webmail-client/backend/app/queue.py

"""arq queue helpers (enqueue side, used by the API).

Two named queues (refactor §6): ``interactive`` (fast user actions) and ``bulk``
(backfills). Enqueue via :func:`enqueue_job`, which routes each job to its queue —
the API never needs to know queue names.
"""

from __future__ import annotations

from typing import Any

from arq import create_pool
from arq.connections import ArqRedis, RedisSettings
from arq.jobs import Job

from app.config import get_settings

_pool: ArqRedis | None = None

QUEUE_INTERACTIVE = "interactive"
QUEUE_BULK = "bulk"

# Jobs default to the interactive queue; only bulk backfills go to the bulk queue.
_BULK_JOBS = frozenset(
    {
        "sync_bootstrap_account",
        "dedupe_existing_job",
        "backfill_list_headers_job",
        "build_index_job",
    }
)


def queue_for(job_name: str) -> str:
    """Return the queue a job should run on."""
    return QUEUE_BULK if job_name in _BULK_JOBS else QUEUE_INTERACTIVE


def redis_settings() -> RedisSettings:
    """Return arq RedisSettings derived from ``REDIS_URL``."""
    return RedisSettings.from_dsn(get_settings().redis_url)


async def get_arq_pool() -> ArqRedis:
    """Return (creating on first use) the shared arq enqueue pool."""
    global _pool
    if _pool is None:
        _pool = await create_pool(redis_settings())
    return _pool


async def enqueue_job(name: str, *args: Any, **kwargs: Any) -> Job | None:
    """Enqueue ``name`` onto its routed queue (interactive/bulk)."""
    pool = await get_arq_pool()
    kwargs.setdefault("_queue_name", queue_for(name))
    return await pool.enqueue_job(name, *args, **kwargs)


async def close_arq_pool() -> None:
    """Close the arq pool."""
    global _pool
    if _pool is not None:
        await _pool.aclose()
        _pool = None