Queue

Added in version 0.2.1.

import asyncgui as ag
from asyncgui_ext.synctools.queue import Queue

async def producer(q):
    for c in "ABC":
        await q.put(c)
        print('produced', c)

async def consumer(q):
    async for c in q:
        print('consumed', c)

q = Queue(capacity=1)
ag.start(producer(q))
ag.start(consumer(q))

produced A
produced B
consumed A
produced C
consumed B
consumed C

癖 – Quirk –

async def async_fn1(q, consumed):
    await q.put('A')
    await q.put('B')
    item = await q.get()
    consumed.append(item)
    await q.put('C')
    item = await q.get()
    consumed.append(item)

async def async_fn2(q, consumed):
    item = await q.get()
    consumed.append(item)

consumed = []
q = Queue(capacity=1)
ag.start(async_fn1(q, consumed))
ag.start(async_fn2(q, consumed))
print(consumed)

['B', 'C', 'A']

上記の出力を見てわかるように A, B, C の順でキューに入れたのに consumed には B, C, A の順で入っています。 このような事が起こるのは asyncgui が自身ではメインループを持たない故にタイマー機能を提供できない事に起因します。 なので外部のタイマー機能を利用する事でこの問題を解消する選択肢を用意する予定なのですが、それまではこういうものだと諦めてください。 因みに Kivy を使っているのであれば Kivy のタイマー機能を用いる事でこの問題を解決済みの asynckivy-ext-queue というモジュールが既にあるので氣になる人はそちらをご利用ください。

exception Closed

Occurs when:

  • one tries to get an item from a queue that is in the CLOSED state.

  • one tries to get an item from an empty queue that is in the HALF_CLOSED state.

  • one tries to put an item into a queue that is in the CLOSED or HALF_CLOSED state.

class Queue(*, capacity: int | None = None, order: Literal['fifo', 'lifo', 'small-first'] = 'fifo')
Parameters:

capacity – Cannot be zero. Unlimited if None.

property capacity: int | None

Number of items allowed in the queue. None if unbounded.

close()

Fully closes the queue. Putting an item into it is no longer allowed. Getting an item from it is no longer allowed. All the items it holds will be discarded.

async get() → Awaitable[Any]
item = await queue.get()
get_nowait() → Any
item = queue.get_nowait()
half_close()

Partially closes the queue. Putting an item into it is no longer allowed.

property is_empty: bool
property is_full: bool
property order: Literal['fifo', 'lifo', 'small-first']
async put(item) → Awaitable
await queue.put(item)
put_nowait(item)
queue.put_nowait(item)
property size: int

Number of items in the queue. This equals to len(queue).

exception QueueException

Base class of all the queue-related exceptions.

class QueueState(value, names=None, *, module=None, qualname=None, type=None, start=1, boundary=None)

Enum class that represents the state of the Queue.

CLOSED

Putting an item into the queue is not allowed. Getting an item from the queue is not allowed.

HALF_CLOSED

Putting an item into the queue is not allowed.

OPENED

All operations are allowed.

exception WouldBlock

Raised by X_nowait functions if X would block.