Persistent

Stores worker state between restarts. This is the persistent data stored by the worker when :option:celery worker --statedb is enabled. Currently only stores revoked task id's.

Attributes

Attribute	Type	Description
storage	module = shelve	The storage module or interface used to open the persistent database file, defaulting to the standard library shelve module.
protocol	int = pickle_protocol	The pickle protocol version used for serializing and deserializing the persistent state data.
compress	callable = zlib.compress	The compression function used to reduce the size of the revoked task data before it is stored in the database.
decompress	callable = zlib.decompress	The decompression function used to restore compressed revoked task data retrieved from the database.

---

Constructor

Signature

def Persistent(
    state: Any,
    filename: str,
    clock: Any = None
)

Parameters

Name	Type	Description
state	Any	The worker state object containing revoked tasks.
filename	str	The path to the database file used for persistence.
clock	Any = None	An optional logical clock for synchronization.

---

Methods

---

open()

@classmethod
def open() - > shelve.DbfilenameShelf

Opens the underlying shelf storage file using the configured protocol and writeback settings.

Returns

Type	Description
shelve.DbfilenameShelf	A shelf object providing dictionary-like access to the persistent storage file.

---

merge()

@classmethod
def merge() - > null

Synchronizes the current in-memory state with the data stored in the persistent database.

Returns

Type	Description
null

---

sync()

@classmethod
def sync() - > null

Updates the persistent database with the current in-memory state and flushes changes to disk.

Returns

Type	Description
null

---

close()

@classmethod
def close() - > null

Closes the persistent database connection if it is currently open.

Returns

Type	Description
null

---

save()

@classmethod
def save() - > null

Saves the current state to the database and closes the storage connection.

Returns

Type	Description
null

---

db()

@classmethod
def db() - > shelve.DbfilenameShelf

Provides a cached connection to the persistent storage, opening it on first access.

Returns

Type	Description
shelve.DbfilenameShelf	The opened shelf database instance.

---