first commit

app/cache.py

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