def test_pool_management(self):
# Ensure that in_flight and request_ids quiesce after cluster operations
cluster = Cluster(
protocol_version=PROTOCOL_VERSION, idle_heartbeat_interval=0
) # no idle heartbeat here, pool management is tested in test_idle_heartbeat
session = cluster.connect()
session2 = cluster.connect()
# prepare
p = session.prepare("SELECT * FROM system.local WHERE key=?")
self.assertTrue(session.execute(p, ('local', )))
# simple
self.assertTrue(
session.execute("SELECT * FROM system.local WHERE key='local'"))
# set keyspace
session.set_keyspace('system')
session.set_keyspace('system_traces')
# use keyspace
session.execute('USE system')
session.execute('USE system_traces')
# refresh schema
cluster.refresh_schema_metadata()
cluster.refresh_schema_metadata(max_schema_agreement_wait=0)
assert_quiescent_pool_state(self, cluster)
cluster.shutdown()
def test_pool_management(self):
# Ensure that in_flight and request_ids quiesce after cluster operations
cluster = Cluster(protocol_version=PROTOCOL_VERSION, idle_heartbeat_interval=0) # no idle heartbeat here, pool management is tested in test_idle_heartbeat
session = cluster.connect()
session2 = cluster.connect()
# prepare
p = session.prepare("SELECT * FROM system.local WHERE key=?")
self.assertTrue(session.execute(p, ('local',)))
# simple
self.assertTrue(session.execute("SELECT * FROM system.local WHERE key='local'"))
# set keyspace
session.set_keyspace('system')
session.set_keyspace('system_traces')
# use keyspace
session.execute('USE system')
session.execute('USE system_traces')
# refresh schema
cluster.refresh_schema_metadata()
cluster.refresh_schema_metadata(max_schema_agreement_wait=0)
# submit schema refresh
future = cluster.submit_schema_refresh()
future.result()
assert_quiescent_pool_state(self, cluster)
cluster.shutdown()
def test_refresh_schema(self):
cluster = Cluster(protocol_version=PROTOCOL_VERSION)
session = cluster.connect()
original_meta = cluster.metadata.keyspaces
# full schema refresh, with wait
cluster.refresh_schema_metadata()
self.assertIsNot(original_meta, cluster.metadata.keyspaces)
self.assertEqual(original_meta, cluster.metadata.keyspaces)
cluster.shutdown()
def test_refresh_schema(self):
cluster = Cluster(protocol_version=PROTOCOL_VERSION)
session = cluster.connect()
original_meta = cluster.metadata.keyspaces
# full schema refresh, with wait
cluster.refresh_schema_metadata()
self.assertIsNot(original_meta, cluster.metadata.keyspaces)
self.assertEqual(original_meta, cluster.metadata.keyspaces)
cluster.shutdown()
class Migrator(object):
"""Execute migration operations in a C* database based on configuration.
`opts` must contain at least the following attributes:
- config_file: path to a YAML file containing the configuration
- profiles: map of profile names to keyspace settings
- user, password: authentication options. May be None to not use it.
- hosts: comma-separated list of contact points
- port: connection port
"""
logger = logging.getLogger("Migrator")
def __init__(self,
config,
profile='dev',
hosts=['127.0.0.1'],
port=9042,
user=None,
password=None,
host_cert_path=None,
client_key_path=None,
client_cert_path=None):
self.config = config
try:
self.current_profile = self.config.profiles[profile]
except KeyError:
raise ValueError("Invalid profile name '{}'".format(profile))
if user:
auth_provider = PlainTextAuthProvider(user, password)
else:
auth_provider = None
if host_cert_path:
ssl_options = self._build_ssl_options(host_cert_path,
client_key_path,
client_cert_path)
else:
ssl_options = None
self.cluster = Cluster(contact_points=hosts,
port=port,
auth_provider=auth_provider,
max_schema_agreement_wait=300,
control_connection_timeout=10,
connect_timeout=30,
ssl_options=ssl_options)
self._session = None
def __enter__(self):
return self
def __exit__(self, exc_type, exc_val, exc_tb):
if self._session is not None:
self._session.shutdown()
self._session = None
if self.cluster is not None:
self.cluster.shutdown()
self.cluster = None
def _build_ssl_options(self, host_cert_path, client_key_path,
client_cert_path):
return {
'ca_certs': host_cert_path,
'certfile': client_cert_path,
'keyfile': client_key_path
}
def _check_cluster(self):
"""Check if the cluster is still alive, raise otherwise"""
if not self.cluster:
raise RuntimeError("Cluster has shut down")
def _init_session(self):
if not self._session:
s = self._session = self.cluster.connect()
s.default_consistency_level = ConsistencyLevel.ALL
s.default_serial_consistency_level = ConsistencyLevel.SERIAL
s.default_timeout = 120
@property
def session(self):
"""Initialize and configure a C* driver session if needed"""
self._check_cluster()
self._init_session()
return self._session
def _get_target_version(self, v):
"""
Parses a version specifier to an actual numeric migration version
`v` might be:
- None: the latest version is chosen
- an int, or a numeric string: that exact version is chosen
- a string: the version with that name is chosen if it exists
If an invalid version is found, `ValueError` is raised.
"""
if v is None:
return len(self.config.migrations)
if isinstance(v, int):
num = v
elif v.isdigit():
num = int(v)
else:
try:
num = self.config.migrations.index(v)
except IndexError:
num = -1
if num <= 0:
raise ValueError('Invalid database version, must be a number > 0 '
'or the name of an existing migration')
return num
def _q(self, query, **kwargs):
"""
Format a query with the configured keyspace and migration table
`keyspace` and `table` are interpolated as named arguments
"""
return query.format(keyspace=self.config.keyspace,
table=self.config.migrations_table,
**kwargs)
def _execute(self, query, *args, **kwargs):
"""Execute a query with the current session"""
self.logger.debug('Executing query: {}'.format(query))
return self.session.execute(query, *args, **kwargs)
def _keyspace_exists(self):
self._init_session()
return self.config.keyspace in self.cluster.metadata.keyspaces
def _ensure_keyspace(self):
"""Create the keyspace if it does not exist"""
if self._keyspace_exists():
return
self.logger.info("Creating keyspace '{}'".format(self.config.keyspace))
profile = self.current_profile
self._execute(
self._q(CREATE_KEYSPACE,
replication=cassandra_ddl_repr(profile['replication']),
durable_writes=cassandra_ddl_repr(
profile['durable_writes'])))
self.cluster.refresh_keyspace_metadata(self.config.keyspace)
def _table_exists(self):
self._init_session()
ks_metadata = self.cluster.metadata.keyspaces.get(
self.config.keyspace, None)
# Fail if the keyspace is missing. If it should be created
# automatically _ensure_keyspace() must be called first.
if not ks_metadata:
raise ValueError("Keyspace '{}' does not exist, "
"stopping".format(self.config.keyspace))
return self.config.migrations_table in ks_metadata.tables
def _ensure_table(self):
"""Create the migration table if it does not exist"""
if self._table_exists():
return
self.logger.info(
"Creating table '{table}' in keyspace '{keyspace}'".format(
keyspace=self.config.keyspace,
table=self.config.migrations_table))
self._execute(self._q(CREATE_MIGRATIONS_TABLE))
self.cluster.refresh_table_metadata(self.config.keyspace,
self.config.migrations_table)
def _verify_migrations(self,
migrations,
ignore_failed=False,
ignore_concurrent=False):
"""Verify if the version history persisted in C* matches the migrations
Migrations with corresponding DB versions must have the same content
and name.
Every DB version must have a corresponding migration.
Migrations without corresponding DB versions are considered pending,
and returned as a result.
Returns a list of tuples of (version, migration), with version starting
from 1 and incrementing linearly.
"""
# Load all the currently existing versions and sort them by version
# number, as Cassandra can only sort it for us by partition.
cur_versions = self._execute(
self._q('SELECT * FROM "{keyspace}"."{table}"'))
cur_versions = sorted(cur_versions, key=lambda v: v.version)
last_version = None
version_pairs = zip_longest(cur_versions, migrations)
# Work through ordered pairs of (existing version, migration), so that
# stored versions and expected migrations can be compared for any
# differences.
for i, (version, migration) in enumerate(version_pairs, 1):
# If version is empty, the migration has not yet been applied.
# Keep track of the first such version, and append it to the
# pending migrations list.
if not version:
break
# If migration is empty, we have a version in the database with
# no corresponding file. That might mean we're running the wrong
# migration or have an out-of-date state, so we must fail.
if not migration:
raise UnknownMigration(version.version, version.name)
# A migration was previously run and failed.
if version.state == Migration.State.FAILED:
if ignore_failed:
break
raise FailedMigration(version.version, version.name)
last_version = version.version
# A stored version's migrations differs from the one in the FS.
if version.content != migration.content or \
version.name != migration.name or \
bytearray(version.checksum) != bytearray(migration.checksum):
raise InconsistentState(migration, version)
if not last_version:
pending_migrations = list(migrations)
else:
pending_migrations = list(migrations)[last_version:]
if not pending_migrations:
self.logger.info('Database is already up-to-date')
else:
self.logger.info('Pending migrations found. Current version: {}, '
'Latest version: {}'.format(
last_version, len(migrations)))
pending_migrations = enumerate(pending_migrations,
(last_version or 0) + 1)
return last_version, cur_versions, list(pending_migrations)
def _create_version(self, version, migration):
"""
Write an in-progress version entry to C*
The migration is inserted with the given `version` number if and only
if it does not exist already (using a CompareAndSet operation).
If the insert suceeds (with the migration marked as in-progress), we
can continue and actually execute it. Otherwise, there was a concurrent
write and we must fail to allow the other write to continue.
"""
self.logger.info('Writing in-progress migration version {}: {}'.format(
version, migration))
version_id = uuid.uuid4()
result = self._execute(
self._q(CREATE_DB_VERSION),
(version_id, version, migration.name, migration.content,
bytearray(migration.checksum), Migration.State.IN_PROGRESS))
return version_id
def _apply_cql_migration(self, version, migration):
"""
Persist and apply a cql migration
First create an in-progress version entry, apply the script, then
finalize the entry as succeeded, failed or skipped.
"""
self.logger.info('Applying cql migration')
statements = CqlSplitter.split(migration.content)
try:
if statements:
self.logger.info('Executing migration with '
'{} CQL statements'.format(len(statements)))
for statement in statements:
self.session.execute(statement)
except Exception:
raise FailedMigration(version, migration.name)
def _apply_python_migration(self, version, migration):
"""
Persist and apply a python migration
First create an in-progress version entry, apply the script, then
finalize the entry as succeeded, failed or skipped.
"""
self.logger.info('Applying python script')
try:
mod, _ = os.path.splitext(os.path.basename(migration.path))
migration_script = importlib.import_module(mod)
migration_script.execute(self._session)
except Exception:
self.logger.exception('Failed to execute script')
raise FailedMigration(version, migration.name)
def _apply_migration(self, version, migration, skip=False):
"""
Persist and apply a migration
When `skip` is True, do everything but actually run the script, for
example, when baselining instead of migrating.
"""
self.logger.info('Advancing to version {}'.format(version))
version_uuid = self._create_version(version, migration)
new_state = Migration.State.FAILED
sys.path.append(self.config.migrations_path)
result = None
try:
if skip:
self.logger.info('Migration is marked for skipping, '
'not actually running script')
else:
if migration.is_python:
self._apply_python_migration(version, migration)
else:
self._apply_cql_migration(version, migration)
except Exception:
self.logger.exception('Failed to execute migration')
raise FailedMigration(version, migration.name)
else:
new_state = (Migration.State.SUCCEEDED
if not skip else Migration.State.SKIPPED)
finally:
self.logger.info('Finalizing migration version with '
'state {}'.format(new_state))
result = self._execute(self._q(FINALIZE_DB_VERSION),
(new_state, version_uuid))
def _cleanup_previous_versions(self, cur_versions):
if not cur_versions:
return
last_version = cur_versions[-1]
if last_version.state != Migration.State.FAILED:
return
self.logger.warn('Cleaning up previous failed migration '
'(version {}): {}'.format(last_version.version,
last_version.name))
result = self._execute(self._q(DELETE_DB_VERSION),
(last_version.id, Migration.State.FAILED))
def _advance(self,
migrations,
target,
cur_versions,
skip=False,
force=False):
"""Apply all necessary migrations to reach a target version"""
if force:
self._cleanup_previous_versions(cur_versions)
target_version = self._get_target_version(target)
if migrations:
# Set default keyspace so migrations don't need to refer to it
# manually
# Fixes https://github.com/Cobliteam/cassandra-migrate/issues/5
self.session.execute('USE {};'.format(self.config.keyspace))
for version, migration in migrations:
if version > target_version:
break
self._apply_migration(version, migration, skip=skip)
self.cluster.refresh_schema_metadata()
def baseline(self, opts):
"""Baseline a database, by advancing migration state without changes"""
self._check_cluster()
self._ensure_table()
last_version, cur_versions, pending_migrations = \
self._verify_migrations(self.config.migrations,
ignore_failed=False)
self._advance(pending_migrations,
opts.db_version,
cur_versions,
skip=True)
@confirmation_required
def migrate(self, opts):
"""
Migrate a database to a given version, applying any needed migrations
"""
self._check_cluster()
self._ensure_keyspace()
self._ensure_table()
last_version, cur_versions, pending_migrations = \
self._verify_migrations(self.config.migrations,
ignore_failed=opts.force)
self._advance(pending_migrations,
opts.db_version,
cur_versions,
force=opts.force)
@confirmation_required
def reset(self, opts):
"""Reset a database, by dropping the keyspace then migrating"""
self._check_cluster()
self.logger.info("Dropping existing keyspace '{}'".format(
self.config.keyspace))
self._execute(self._q(DROP_KEYSPACE))
self.cluster.refresh_schema_metadata()
opts.force = False
self.migrate(opts)
@staticmethod
def _bytes_to_hex(bs):
return codecs.getencoder('hex')(bs)[0]
def status(self, opts):
self._check_cluster()
if not self._keyspace_exists():
print("Keyspace '{}' does not exist".format(self.config.keyspace))
return
if not self._table_exists():
print("Migration table '{table}' does not exist in "
"keyspace '{keyspace}'".format(
keyspace=self.config.keyspace,
table=self.config.migrations_table))
return
last_version, cur_versions, pending_migrations = \
self._verify_migrations(self.config.migrations,
ignore_failed=True,
ignore_concurrent=True)
latest_version = len(self.config.migrations)
print(
tabulate((('Keyspace:', self.config.keyspace),
('Migrations table:', self.config.migrations_table),
('Current DB version:', last_version),
('Latest DB version:', latest_version)),
tablefmt='plain'))
if cur_versions:
print('\n## Applied migrations\n')
data = []
for version in cur_versions:
checksum = self._bytes_to_hex(version.checksum)
date = arrow.get(version.applied_at).format()
data.append((str(version.version), version.name, version.state,
date, checksum))
print(
tabulate(
data,
headers=['#', 'Name', 'State', 'Date applied',
'Checksum']))
if pending_migrations:
print('\n## Pending migrations\n')
data = []
for version, migration in pending_migrations:
checksum = self._bytes_to_hex(migration.checksum)
data.append((str(version), migration.name, checksum))
print(tabulate(data, headers=['#', 'Name', 'Checksum']))
def test_refresh_schema_no_wait(self):
contact_points = ['127.0.0.1']
cluster = Cluster(protocol_version=PROTOCOL_VERSION, max_schema_agreement_wait=10,
contact_points=contact_points, load_balancing_policy=WhiteListRoundRobinPolicy(contact_points))
session = cluster.connect()
schema_ver = session.execute("SELECT schema_version FROM system.local WHERE key='local'")[0][0]
# create a schema disagreement
session.execute("UPDATE system.local SET schema_version=%s WHERE key='local'", (uuid4(),))
try:
agreement_timeout = 1
# cluster agreement wait exceeded
c = Cluster(protocol_version=PROTOCOL_VERSION, max_schema_agreement_wait=agreement_timeout)
start_time = time.time()
s = c.connect()
end_time = time.time()
self.assertGreaterEqual(end_time - start_time, agreement_timeout)
self.assertTrue(c.metadata.keyspaces)
# cluster agreement wait used for refresh
original_meta = c.metadata.keyspaces
start_time = time.time()
self.assertRaisesRegexp(Exception, r"Schema metadata was not refreshed.*", c.refresh_schema_metadata)
end_time = time.time()
self.assertGreaterEqual(end_time - start_time, agreement_timeout)
self.assertIs(original_meta, c.metadata.keyspaces)
# refresh wait overrides cluster value
original_meta = c.metadata.keyspaces
start_time = time.time()
c.refresh_schema_metadata(max_schema_agreement_wait=0)
end_time = time.time()
self.assertLess(end_time - start_time, agreement_timeout)
self.assertIsNot(original_meta, c.metadata.keyspaces)
self.assertEqual(original_meta, c.metadata.keyspaces)
c.shutdown()
refresh_threshold = 0.5
# cluster agreement bypass
c = Cluster(protocol_version=PROTOCOL_VERSION, max_schema_agreement_wait=0)
start_time = time.time()
s = c.connect()
end_time = time.time()
self.assertLess(end_time - start_time, refresh_threshold)
self.assertTrue(c.metadata.keyspaces)
# cluster agreement wait used for refresh
original_meta = c.metadata.keyspaces
start_time = time.time()
c.refresh_schema_metadata()
end_time = time.time()
self.assertLess(end_time - start_time, refresh_threshold)
self.assertIsNot(original_meta, c.metadata.keyspaces)
self.assertEqual(original_meta, c.metadata.keyspaces)
# refresh wait overrides cluster value
original_meta = c.metadata.keyspaces
start_time = time.time()
self.assertRaisesRegexp(Exception, r"Schema metadata was not refreshed.*", c.refresh_schema_metadata,
max_schema_agreement_wait=agreement_timeout)
end_time = time.time()
self.assertGreaterEqual(end_time - start_time, agreement_timeout)
self.assertIs(original_meta, c.metadata.keyspaces)
c.shutdown()
finally:
session.execute("UPDATE system.local SET schema_version=%s WHERE key='local'", (schema_ver,))
cluster.shutdown()
def test_refresh_schema_no_wait(self):
contact_points = ['127.0.0.1']
cluster = Cluster(
protocol_version=PROTOCOL_VERSION,
max_schema_agreement_wait=10,
contact_points=contact_points,
load_balancing_policy=WhiteListRoundRobinPolicy(contact_points))
session = cluster.connect()
schema_ver = session.execute(
"SELECT schema_version FROM system.local WHERE key='local'")[0][0]
new_schema_ver = uuid4()
session.execute(
"UPDATE system.local SET schema_version=%s WHERE key='local'",
(new_schema_ver, ))
try:
agreement_timeout = 1
# cluster agreement wait exceeded
c = Cluster(protocol_version=PROTOCOL_VERSION,
max_schema_agreement_wait=agreement_timeout)
c.connect()
self.assertTrue(c.metadata.keyspaces)
# cluster agreement wait used for refresh
original_meta = c.metadata.keyspaces
start_time = time.time()
self.assertRaisesRegexp(Exception,
r"Schema metadata was not refreshed.*",
c.refresh_schema_metadata)
end_time = time.time()
self.assertGreaterEqual(end_time - start_time, agreement_timeout)
self.assertIs(original_meta, c.metadata.keyspaces)
# refresh wait overrides cluster value
original_meta = c.metadata.keyspaces
start_time = time.time()
c.refresh_schema_metadata(max_schema_agreement_wait=0)
end_time = time.time()
self.assertLess(end_time - start_time, agreement_timeout)
self.assertIsNot(original_meta, c.metadata.keyspaces)
self.assertEqual(original_meta, c.metadata.keyspaces)
c.shutdown()
refresh_threshold = 0.5
# cluster agreement bypass
c = Cluster(protocol_version=PROTOCOL_VERSION,
max_schema_agreement_wait=0)
start_time = time.time()
s = c.connect()
end_time = time.time()
self.assertLess(end_time - start_time, refresh_threshold)
self.assertTrue(c.metadata.keyspaces)
# cluster agreement wait used for refresh
original_meta = c.metadata.keyspaces
start_time = time.time()
c.refresh_schema_metadata()
end_time = time.time()
self.assertLess(end_time - start_time, refresh_threshold)
self.assertIsNot(original_meta, c.metadata.keyspaces)
self.assertEqual(original_meta, c.metadata.keyspaces)
# refresh wait overrides cluster value
original_meta = c.metadata.keyspaces
start_time = time.time()
self.assertRaisesRegexp(
Exception,
r"Schema metadata was not refreshed.*",
c.refresh_schema_metadata,
max_schema_agreement_wait=agreement_timeout)
end_time = time.time()
self.assertGreaterEqual(end_time - start_time, agreement_timeout)
self.assertIs(original_meta, c.metadata.keyspaces)
c.shutdown()
finally:
# TODO once fixed this connect call
session = cluster.connect()
session.execute(
"UPDATE system.local SET schema_version=%s WHERE key='local'",
(schema_ver, ))
cluster.shutdown()
"-mode cql3", "native", "-rate threads=1",
"-log level=verbose interval=5",
"-errors retries=999 ignore", "-node {}".format(
master_nodes[0].ip())
],
stdout=stressor_log,
stderr=subprocess.STDOUT))
log('Letting stressor run for a while...')
# Sleep long enough for stressor to create the keyspace
time.sleep(10)
log('Fetching schema definitions from master cluster.')
cm.control_connection_timeout = 20
with cm.connect() as _:
cm.refresh_schema_metadata(max_schema_agreement_wait=10)
ks = cm.metadata.keyspaces[KS_NAME]
ut_ddls = [t[1].as_cql_query() for t in ks.user_types.items()]
table_ddls = []
for name, table in ks.tables.items():
if name.endswith('_scylla_cdc_log'):
continue
if 'cdc' in table.extensions:
del table.extensions['cdc']
table_ddls.append(table.as_cql_query())
log('User types:\n{}'.format('\n'.join(ut_ddls)))
log('Table definitions:\n{}'.format('\n'.join(table_ddls)))
log('Letting stressor run for a while...')
time.sleep(5)
def prime_cassandra(replication):
""" Create Cassandra keyspace and initial tables.
Args:
replication: An integer specifying the replication factor for the keyspace.
Raises:
AppScaleBadArg if replication factor is not greater than 0.
TypeError if replication is not an integer.
"""
if not isinstance(replication, int):
raise TypeError('Replication must be an integer')
if int(replication) <= 0:
raise dbconstants.AppScaleBadArg('Replication must be greater than zero')
hosts = appscale_info.get_db_ips()
cluster = None
session = None
remaining_retries = INITIAL_CONNECT_RETRIES
while True:
try:
cluster = Cluster(hosts)
session = cluster.connect()
break
except cassandra.cluster.NoHostAvailable as connection_error:
remaining_retries -= 1
if remaining_retries < 0:
raise connection_error
time.sleep(3)
session.default_consistency_level = ConsistencyLevel.QUORUM
create_keyspace = """
CREATE KEYSPACE IF NOT EXISTS "{keyspace}"
WITH REPLICATION = %(replication)s
""".format(keyspace=KEYSPACE)
keyspace_replication = {'class': 'SimpleStrategy',
'replication_factor': replication}
session.execute(create_keyspace, {'replication': keyspace_replication})
session.set_keyspace(KEYSPACE)
for table in dbconstants.INITIAL_TABLES:
create_table = """
CREATE TABLE IF NOT EXISTS "{table}" (
{key} blob,
{column} text,
{value} blob,
PRIMARY KEY ({key}, {column})
) WITH COMPACT STORAGE
""".format(table=table,
key=ThriftColumn.KEY,
column=ThriftColumn.COLUMN_NAME,
value=ThriftColumn.VALUE)
logging.info('Trying to create {}'.format(table))
cluster.refresh_schema_metadata()
session.execute(create_table)
create_batch_tables(cluster, session)
create_pull_queue_tables(cluster, session)
first_entity = session.execute(
'SELECT * FROM "{}" LIMIT 1'.format(dbconstants.APP_ENTITY_TABLE))
existing_entities = len(list(first_entity)) == 1
define_ua_schema(session)
metadata_insert = """
INSERT INTO "{table}" ({key}, {column}, {value})
VALUES (%(key)s, %(column)s, %(value)s)
""".format(
table=dbconstants.DATASTORE_METADATA_TABLE,
key=ThriftColumn.KEY,
column=ThriftColumn.COLUMN_NAME,
value=ThriftColumn.VALUE
)
if not existing_entities:
parameters = {'key': bytearray(cassandra_interface.VERSION_INFO_KEY),
'column': cassandra_interface.VERSION_INFO_KEY,
'value': bytearray(str(POST_JOURNAL_VERSION))}
session.execute(metadata_insert, parameters)
# Indicate that the database has been successfully primed.
parameters = {'key': bytearray(cassandra_interface.PRIMED_KEY),
'column': cassandra_interface.PRIMED_KEY,
'value': bytearray('true')}
session.execute(metadata_insert, parameters)
logging.info('Cassandra is primed.')
class DatastoreProxy(AppDBInterface):
"""
Cassandra implementation of the AppDBInterface
"""
def __init__(self, log_level=logging.INFO):
"""
Constructor.
"""
class_name = self.__class__.__name__
self.logger = logging.getLogger(class_name)
self.logger.setLevel(log_level)
self.logger.info("Starting {}".format(class_name))
self.hosts = appscale_info.get_db_ips()
remaining_retries = INITIAL_CONNECT_RETRIES
while True:
try:
self.cluster = Cluster(self.hosts)
self.session = self.cluster.connect(KEYSPACE)
break
except cassandra.cluster.NoHostAvailable as connection_error:
remaining_retries -= 1
if remaining_retries < 0:
raise connection_error
time.sleep(3)
self.session.default_consistency_level = ConsistencyLevel.QUORUM
self.retry_policy = IdempotentRetryPolicy()
def close(self):
""" Close all sessions and connections to Cassandra. """
self.cluster.shutdown()
def batch_get_entity(self, table_name, row_keys, column_names):
"""
Takes in batches of keys and retrieves their corresponding rows.
Args:
table_name: The table to access
row_keys: A list of keys to access
column_names: A list of columns to access
Returns:
A dictionary of rows and columns/values of those rows. The format
looks like such: {key:{column_name:value,...}}
Raises:
TypeError: If an argument passed in was not of the expected type.
AppScaleDBConnectionError: If the batch_get could not be performed due to
an error with Cassandra.
"""
if not isinstance(table_name, str):
raise TypeError("Expected a str")
if not isinstance(column_names, list):
raise TypeError("Expected a list")
if not isinstance(row_keys, list):
raise TypeError("Expected a list")
row_keys_bytes = [bytearray(row_key) for row_key in row_keys]
statement = 'SELECT * FROM "{table}" ' "WHERE {key} IN %s and {column} IN %s".format(
table=table_name, key=ThriftColumn.KEY, column=ThriftColumn.COLUMN_NAME
)
query = SimpleStatement(statement, retry_policy=self.retry_policy)
parameters = (ValueSequence(row_keys_bytes), ValueSequence(column_names))
try:
results = self.session.execute(query, parameters=parameters)
results_dict = {row_key: {} for row_key in row_keys}
for (key, column, value) in results:
if key not in results_dict:
results_dict[key] = {}
results_dict[key][column] = value
return results_dict
except (cassandra.Unavailable, cassandra.Timeout, cassandra.CoordinationFailure, cassandra.OperationTimedOut):
message = "Exception during batch_get_entity"
logging.exception(message)
raise AppScaleDBConnectionError(message)
def batch_put_entity(self, table_name, row_keys, column_names, cell_values, ttl=None):
"""
Allows callers to store multiple rows with a single call. A row can
have multiple columns and values with them. We refer to each row as
an entity.
Args:
table_name: The table to mutate
row_keys: A list of keys to store on
column_names: A list of columns to mutate
cell_values: A dict of key/value pairs
ttl: The number of seconds to keep the row.
Raises:
TypeError: If an argument passed in was not of the expected type.
AppScaleDBConnectionError: If the batch_put could not be performed due to
an error with Cassandra.
"""
if not isinstance(table_name, str):
raise TypeError("Expected a str")
if not isinstance(column_names, list):
raise TypeError("Expected a list")
if not isinstance(row_keys, list):
raise TypeError("Expected a list")
if not isinstance(cell_values, dict):
raise TypeError("Expected a dict")
insert_str = """
INSERT INTO "{table}" ({key}, {column}, {value})
VALUES (?, ?, ?)
""".format(
table=table_name, key=ThriftColumn.KEY, column=ThriftColumn.COLUMN_NAME, value=ThriftColumn.VALUE
)
if ttl is not None:
insert_str += "USING TTL {}".format(ttl)
statement = self.session.prepare(insert_str)
batch_insert = BatchStatement(retry_policy=self.retry_policy)
for row_key in row_keys:
for column in column_names:
batch_insert.add(statement, (bytearray(row_key), column, bytearray(cell_values[row_key][column])))
try:
self.session.execute(batch_insert)
except (cassandra.Unavailable, cassandra.Timeout, cassandra.CoordinationFailure, cassandra.OperationTimedOut):
message = "Exception during batch_put_entity"
logging.exception(message)
raise AppScaleDBConnectionError(message)
def prepare_insert(self, table):
""" Prepare an insert statement.
Args:
table: A string containing the table name.
Returns:
A PreparedStatement object.
"""
statement = """
INSERT INTO "{table}" ({key}, {column}, {value})
VALUES (?, ?, ?)
""".format(
table=table, key=ThriftColumn.KEY, column=ThriftColumn.COLUMN_NAME, value=ThriftColumn.VALUE
)
return self.session.prepare(statement)
def prepare_delete(self, table):
""" Prepare a delete statement.
Args:
table: A string containing the table name.
Returns:
A PreparedStatement object.
"""
statement = """
DELETE FROM "{table}" WHERE {key} = ?
""".format(
table=table, key=ThriftColumn.KEY
)
return self.session.prepare(statement)
def _normal_batch(self, mutations):
""" Use Cassandra's native batch statement to apply mutations atomically.
Args:
mutations: A list of dictionaries representing mutations.
"""
self.logger.debug("Normal batch: {} mutations".format(len(mutations)))
batch = BatchStatement(consistency_level=ConsistencyLevel.QUORUM, retry_policy=self.retry_policy)
prepared_statements = {"insert": {}, "delete": {}}
for mutation in mutations:
table = mutation["table"]
if mutation["operation"] == TxnActions.PUT:
if table not in prepared_statements["insert"]:
prepared_statements["insert"][table] = self.prepare_insert(table)
values = mutation["values"]
for column in values:
batch.add(
prepared_statements["insert"][table],
(bytearray(mutation["key"]), column, bytearray(values[column])),
)
elif mutation["operation"] == TxnActions.DELETE:
if table not in prepared_statements["delete"]:
prepared_statements["delete"][table] = self.prepare_delete(table)
batch.add(prepared_statements["delete"][table], (bytearray(mutation["key"]),))
try:
self.session.execute(batch)
except (cassandra.Unavailable, cassandra.Timeout, cassandra.CoordinationFailure, cassandra.OperationTimedOut):
message = "Exception during batch_mutate"
logging.exception(message)
raise AppScaleDBConnectionError(message)
def apply_mutations(self, mutations):
""" Apply mutations across tables.
Args:
mutations: A list of dictionaries representing mutations.
"""
for mutation in mutations:
table = mutation["table"]
if mutation["operation"] == TxnActions.PUT:
values = mutation["values"]
for column in values:
insert_row = """
INSERT INTO "{table}" ({key}, {column}, {value})
VALUES (%(key)s, %(column)s, %(value)s)
""".format(
table=table, key=ThriftColumn.KEY, column=ThriftColumn.COLUMN_NAME, value=ThriftColumn.VALUE
)
parameters = {
"key": bytearray(mutation["key"]),
"column": column,
"value": bytearray(values[column]),
}
self.session.execute(insert_row, parameters)
elif mutation["operation"] == TxnActions.DELETE:
delete_row = """
DELETE FROM "{table}" WHERE {key} = %(key)s
""".format(
table=table, key=ThriftColumn.KEY
)
parameters = {"key": bytearray(mutation["key"])}
self.session.execute(delete_row, parameters)
def _large_batch(self, app, mutations, entity_changes, txn):
""" 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 the batch status.
"""
self.logger.debug("Large batch: transaction {}, {} mutations".format(txn, len(mutations)))
set_status = """
INSERT INTO batch_status (app, transaction, applied)
VALUES (%(app)s, %(transaction)s, False)
IF NOT EXISTS
"""
parameters = {"app": app, "transaction": txn}
result = self.session.execute(set_status, parameters)
if not result.was_applied:
raise FailedBatch("A batch for transaction {} already exists".format(txn))
for entity_change in entity_changes:
insert_item = """
INSERT INTO batches (app, transaction, namespace, path,
old_value, new_value)
VALUES (%(app)s, %(transaction)s, %(namespace)s, %(path)s,
%(old_value)s, %(new_value)s)
"""
old_value = None
if entity_change["old"] is not None:
old_value = bytearray(entity_change["old"].Encode())
new_value = None
if entity_change["new"] is not None:
new_value = bytearray(entity_change["new"].Encode())
parameters = {
"app": app,
"transaction": txn,
"namespace": entity_change["key"].name_space(),
"path": bytearray(entity_change["key"].path().Encode()),
"old_value": old_value,
"new_value": new_value,
}
self.session.execute(insert_item, parameters)
update_status = """
UPDATE batch_status
SET applied = True
WHERE app = %(app)s
AND transaction = %(transaction)s
IF applied = False
"""
parameters = {"app": app, "transaction": txn}
result = self.session.execute(update_status, parameters)
if not result.was_applied:
raise FailedBatch("Another process modified batch for transaction {}".format(txn))
self.apply_mutations(mutations)
clear_batch = """
DELETE FROM batches
WHERE app = %(app)s AND transaction = %(transaction)s
"""
parameters = {"app": app, "transaction": txn}
self.session.execute(clear_batch, parameters)
clear_status = """
DELETE FROM batch_status
WHERE app = %(app)s and transaction = %(transaction)s
"""
parameters = {"app": app, "transaction": txn}
self.session.execute(clear_status, parameters)
def batch_mutate(self, app, mutations, entity_changes, txn):
""" 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.
"""
size = batch_size(mutations)
self.logger.debug("batch_size: {}".format(size))
if size > LARGE_BATCH_THRESHOLD:
self._large_batch(app, mutations, entity_changes, txn)
else:
self._normal_batch(mutations)
def batch_delete(self, table_name, row_keys, column_names=()):
"""
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 Cassandra.
"""
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'.format(table=table_name, key=ThriftColumn.KEY)
query = SimpleStatement(statement, retry_policy=self.retry_policy)
parameters = (ValueSequence(row_keys_bytes),)
try:
self.session.execute(query, parameters=parameters)
except (cassandra.Unavailable, cassandra.Timeout, cassandra.CoordinationFailure, cassandra.OperationTimedOut):
message = "Exception during batch_delete"
logging.exception(message)
raise AppScaleDBConnectionError(message)
def delete_table(self, table_name):
"""
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.
"""
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=self.retry_policy)
try:
self.session.execute(query)
except (cassandra.Unavailable, cassandra.Timeout, cassandra.CoordinationFailure, cassandra.OperationTimedOut):
message = "Exception during delete_table"
logging.exception(message)
raise AppScaleDBConnectionError(message)
def create_table(self, table_name, column_names):
"""
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.
"""
if not isinstance(table_name, str):
raise TypeError("Expected a str")
if not isinstance(column_names, list):
raise TypeError("Expected a list")
self.cluster.refresh_schema_metadata()
statement = (
'CREATE TABLE IF NOT EXISTS "{table}" ('
"{key} blob,"
"{column} text,"
"{value} blob,"
"PRIMARY KEY ({key}, {column})"
") WITH COMPACT STORAGE".format(
table=table_name, key=ThriftColumn.KEY, column=ThriftColumn.COLUMN_NAME, value=ThriftColumn.VALUE
)
)
query = SimpleStatement(statement)
try:
self.session.execute(query)
except (cassandra.Unavailable, cassandra.Timeout, cassandra.CoordinationFailure, cassandra.OperationTimedOut):
message = "Exception during create_table"
logging.exception(message)
raise AppScaleDBConnectionError(message)
def range_query(
self,
table_name,
column_names,
start_key,
end_key,
limit,
offset=0,
start_inclusive=True,
end_inclusive=True,
keys_only=False,
):
"""
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: String for which the query ends at
limit: Maximum number of results to return
offset: Cuts off these many from the results [offset:]
start_inclusive: Boolean if results should include the start_key
end_inclusive: Boolean if results should include the end_key
keys_only: Boolean if to only keys and not values
Raises:
TypeError: If an argument passed in was not of the expected type.
AppScaleDBConnectionError: If the range_query could not be performed due
to an error with Cassandra.
Returns:
An ordered list of dictionaries of key=>columns/values
"""
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 string")
if not isinstance(end_key, str):
raise TypeError("end_key must be a string")
if not isinstance(limit, (int, long)) and limit is not None:
raise TypeError("limit must be int, long, or NoneType")
if not isinstance(offset, (int, long)):
raise TypeError("offset must be int or long")
if start_inclusive:
gt_compare = ">="
else:
gt_compare = ">"
if end_inclusive:
lt_compare = "<="
else:
lt_compare = "<"
query_limit = ""
if limit is not None:
query_limit = "LIMIT {}".format(len(column_names) * limit)
statement = """
SELECT * FROM "{table}" WHERE
token({key}) {gt_compare} %s AND
token({key}) {lt_compare} %s AND
{column} IN %s
{limit}
ALLOW FILTERING
""".format(
table=table_name,
key=ThriftColumn.KEY,
gt_compare=gt_compare,
lt_compare=lt_compare,
column=ThriftColumn.COLUMN_NAME,
limit=query_limit,
)
query = SimpleStatement(statement, retry_policy=self.retry_policy)
parameters = (bytearray(start_key), bytearray(end_key), ValueSequence(column_names))
try:
results = self.session.execute(query, parameters=parameters)
results_list = []
current_item = {}
current_key = None
for (key, column, value) in results:
if keys_only:
results_list.append(key)
continue
if key != current_key:
if current_item:
results_list.append({current_key: current_item})
current_item = {}
current_key = key
current_item[column] = value
if current_item:
results_list.append({current_key: current_item})
return results_list[offset:]
except (cassandra.Unavailable, cassandra.Timeout, cassandra.CoordinationFailure, cassandra.OperationTimedOut):
message = "Exception during range_query"
logging.exception(message)
raise AppScaleDBConnectionError(message)
def get_metadata(self, key):
""" 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.
"""
statement = """
SELECT {value} FROM "{table}"
WHERE {key} = %s
AND {column} = %s
""".format(
value=ThriftColumn.VALUE,
table=dbconstants.DATASTORE_METADATA_TABLE,
key=ThriftColumn.KEY,
column=ThriftColumn.COLUMN_NAME,
)
try:
results = self.session.execute(statement, (bytearray(key), key))
except (cassandra.Unavailable, cassandra.Timeout, cassandra.CoordinationFailure, cassandra.OperationTimedOut):
message = "Unable to fetch {} from datastore metadata".format(key)
logging.exception(message)
raise AppScaleDBConnectionError(message)
try:
return results[0].value
except IndexError:
return None
def set_metadata(self, key, value):
""" Set a datastore metadata value.
Args:
key: A string containing the key to set.
value: A string containing the value to set.
"""
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 = """
INSERT INTO "{table}" ({key}, {column}, {value})
VALUES (%(key)s, %(column)s, %(value)s)
""".format(
table=dbconstants.DATASTORE_METADATA_TABLE,
key=ThriftColumn.KEY,
column=ThriftColumn.COLUMN_NAME,
value=ThriftColumn.VALUE,
)
parameters = {"key": bytearray(key), "column": key, "value": bytearray(value)}
try:
self.session.execute(statement, parameters)
except (cassandra.Unavailable, cassandra.Timeout, cassandra.CoordinationFailure, cassandra.OperationTimedOut):
message = "Unable to set datastore metadata for {}".format(key)
logging.exception(message)
raise AppScaleDBConnectionError(message)
except cassandra.InvalidRequest:
self.create_table(dbconstants.DATASTORE_METADATA_TABLE, dbconstants.DATASTORE_METADATA_SCHEMA)
self.session.execute(statement, parameters)
def get_indices(self, app_id):
""" Gets the indices of the given application.
Args:
app_id: Name of the application.
Returns:
Returns a list of encoded entity_pb.CompositeIndex objects.
"""
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,
offset=0,
start_inclusive=True,
end_inclusive=True,
)
list_result = []
for list_item in result:
for key, value in list_item.iteritems():
list_result.append(value["data"])
return list_result
def valid_data_version(self):
""" Checks whether or not the data layout can be used.
Returns:
A boolean.
"""
try:
version = self.get_metadata(VERSION_INFO_KEY)
except cassandra.InvalidRequest:
return False
return version is not None and float(version) == EXPECTED_DATA_VERSION
def prime_cassandra(replication):
""" Create Cassandra keyspace and initial tables.
Args:
replication: An integer specifying the replication factor for the keyspace.
Raises:
AppScaleBadArg if replication factor is not greater than 0.
TypeError if replication is not an integer.
"""
if not isinstance(replication, int):
raise TypeError('Replication must be an integer')
if int(replication) <= 0:
raise dbconstants.AppScaleBadArg(
'Replication must be greater than zero')
hosts = appscale_info.get_db_ips()
cluster = None
session = None
remaining_retries = INITIAL_CONNECT_RETRIES
while True:
try:
cluster = Cluster(hosts)
session = cluster.connect()
break
except cassandra.cluster.NoHostAvailable as connection_error:
remaining_retries -= 1
if remaining_retries < 0:
raise connection_error
time.sleep(3)
session.default_consistency_level = ConsistencyLevel.QUORUM
create_keyspace = """
CREATE KEYSPACE IF NOT EXISTS "{keyspace}"
WITH REPLICATION = %(replication)s
""".format(keyspace=KEYSPACE)
keyspace_replication = {
'class': 'SimpleStrategy',
'replication_factor': replication
}
session.execute(create_keyspace, {'replication': keyspace_replication})
session.set_keyspace(KEYSPACE)
for table in dbconstants.INITIAL_TABLES:
create_table = """
CREATE TABLE IF NOT EXISTS "{table}" (
{key} blob,
{column} text,
{value} blob,
PRIMARY KEY ({key}, {column})
) WITH COMPACT STORAGE
""".format(table=table,
key=ThriftColumn.KEY,
column=ThriftColumn.COLUMN_NAME,
value=ThriftColumn.VALUE)
logging.info('Trying to create {}'.format(table))
cluster.refresh_schema_metadata()
session.execute(create_table)
create_batch_tables(cluster, session)
create_pull_queue_tables(cluster, session)
first_entity = session.execute('SELECT * FROM "{}" LIMIT 1'.format(
dbconstants.APP_ENTITY_TABLE))
existing_entities = len(list(first_entity)) == 1
define_ua_schema(session)
metadata_insert = """
INSERT INTO "{table}" ({key}, {column}, {value})
VALUES (%(key)s, %(column)s, %(value)s)
""".format(table=dbconstants.DATASTORE_METADATA_TABLE,
key=ThriftColumn.KEY,
column=ThriftColumn.COLUMN_NAME,
value=ThriftColumn.VALUE)
if not existing_entities:
parameters = {
'key': bytearray(cassandra_interface.VERSION_INFO_KEY),
'column': cassandra_interface.VERSION_INFO_KEY,
'value': bytearray(str(POST_JOURNAL_VERSION))
}
session.execute(metadata_insert, parameters)
# Indicate that the database has been successfully primed.
parameters = {
'key': bytearray(cassandra_interface.PRIMED_KEY),
'column': cassandra_interface.PRIMED_KEY,
'value': bytearray('true')
}
session.execute(metadata_insert, parameters)
logging.info('Cassandra is primed.')
class DatastoreProxy(AppDBInterface):
"""
Cassandra implementation of the AppDBInterface
"""
def __init__(self, log_level=logging.INFO):
"""
Constructor.
"""
class_name = self.__class__.__name__
self.logger = logging.getLogger(class_name)
self.logger.setLevel(log_level)
self.logger.info('Starting {}'.format(class_name))
self.hosts = appscale_info.get_db_ips()
remaining_retries = INITIAL_CONNECT_RETRIES
while True:
try:
self.cluster = Cluster(self.hosts)
self.session = self.cluster.connect(KEYSPACE)
break
except cassandra.cluster.NoHostAvailable as connection_error:
remaining_retries -= 1
if remaining_retries < 0:
raise connection_error
time.sleep(3)
self.session.default_consistency_level = ConsistencyLevel.QUORUM
self.retry_policy = IdempotentRetryPolicy()
def close(self):
""" Close all sessions and connections to Cassandra. """
self.cluster.shutdown()
def batch_get_entity(self, table_name, row_keys, column_names):
"""
Takes in batches of keys and retrieves their corresponding rows.
Args:
table_name: The table to access
row_keys: A list of keys to access
column_names: A list of columns to access
Returns:
A dictionary of rows and columns/values of those rows. The format
looks like such: {key:{column_name:value,...}}
Raises:
TypeError: If an argument passed in was not of the expected type.
AppScaleDBConnectionError: If the batch_get could not be performed due to
an error with Cassandra.
"""
if not isinstance(table_name, str): raise TypeError("Expected a str")
if not isinstance(column_names, list):
raise TypeError("Expected a list")
if not isinstance(row_keys, list): raise TypeError("Expected a list")
row_keys_bytes = [bytearray(row_key) for row_key in row_keys]
statement = 'SELECT * FROM "{table}" '\
'WHERE {key} IN %s and {column} IN %s'.format(
table=table_name,
key=ThriftColumn.KEY,
column=ThriftColumn.COLUMN_NAME,
)
query = SimpleStatement(statement, retry_policy=self.retry_policy)
parameters = (ValueSequence(row_keys_bytes),
ValueSequence(column_names))
try:
results = self.session.execute(query, parameters=parameters)
results_dict = {row_key: {} for row_key in row_keys}
for (key, column, value) in results:
if key not in results_dict:
results_dict[key] = {}
results_dict[key][column] = value
return results_dict
except dbconstants.TRANSIENT_CASSANDRA_ERRORS:
message = 'Exception during batch_get_entity'
logging.exception(message)
raise AppScaleDBConnectionError(message)
def batch_put_entity(self,
table_name,
row_keys,
column_names,
cell_values,
ttl=None):
"""
Allows callers to store multiple rows with a single call. A row can
have multiple columns and values with them. We refer to each row as
an entity.
Args:
table_name: The table to mutate
row_keys: A list of keys to store on
column_names: A list of columns to mutate
cell_values: A dict of key/value pairs
ttl: The number of seconds to keep the row.
Raises:
TypeError: If an argument passed in was not of the expected type.
AppScaleDBConnectionError: If the batch_put could not be performed due to
an error with Cassandra.
"""
if not isinstance(table_name, str):
raise TypeError("Expected a str")
if not isinstance(column_names, list):
raise TypeError("Expected a list")
if not isinstance(row_keys, list):
raise TypeError("Expected a list")
if not isinstance(cell_values, dict):
raise TypeError("Expected a dict")
insert_str = """
INSERT INTO "{table}" ({key}, {column}, {value})
VALUES (?, ?, ?)
""".format(table=table_name,
key=ThriftColumn.KEY,
column=ThriftColumn.COLUMN_NAME,
value=ThriftColumn.VALUE)
if ttl is not None:
insert_str += 'USING TTL {}'.format(ttl)
statement = self.session.prepare(insert_str)
batch_insert = BatchStatement(retry_policy=self.retry_policy)
for row_key in row_keys:
for column in column_names:
batch_insert.add(statement,
(bytearray(row_key), column,
bytearray(cell_values[row_key][column])))
try:
self.session.execute(batch_insert)
except dbconstants.TRANSIENT_CASSANDRA_ERRORS:
message = 'Exception during batch_put_entity'
logging.exception(message)
raise AppScaleDBConnectionError(message)
def prepare_insert(self, table):
""" Prepare an insert statement.
Args:
table: A string containing the table name.
Returns:
A PreparedStatement object.
"""
statement = """
INSERT INTO "{table}" ({key}, {column}, {value})
VALUES (?, ?, ?)
""".format(table=table,
key=ThriftColumn.KEY,
column=ThriftColumn.COLUMN_NAME,
value=ThriftColumn.VALUE)
return self.session.prepare(statement)
def prepare_delete(self, table):
""" Prepare a delete statement.
Args:
table: A string containing the table name.
Returns:
A PreparedStatement object.
"""
statement = """
DELETE FROM "{table}" WHERE {key} = ?
""".format(table=table, key=ThriftColumn.KEY)
return self.session.prepare(statement)
def _normal_batch(self, mutations):
""" Use Cassandra's native batch statement to apply mutations atomically.
Args:
mutations: A list of dictionaries representing mutations.
"""
self.logger.debug('Normal batch: {} mutations'.format(len(mutations)))
batch = BatchStatement(consistency_level=ConsistencyLevel.QUORUM,
retry_policy=self.retry_policy)
prepared_statements = {'insert': {}, 'delete': {}}
for mutation in mutations:
table = mutation['table']
if mutation['operation'] == TxnActions.PUT:
if table not in prepared_statements['insert']:
prepared_statements['insert'][table] = self.prepare_insert(
table)
values = mutation['values']
for column in values:
batch.add(prepared_statements['insert'][table], (bytearray(
mutation['key']), column, bytearray(values[column])))
elif mutation['operation'] == TxnActions.DELETE:
if table not in prepared_statements['delete']:
prepared_statements['delete'][table] = self.prepare_delete(
table)
batch.add(prepared_statements['delete'][table],
(bytearray(mutation['key']), ))
try:
self.session.execute(batch)
except dbconstants.TRANSIENT_CASSANDRA_ERRORS:
message = 'Exception during batch_mutate'
logging.exception(message)
raise AppScaleDBConnectionError(message)
def apply_mutations(self, mutations):
""" Apply mutations across tables.
Args:
mutations: A list of dictionaries representing mutations.
"""
for mutation in mutations:
table = mutation['table']
if mutation['operation'] == TxnActions.PUT:
values = mutation['values']
for column in values:
insert_row = """
INSERT INTO "{table}" ({key}, {column}, {value})
VALUES (%(key)s, %(column)s, %(value)s)
""".format(table=table,
key=ThriftColumn.KEY,
column=ThriftColumn.COLUMN_NAME,
value=ThriftColumn.VALUE)
parameters = {
'key': bytearray(mutation['key']),
'column': column,
'value': bytearray(values[column])
}
self.session.execute(insert_row, parameters)
elif mutation['operation'] == TxnActions.DELETE:
delete_row = """
DELETE FROM "{table}" WHERE {key} = %(key)s
""".format(table=table, key=ThriftColumn.KEY)
parameters = {'key': bytearray(mutation['key'])}
self.session.execute(delete_row, parameters)
def _large_batch(self, app, mutations, entity_changes, txn):
""" 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 the batch status.
"""
self.logger.debug('Large batch: transaction {}, {} mutations'.format(
txn, len(mutations)))
set_status = """
INSERT INTO batch_status (app, transaction, applied)
VALUES (%(app)s, %(transaction)s, False)
IF NOT EXISTS
"""
parameters = {'app': app, 'transaction': txn}
result = self.session.execute(set_status, parameters)
if not result.was_applied:
raise FailedBatch(
'A batch for transaction {} already exists'.format(txn))
for entity_change in entity_changes:
insert_item = """
INSERT INTO batches (app, transaction, namespace, path,
old_value, new_value)
VALUES (%(app)s, %(transaction)s, %(namespace)s, %(path)s,
%(old_value)s, %(new_value)s)
"""
old_value = None
if entity_change['old'] is not None:
old_value = bytearray(entity_change['old'].Encode())
new_value = None
if entity_change['new'] is not None:
new_value = bytearray(entity_change['new'].Encode())
parameters = {
'app': app,
'transaction': txn,
'namespace': entity_change['key'].name_space(),
'path': bytearray(entity_change['key'].path().Encode()),
'old_value': old_value,
'new_value': new_value
}
self.session.execute(insert_item, parameters)
update_status = """
UPDATE batch_status
SET applied = True
WHERE app = %(app)s
AND transaction = %(transaction)s
IF applied = False
"""
parameters = {'app': app, 'transaction': txn}
result = self.session.execute(update_status, parameters)
if not result.was_applied:
raise FailedBatch(
'Another process modified batch for transaction {}'.format(
txn))
self.apply_mutations(mutations)
clear_batch = """
DELETE FROM batches
WHERE app = %(app)s AND transaction = %(transaction)s
"""
parameters = {'app': app, 'transaction': txn}
self.session.execute(clear_batch, parameters)
clear_status = """
DELETE FROM batch_status
WHERE app = %(app)s and transaction = %(transaction)s
"""
parameters = {'app': app, 'transaction': txn}
self.session.execute(clear_status, parameters)
def batch_mutate(self, app, mutations, entity_changes, txn):
""" 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.
"""
size = batch_size(mutations)
self.logger.debug('batch_size: {}'.format(size))
if size > LARGE_BATCH_THRESHOLD:
self._large_batch(app, mutations, entity_changes, txn)
else:
self._normal_batch(mutations)
def batch_delete(self, table_name, row_keys, column_names=()):
"""
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 Cassandra.
"""
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'.\
format(
table=table_name,
key=ThriftColumn.KEY
)
query = SimpleStatement(statement, retry_policy=self.retry_policy)
parameters = (ValueSequence(row_keys_bytes), )
try:
self.session.execute(query, parameters=parameters)
except dbconstants.TRANSIENT_CASSANDRA_ERRORS:
message = 'Exception during batch_delete'
logging.exception(message)
raise AppScaleDBConnectionError(message)
def delete_table(self, table_name):
"""
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.
"""
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=self.retry_policy)
try:
self.session.execute(query)
except dbconstants.TRANSIENT_CASSANDRA_ERRORS:
message = 'Exception during delete_table'
logging.exception(message)
raise AppScaleDBConnectionError(message)
def create_table(self, table_name, column_names):
"""
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.
"""
if not isinstance(table_name, str): raise TypeError("Expected a str")
if not isinstance(column_names, list):
raise TypeError("Expected a list")
self.cluster.refresh_schema_metadata()
statement = 'CREATE TABLE IF NOT EXISTS "{table}" ('\
'{key} blob,'\
'{column} text,'\
'{value} blob,'\
'PRIMARY KEY ({key}, {column})'\
') WITH COMPACT STORAGE'.format(
table=table_name,
key=ThriftColumn.KEY,
column=ThriftColumn.COLUMN_NAME,
value=ThriftColumn.VALUE
)
query = SimpleStatement(statement)
try:
self.session.execute(query)
except dbconstants.TRANSIENT_CASSANDRA_ERRORS:
message = 'Exception during create_table'
logging.exception(message)
raise AppScaleDBConnectionError(message)
def range_query(self,
table_name,
column_names,
start_key,
end_key,
limit,
offset=0,
start_inclusive=True,
end_inclusive=True,
keys_only=False):
"""
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: String for which the query ends at
limit: Maximum number of results to return
offset: Cuts off these many from the results [offset:]
start_inclusive: Boolean if results should include the start_key
end_inclusive: Boolean if results should include the end_key
keys_only: Boolean if to only keys and not values
Raises:
TypeError: If an argument passed in was not of the expected type.
AppScaleDBConnectionError: If the range_query could not be performed due
to an error with Cassandra.
Returns:
An ordered list of dictionaries of key=>columns/values
"""
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 string')
if not isinstance(end_key, str):
raise TypeError('end_key must be a string')
if not isinstance(limit, (int, long)) and limit is not None:
raise TypeError('limit must be int, long, or NoneType')
if not isinstance(offset, (int, long)):
raise TypeError('offset must be int or long')
if start_inclusive:
gt_compare = '>='
else:
gt_compare = '>'
if end_inclusive:
lt_compare = '<='
else:
lt_compare = '<'
query_limit = ''
if limit is not None:
query_limit = 'LIMIT {}'.format(len(column_names) * limit)
statement = """
SELECT * FROM "{table}" WHERE
token({key}) {gt_compare} %s AND
token({key}) {lt_compare} %s AND
{column} IN %s
{limit}
ALLOW FILTERING
""".format(table=table_name,
key=ThriftColumn.KEY,
gt_compare=gt_compare,
lt_compare=lt_compare,
column=ThriftColumn.COLUMN_NAME,
limit=query_limit)
query = SimpleStatement(statement, retry_policy=self.retry_policy)
parameters = (bytearray(start_key), bytearray(end_key),
ValueSequence(column_names))
try:
results = self.session.execute(query, parameters=parameters)
results_list = []
current_item = {}
current_key = None
for (key, column, value) in results:
if keys_only:
results_list.append(key)
continue
if key != current_key:
if current_item:
results_list.append({current_key: current_item})
current_item = {}
current_key = key
current_item[column] = value
if current_item:
results_list.append({current_key: current_item})
return results_list[offset:]
except dbconstants.TRANSIENT_CASSANDRA_ERRORS:
message = 'Exception during range_query'
logging.exception(message)
raise AppScaleDBConnectionError(message)
def get_metadata(self, key):
""" 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.
"""
statement = """
SELECT {value} FROM "{table}"
WHERE {key} = %s
AND {column} = %s
""".format(value=ThriftColumn.VALUE,
table=dbconstants.DATASTORE_METADATA_TABLE,
key=ThriftColumn.KEY,
column=ThriftColumn.COLUMN_NAME)
try:
results = self.session.execute(statement, (bytearray(key), key))
except dbconstants.TRANSIENT_CASSANDRA_ERRORS:
message = 'Unable to fetch {} from datastore metadata'.format(key)
logging.exception(message)
raise AppScaleDBConnectionError(message)
try:
return results[0].value
except IndexError:
return None
def set_metadata(self, key, value):
""" Set a datastore metadata value.
Args:
key: A string containing the key to set.
value: A string containing the value to set.
"""
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 = """
INSERT INTO "{table}" ({key}, {column}, {value})
VALUES (%(key)s, %(column)s, %(value)s)
""".format(table=dbconstants.DATASTORE_METADATA_TABLE,
key=ThriftColumn.KEY,
column=ThriftColumn.COLUMN_NAME,
value=ThriftColumn.VALUE)
parameters = {
'key': bytearray(key),
'column': key,
'value': bytearray(value)
}
try:
self.session.execute(statement, parameters)
except dbconstants.TRANSIENT_CASSANDRA_ERRORS:
message = 'Unable to set datastore metadata for {}'.format(key)
logging.exception(message)
raise AppScaleDBConnectionError(message)
except cassandra.InvalidRequest:
self.create_table(dbconstants.DATASTORE_METADATA_TABLE,
dbconstants.DATASTORE_METADATA_SCHEMA)
self.session.execute(statement, parameters)
def get_indices(self, app_id):
""" Gets the indices of the given application.
Args:
app_id: Name of the application.
Returns:
Returns a list of encoded entity_pb.CompositeIndex objects.
"""
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,
offset=0,
start_inclusive=True,
end_inclusive=True)
list_result = []
for list_item in result:
for key, value in list_item.iteritems():
list_result.append(value['data'])
return list_result
def valid_data_version(self):
""" Checks whether or not the data layout can be used.
Returns:
A boolean.
"""
try:
version = self.get_metadata(VERSION_INFO_KEY)
except cassandra.InvalidRequest:
return False
return version is not None and float(version) == EXPECTED_DATA_VERSION
