124 lines
4.3 KiB
Python
124 lines
4.3 KiB
Python
"""SSE stream of campaign events — one connection per viewer.
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Subscribes to ``campaign.>`` on the bus for the duration of the
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request and forwards each matching event as a Server-Sent Event.
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Emits a one-shot snapshot on connect (current paginated campaign
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list).
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Mirror of :mod:`decnet.web.router.identities.api_events`. Auth: JWT
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via ``?token=`` query param + ``require_stream_viewer`` role.
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"""
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from __future__ import annotations
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import asyncio
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from typing import AsyncGenerator
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import orjson
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from fastapi import APIRouter, Depends, Request
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from fastapi.responses import StreamingResponse
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from decnet.bus import topics as _topics
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from decnet.bus.app import get_app_bus
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from decnet.logging import get_logger
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from decnet.telemetry import traced as _traced
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from decnet.web.dependencies import repo, require_stream_viewer
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from decnet.web.sse_limits import sse_connection_slot
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log = get_logger("api.campaigns.events")
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router = APIRouter()
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_KEEPALIVE_SECS = 15.0
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_SNAPSHOT_LIMIT = 50
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def _format_sse(event_name: str, data: dict) -> str:
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return f"event: {event_name}\ndata: {orjson.dumps(data).decode()}\n\n"
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@router.get(
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"/campaigns/events",
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tags=["Campaign Clustering"],
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responses={
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200: {
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"content": {"text/event-stream": {}},
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"description": "SSE stream of campaign-clustering events",
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},
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401: {"description": "Could not validate credentials"},
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403: {"description": "Insufficient permissions"},
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429: {"description": "Per-user SSE connection cap reached"},
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},
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)
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@_traced("api.campaigns.events")
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async def api_campaigns_events(
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request: Request,
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user: dict = Depends(require_stream_viewer),
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) -> StreamingResponse:
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# Event types: snapshot, formed, identity.assigned, merged, unmerged.
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snapshot = await repo.list_campaigns(limit=_SNAPSHOT_LIMIT, offset=0)
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async def generator() -> AsyncGenerator[str, None]:
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async with sse_connection_slot(user["uuid"]):
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yield ": keepalive\n\n"
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yield _format_sse("snapshot", {"campaigns": snapshot})
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bus = await get_app_bus()
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if bus is None:
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while not await request.is_disconnected():
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try:
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await asyncio.sleep(_KEEPALIVE_SECS)
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except asyncio.CancelledError:
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break
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yield ": keepalive\n\n"
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return
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sub = bus.subscribe(f"{_topics.CAMPAIGN}.>")
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try:
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async with sub:
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sub_iter = sub.__aiter__()
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while True:
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if await request.is_disconnected():
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break
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next_task = asyncio.ensure_future(sub_iter.__anext__())
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try:
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event = await asyncio.wait_for(
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next_task, timeout=_KEEPALIVE_SECS,
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)
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except asyncio.TimeoutError:
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next_task.cancel()
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yield ": keepalive\n\n"
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continue
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except StopAsyncIteration:
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break
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yield _format_sse(
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_sse_name_for(event.topic),
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{
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"topic": event.topic,
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"type": event.type,
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"ts": event.ts,
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"payload": event.payload,
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},
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)
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except asyncio.CancelledError:
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pass
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except Exception:
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log.exception("campaign events stream crashed")
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yield _format_sse("error", {"message": "Stream interrupted"})
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return StreamingResponse(
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generator(),
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media_type="text/event-stream",
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headers={
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"Cache-Control": "no-cache",
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"X-Accel-Buffering": "no",
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},
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)
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def _sse_name_for(topic: str) -> str:
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"""``campaign.formed`` → ``formed``;
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``campaign.identity.assigned`` → ``identity.assigned``."""
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if topic.startswith(f"{_topics.CAMPAIGN}."):
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return topic[len(_topics.CAMPAIGN) + 1:]
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return topic
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