87 lines
2.5 KiB
Python
87 lines
2.5 KiB
Python
"""LRU cache wrapper with per-ticker invalidation.
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Provides an in-memory cache (max 1000 entries) keyed on
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(ticker, start_date, end_date, indicator_type). Supports selective
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invalidation of all entries for a given ticker — needed when new
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OHLCV data is ingested.
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"""
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from __future__ import annotations
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from collections import OrderedDict
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from typing import Any, Hashable
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CacheKey = tuple[str, Any, Any, str] # (ticker, start_date, end_date, indicator_type)
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_DEFAULT_MAX_SIZE = 1000
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class LRUCache:
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"""Simple LRU cache backed by an ``OrderedDict``.
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Parameters
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----------
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max_size:
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Maximum number of entries. When exceeded the least-recently-used
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entry is evicted. Defaults to 1000.
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"""
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def __init__(self, max_size: int = _DEFAULT_MAX_SIZE) -> None:
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self._max_size = max_size
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self._store: OrderedDict[Hashable, Any] = OrderedDict()
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# ------------------------------------------------------------------
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# Public API
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# ------------------------------------------------------------------
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def get(self, key: CacheKey) -> Any | None:
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"""Return cached value or ``None`` on miss.
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Accessing an entry promotes it to most-recently-used.
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"""
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if key not in self._store:
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return None
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self._store.move_to_end(key)
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return self._store[key]
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def set(self, key: CacheKey, value: Any) -> None:
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"""Insert or update *key* with *value*.
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If the cache is full the least-recently-used entry is evicted.
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"""
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if key in self._store:
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self._store.move_to_end(key)
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self._store[key] = value
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return
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if len(self._store) >= self._max_size:
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self._store.popitem(last=False) # evict LRU
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self._store[key] = value
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def invalidate_ticker(self, ticker: str) -> int:
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"""Remove all entries whose first key element matches *ticker*.
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Returns the number of evicted entries.
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"""
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keys_to_remove = [k for k in self._store if k[0] == ticker]
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for k in keys_to_remove:
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del self._store[k]
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return len(keys_to_remove)
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def clear(self) -> None:
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"""Remove all entries."""
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self._store.clear()
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@property
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def size(self) -> int:
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"""Current number of cached entries."""
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return len(self._store)
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@property
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def max_size(self) -> int:
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"""Maximum capacity."""
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return self._max_size
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# Module-level singleton used by the indicator service.
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indicator_cache = LRUCache()
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