to reserve. retries: The number of times to retry the reservation. Returns: A tuple of integers specifying the start and end ID. Raises: AppScaleDBConnectionError if the reservation is tried too many times. AppScaleBadArg if the ID space has been e...
def allocate_size(self, size, retries=5):
if (retries < 0): raise AppScaleDBConnectionError('Unable to reserve new block') try: last_reserved = self._get_last_reserved() except TRANSIENT_CASSANDRA_ERRORS: raise AppScaleDBConnectionError('Unable to get last reserved ID') new_reserved = (last_res...
'Reserves all IDs up to the one given. Args: max_id: An integer specifying the maximum ID to allocated. retries: The number of times to retry the reservation. Returns: A tuple of integers specifying the start and end ID. Raises: AppScaleDBConnectionError if the reservation is tried too many times. AppScaleBadArg if the...
def allocate_max(self, max_id, retries=5):
if (retries < 0): raise AppScaleDBConnectionError('Unable to reserve new block') if (max_id > self.max_allowed): raise AppScaleBadArg('Exceeded maximum allocated IDs') try: last_reserved = self._get_last_reserved() except TRANSIENT_CASSANDRA_ERRORS: r...
'Creates a new ScatteredAllocator instance. Each project should just have one instance since it reserves a large block of IDs at a time. Args: session: A cassandra-driver session. project: A string specifying a project ID.'
def __init__(self, session, project):
super(ScatteredAllocator, self).__init__(session, project, scattered=True) self.start_id = None self.end_id = None
'Returns a new iterator object.'
def __iter__(self):
return self
'Generates a new entity ID. Returns: An integer specifying an entity ID.'
def next(self):
if ((self.start_id is None) or (self.start_id > self.end_id)): (self.start_id, self.end_id) = self.allocate_size(DEFAULT_RESERVATION_SIZE) next_id = ToScatteredId(self.start_id) self.start_id += 1 return next_id
'Create an entity lock. Args: client: A kazoo client. keys: A list of entity Reference objects. txid: An integer specifying the transaction ID.'
def __init__(self, client, keys, txid=None):
self.client = client self.paths = [zk_group_path(key) for key in keys] self.data = str((txid or '')) self.wake_event = client.handler.event_object() self.prefix = (uuid.uuid4().hex + self._NODE_NAME) self.create_paths = [((path + '/') + self.prefix) for path in self.paths] self.create_tried ...
'Make sure the ZooKeeper lock paths have been created.'
def _ensure_path(self):
for path in self.paths: self.client.ensure_path(path)
'Cancel a pending lock acquire.'
def cancel(self):
self.cancelled = True self.wake_event.set()
'Acquire the lock. By default blocks and waits forever. Returns: A boolean indicating whether or not the lock was acquired.'
def acquire(self):
def _acquire_lock(): ' Acquire a kazoo thread lock. ' got_it = self._lock.acquire(False) if (not got_it): raise ForceRetryError() return True retry = self._retry.copy() retry.deadline = LOCK_TIMEOUT locked = self._lock.acquire(False) if (...
'A callback function for handling connection state changes. Args: state: The new connection state.'
def _watch_session(self, state):
self.wake_event.set() return True
'Check if there are any concurrent cross-group locks. Args: children_list: A list of current transactions for each group.'
def _resolve_deadlocks(self, children_list):
current_txid = int(self.data) for (index, children) in enumerate(children_list): our_index = children.index(self.nodes[index]) if (our_index == 0): continue for child in children[:(our_index - 1)]: try: (data, _) = self.client.get(((self.paths[inde...
'Create contender node(s) and wait until the lock is acquired.'
def _inner_acquire(self):
self._ensure_path() nodes = [None for _ in self.paths] if self.create_tried: nodes = self._find_nodes() else: self.create_tried = True for (index, node) in enumerate(nodes): if (node is not None): continue try_num = 0 while True: try: ...
'A callback function for handling contender deletions. Args: event: A ZooKeeper event.'
def _watch_predecessor(self, event):
self.wake_event.set()
'Retrieve a list of sorted contenders for each group. Returns: A list of contenders for each group.'
def _get_sorted_children(self):
children = [] for path in self.paths: try: children.append(self.client.get_children(path)) except NoNodeError: children.append([]) lockname = self._NODE_NAME for child_list in children: child_list.sort(key=(lambda c: c[(c.find(lockname) + len(lockname)):])...
'Retrieve a list of paths this lock has created. Returns: A list of ZooKeeper paths.'
def _find_nodes(self):
nodes = [] for path in self.paths: try: children = self.client.get_children(path) except NoNodeError: children = [] node = None for child in children: if child.startswith(self.prefix): node = child nodes.append(node) ...
'Remove ZooKeeper nodes. Args: nodes: A list of nodes to delete.'
def _delete_nodes(self, nodes):
for (index, node) in enumerate(nodes): if (node is None): continue self.client.delete(((self.paths[index] + '/') + node))
'Attempt to delete nodes that this lock has created.'
def _best_effort_cleanup(self):
try: nodes = self._find_nodes() self._delete_nodes(nodes) except KazooException: pass
'Release the lock immediately.'
def release(self):
self.client.retry(self._inner_release) for path in self.paths: try: self.client.delete(path) except (NotEmptyError, NoNodeError): pass return
'Release the lock by removing created nodes.'
def _inner_release(self):
if (not self.is_acquired): return False try: self._delete_nodes(self.nodes) except NoNodeError: pass self.is_acquired = False self.nodes = [None for _ in self.paths] return True
'Creates a new ZKTransaction, which will communicate with Zookeeper on the given host. Args: host: A str that indicates which machine runs the Zookeeper service. start_gc: A bool that indicates if we should start the garbage collector for timed out transactions. db_access: A DatastoreProxy instance. log_level: A loggin...
def __init__(self, host=DEFAULT_HOST, start_gc=False, db_access=None, log_level=logging.INFO):
retry_policy = KazooRetry(max_tries=5) class_name = self.__class__.__name__ self.logger = logging.getLogger(class_name) self.logger.setLevel(log_level) self.logger.info('Starting {}'.format(class_name)) self.host = host self.handle = kazoo.client.KazooClient(hosts=host, connection_retry=Z...
'Starts a new thread that cleans up failed transactions. If called when the GC thread is already started, this causes the GC thread to reload its GC settings.'
def start_gc(self):
self.logger.info('Starting GC thread') with self.gc_cv: if self.gc_running: self.gc_cv.notifyAll() else: self.gc_running = True self.gcthread = threading.Thread(target=self.gc_runner) self.gcthread.daemon = True self.gcthread.star...
'Stops the thread that cleans up failed transactions.'
def stop_gc(self):
self.logger.info('Stopping GC thread') if self.gc_running: with self.gc_cv: self.gc_running = False self.gc_cv.notifyAll() self.gcthread.join() self.logger.info('GC is done')
'Stops the thread that cleans up failed transactions and closes its connection to Zookeeper.'
def close(self):
self.logger.info('Closing ZK connection') self.stop_gc() self.handle.stop() self.handle.close()
'Increment a counter atomically. Args: path: A str of unique path to the counter. value: An int of how much to increment the counter by. Returns: A tuple (int, int) of the previous value and the new value. Raises: ZKTransactionException: If it could not increment the counter.'
def increment_and_get_counter(self, path, value):
if (path not in self.__counter_cache): self.__counter_cache[path] = InspectableCounter(self.handle, path) counter = self.__counter_cache[path] try: new_value = (counter + value) return ((new_value - value), new_value) except kazoo.exceptions.ZookeeperError as zoo_exception: ...
'Fetch the ZooKeeper node at the given path. Args: path: A PATH_SEPARATOR-separated str that represents the node whose value should be updated. retries: The number of times to retry fetching the node. Returns: The value of the node. Raises: ZKInternalException: If there was an error trying to fetch the node.'
def get_node(self, path, retries=5):
try: return self.run_with_retry(self.handle.get, path) except kazoo.exceptions.NoNodeError: return False except kazoo.exceptions.ZookeeperError as zoo_exception: self.logger.exception(zoo_exception) if (retries > 0): self.logger.info('Trying again to fetc...
'Sets the ZooKeeper node at path to value, creating the node if it doesn\'t exist. Args: path: A PATH_SEPARATOR-separated str that represents the node whose value should be updated. value: A str representing the value that should be associated with the updated node.'
def update_node(self, path, value):
self.logger.debug('Updating node at {}, with new value {}'.format(path, value)) try: self.run_with_retry(self.handle.set, path, str(value)) except kazoo.exceptions.NoNodeError: self.run_with_retry(self.handle.create, path, str(value), ZOO_ACL_OPEN, makepath=True)
'Deletes the ZooKeeper node at path, and any child nodes it may have. Args: path: A PATH_SEPARATOR-separated str that represents the node to delete.'
def delete_recursive(self, path):
try: children = self.run_with_retry(self.handle.get_children, path) for child in children: self.delete_recursive(PATH_SEPARATOR.join([path, child])) self.run_with_retry(self.handle.delete, path) except kazoo.exceptions.NoNodeError: pass
'Prints information about the given ZooKeeper node and its children. Args: path: A PATH_SEPARATOR-separated str that represents the node to print info about.'
def dump_tree(self, path):
try: value = self.run_with_retry(self.handle.get, path)[0] self.logger.info('{0} = "{1}"'.format(path, value)) children = self.run_with_retry(self.handle.get_children, path) for child in children: self.dump_tree(PATH_SEPARATOR.join([path, child])) except kazoo.e...
'Returns the ZooKeeper path that holds all information for the given application. Args: app_id: A str that represents the application we wish to get the root path for. Returns: A str that represents a ZooKeeper node, whose immediate children are the transaction prefix path and the locks prefix path.'
def get_app_root_path(self, app_id):
return PATH_SEPARATOR.join([APPS_PATH, urllib.quote_plus(app_id)])
'Returns the location of the ZooKeeper node who contains all transactions in progress for the given application. Args: app_id: A str that represents the application we wish to get all transaction information for. Returns: A str that represents a ZooKeeper node, whose immediate children are all of the transactions curre...
def get_transaction_prefix_path(self, app_id):
return PATH_SEPARATOR.join([self.get_app_root_path(app_id), APP_TX_PATH])
'Returns a path that callers can use to get new transaction IDs from ZooKeeper, which are given as sequence nodes. Args: app_id: A str that represents the application we wish to build a new transaction path for. Returns: A str that can be used to create new transactions.'
def get_txn_path_before_getting_id(self, app_id):
return PATH_SEPARATOR.join([self.get_transaction_prefix_path(app_id), APP_TX_PREFIX])
'Returns the location of the ZooKeeper node who contains all information for a transaction, and is the parent of the transaction lock list and registered keys for the transaction. Args: app_id: A str that represents the application we wish to get the prefix path for. txid: An int that represents the transaction ID whos...
def get_transaction_path(self, app_id, txid):
txstr = (APP_TX_PREFIX + ('%010d' % txid)) return PATH_SEPARATOR.join([self.get_app_root_path(app_id), APP_TX_PATH, txstr])
'Returns the location of the ZooKeeper node whose value is a XG_LIST-separated str, representing all of the locks that have been acquired for the given transaction ID. Args: app_id: A str that represents the application we wish to get the transaction information about. txid: A str that represents the transaction ID we ...
def get_transaction_lock_list_path(self, app_id, txid):
return PATH_SEPARATOR.join([self.get_transaction_path(app_id, txid), TX_LOCK_PATH])
'Returns the location of the ZooKeeper node whose children are all of the blacklisted transaction IDs for the given application ID. Args: app_id: A str corresponding to the application who we want to get blacklisted transaction IDs for. Returns: A str corresponding to the ZooKeeper node whose children are blacklisted t...
def get_blacklist_root_path(self, app_id):
return PATH_SEPARATOR.join([self.get_transaction_prefix_path(app_id), TX_BLACKLIST_PATH])
'Returns the location of the ZooKeeper node whose children are all of the valid transaction IDs for the given application ID. Args: app_id: A str corresponding to the application who we want to get valid transaction IDs for. Returns: A str corresponding to the ZooKeeper node whose children are valid transaction IDs.'
def get_valid_transaction_root_path(self, app_id):
return PATH_SEPARATOR.join([self.get_transaction_prefix_path(app_id), TX_VALIDLIST_PATH])
'Gets the valid transaction path with the entity key. Args: app_id: The application ID. entity_key: The entity within the path. Returns: A str representing the transaction path.'
def get_valid_transaction_path(self, app_id, entity_key):
return PATH_SEPARATOR.join([self.get_valid_transaction_root_path(app_id), urllib.quote_plus(entity_key)])
'Gets the root path of the lock for a particular app. Args: app_id: The application ID. key: The key for which we\'re getting the root path lock. Returns: A str of the root lock path.'
def get_lock_root_path(self, app_id, key):
return PATH_SEPARATOR.join([self.get_app_root_path(app_id), APP_LOCK_PATH, urllib.quote_plus(key)])
'Gets the XG path for a transaction. Args: app_id: The application ID whose XG path we want. tx_id: The transaction ID whose XG path we want. Returns: A str representing the XG path for the given transaction.'
def get_xg_path(self, app_id, tx_id):
txstr = (APP_TX_PREFIX + ('%010d' % tx_id)) return PATH_SEPARATOR.join([self.get_app_root_path(app_id), APP_TX_PATH, txstr, XG_PREFIX])
'Creates a new node in ZooKeeper, with the given value. Args: path: The path to create the node at. value: The value that we should store in the node. Raises: ZKTransactionException: If the sequence node couldn\'t be created.'
def create_node(self, path, value):
try: self.run_with_retry(self.handle.create, path, value=str(value), acl=ZOO_ACL_OPEN, ephemeral=False, sequence=False, makepath=True) except kazoo.exceptions.KazooException as kazoo_exception: self.logger.exception(kazoo_exception) raise ZKTransactionException("Couldn't create pat...
'Creates a new sequence node in ZooKeeper, with a non-zero initial ID. We avoid using zero as the initial ID because Google App Engine apps can use a zero ID as a sentinel value, to indicate that an ID should be allocated for them. Args: path: The prefix to create the sequence node at. For example, a prefix of \'/abc\'...
def create_sequence_node(self, path, value):
try: txn_id_path = self.run_with_retry(self.handle.create, path, value=str(value), acl=ZOO_ACL_OPEN, ephemeral=False, sequence=True, makepath=True) if txn_id_path: txn_id = long(txn_id_path.split(PATH_SEPARATOR)[(-1)].lstrip(APP_TX_PREFIX)) if (txn_id == 0): s...
'Acquires a new id for an upcoming transaction. Note that the caller must lock particular root entities using acquire_lock, and that the transaction ID expires after a constant amount of time. Args: app_id: A str representing the application we want to perform a transaction on. is_xg: A bool that indicates if this tran...
def get_transaction_id(self, app_id, is_xg=False):
timestamp = str(time.time()) app_path = self.get_txn_path_before_getting_id(app_id) txn_id = self.create_sequence_node(app_path, timestamp) if is_xg: xg_path = self.get_xg_path(app_id, txn_id) self.create_node(xg_path, timestamp) return txn_id
'Gets the status of the given transaction. Args: app_id: A str representing the application whose transaction we wish to query. txid: An int that indicates the transaction ID we should query. Returns: True if the transaction is in progress. Raises: ZKTransactionException: If the transaction is not in progress, or it ha...
def check_transaction(self, app_id, txid):
txpath = self.get_transaction_path(app_id, txid) try: if self.is_blacklisted(app_id, txid): raise ZKTransactionException('Transaction {0} timed out.'.format(txid)) except ZKInternalException as zk_exception: self.logger.exception(zk_exception) raise ZKTransaction...
'Checks to see if the named transaction is currently running. Args: app_id: A str representing the application whose transaction we wish to query. txid: An int that indicates the transaction ID we should query. Returns: True if the transaction is in progress, and False otherwise. Raises: ZKTransactionException: If the ...
def is_in_transaction(self, app_id, txid, retries=5):
tx_lock_path = self.get_transaction_lock_list_path(app_id, txid) if self.is_blacklisted(app_id, txid): raise ZKTransactionException('Transaction {} is blacklisted'.format(txid)) try: if (not self.run_with_retry(self.handle.exists, tx_lock_path)): return False ret...
'Checks to see if a lock does not have a transaction linked. If the groomer misses to unlock a lock for whatever reason, we need to make sure the lock is eventually released. Args: tx_lockpath: A str, the path to the transaction using the lock. Returns: True if the lock is an orphan, and False otherwise.'
def is_orphan_lock(self, tx_lockpath):
try: self.handle.get(tx_lockpath) return False except kazoo.exceptions.NoNodeError: return True
'Acquire an additional lock for a cross group transaction. Args: app_id: A str representing the application ID. txid: The transaction ID you are acquiring a lock for. Built into the path. entity_key: Used to get the root path. create: A bool that indicates if we should create a new Zookeeper node to store the lock info...
def acquire_additional_lock(self, app_id, txid, entity_key, create):
txpath = self.get_transaction_path(app_id, txid) lockrootpath = self.get_lock_root_path(app_id, entity_key) lockpath = None try: lockpath = self.run_with_retry(self.handle.create, lockrootpath, value=str(txpath), acl=ZOO_ACL_OPEN, ephemeral=False, sequence=False, makepath=True) except kazoo....
'Checks to see if the transaction can operate over multiple entity groups. Args: app_id: The application ID that the transaction operates over. tx_id: The transaction ID that may or may not be XG. Returns: True if the transaction is XG, False otherwise. Raises: ZKTransactionException: on ZooKeeper exceptions. ZKInterna...
def is_xg(self, app_id, tx_id):
try: return self.run_with_retry(self.handle.exists, self.get_xg_path(app_id, tx_id)) except kazoo.exceptions.ZookeeperError as zk_exception: raise ZKTransactionException('ZooKeeper exception:{0}'.format(zk_exception)) except kazoo.exceptions.KazooException as kazoo_exception: self...
'Acquire lock for transaction. It will acquire additional locks if the transactions is XG. You must call get_transaction_id() first to obtain transaction ID. You could call this method anytime if the root entity key is same, or different in the case of it being XG. Args: app_id: The application ID to acquire a lock for...
def acquire_lock(self, app_id, txid, entity_key):
lockrootpath = self.get_lock_root_path(app_id, entity_key) try: if self.is_in_transaction(app_id, txid): transaction_lock_path = self.get_transaction_lock_list_path(app_id, txid) prelockpath = self.run_with_retry(self.handle.get, transaction_lock_path)[0] lock_list = ...
'Gets a list of keys updated in this transaction. Args: app_id: A str corresponding to the application ID whose transaction we wish to query. txid: The transaction ID that we want to get a list of updated keys for. Returns: A list of (keys, txn_id) that have been updated in this transaction. Raises: ZKTransactionExcept...
def get_updated_key_list(self, app_id, txid):
txpath = self.get_transaction_path(app_id, txid) try: child_list = self.run_with_retry(self.handle.get_children, txpath) keylist = [] for item in child_list: if re.match(('^' + TX_UPDATEDKEY_PREFIX), item): keyandtx = self.run_with_retry(self.handle.get, PATH_...
'Remove a transaction\'s sequence node. Args: app_id: A string specifying an application ID. txid: An integer specifying a transaction ID.'
def remove_tx_node(self, app_id, txid):
txpath = self.get_transaction_path(app_id, txid) try: self.run_with_retry(self.handle.delete, txpath, (-1), True) except NoNodeError: return except RetryFailedError: raise ZKInternalException('Unable to remove transaction for {}'.format(txid))
'Releases all locks acquired during this transaction. Callers must call acquire_lock before calling release_lock. Upon calling release_lock, the given transaction ID is no longer valid. Args: app_id: The application ID we are releasing a lock for. txid: The transaction ID we are releasing a lock for. Returns: True if t...
def release_lock(self, app_id, txid):
self.check_transaction(app_id, txid) txpath = self.get_transaction_path(app_id, txid) transaction_lock_path = self.get_transaction_lock_list_path(app_id, txid) try: lock_list_str = self.run_with_retry(self.handle.get, transaction_lock_path)[0] lock_list = lock_list_str.split(LOCK_LIST_SE...
'Checks to see if the given transaction ID has been blacklisted (that is, if it is no longer considered to be a valid transaction). Args: app_id: The application ID whose transaction ID we want to validate. txid: The transaction ID that we want to validate. Returns: True if the transaction is blacklisted, False otherwi...
def is_blacklisted(self, app_id, txid, retries=5):
try: blacklist_root = self.get_blacklist_root_path(app_id) blacklist_txn = PATH_SEPARATOR.join([blacklist_root, str(txid)]) return self.run_with_retry(self.handle.exists, blacklist_txn) except kazoo.exceptions.KazooException as kazoo_exception: self.logger.exception(kazoo_excepti...
'This returns valid transaction id for the entity key. Args: app_id: A str representing the application ID. target_txid: The transaction id that we want to check for validness. entity_key: The entity that the transaction operates over. Returns: A long containing the latest valid transaction id, or zero if there is none...
def get_valid_transaction_id(self, app_id, target_txid, entity_key):
try: if self.is_in_transaction(app_id, target_txid): key_list = self.get_updated_key_list(app_id, target_txid) for (key, txn_id) in key_list: if (entity_key == key): return long(txn_id) except ZKTransactionException as zk_exception: vtx...
'Registers a key which is a part of a transaction. This is to know what journal version we must rollback to upon failure. Args: app_id: A str representing the application ID. current_txid: The current transaction ID for which we\'ll rollback to upon failure. target_txid: A long transaction ID we are rolling forward to....
def register_updated_key(self, app_id, current_txid, target_txid, entity_key):
vtxpath = self.get_valid_transaction_path(app_id, entity_key) try: if self.run_with_retry(self.handle.exists, vtxpath): self.run_with_retry(self.handle.set_async, vtxpath, str(target_txid)) else: value = PATH_SEPARATOR.join([urllib.quote_plus(entity_key), str(target_txid)...
'Marks the given transaction as failed, invalidating its use by future callers. This function also cleans up successful transactions that have expired. Args: app_id: The application ID whose transaction we wish to invalidate. txid: An int representing the transaction ID we wish to invalidate. Returns: True if the trans...
def notify_failed_transaction(self, app_id, txid):
self.logger.debug('notify_failed_trasnsaction: app={}, txid={}'.format(app_id, txid)) lockpath = None lock_list = [] txpath = self.get_transaction_path(app_id, txid) try: lockpath = self.run_with_retry(self.handle.get, PATH_SEPARATOR.join([txpath, TX_LOCK_PATH]))[0] lock_list =...
'Transaction ID garbage collection (GC) runner. Note: This must be running as separate thread.'
def gc_runner(self):
self.logger.debug('Starting GC thread.') while self.gc_running: try: app_list = self.run_with_retry(self.handle.get_children, APPS_PATH) for app in app_list: app_id = urllib.unquote_plus(app) app_path = PATH_SEPARATOR.join([APPS_PATH, app]) ...
'Try to garbage collect timed out transactions. Args: app_id: The application ID. app_path: The application path for which we\'re garbage collecting. Returns: True if the garbage collector ran, False otherwise.'
def try_garbage_collection(self, app_id, app_path):
last_time = 0 gc_time_path = PATH_SEPARATOR.join([app_path, GC_TIME_PATH]) try: val = self.run_with_retry(self.handle.get, gc_time_path)[0] last_time = float(val) except kazoo.exceptions.NoNodeError: last_time = 0 except (ZookeeperError, KazooException): self.logger.e...
'Tries to get the lock based on path. Args: path: A str, the lock path. Returns: True if the lock was obtained, False otherwise.'
def get_lock_with_path(self, path):
try: now = str(time.time()) self.run_with_retry(self.handle.create, path, value=now, acl=ZOO_ACL_OPEN, ephemeral=True) except kazoo.exceptions.NoNodeError: self.logger.error('Unable to create {}'.format(path)) return False except kazoo.exceptions.NodeExistsError: ...
'Releases lock based on path. Args: path: A str, the lock path. Returns: True on success, False on system failures. Raises: ZKTransactionException: If the lock could not be released.'
def release_lock_with_path(self, path):
try: self.run_with_retry(self.handle.delete, path) except kazoo.exceptions.NoNodeError: raise ZKTransactionException('Unable to delete lock: {0}'.format(path)) except (kazoo.exceptions.SystemZookeeperError, KazooException, SystemError): self.logger.exception('Unable to...
'Clean up temporary batch data. Args: app: A string containing the application ID. transaction: An integer containing the transaction ID.'
def clean_up_batch(self, app, transaction):
self.logger.debug('Cleaning up batch: app={}, transaction={}'.format(app, transaction)) clear_batch = '\n DELETE FROM batches\n WHERE app = %(app)s AND transaction = %(transaction)s\n ' parameters = {'app': a...
'Write the batch to the entities table. Args: app: a string specifying the application ID. txid: An integer specifying the transaction ID.'
def _write_batch(self, app, txid):
composite_indices = [entity_pb.CompositeIndex(index) for index in self.db_access.get_indices(str(app))] self.logger.debug('Applying batch: app={}, transaction={}'.format(app, txid)) select_mutations = '\n SELECT old_value, new_value FROM batches\n ...
'Check if batch completed and apply mutations if necessary. Args: app: A string containing the application ID. transaction: An integer containing the transaction ID.'
def resolve_batch(self, app, transaction):
session = self.db_access.session large_batch = LargeBatch(session, app, transaction) large_batch.claim() if large_batch.applied: self._write_batch(app, transaction) self.clean_up_batch(app, transaction) large_batch.cleanup()
'Execute garbage collection for an application. Args: app_id: The application ID. app_path: The application path.'
def execute_garbage_collection(self, app_id, app_path):
start = time.time() txrootpath = PATH_SEPARATOR.join([app_path, APP_TX_PATH]) try: txlist = self.run_with_retry(self.handle.get_children, txrootpath) except kazoo.exceptions.NoNodeError: return except (ZookeeperError, KazooException): self.logger.exception('Unable to ge...
'Fetch a list of open transactions for a given project. Args: project: A string containing a project ID. Returns: A list of integers specifying transaction IDs.'
def get_current_transactions(self, project):
project_path = PATH_SEPARATOR.join([APPS_PATH, project]) txrootpath = PATH_SEPARATOR.join([project_path, APP_TX_PATH]) try: txlist = self.run_with_retry(self.handle.get_children, txrootpath) except kazoo.exceptions.NoNodeError: return [] return [int(txid.lstrip(APP_TX_PREFIX)) for tx...
'Create an InspectableCounter. Args: client: A KazooClient object. path: A string containing the ZooKeeper path to use for the counter. default: An integer containing the default counter value.'
def __init__(self, client, path, default=0):
self.client = client self.path = path self.default = default self.default_type = type(default) self._ensured_path = False
'Make sure the ZooKeeper path that stores the counter value exists.'
def _ensure_node(self):
if (not self._ensured_path): self.client.ensure_path(self.path) self._ensured_path = True
'Retrieve the current value and node version from ZooKeeper. Returns: A tuple consisting of the current count and node version.'
def _value(self):
self._ensure_node() (old, stat) = self.client.get(self.path) old = (old.decode('ascii') if (old != '') else self.default) version = stat.version data = self.default_type(old) return (data, version)
'Retrieve the current value from ZooKeeper. Returns: An integer containing the current count.'
@property def value(self):
return self._value()[0]
'Add a value to the counter. Args: value: An integer specifying how much to add. Returns: An integer indicating the new count after the change.'
def _change(self, value):
if (not isinstance(value, self.default_type)): raise TypeError('Invalid type for value change') return self.client.retry(self._inner_change, value)
'Add a value to the counter. Args: value: An integer specifying how much to add. Returns: An integer indicating the new count after the change.'
def _inner_change(self, value):
(data, version) = self._value() new_value = (data + value) new_data = repr(new_value).encode('ascii') try: self.client.set(self.path, new_data, version=version) return new_value except BadVersionError: raise ForceRetryError()
'Add value to counter. Returns: An integer indicating the new count after the change.'
def __add__(self, value):
return self._change(value)
'Subtract value from counter. Returns: An integer indicating the new count after the change.'
def __sub__(self, value):
return self._change((- value))
'Create a Queue object. Args: queue_info: A dictionary containing queue info. app: A string containing the application ID.'
def __init__(self, queue_info, app):
self.app = app if ('name' not in queue_info): raise InvalidQueueConfiguration('Queue requires a name: {}'.format(queue_info)) self.name = queue_info['name'] self.task_retry_limit = self.DEFAULT_RETRY_LIMIT if ('retry_parameters' in queue_info): retry_params = queue_info['...
'Ensures all of the Queue\'s attributes are valid. Raises: InvalidQueueConfiguration if there is an invalid attribute.'
def validate_config(self):
for (attribute, rule) in QUEUE_ATTRIBUTE_RULES.iteritems(): try: value = getattr(self, attribute) except AttributeError: continue if (not rule(value)): message = 'Invalid queue configuration for {queue}.{param}: {value}'.format(queue=self.na...
'Checks if this Queue is equivalent to another. Returns: A boolean indicating whether or not the two Queues are equal.'
def __eq__(self, other):
if (not isinstance(other, self.__class__)): return False if ((self.app != other.app) or (self.name != other.name)): return False for attribute in self.OPTIONAL_ATTRS: if hasattr(self, attribute): if (not hasattr(other, attribute)): return False ...
'Checks if this Queue is different than another. Returns: A boolean indicating whether or not the two Queues are different.'
def __ne__(self, other):
return (not self.__eq__(other))