params helpers (#19788)

* params helpers

* add validation

common/params.py

@@ -2,3 +2,22 @@ from common.params_pyx import Params, UnknownKeyName, put_nonblocking # pylint:
 assert Params
 assert UnknownKeyName
 assert put_nonblocking
+
+if __name__ == "__main__":
+  import sys
+  from common.params_pyx import keys # pylint: disable=no-name-in-module, import-error
+
+  params = Params()
+  if len(sys.argv) == 3:
+    name = sys.argv[1]
+    val = sys.argv[2]
+    assert name.encode("utf-8") in keys.keys(), f"unknown param: {name}"
+    print(f"SET: {name} = {val}")
+    params.put(name, val)
+  elif len(sys.argv) == 2:
+    name = sys.argv[1]
+    assert name.encode("utf-8") in keys.keys(), f"unknown param: {name}"
+    print(f"GET: {name} = {params.get(name)}")
+  else:
+    for k in keys.keys():
+      print(f"GET: {k} = {params.get(k)}")