# SPDX-License-Identifier: AGPL-3.0-or-later
"""Implementations of the framework for the SearXNG engines.
- :py:obj:`searx.enginelib.EngineCache`
- :py:obj:`searx.enginelib.Engine`
- :py:obj:`searx.enginelib.traits`
There is a command line for developer purposes and for deeper analysis. Here is
an example in which the command line is called in the development environment::
$ ./manage pyenv.cmd bash --norc --noprofile
(py3) python -m searx.enginelib --help
.. hint::
The long term goal is to modularize all implementations of the engine
framework here in this Python package. ToDo:
- move implementations of the :ref:`searx.engines loader` to a new module in
the :py:obj:`searx.enginelib` namespace.
-----
"""
__all__ = ["EngineCache", "Engine", "ENGINES_CACHE"]
import typing as t
import abc
from collections.abc import Callable
import logging
import string
import typer
from ..cache import ExpireCacheSQLite, ExpireCacheCfg
if t.TYPE_CHECKING:
from searx.enginelib import traits
from searx.enginelib.traits import EngineTraits
from searx.extended_types import SXNG_Response
from searx.result_types import EngineResults
from searx.search.processors import OfflineParamTypes, OnlineParamTypes
ENGINES_CACHE: ExpireCacheSQLite = ExpireCacheSQLite.build_cache(
ExpireCacheCfg(
name="ENGINES_CACHE",
MAXHOLD_TIME=60 * 60 * 24 * 7, # 7 days
MAINTENANCE_PERIOD=60 * 60, # 2h
)
)
"""Global :py:obj:`searx.cache.ExpireCacheSQLite` instance where the cached
values from all engines are stored. The `MAXHOLD_TIME` is 7 days and the
`MAINTENANCE_PERIOD` is set to two hours."""
app = typer.Typer()
@app.command()
def state():
"""Show state for the caches of the engines."""
title = "cache tables and key/values"
print(title)
print("=" * len(title))
print(ENGINES_CACHE.state().report())
print()
title = f"properties of {ENGINES_CACHE.cfg.name}"
print(title)
print("=" * len(title))
print(str(ENGINES_CACHE.properties))
@app.command()
def maintenance(force: bool = True):
"""Carry out maintenance on cache of the engines."""
ENGINES_CACHE.maintenance(force=force)
[docs]
class EngineCache:
"""Persistent (SQLite) key/value cache that deletes its values again after
``expire`` seconds (default/max: :py:obj:`MAXHOLD_TIME
<searx.cache.ExpireCacheCfg.MAXHOLD_TIME>`). This class is a wrapper around
:py:obj:`ENGINES_CACHE` (:py:obj:`ExpireCacheSQLite
<searx.cache.ExpireCacheSQLite>`).
In the :origin:`searx/engines/demo_offline.py` engine you can find an
exemplary implementation of such a cache other examples are implemented
in:
- :origin:`searx/engines/radio_browser.py`
- :origin:`searx/engines/soundcloud.py`
- :origin:`searx/engines/startpage.py`
.. code: python
from searx.enginelib import EngineCache
CACHE: EngineCache
def init(engine_settings):
global CACHE
CACHE = EngineCache(engine_settings["name"])
def request(query, params):
token = CACHE.get(key="token")
if token is None:
token = get_token()
# cache token of this engine for 1h
CACHE.set(key="token", value=token, expire=3600)
...
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 : ca612e3566fdfd7cf7efe...
[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).
"""
def __init__(self, engine_name: str, expire: int | None = None):
self.expire: int = expire or ENGINES_CACHE.cfg.MAXHOLD_TIME
_valid = "-_." + string.ascii_letters + string.digits
self.table_name: str = "".join([c if c in _valid else "_" for c in engine_name])
def set(self, key: str, value: t.Any, expire: int | None = None) -> bool:
return ENGINES_CACHE.set(
key=key,
value=value,
expire=expire or self.expire,
ctx=self.table_name,
)
def get(self, key: str, default: t.Any = None) -> t.Any:
return ENGINES_CACHE.get(key, default=default, ctx=self.table_name)
def secret_hash(self, name: str | bytes) -> str:
return ENGINES_CACHE.secret_hash(name=name)
[docs]
class Engine(abc.ABC): # pylint: disable=too-few-public-methods
"""Class of engine instances build from YAML settings.
Further documentation see :ref:`general engine configuration`.
.. hint::
This class is currently never initialized and only used for type hinting.
"""
logger: logging.Logger
# Common options in the engine module
engine_type: str
"""Type of the engine (:ref:`searx.search.processors`)"""
paging: bool
"""Engine supports multiple pages."""
max_page: int = 0
"""If the engine supports paging, then this is the value for the last page
that is still supported. ``0`` means unlimited numbers of pages."""
time_range_support: bool
"""Engine supports search time range."""
safesearch: bool
"""Engine supports SafeSearch"""
language_support: bool
"""Engine supports languages (locales) search."""
language: str
"""For an engine, when there is ``language: ...`` in the YAML settings the engine
does support only this one language:
.. code:: yaml
- name: google french
engine: google
language: fr
"""
region: str
"""For an engine, when there is ``region: ...`` in the YAML settings the engine
does support only this one region::
.. code:: yaml
- name: google belgium
engine: google
region: fr-BE
"""
fetch_traits: "Callable[[EngineTraits, bool], None]"
"""Function to to fetch engine's traits from origin."""
traits: "traits.EngineTraits"
"""Traits of the engine."""
# settings.yml
categories: list[str]
"""Specifies to which :ref:`engine categories` the engine should be added."""
name: str
"""Name that will be used across SearXNG to define this engine. In settings, on
the result page .."""
engine: str
"""Name of the python file used to handle requests and responses to and from
this search engine (file name from :origin:`searx/engines` without
``.py``)."""
enable_http: bool
"""Enable HTTP (by default only HTTPS is enabled)."""
shortcut: str
"""Code used to execute bang requests (``!foo``)"""
timeout: float
"""Specific timeout for search-engine."""
display_error_messages: bool
"""Display error messages on the web UI."""
proxies: dict[str, dict[str, str]]
"""Set proxies for a specific engine (YAML):
.. code:: yaml
proxies :
http: socks5://proxy:port
https: socks5://proxy:port
"""
disabled: bool
"""To disable by default the engine, but not deleting it. It will allow the
user to manually activate it in the settings."""
inactive: bool
"""Remove the engine from the settings (*disabled & removed*)."""
about: dict[str, dict[str, str]]
"""Additional fields describing the engine.
.. code:: yaml
about:
website: https://example.com
wikidata_id: Q306656
official_api_documentation: https://example.com/api-doc
use_official_api: true
require_api_key: true
results: HTML
"""
using_tor_proxy: bool
"""Using tor proxy (``true``) or not (``false``) for this engine."""
send_accept_language_header: bool
"""When this option is activated, the language (locale) that is selected by
the user is used to build and send a ``Accept-Language`` header in the
request to the origin search engine."""
tokens: list[str]
"""A list of secret tokens to make this engine *private*, more details see
:ref:`private engines`."""
weight: int
"""Weighting of the results of this engine (:ref:`weight <settings engines>`)."""
[docs]
def setup(self, engine_settings: dict[str, t.Any]) -> bool: # pylint: disable=unused-argument
"""Dynamic setup of the engine settings.
With this method, the engine's setup is carried out. For example, to
check or dynamically adapt the values handed over in the parameter
``engine_settings``. The return value (True/False) indicates whether
the setup was successful and the engine can be built or rejected.
The method is optional and is called synchronously as part of the
initialization of the service and is therefore only suitable for simple
(local) exams/changes at the engine setting. The :py:obj:`Engine.init`
method must be used for longer tasks in which values of a remote must be
determined, for example.
"""
return True
[docs]
def init(self, engine_settings: dict[str, t.Any]) -> bool | None: # pylint: disable=unused-argument
"""Initialization of the engine.
The method is optional and asynchronous (in a thread). It is suitable,
for example, for setting up a cache (for the engine) or for querying
values (required by the engine) from a remote.
Whether the initialization was successful can be indicated by the return
value ``True`` or even ``False``.
- If no return value is given from this init method (``None``), this is
equivalent to ``True``.
- If an exception is thrown as part of the initialization, this is
equivalent to ``False``.
"""
return True
[docs]
@abc.abstractmethod
def search(self, query: str, params: "OfflineParamTypes") -> "EngineResults":
"""Search method of the ``offline`` engines"""
[docs]
@abc.abstractmethod
def request(self, query: str, params: "OnlineParamTypes") -> None:
"""Method to build the parameters for the request of an ``online``
engine."""
[docs]
@abc.abstractmethod
def response(self, resp: "SXNG_Response") -> "EngineResults":
"""Method to parse the response of an ``online`` engine."""
