[mod] ExpireCacheSQLite - implement .setmany() for bulk loading

[1] https://github.com/searxng/searxng/issues/5223#issuecomment-3328597147

Suggested-by: Ivan G <igabaldon@inetol.net> [1]
Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

searx/cache.py

@@ -29,6 +29,8 @@ from searx import get_setting
 
 log = logger.getChild("cache")
 
+CacheRowType: typing.TypeAlias = tuple[str, typing.Any, int | None]
+
 
 class ExpireCacheCfg(msgspec.Struct):  # pylint: disable=too-few-public-methods
     """Configuration of a :py:obj:`ExpireCache` cache."""
@@ -81,7 +83,7 @@ class ExpireCacheCfg(msgspec.Struct):  # pylint: disable=too-few-public-methods
 class ExpireCacheStats:
     """Dataclass which provides information on the status of the cache."""
 
-    cached_items: dict[str, list[tuple[str, typing.Any, int]]]
+    cached_items: dict[str, list[CacheRowType]]
     """Values in the cache mapped by context name.
 
     .. code: python
@@ -108,7 +110,9 @@ class ExpireCacheStats:
                 continue
 
             for key, value, expire in kv_list:
-                valid_until = datetime.datetime.fromtimestamp(expire).strftime("%Y-%m-%d %H:%M:%S")
+                valid_until = ""
+                if expire:
+                    valid_until = datetime.datetime.fromtimestamp(expire).strftime("%Y-%m-%d %H:%M:%S")
                 c_kv += 1
                 lines.append(f"[{ctx_name:20s}] {valid_until} {key:12}" f" --> ({type(value).__name__}) {value} ")
 
@@ -339,38 +343,97 @@ class ExpireCacheSQLite(sqlitedb.SQLiteAppl, ExpireCache):
         exists, it will be created (on demand) by :py:obj:`self.create_table
         <ExpireCacheSQLite.create_table>`.
         """
+        c, err_msg_list = self._setmany([(key, value, expire)], ctx=ctx)
+        if c:
+            log.debug("%s -- %s: key '%s' updated or inserted (%s errors)", self.cfg.name, ctx, key, len(err_msg_list))
+        else:
+            for msg in err_msg_list:
+                log.error("%s -- %s: %s", self.cfg.name, ctx, msg)
+        return bool(c)
+
+    def setmany(
+        self,
+        opt_list: list[CacheRowType],
+        ctx: str | None = None,
+    ) -> int:
+        """Efficient bootload of the cache from a list of options.  The list
+        contains tuples with the arguments described in
+        :py:obj:`ExpireCacheSQLite.set`."""
+        _start = time.time()
+        c, err_msg_list = self._setmany(opt_list=opt_list, ctx=ctx)
+        _end = time.time()
+        for msg in err_msg_list:
+            log.error("%s -- %s: %s", self.cfg.name, ctx, msg)
+
+        log.debug(
+            "%s -- %s: %s/%s key/value pairs updated or inserted in %s sec (%s errors)",
+            self.cfg.name,
+            ctx,
+            c,
+            len(opt_list),
+            _end - _start,
+            len(err_msg_list),
+        )
+        return c
+
+    def _setmany(
+        self,
+        opt_list: list[CacheRowType],
+        ctx: str | None = None,
+    ) -> tuple[int, list[str]]:
+
         table = ctx
         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 = (
+        sql_str = (
             f"INSERT INTO {table_name} (key, value, expire) VALUES (?, ?, ?)"
             f"    ON CONFLICT DO "
             f"UPDATE SET value=?, expire=?"
         )
 
+        sql_rows: list[
+            tuple[
+                str,  # key
+                typing.Any,  # value
+                int | None,  # expire
+                typing.Any,  # value
+                int | None,  # expire
+            ]
+        ] = []
+
+        err_msg_list: list[str] = []
+        for key, _val, expire in opt_list:
+
+            value: bytes = self.serialize(value=_val)
+            if len(value) > self.cfg.MAX_VALUE_LEN:
+                err_msg_list.append(f"{table}.key='{key}' - serialized value too big to cache (len: {len(value)}) ")
+                continue
+
+            if not expire:
+                expire = self.cfg.MAXHOLD_TIME
+            expire = int(time.time()) + expire
+
+            # positional arguments of the INSERT INTO statement
+            sql_args = (key, value, expire, value, expire)
+            sql_rows.append(sql_args)
+
+        if not sql_rows:
+            return 0, err_msg_list
+
         if table:
             with self.DB:
-                self.DB.execute(sql, (key, value, expire, value, expire))
+                self.DB.executemany(sql_str, sql_rows)
         else:
             with self.connect() as conn:
-                conn.execute(sql, (key, value, expire, value, expire))
+                conn.executemany(sql_str, sql_rows)
             conn.close()
 
-        return True
+        return len(sql_rows), err_msg_list
 
     def get(self, key: str, default: typing.Any = None, ctx: str | None = None) -> typing.Any:
         """Get value of ``key`` from table given by argument ``ctx``.  If
@@ -410,7 +473,7 @@ class ExpireCacheSQLite(sqlitedb.SQLiteAppl, ExpireCache):
                 yield row[0], self.deserialize(row[1])
 
     def state(self) -> ExpireCacheStats:
-        cached_items: dict[str, list[tuple[str, typing.Any, int]]] = {}
+        cached_items: dict[str, list[CacheRowType]] = {}
         for table in self.table_names:
             cached_items[table] = []
             for row in self.DB.execute(f"SELECT key, value, expire FROM {table}"):