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a382192 080d003 a382192 080d003 a382192 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 | """Query result caching with Redis fallback to in-memory.
Caches RAG pipeline results to avoid redundant LLM calls and retrieval
for identical queries from the same user. Uses Redis when available for
distributed caching across multiple app instances.
"""
from __future__ import annotations
import hashlib
import json
import time
from typing import Any
from config.settings import settings
from utils.logging import get_logger
from utils.pii import redact_dict
logger = get_logger(__name__)
# In-memory fallback cache
_memory_cache: dict[str, tuple[dict[str, Any], float]] = {}
_memory_cache_ttl_seconds: float = 300.0 # 5 minutes default
# Redis singleton
_redis_client = None
# Cache metrics counters
_cache_hits: int = 0
_cache_misses: int = 0
def get_cache_metrics() -> dict[str, int]:
"""Return cache hit/miss counters."""
total = _cache_hits + _cache_misses
return {
"hits": _cache_hits,
"misses": _cache_misses,
"total": total,
"hit_rate": round(_cache_hits / total, 4) if total > 0 else 0.0,
}
def reset_cache_metrics() -> None:
"""Reset cache hit/miss counters."""
global _cache_hits, _cache_misses
_cache_hits = 0
_cache_misses = 0
def _get_redis_client():
"""Lazy-initialize Redis client for query caching.
Returns:
Redis client instance or None if unavailable.
"""
global _redis_client
if _redis_client is not None:
return _redis_client
if not settings.redis_url:
return None
try:
import redis
_redis_client = redis.from_url(settings.redis_url, decode_responses=True)
_redis_client.ping()
logger.info("query_cache_redis_connected")
return _redis_client
except ImportError:
logger.debug("redis_not_installed_for_query_cache")
except Exception as exc:
logger.warning("query_cache_redis_connection_failed", error=str(exc))
_redis_client = False # Mark as unavailable
return None
def _user_prefix(user_id: str) -> str:
"""Stable per-user key prefix so ``invalidate_user_cache`` can scan by user."""
return hashlib.sha256(user_id.encode()).hexdigest()[:12]
def _build_cache_key(user_id: str, query: str, context_hash: str = "") -> str:
"""Build a deterministic cache key from user + query.
The key is ``<user_prefix><body_hash>`` so a single user's entries share a
common prefix — that is what makes ``invalidate_user_cache`` work (a hash of
one string is never a prefix of a hash of a different string, so the old
``startswith(sha256(user_id))`` scan silently matched nothing).
Args:
user_id: The user's identifier.
query: The query text.
context_hash: Optional hash of additional context (model, filters, etc.).
Returns:
A hash string suitable for use as a cache key.
"""
body = f"{query.lower().strip()}:{context_hash}"
body_hash = hashlib.sha256(body.encode()).hexdigest()[:20]
return f"{_user_prefix(user_id)}{body_hash}"
def get_cached_result(
user_id: str,
query: str,
context_hash: str = "",
ttl_seconds: float | None = None,
) -> dict[str, Any] | None:
"""Retrieve a cached query result if available and not expired.
Args:
user_id: The user's identifier.
query: The query text.
context_hash: Optional hash of additional context.
ttl_seconds: Cache TTL. Defaults to settings or 300s.
Returns:
Cached result dict, or None if not found or expired.
"""
cache_key = _build_cache_key(user_id, query, context_hash)
_ = ttl_seconds or _memory_cache_ttl_seconds
global _cache_hits, _cache_misses
# Try Redis first
redis_client = _get_redis_client()
if redis_client:
try:
cached = redis_client.get(f"rag:query:{cache_key}")
if cached:
result = json.loads(cached)
_cache_hits += 1
logger.info("query_cache_hit", source="redis", user_id=user_id)
return result
except Exception as exc:
logger.debug("query_cache_redis_read_failed", error=str(exc))
# Fallback to in-memory
if cache_key in _memory_cache:
result, expiry = _memory_cache[cache_key]
if time.time() < expiry:
_cache_hits += 1
logger.info("query_cache_hit", source="memory", user_id=user_id)
return result
# Expired — clean up
del _memory_cache[cache_key]
_cache_misses += 1
return None
def set_cached_result(
user_id: str,
query: str,
result: dict[str, Any],
context_hash: str = "",
ttl_seconds: float | None = None,
) -> None:
"""Store a query result in the cache.
Args:
user_id: The user's identifier.
query: The query text.
result: The result dict to cache.
context_hash: Optional hash of additional context.
ttl_seconds: Cache TTL. Defaults to settings or 300s.
"""
cache_key = _build_cache_key(user_id, query, context_hash)
ttl = ttl_seconds or _memory_cache_ttl_seconds
# Serialize result (exclude non-serializable fields) + redact PII before
# persistence so disk/Redis never sees emails, phones, card numbers, etc.
serializable_result = redact_dict(_make_serializable(result))
# Try Redis first
redis_client = _get_redis_client()
if redis_client:
try:
redis_client.setex(
f"rag:query:{cache_key}",
int(ttl),
json.dumps(serializable_result),
)
logger.info("query_cache_stored", source="redis", user_id=user_id)
return
except Exception as exc:
logger.debug("query_cache_redis_write_failed", error=str(exc))
# Fallback to in-memory
_memory_cache[cache_key] = (serializable_result, time.time() + ttl)
logger.info("query_cache_stored", source="memory", user_id=user_id)
# Prune memory cache if too large
if len(_memory_cache) > 1000:
_prune_memory_cache()
def _make_serializable(obj: Any) -> Any:
"""Convert an object to a JSON-serializable form.
Args:
obj: Object to serialize.
Returns:
JSON-serializable representation.
"""
if isinstance(obj, dict):
return {k: _make_serializable(v) for k, v in obj.items()}
if isinstance(obj, list):
return [_make_serializable(v) for v in obj]
if isinstance(obj, (str, int, float, bool, type(None))):
return obj
return str(obj)
def _prune_memory_cache() -> None:
"""Remove expired entries from the in-memory cache."""
now = time.time()
expired_keys = [k for k, (_, expiry) in _memory_cache.items() if expiry < now]
for k in expired_keys:
del _memory_cache[k]
# If still too large, remove oldest
if len(_memory_cache) > 1000:
sorted_items = sorted(_memory_cache.items(), key=lambda x: x[1][1])
for k, _ in sorted_items[:100]:
del _memory_cache[k]
def invalidate_user_cache(user_id: str) -> int:
"""Invalidate all cached queries for a specific user.
Args:
user_id: The user's identifier.
Returns:
Number of entries invalidated.
"""
count = 0
# In-memory — keys are namespaced ``<user_prefix><body_hash>`` so a single
# user's entries share this prefix (see _build_cache_key).
prefix = _user_prefix(user_id)
keys_to_remove = [k for k in _memory_cache if k.startswith(prefix)]
for k in keys_to_remove:
del _memory_cache[k]
count += 1
# Redis — keys are stored under ``rag:query:<user_prefix><body_hash>`` so a
# single user's entries share the ``rag:query:<prefix>`` namespace. Scan by
# that scoped pattern so invalidating one user never flushes another tenant's
# cache (the old ``rag:query:*`` scan nuked everyone).
redis_client = _get_redis_client()
if redis_client:
try:
pattern = f"rag:query:{prefix}*"
for key in redis_client.scan_iter(match=pattern, count=100):
redis_client.delete(key)
count += 1
except Exception as exc:
logger.debug("query_cache_redis_invalidate_failed", error=str(exc))
logger.info("query_cache_invalidated", user_id=user_id, count=count)
return count
def clear_all_cache() -> int:
"""Clear all query caches (memory + Redis).
Returns:
Number of entries cleared.
"""
count = len(_memory_cache)
_memory_cache.clear()
redis_client = _get_redis_client()
if redis_client:
try:
pattern = "rag:query:*"
for key in redis_client.scan_iter(match=pattern, count=100):
redis_client.delete(key)
count += 1
except Exception as exc:
logger.debug("query_cache_redis_clear_failed", error=str(exc))
logger.info("query_cache_cleared_all", count=count)
return count
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