Teknium
102 lines
3.9 KiB
Python
102 lines
3.9 KiB
Python
"""Per-session event sequencing + bounded replay for WS reconnects.
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Every event frame through :func:`server.write_json` (hence ``_emit``) gets a per-session monotonic
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``seq`` and lands in a small ring per session; a reconnecting client calls ``session.events.since``
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with its last seen seq and gets everything newer. Invariants: stdio TUI unaffected (``seq`` only on
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event frames; Ink ignores unknown keys); one lock guards counters + buffers, and write_json already
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serializes per-transport writes so stamping cannot reorder frames; memory bound =
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_REPLAY_BUFFER_MAX events x _REPLAY_SESSIONS_MAX sessions, oldest session evicted FIFO.
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"""
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from __future__ import annotations
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import threading
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import uuid
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from collections import OrderedDict, deque
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# Seq counters live in-process, so a restart resets them to 1 while clients hold high
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# watermarks — events_since(sid, 97) would return [] with truncated=False forever. The
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# epoch lets clients detect the restart and reset their watermarks.
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_REPLAY_EPOCH = uuid.uuid4().hex
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# A long turn emits ~hundreds of token events; 512 covers minutes of streaming plus
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# all control events. Desktop users rarely exceed a dozen live chats.
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_REPLAY_BUFFER_MAX = 512
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_REPLAY_SESSIONS_MAX = 64
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_replay_lock = threading.Lock()
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# sid -> deque of (seq, params dict) — the bare event (type/session_id/seq/payload),
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# the exact shape the client's dispatch path consumes.
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_replay_buffers: "OrderedDict[str, deque]" = OrderedDict()
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_replay_next_seq: dict[str, int] = {}
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def replay_epoch() -> str:
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"""Opaque token identifying this server process's seq numbering."""
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return _REPLAY_EPOCH
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def _stamp_event(obj: dict) -> None:
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"""Stamp one outgoing event frame (mutates obj in place) and record it."""
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if obj.get("method") != "event":
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return
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params = obj.get("params")
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if not isinstance(params, dict):
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return
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sid = params.get("session_id") or ""
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if not sid:
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# Session-less global events (skin.changed etc.) are re-fetchable via their own RPCs.
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return
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with _replay_lock:
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seq = _replay_next_seq.get(sid, 0) + 1
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_replay_next_seq[sid] = seq
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params["seq"] = seq
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buf = _replay_buffers.get(sid)
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if buf is None:
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buf = _replay_buffers[sid] = deque(maxlen=_REPLAY_BUFFER_MAX)
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while len(_replay_buffers) > _REPLAY_SESSIONS_MAX:
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_oldest_sid, _oldest_buf = _replay_buffers.popitem(last=False)
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_replay_next_seq.pop(_oldest_sid, None)
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buf.append((seq, params))
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def events_since(sid: str, last_seen: int) -> list[dict]:
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"""Recorded EVENT OBJECTS (each frame's ``params`` dict) with seq > last_seen for *sid*.
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Returning the full JSON-RPC envelope would make every replayed event fail the
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client's ``event.type`` gate and be silently dropped.
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"""
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with _replay_lock:
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buf = _replay_buffers.get(sid or "")
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return [event for seq, event in buf if seq > last_seen] if buf else []
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def is_truncated(sid: str, last_seen: int) -> bool:
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"""True when events between *last_seen* and the ring's oldest retained seq were
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evicted — the client must refetch history instead of trusting the replay."""
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with _replay_lock:
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buf = _replay_buffers.get(sid or "")
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return bool(buf) and last_seen + 1 < buf[0][0]
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def latest_seq(sid: str) -> int:
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"""Current highest stamped seq for *sid* (0 when unknown)."""
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with _replay_lock:
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return _replay_next_seq.get(sid or "", 0)
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def reset_replay_state() -> None:
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"""Test hook."""
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with _replay_lock:
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_replay_buffers.clear()
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_replay_next_seq.clear()
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def replay_stats() -> dict:
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"""Telemetry: buffer occupancy for the ops/debug surface."""
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with _replay_lock:
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return {
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"sessions": len(_replay_buffers),
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"events": sum(len(b) for b in _replay_buffers.values()),
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"max_per_session": _REPLAY_BUFFER_MAX}
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