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backend/app/data/fetcher.py

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+"""数据编排：拉取（Tushare 主 -> AKShare 兜底）+ 本地缓存。
+
+真实行情落库到 candles 表（timeframe='1d'），回测统一从库读，与 DEMO 同路径。
+"""
+from __future__ import annotations
+
+import asyncio
+
+from sqlalchemy import delete, func, select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from ..config import settings
+from ..domain import Bar
+from ..models import Candle
+from . import akshare_provider, tushare_provider
+
+DEFAULT_START = settings.data_default_start or "20200101"
+
+
+def _providers(source: str):
+    """按优先级返回 (名称, 同步拉取函数) 列表。"""
+    seq = []
+    if source in ("auto", "tushare") and settings.tushare_token:
+        seq.append(("tushare", tushare_provider.fetch_daily))
+    if source in ("auto", "akshare"):
+        seq.append(("akshare", akshare_provider.fetch_daily))
+    return seq
+
+
+async def count_cached(session: AsyncSession, symbol: str) -> int:
+    res = await session.execute(
+        select(func.count()).select_from(Candle).where(
+            Candle.symbol == symbol, Candle.timeframe == "1d"
+        )
+    )
+    return int(res.scalar() or 0)
+
+
+async def is_cached(session: AsyncSession, symbol: str) -> bool:
+    return await count_cached(session, symbol) > 0
+
+
+async def sync_symbol(
+    session: AsyncSession,
+    code: str,
+    start: str | None = None,
+    end: str | None = None,
+    source: str = "auto",
+    force: bool = False,
+) -> dict:
+    """拉取并缓存某标的日线。已缓存且非 force 时直接返回缓存计数。"""
+    if not force and await is_cached(session, code):
+        return {"symbol": code, "bars": await count_cached(session, code), "source": "cache"}
+
+    start = start or DEFAULT_START
+    adjust = settings.data_adjust
+    errors: list[str] = []
+    bars: list[Bar] = []
+    used = None
+
+    for name, fn in _providers(source):
+        try:
+            # tushare/akshare 是同步网络 IO，丢到线程池避免阻塞事件循环
+            bars = await asyncio.to_thread(fn, code, start, end, adjust)
+            used = name
+            break
+        except Exception as e:  # noqa: BLE001
+            errors.append(f"{name}: {e}")
+
+    if not bars:
+        raise RuntimeError("所有数据源均失败 -> " + " | ".join(errors) if errors else "无可用数据源")
+
+    # 全量替换该标的日线（避免重复主键）
+    await session.execute(delete(Candle).where(Candle.symbol == code, Candle.timeframe == "1d"))
+    for b in bars:
+        session.add(
+            Candle(symbol=code, timeframe="1d", ts=b.ts, open=b.open, high=b.high,
+                   low=b.low, close=b.close, volume=b.volume)
+        )
+    await session.commit()
+    return {"symbol": code, "bars": len(bars), "source": used}