Teknium
8adef09be8
Review fixes for #94618 (all three blockers reproduced by the reviewer through the real web_extract_tool): 1. Cache lookup moved AFTER provider resolution and strict-selection validation, and gated per-URL on the website blocklist policy — a blocklist-blocked or misconfigured-backend call now behaves exactly as it would without a cache instead of serving cached content. 2. Rescue-served extract batches are never cached (mirrors the search memo's exclusion), keeping one-shot rescue one-shot. 3. Cache entries now get dedicated per-(url, format, provider) files instead of sharing the URL-keyed truncate-store file — html and markdown (or two backends') copies of one URL no longer overwrite each other, and switching extract backends within the TTL never serves the old backend's rendering. Also from review: per-process index tmp filename (cross-process writers can no longer truncate each other mid-write) and held flight locks are never evicted from the bounded lock table (eviction could have allowed a duplicate paid request). New regression tests for formats/provider keying; E2E harness extended with policy-block, strict-selection, rescue-two-call, and dual-format scenarios — 6/6 pass; original 13/13 still pass.
350 lines
13 KiB
Python
350 lines
13 KiB
Python
"""Result caching for web_search / web_extract.
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Two caches, both TTL-bounded (default 20 minutes, ``web.cache_ttl_minutes``):
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* **Search memo** — in-memory, per-process. Keyed by (provider, normalized
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query, bucketed limit). Concurrent identical queries are single-flighted:
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the first caller performs the paid request while the rest wait and share
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the response. Requested limits are bucketed up to 10/20/50/100 so
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near-identical requests (limit=5 vs limit=8) share one entry; callers get
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their requested count sliced from the bucket.
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* **Extract cache** — disk-backed, cross-process. Reuses the existing
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``cache/web`` full-text store (the same files the truncate-store footer
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points read_file at) plus a small JSON sidecar index mapping URL digest →
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(file, fetched_at, title). A repeat ``web_extract`` of the same URL within
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TTL reads the stored clean text back instead of re-scraping, then re-runs
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the normal truncate pipeline with the caller's char_limit.
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Why this lives here and not in generic tool dispatch (issue #8126): a
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dispatch-level memo would have to reason about middleware, approval gates,
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and hooks on cache hits. Down here the cache sits *after* every safety check
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(secret-in-URL, SSRF, policy) and *before* the paid vendor call — hits skip
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only the network request, never a control.
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Disable with ``web.cache_enabled: false``; both TTLs come from
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``web.cache_ttl_minutes``. Only successful responses are ever cached.
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"""
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import hashlib
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import json
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import logging
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import os
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import re
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import threading
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import time
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from pathlib import Path
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from typing import Any, Dict, List, Optional, Tuple
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logger = logging.getLogger(__name__)
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# Requested search limits are rounded UP to one of these buckets so cache
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# keys collide on purpose (idea borrowed from Apodex FrontierAgent's
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# web_search num-bucketing). Callers get their requested count sliced out.
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_LIMIT_BUCKETS = (10, 20, 50, 100)
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DEFAULT_TTL_MINUTES = 20
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# Extract-index sidecar filename inside cache/web.
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_INDEX_FILENAME = "extract-index.json"
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# Cap index growth; oldest entries evicted past this.
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_INDEX_MAX_ENTRIES = 500
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def _web_config() -> dict:
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try:
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from tools.web_tools import _load_web_config
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return _load_web_config()
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except Exception: # noqa: BLE001 — config problems must never break tools
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return {}
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def cache_enabled() -> bool:
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"""Both caches honor ``web.cache_enabled`` (default: on)."""
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val = _web_config().get("cache_enabled")
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if val is None:
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return True
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return bool(val)
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def ttl_seconds() -> float:
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"""TTL from ``web.cache_ttl_minutes`` (default 20, clamped 1–1440)."""
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raw = _web_config().get("cache_ttl_minutes")
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try:
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minutes = float(raw) if raw is not None else DEFAULT_TTL_MINUTES
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except (TypeError, ValueError):
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minutes = DEFAULT_TTL_MINUTES
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minutes = max(1.0, min(minutes, 1440.0))
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return minutes * 60.0
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def bucket_limit(limit: int) -> int:
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"""Round a requested result count up to the nearest bucket."""
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for b in _LIMIT_BUCKETS:
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if limit <= b:
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return b
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return _LIMIT_BUCKETS[-1]
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def normalize_query(query: str) -> str:
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"""Case-fold and collapse whitespace so trivial variants share an entry."""
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return re.sub(r"\s+", " ", (query or "").strip().lower())
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# ---------------------------------------------------------------------------
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# Search memo (in-memory, single-flight)
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# ---------------------------------------------------------------------------
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class SearchMemo:
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"""TTL memo + single-flight coalescer for search responses.
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Thread-safe: web tools run inside the parallel tool-dispatch thread pool
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and subagents share this process, so identical queries can genuinely race.
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Per-key locks make the losers of that race wait for (and share) the
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winner's response instead of issuing their own paid request.
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"""
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def __init__(self) -> None:
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self._store: Dict[tuple, Tuple[float, dict]] = {}
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self._store_lock = threading.Lock()
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self._key_locks: Dict[tuple, threading.Lock] = {}
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def _key(self, provider: str, query: str, limit: int) -> tuple:
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return (provider, normalize_query(query), bucket_limit(limit))
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def lookup(self, provider: str, query: str, limit: int) -> Optional[dict]:
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if not cache_enabled():
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return None
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key = self._key(provider, query, limit)
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with self._store_lock:
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hit = self._store.get(key)
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if hit is None:
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return None
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expires, response = hit
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if time.monotonic() >= expires:
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del self._store[key]
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return None
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logger.info("web_search cache hit: %r via %s", query, provider)
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return json.loads(json.dumps(response)) # defensive copy
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def store(self, provider: str, query: str, limit: int, response: dict) -> None:
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"""Cache a SUCCESSFUL response for the bucketed key."""
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if not cache_enabled():
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return
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if not isinstance(response, dict) or not response.get("success"):
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return
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key = self._key(provider, query, limit)
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with self._store_lock:
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# Opportunistic expiry sweep to bound memory.
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now = time.monotonic()
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for k in [k for k, (exp, _) in self._store.items() if now >= exp]:
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del self._store[k]
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self._store[key] = (now + ttl_seconds(), json.loads(json.dumps(response)))
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def flight_lock(self, provider: str, query: str, limit: int) -> threading.Lock:
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"""Per-key lock for single-flight coalescing.
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Callers hold this around lookup-miss → paid request → store, so a
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concurrent identical call blocks until the winner has stored, then
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finds the entry on its own lookup.
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"""
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key = self._key(provider, query, limit)
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with self._store_lock:
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lock = self._key_locks.get(key)
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if lock is None:
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# Bound the lock table alongside the store — but never evict
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# a HELD lock: dropping one lets a concurrent identical
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# request mint a fresh lock and issue a duplicate paid call
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# (review finding on #94618). locked() under _store_lock is
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# a safe snapshot because flight locks are only ever
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# acquired by callers that already hold a reference.
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if len(self._key_locks) > 256:
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self._key_locks = {
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k: v for k, v in self._key_locks.items() if v.locked()
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}
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lock = threading.Lock()
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self._key_locks[key] = lock
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return lock
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def clear(self) -> None:
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"""Drop all cached entries (tests; config changes)."""
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with self._store_lock:
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self._store.clear()
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self._key_locks.clear()
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search_memo = SearchMemo()
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def slice_search_response(response: dict, limit: int) -> dict:
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"""Trim a bucketed response's result list down to the caller's limit."""
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try:
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web = response.get("data", {}).get("web")
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if isinstance(web, list) and len(web) > limit:
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out = json.loads(json.dumps(response))
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out["data"]["web"] = out["data"]["web"][:limit]
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return out
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except Exception: # noqa: BLE001
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pass
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return response
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# ---------------------------------------------------------------------------
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# Extract cache (disk-backed, reuses cache/web)
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# ---------------------------------------------------------------------------
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_index_lock = threading.Lock()
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def _cache_dir() -> Optional[Path]:
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try:
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from hermes_constants import get_hermes_dir
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d = get_hermes_dir("cache/web", "web_cache")
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d.mkdir(parents=True, exist_ok=True)
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return d
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except Exception: # noqa: BLE001
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return None
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def _index_path() -> Optional[Path]:
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d = _cache_dir()
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return (d / _INDEX_FILENAME) if d else None
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def _load_index() -> dict:
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path = _index_path()
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if path is None or not path.exists():
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return {}
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try:
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data = json.loads(path.read_text(encoding="utf-8"))
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return data if isinstance(data, dict) else {}
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except Exception: # noqa: BLE001 — corrupt index == empty cache
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return {}
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def _save_index(index: dict) -> None:
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path = _index_path()
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if path is None:
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return
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try:
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if len(index) > _INDEX_MAX_ENTRIES:
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newest = sorted(
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index.items(),
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key=lambda kv: kv[1].get("fetched_at", 0),
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reverse=True,
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)[:_INDEX_MAX_ENTRIES]
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index = dict(newest)
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# Per-process tmp name: CLI, gateway, cron, and subagent processes
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# all write this index; a shared fixed tmp filename would let two
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# concurrent writers truncate each other mid-write. os.replace is
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# atomic per writer, so the worst cross-process outcome is one
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# writer's entry winning — a lost cache insert, never a torn file.
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tmp = path.with_suffix(f".tmp.{os.getpid()}")
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tmp.write_text(json.dumps(index), encoding="utf-8")
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tmp.replace(path)
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except Exception as exc: # noqa: BLE001
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logger.debug("Failed to save web extract cache index: %s", exc)
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def _url_digest(url: str, format: Optional[str], provider: str = "") -> str:
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# format AND provider participate in the key: an html extract is not a
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# markdown one, and one backend's rendering of a page is not another's.
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raw = f"{url}\n{format or 'markdown'}\n{provider or ''}"
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return hashlib.sha256(raw.encode("utf-8")).hexdigest()[:16]
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def _entry_file_path(url: str, format: Optional[str], provider: str) -> Optional[Path]:
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"""Dedicated cache file per (url, format, provider) entry.
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Deliberately NOT the truncate-store file from ``_store_full_text`` — that
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filename keys on URL alone, so html/markdown (or two providers') copies
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of one URL would overwrite each other (review finding on #94618). The
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truncate-store file keeps its role for read_file paging; these files
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exist only for cache reuse and carry the full key in their name.
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"""
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d = _cache_dir()
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if d is None:
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return None
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try:
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from urllib.parse import urlparse
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host = (urlparse(url).hostname or "page").replace(":", "_")
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slug = re.sub(r"[^A-Za-z0-9._-]", "-", host)[:60].strip("-") or "page"
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except Exception: # noqa: BLE001
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slug = "page"
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return d / f"{slug}-{_url_digest(url, format, provider)}.cache.md"
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def extract_cache_get(
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url: str,
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format: Optional[str] = None,
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provider: str = "",
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) -> Optional[dict]:
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"""Return {'url','title','content'} for a fresh cached page, else None."""
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if not cache_enabled():
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return None
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with _index_lock:
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index = _load_index()
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entry = index.get(_url_digest(url, format, provider))
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if not entry:
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return None
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if (time.time() - float(entry.get("fetched_at", 0))) >= ttl_seconds():
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return None
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try:
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file_path = Path(entry["file"])
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cache_root = _cache_dir()
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# The index is plain JSON on disk; never let a tampered entry read
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# outside cache/web.
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if cache_root is None or cache_root.resolve() not in file_path.resolve().parents:
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return None
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content = file_path.read_text(encoding="utf-8")
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except Exception: # noqa: BLE001 — evicted/pruned file == miss
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return None
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logger.info("web_extract cache hit: %s", url)
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return {
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"url": url,
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"title": entry.get("title", ""),
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"content": content,
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"error": None,
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"cached": True,
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}
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def extract_cache_put(
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url: str,
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content: str,
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title: str = "",
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format: Optional[str] = None,
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provider: str = "",
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) -> None:
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"""Store one successful extraction's full clean text for TTL reuse.
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Writes a dedicated per-(url, format, provider) cache file (see
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``_entry_file_path``) — never the URL-keyed truncate-store file, which
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different formats/providers would overwrite. Pages larger than the
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truncate-store ceiling are not cached: serving a capped copy back as if
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whole would silently lose the tail.
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"""
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if not cache_enabled() or not content:
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return
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try:
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from tools.web_tools import MAX_STORED_TEXT_CHARS
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if len(content) > MAX_STORED_TEXT_CHARS:
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return
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file_path = _entry_file_path(url, format, provider)
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if file_path is None:
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return
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from tools.spill_safety import write_text_exclusive
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write_text_exclusive(file_path, content, private=False, overwrite=True)
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with _index_lock:
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index = _load_index()
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index[_url_digest(url, format, provider)] = {
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"url": url,
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"file": str(file_path),
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"title": title or "",
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"fetched_at": time.time(),
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}
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_save_index(index)
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except Exception as exc: # noqa: BLE001 — cache writes are best-effort
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logger.debug("Failed to cache web extract for %s: %s", url, exc)
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