Files
superset2/superset/commands/distributed_lock/acquire.py

133 lines
4.4 KiB
Python

# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements. See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership. The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License. You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied. See the License for the
# specific language governing permissions and limitations
# under the License.
from __future__ import annotations
import logging
from datetime import datetime, timedelta, timezone
from functools import partial
from typing import Any
import redis
from sqlalchemy.exc import SQLAlchemyError
from superset.commands.distributed_lock.base import (
BaseDistributedLockCommand,
get_default_lock_ttl,
get_redis_client,
)
from superset.daos.key_value import KeyValueDAO
from superset.exceptions import AcquireDistributedLockFailedException
from superset.key_value.exceptions import (
KeyValueCodecEncodeException,
KeyValueUpsertFailedError,
)
from superset.key_value.types import KeyValueResource
from superset.utils.decorators import on_error, transaction
logger = logging.getLogger(__name__)
class AcquireDistributedLock(BaseDistributedLockCommand):
"""
Acquire a distributed lock with automatic backend selection.
Uses Redis SET NX EX when DISTRIBUTED_COORDINATION_CONFIG is configured,
otherwise falls back to KeyValue table.
Raises AcquireDistributedLockFailedException if:
- Lock is already held by another process
- Redis connection fails
"""
ttl_seconds: int
def __init__(
self,
namespace: str,
params: dict[str, Any] | None = None,
ttl_seconds: int | None = None,
) -> None:
super().__init__(namespace, params)
self.ttl_seconds = ttl_seconds or get_default_lock_ttl()
def run(self) -> None:
if (redis_client := get_redis_client()) is not None:
self._acquire_redis(redis_client)
else:
self._acquire_kv()
def _acquire_redis(self, redis_client: Any) -> None:
"""Acquire lock using Redis SET NX EX (atomic)."""
try:
# SET NX EX: Set if not exists, with expiration
# Returns True if lock acquired, None if already exists
acquired = redis_client.set(
self.redis_lock_key,
"1",
nx=True,
ex=self.ttl_seconds,
)
if not acquired:
logger.debug("Redis lock on %s already taken", self.redis_lock_key)
raise AcquireDistributedLockFailedException("Lock already taken")
logger.debug(
"Acquired Redis lock: %s (TTL=%ds)",
self.redis_lock_key,
self.ttl_seconds,
)
except redis.RedisError as ex:
logger.error("Redis lock error for %s: %s", self.redis_lock_key, ex)
raise AcquireDistributedLockFailedException(
f"Redis lock failed: {ex}"
) from ex
@transaction(
on_error=partial(
on_error,
catches=(
KeyValueCodecEncodeException,
KeyValueUpsertFailedError,
SQLAlchemyError,
),
reraise=AcquireDistributedLockFailedException,
),
)
def _acquire_kv(self) -> None:
"""Acquire lock using KeyValue table (database)."""
# Delete expired entries first to prevent stale locks from blocking
KeyValueDAO.delete_expired_entries(self.resource)
# Create entry - unique constraint will raise if lock already exists
KeyValueDAO.create_entry(
resource=KeyValueResource.LOCK,
value={"value": True},
codec=self.codec,
key=self.key,
expires_on=datetime.now(timezone.utc) + timedelta(seconds=self.ttl_seconds),
)
logger.debug(
"Acquired KV lock: namespace=%s key=%s (TTL=%ds)",
self.namespace,
self.key,
self.ttl_seconds,
)