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"""Hook for Level DB."""
from __future__ import annotations
from airflow.exceptions import AirflowException, AirflowOptionalProviderFeatureException
from airflow.hooks.base import BaseHook
try:
import plyvel
from plyvel import DB
except ImportError as e:
raise AirflowOptionalProviderFeatureException(e)
[docs]DB_NOT_INITIALIZED_BEFORE = "The `get_conn` method should be called before!"
[docs]class LevelDBHookException(AirflowException):
"""Exception specific for LevelDB."""
[docs]class LevelDBHook(BaseHook):
"""
Plyvel Wrapper to Interact With LevelDB Database.
`LevelDB Connection Documentation <https://plyvel.readthedocs.io/en/latest/>`__
"""
[docs] conn_name_attr = "leveldb_conn_id"
[docs] default_conn_name = "leveldb_default"
def __init__(self, leveldb_conn_id: str = default_conn_name):
super().__init__()
self.leveldb_conn_id = leveldb_conn_id
self.connection = self.get_connection(leveldb_conn_id)
self.db: plyvel.DB | None = None
[docs] def get_conn(self, name: str = "/tmp/testdb/", create_if_missing: bool = False, **kwargs) -> DB:
"""
Creates `Plyvel DB <https://plyvel.readthedocs.io/en/latest/api.html#DB>`__.
:param name: path to create database e.g. `/tmp/testdb/`)
:param create_if_missing: whether a new database should be created if needed
:param kwargs: other options of creation plyvel.DB. See more in the link above.
:returns: DB
"""
if self.db is not None:
return self.db
self.db = plyvel.DB(name=name, create_if_missing=create_if_missing, **kwargs)
return self.db
[docs] def close_conn(self) -> None:
"""Closes connection."""
db = self.db
if db is not None:
db.close()
self.db = None
[docs] def run(
self,
command: str,
key: bytes,
value: bytes | None = None,
keys: list[bytes] | None = None,
values: list[bytes] | None = None,
) -> bytes | None:
"""
Execute operation with leveldb.
:param command: command of plyvel(python wrap for leveldb) for DB object e.g.
``"put"``, ``"get"``, ``"delete"``, ``"write_batch"``.
:param key: key for command(put,get,delete) execution(, e.g. ``b'key'``, ``b'another-key'``)
:param value: value for command(put) execution(bytes, e.g. ``b'value'``, ``b'another-value'``)
:param keys: keys for command(write_batch) execution(list[bytes], e.g. ``[b'key', b'another-key'])``
:param values: values for command(write_batch) execution e.g. ``[b'value'``, ``b'another-value']``
:returns: value from get or None
"""
if command == "put":
if not value:
raise Exception("Please provide `value`!")
return self.put(key, value)
elif command == "get":
return self.get(key)
elif command == "delete":
return self.delete(key)
elif command == "write_batch":
if not keys:
raise Exception("Please provide `keys`!")
if not values:
raise Exception("Please provide `values`!")
return self.write_batch(keys, values)
else:
raise LevelDBHookException("Unknown command for LevelDB hook")
[docs] def put(self, key: bytes, value: bytes):
"""
Put a single value into a leveldb db by key.
:param key: key for put execution, e.g. ``b'key'``, ``b'another-key'``
:param value: value for put execution e.g. ``b'value'``, ``b'another-value'``
"""
if not self.db:
raise Exception(DB_NOT_INITIALIZED_BEFORE)
self.db.put(key, value)
[docs] def get(self, key: bytes) -> bytes:
"""
Get a single value into a leveldb db by key.
:param key: key for get execution, e.g. ``b'key'``, ``b'another-key'``
:returns: value of key from db.get
"""
if not self.db:
raise Exception(DB_NOT_INITIALIZED_BEFORE)
return self.db.get(key)
[docs] def delete(self, key: bytes):
"""
Delete a single value in a leveldb db by key.
:param key: key for delete execution, e.g. ``b'key'``, ``b'another-key'``
"""
if not self.db:
raise Exception(DB_NOT_INITIALIZED_BEFORE)
self.db.delete(key)
[docs] def write_batch(self, keys: list[bytes], values: list[bytes]):
"""
Write batch of values in a leveldb db by keys.
:param keys: keys for write_batch execution e.g. ``[b'key', b'another-key']``
:param values: values for write_batch execution e.g. ``[b'value', b'another-value']``
"""
if not self.db:
raise Exception(DB_NOT_INITIALIZED_BEFORE)
with self.db.write_batch() as batch:
for i, key in enumerate(keys):
batch.put(key, values[i])
