[mod] engines: migration of the individual cache solutions to EngineCache

The EngineCache class replaces all previously individual solutions for caches in
the context of the engines.

- demo_offline.py
- duckduckgo.py
- radio_browser.py
- soundcloud.py
- startpage.py
- wolframalpha_api.py
- wolframalpha_noapi.py

Search term to test most of the modified engines::

    !ddg !rb !sc !sp !wa test

    !ddg !rb !sc !sp !wa foo

For introspection of the DB, jump into developer environment and run command to
show cache state::

    $ ./manage pyenv.cmd bash --norc --noprofile
    (py3) python -m searx.enginelib cache state

    cache tables and key/values
    ===========================
    [demo_offline        ] 2025-04-22 11:32:50 count        --> (int) 4
    [startpage           ] 2025-04-22 12:32:30 SC_CODE      --> (str) fSOBnhEMlDfE20
    [duckduckgo          ] 2025-04-22 12:32:31 4dff493e.... --> (str) 4-128634958369380006627592672385352473325
    [duckduckgo          ] 2025-04-22 12:40:06 3e2583e2.... --> (str) 4-263126175288871260472289814259666848451
    [radio_browser       ] 2025-04-23 11:33:08 servers      --> (list) ['https://de2.api.radio-browser.info',  ...]
    [soundcloud          ] 2025-04-29 11:40:06 guest_client_id --> (str) EjkRJG0BLNEZquRiPZYdNtJdyGtTuHdp
    [wolframalpha        ] 2025-04-22 12:40:06 code         --> (str) 5aa79f86205ad26188e0e26e28fb7ae7
    number of tables: 6
    number of key/value pairs: 7

In the "cache tables and key/values" section, the table name (engine name) is at
first position on the second there is the calculated expire date and on the
third and fourth position the key/value is shown.

About duckduckgo: The *vqd coode* of ddg depends on the query term and therefore
the key is a hash value of the query term (to not to store the raw query term).

In the "properties of ENGINES_CACHE" section all properties of the SQLiteAppl /
ExpireCache and their last modification date are shown::

    properties of ENGINES_CACHE
    ===========================
    [last modified: 2025-04-22 11:32:27] DB_SCHEMA           : 1
    [last modified: 2025-04-22 11:32:27] LAST_MAINTENANCE    :
    [last modified: 2025-04-22 11:32:27] crypt_hash          : ca612e3566fdfd7cf7efe2b1c9349f461158d07cb78a3750e5c5be686aa8ebdc
    [last modified: 2025-04-22 11:32:30] CACHE-TABLE--demo_offline: demo_offline
    [last modified: 2025-04-22 11:32:30] CACHE-TABLE--startpage: startpage
    [last modified: 2025-04-22 11:32:31] CACHE-TABLE--duckduckgo: duckduckgo
    [last modified: 2025-04-22 11:33:08] CACHE-TABLE--radio_browser: radio_browser
    [last modified: 2025-04-22 11:40:06] CACHE-TABLE--soundcloud: soundcloud
    [last modified: 2025-04-22 11:40:06] CACHE-TABLE--wolframalpha: wolframalpha

These properties provide information about the state of the ExpireCache and
control the behavior.  For example, the maintenance intervals are controlled by
the last modification date of the LAST_MAINTENANCE property and the hash value
of the password can be used to detect whether the password has been changed (in
this case the DB entries can no longer be decrypted and the entire cache must be
discarded).

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>
This commit is contained in:
Markus Heiser 2025-04-21 14:17:49 +02:00 committed by Markus Heiser
parent 4cbfba9d7b
commit bdfe1c2a15
7 changed files with 169 additions and 103 deletions

View file

@ -15,6 +15,7 @@ close to the implementation, its just a simple example. To get in use of this
import json
from searx.result_types import EngineResults
from searx.enginelib import EngineCache
engine_type = 'offline'
categories = ['general']
@ -32,14 +33,18 @@ about = {
# if there is a need for globals, use a leading underline
_my_offline_engine: str = ""
CACHE: EngineCache
"""Persistent (SQLite) key/value cache that deletes its values after ``expire``
seconds."""
def init(engine_settings=None):
def init(engine_settings):
"""Initialization of the (offline) engine. The origin of this demo engine is a
simple json string which is loaded in this example while the engine is
initialized.
initialized."""
global _my_offline_engine, CACHE # pylint: disable=global-statement
"""
global _my_offline_engine # pylint: disable=global-statement
CACHE = EngineCache(engine_settings["name"]) # type:ignore
_my_offline_engine = (
'[ {"value": "%s"}'
@ -57,8 +62,8 @@ def search(query, request_params) -> EngineResults:
results.
"""
res = EngineResults()
count = CACHE.get("count", 0)
count = 0
for row in json.loads(_my_offline_engine):
count += 1
kvmap = {
@ -75,4 +80,7 @@ def search(query, request_params) -> EngineResults:
)
)
res.add(res.types.LegacyResult(number_of_results=count))
# cache counter value for 20sec
CACHE.set("count", count, expire=20)
return res