Cache.push()

Push value onto a queue and return its key, as diskcache’s push.

Usage

Cache.push(
    value, prefix=None, side="back", expire=None, *, tag=None, retry=False
)

With prefix=None the queue’s keys are ints, numbered from 500,000,000,000,000; with a prefix, str keys '{prefix}-' and 15 digits. side='back' takes the next number up, 'front' the next down. Only keys of exactly that shape belong to the queue: a float, an ordinary key that shares the prefix, or a nested prefix’s items are ignored (D-054), so use a prefix no other key starts with. The number is found and the item stored in one write transaction, so concurrent pushes in any process never collide, and a push never overwrites a key.

Parameters

value: Any: The value, as for set().
prefix: None = None: The queue’s name, or None for the int queue.
side: bool = "back": 'back' (the default) or 'front'.
expire: float | None = None: Seconds until the item expires, or None for never.
tag: Key = None: The item’s tag, as for set().
retry: bool = False: As for set().

Returns

int | None | str | None | int | str | None: The item’s key. With durable=True, None if the write failed (nothing was stored).

Raises

OverflowError: The queue’s numbers are used up on that side (D-057).
ValueError: side isn’t 'front' or 'back'.
TypeError: prefix isn’t a str or None, or as for set().

Examples

jobs = Cache('/var/lib/my-app/state/jobs', timeout=3.0, eviction_policy='none')
jobs.push({'episode': 512}, prefix='transcode')   # 'transcode-500000000000000'