7351c38e6c
Prophylactic encryption of the value currently makes no sense; on the contrary, since the ``cryptography`` package is not available on armv7, it would cause further problems. Suggested-by: @dalf https://github.com/searxng/searxng/pull/4650#issuecomment-2830786661 Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>
391 lines
13 KiB
Python
391 lines
13 KiB
Python
"""Implementation of caching solutions.
|
|
|
|
- :py:obj:`searx.cache.ExpireCache` and its :py:obj:`searx.cache.ExpireCacheCfg`
|
|
|
|
----
|
|
"""
|
|
|
|
from __future__ import annotations
|
|
|
|
__all__ = ["ExpireCacheCfg", "ExpireCacheStats", "ExpireCache", "ExpireCacheSQLite"]
|
|
|
|
import abc
|
|
import dataclasses
|
|
import datetime
|
|
import hashlib
|
|
import hmac
|
|
import os
|
|
import pickle
|
|
import sqlite3
|
|
import string
|
|
import tempfile
|
|
import time
|
|
import typing
|
|
|
|
import msgspec
|
|
|
|
from searx import sqlitedb
|
|
from searx import logger
|
|
from searx import get_setting
|
|
|
|
log = logger.getChild("cache")
|
|
|
|
|
|
class ExpireCacheCfg(msgspec.Struct): # pylint: disable=too-few-public-methods
|
|
"""Configuration of a :py:obj:`ExpireCache` cache."""
|
|
|
|
name: str
|
|
"""Name of the cache."""
|
|
|
|
db_url: str = ""
|
|
"""URL of the SQLite DB, the path to the database file. If unset a default
|
|
DB will be created in `/tmp/sxng_cache_{self.name}.db`"""
|
|
|
|
MAX_VALUE_LEN: int = 1024 * 10
|
|
"""Max lenght of a *serialized* value."""
|
|
|
|
MAXHOLD_TIME: int = 60 * 60 * 24 * 7 # 7 days
|
|
"""Hold time (default in sec.), after which a value is removed from the cache."""
|
|
|
|
MAINTENANCE_PERIOD: int = 60 * 60 # 2h
|
|
"""Maintenance period in seconds / when :py:obj:`MAINTENANCE_MODE` is set to
|
|
``auto``."""
|
|
|
|
MAINTENANCE_MODE: typing.Literal["auto", "off"] = "auto"
|
|
"""Type of maintenance mode
|
|
|
|
``auto``:
|
|
Maintenance is carried out automatically as part of the maintenance
|
|
intervals (:py:obj:`MAINTENANCE_PERIOD`); no external process is required.
|
|
|
|
``off``:
|
|
Maintenance is switched off and must be carried out by an external process
|
|
if required.
|
|
"""
|
|
|
|
password: bytes = get_setting("server.secret_key").encode() # type: ignore
|
|
"""Password used by :py:obj:`ExpireCache.secret_hash`.
|
|
|
|
The default password is taken from :ref:`secret_key <server.secret_key>`.
|
|
When the password is changed, the hashed keys in the cache can no longer be
|
|
used, which is why all values in the cache are deleted when the password is
|
|
changed.
|
|
"""
|
|
|
|
def __post_init__(self):
|
|
# if db_url is unset, use a default DB in /tmp/sxng_cache_{name}.db
|
|
if not self.db_url:
|
|
self.db_url = tempfile.gettempdir() + os.sep + f"sxng_cache_{ExpireCache.normalize_name(self.name)}.db"
|
|
|
|
|
|
@dataclasses.dataclass
|
|
class ExpireCacheStats:
|
|
"""Dataclass wich provides information on the status of the cache."""
|
|
|
|
cached_items: dict[str, list[tuple[str, typing.Any, int]]]
|
|
"""Values in the cache mapped by table name.
|
|
|
|
.. code: python
|
|
|
|
{
|
|
"table name": [
|
|
("foo key": "foo value", <expire>),
|
|
("bar key": "bar value", <expire>),
|
|
# ...
|
|
],
|
|
# ...
|
|
}
|
|
"""
|
|
|
|
def report(self):
|
|
c_tables = 0
|
|
c_kv = 0
|
|
lines = []
|
|
|
|
for table_name, kv_list in self.cached_items.items():
|
|
c_tables += 1
|
|
if not kv_list:
|
|
lines.append(f"[{table_name:20s}] empty")
|
|
continue
|
|
|
|
for key, value, expire in kv_list:
|
|
valid_until = datetime.datetime.fromtimestamp(expire).strftime("%Y-%m-%d %H:%M:%S")
|
|
c_kv += 1
|
|
lines.append(f"[{table_name:20s}] {valid_until} {key:12}" f" --> ({type(value).__name__}) {value} ")
|
|
|
|
lines.append(f"number of tables: {c_tables}")
|
|
lines.append(f"number of key/value pairs: {c_kv}")
|
|
return "\n".join(lines)
|
|
|
|
|
|
class ExpireCache(abc.ABC):
|
|
"""Abstract base class for the implementation of a key/value cache
|
|
with expire date."""
|
|
|
|
cfg: ExpireCacheCfg
|
|
|
|
hash_token = "hash_token"
|
|
|
|
@abc.abstractmethod
|
|
def set(self, key: str, value: typing.Any, expire: int | None) -> bool:
|
|
"""Set *key* to *value*. To set a timeout on key use argument
|
|
``expire`` (in sec.). If expire is unset the default is taken from
|
|
:py:obj:`ExpireCacheCfg.MAXHOLD_TIME`. After the timeout has expired,
|
|
the key will automatically be deleted.
|
|
"""
|
|
|
|
@abc.abstractmethod
|
|
def get(self, key: str, default=None) -> typing.Any:
|
|
"""Return *value* of *key*. If key is unset, ``None`` is returned."""
|
|
|
|
@abc.abstractmethod
|
|
def maintenance(self, force: bool = False, truncate: bool = False) -> bool:
|
|
"""Performs maintenance on the cache.
|
|
|
|
``force``:
|
|
Maintenance should be carried out even if the maintenance interval has
|
|
not yet been reached.
|
|
|
|
``truncate``:
|
|
Truncate the entire cache, which is necessary, for example, if the
|
|
password has changed.
|
|
"""
|
|
|
|
@abc.abstractmethod
|
|
def state(self) -> ExpireCacheStats:
|
|
"""Returns a :py:obj:`ExpireCacheStats`, which provides information
|
|
about the status of the cache."""
|
|
|
|
@staticmethod
|
|
def build_cache(cfg: ExpireCacheCfg) -> ExpireCache:
|
|
"""Factory to build a caching instance.
|
|
|
|
.. note::
|
|
|
|
Currently, only the SQLite adapter is available, but other database
|
|
types could be implemented in the future, e.g. a Valkey (Redis)
|
|
adapter.
|
|
"""
|
|
return ExpireCacheSQLite(cfg)
|
|
|
|
@staticmethod
|
|
def normalize_name(name: str) -> str:
|
|
"""Returns a normalized name that can be used as a file name or as a SQL
|
|
table name."""
|
|
|
|
_valid = "-_." + string.ascii_letters + string.digits
|
|
return "".join([c for c in name if c in _valid])
|
|
|
|
def serialize(self, value: typing.Any) -> bytes:
|
|
dump: bytes = pickle.dumps(value)
|
|
return dump
|
|
|
|
def deserialize(self, value: bytes) -> typing.Any:
|
|
obj = pickle.loads(value)
|
|
return obj
|
|
|
|
def secret_hash(self, name: str | bytes) -> str:
|
|
"""Creates a hash of the argument ``name``. The hash value is formed
|
|
from the ``name`` combined with the :py:obj:`password
|
|
<ExpireCacheCfg.password>`. Can be used, for example, to make the
|
|
``key`` stored in the DB unreadable for third parties."""
|
|
|
|
if isinstance(name, str):
|
|
name = bytes(name, encoding='utf-8')
|
|
m = hmac.new(name + self.cfg.password, digestmod='sha256')
|
|
return m.hexdigest()
|
|
|
|
|
|
class ExpireCacheSQLite(sqlitedb.SQLiteAppl, ExpireCache):
|
|
"""Cache that manages key/value pairs in a SQLite DB. The DB model in the
|
|
SQLite DB is implemented in abstract class :py:obj:`SQLiteAppl
|
|
<searx.sqlitedb.SQLiteAppl>`.
|
|
|
|
The following configurations are required / supported:
|
|
|
|
- :py:obj:`ExpireCacheCfg.db_url`
|
|
- :py:obj:`ExpireCacheCfg.MAXHOLD_TIME`
|
|
- :py:obj:`ExpireCacheCfg.MAINTENANCE_PERIOD`
|
|
- :py:obj:`ExpireCacheCfg.MAINTENANCE_MODE`
|
|
"""
|
|
|
|
DB_SCHEMA = 1
|
|
|
|
# The key/value tables will be created on demand by self.create_table
|
|
DDL_CREATE_TABLES = {}
|
|
|
|
CACHE_TABLE_PREFIX = "CACHE-TABLE-"
|
|
|
|
def __init__(self, cfg: ExpireCacheCfg):
|
|
"""An instance of the SQLite expire cache is build up from a
|
|
:py:obj:`config <ExpireCacheCfg>`."""
|
|
|
|
self.cfg = cfg
|
|
if cfg.db_url == ":memory:":
|
|
log.critical("don't use SQLite DB in :memory: in production!!")
|
|
super().__init__(cfg.db_url)
|
|
|
|
def init(self, conn: sqlite3.Connection) -> bool:
|
|
ret_val = super().init(conn)
|
|
if not ret_val:
|
|
return False
|
|
|
|
new = hashlib.sha256(self.cfg.password).hexdigest()
|
|
old = self.properties(self.hash_token)
|
|
if old != new:
|
|
if old is not None:
|
|
log.warning("[%s] hash token changed: truncate all cache tables", self.cfg.name)
|
|
self.maintenance(force=True, truncate=True)
|
|
self.properties.set(self.hash_token, new)
|
|
|
|
return True
|
|
|
|
def maintenance(self, force: bool = False, truncate: bool = False) -> bool:
|
|
|
|
if not force and int(time.time()) < self.next_maintenance_time:
|
|
# log.debug("no maintenance required yet, next maintenance interval is in the future")
|
|
return False
|
|
|
|
# Prevent parallel DB maintenance cycles from other DB connections
|
|
# (e.g. in multi thread or process environments).
|
|
self.properties.set("LAST_MAINTENANCE", "") # hint: this (also) sets the m_time of the property!
|
|
|
|
if truncate:
|
|
self.truncate_tables(self.table_names)
|
|
return True
|
|
|
|
# drop items by expire time stamp ..
|
|
expire = int(time.time())
|
|
|
|
with self.connect() as conn:
|
|
for table in self.table_names:
|
|
res = conn.execute(f"DELETE FROM {table} WHERE expire < ?", (expire,))
|
|
log.debug("deleted %s keys from table %s (expire date reached)", res.rowcount, table)
|
|
|
|
# Vacuuming the WALs
|
|
# https://www.theunterminatedstring.com/sqlite-vacuuming/
|
|
|
|
conn.execute("PRAGMA wal_checkpoint(TRUNCATE)")
|
|
conn.close()
|
|
|
|
return True
|
|
|
|
def create_table(self, table: str) -> bool:
|
|
"""Create DB ``table`` if it has not yet been created, no recreates are
|
|
initiated if the table already exists.
|
|
"""
|
|
if table in self.table_names:
|
|
# log.debug("key/value table %s exists in DB (no need to recreate)", table)
|
|
return False
|
|
|
|
log.info("key/value table '%s' NOT exists in DB -> create DB table ..", table)
|
|
sql_table = "\n".join(
|
|
[
|
|
f"CREATE TABLE IF NOT EXISTS {table} (",
|
|
" key TEXT,",
|
|
" value BLOB,",
|
|
f" expire INTEGER DEFAULT (strftime('%s', 'now') + {self.cfg.MAXHOLD_TIME}),",
|
|
"PRIMARY KEY (key))",
|
|
]
|
|
)
|
|
sql_index = f"CREATE INDEX IF NOT EXISTS index_expire_{table} ON {table}(expire);"
|
|
with self.connect() as conn:
|
|
conn.execute(sql_table)
|
|
conn.execute(sql_index)
|
|
conn.close()
|
|
|
|
self.properties.set(f"{self.CACHE_TABLE_PREFIX}-{table}", table)
|
|
return True
|
|
|
|
@property
|
|
def table_names(self) -> list[str]:
|
|
"""List of key/value tables already created in the DB."""
|
|
sql = f"SELECT value FROM properties WHERE name LIKE '{self.CACHE_TABLE_PREFIX}%%'"
|
|
rows = self.DB.execute(sql).fetchall() or []
|
|
return [r[0] for r in rows]
|
|
|
|
def truncate_tables(self, table_names: list[str]):
|
|
log.debug("truncate table: %s", ",".join(table_names))
|
|
with self.connect() as conn:
|
|
for table in table_names:
|
|
conn.execute(f"DELETE FROM {table}")
|
|
conn.close()
|
|
return True
|
|
|
|
@property
|
|
def next_maintenance_time(self) -> int:
|
|
"""Returns (unix epoch) time of the next maintenance."""
|
|
|
|
return self.cfg.MAINTENANCE_PERIOD + self.properties.m_time("LAST_MAINTENANCE", int(time.time()))
|
|
|
|
# implement ABC methods of ExpireCache
|
|
|
|
def set(self, key: str, value: typing.Any, expire: int | None, table: str | None = None) -> bool:
|
|
"""Set key/value in ``table``. If expire is unset the default is taken
|
|
from :py:obj:`ExpireCacheCfg.MAXHOLD_TIME`. If ``table`` argument is
|
|
``None`` (the default), a table name is generated from the
|
|
:py:obj:`ExpireCacheCfg.name`. If DB ``table`` does not exists, it will be
|
|
created (on demand) by :py:obj:`self.create_table
|
|
<ExpireCacheSQLite.create_table>`.
|
|
"""
|
|
self.maintenance()
|
|
|
|
value = self.serialize(value=value)
|
|
if len(value) > self.cfg.MAX_VALUE_LEN:
|
|
log.warning("ExpireCache.set(): %s.key='%s' - value too big to cache (len: %s) ", table, value, len(value))
|
|
return False
|
|
|
|
if not expire:
|
|
expire = self.cfg.MAXHOLD_TIME
|
|
expire = int(time.time()) + expire
|
|
|
|
table_name = table
|
|
if not table_name:
|
|
table_name = self.normalize_name(self.cfg.name)
|
|
self.create_table(table_name)
|
|
|
|
sql = (
|
|
f"INSERT INTO {table_name} (key, value, expire) VALUES (?, ?, ?)"
|
|
f" ON CONFLICT DO "
|
|
f"UPDATE SET value=?, expire=?"
|
|
)
|
|
|
|
if table:
|
|
with self.DB:
|
|
self.DB.execute(sql, (key, value, expire, value, expire))
|
|
else:
|
|
with self.connect() as conn:
|
|
conn.execute(sql, (key, value, expire, value, expire))
|
|
conn.close()
|
|
|
|
return True
|
|
|
|
def get(self, key: str, default=None, table: str | None = None) -> typing.Any:
|
|
"""Get value of ``key`` from ``table``. If ``table`` argument is
|
|
``None`` (the default), a table name is generated from the
|
|
:py:obj:`ExpireCacheCfg.name`. If ``key`` not exists (in table), the
|
|
``default`` value is returned.
|
|
"""
|
|
self.maintenance()
|
|
|
|
if not table:
|
|
table = self.normalize_name(self.cfg.name)
|
|
|
|
if table not in self.table_names:
|
|
return default
|
|
|
|
sql = f"SELECT value FROM {table} WHERE key = ?"
|
|
row = self.DB.execute(sql, (key,)).fetchone()
|
|
if row is None:
|
|
return default
|
|
|
|
return self.deserialize(row[0])
|
|
|
|
def state(self) -> ExpireCacheStats:
|
|
cached_items = {}
|
|
for table in self.table_names:
|
|
cached_items[table] = []
|
|
for row in self.DB.execute(f"SELECT key, value, expire FROM {table}"):
|
|
cached_items[table].append((row[0], self.deserialize(row[1]), row[2]))
|
|
return ExpireCacheStats(cached_items=cached_items)
|