rpc.py: add framework for detecting deprecated aliases

This will get used in upcoming patches that actually
create RPC aliases.

Thanks to Ben Walker for help on the deprecated_alias
helper.

Signed-off-by: Jim Harris <james.r.harris@intel.com>
Change-Id: Ica4432888b1ecb9bd234690758f67ef82794c50a

Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/453035
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>

scripts/rpc.py

@@ -1,6 +1,7 @@
 #!/usr/bin/env python3
 
 from rpc.client import print_dict, JSONRPCException
+from rpc.helpers import deprecated_aliases
 
 import logging
 import argparse
@@ -33,7 +34,7 @@ if __name__ == "__main__":
                         help='Set verbose mode to INFO', default="ERROR")
     parser.add_argument('--verbose', dest='verbose', choices=['DEBUG', 'INFO', 'ERROR'],
                         help="""Set verbose level. """)
-    subparsers = parser.add_subparsers(help='RPC methods')
+    subparsers = parser.add_subparsers(help='RPC methods', dest='called_rpc_name')
 
     def start_subsystem_init(args):
         rpc.start_subsystem_init(args.client)
@@ -1793,9 +1794,14 @@ Format: 'user:u1 secret:s1 muser:mu1 msecret:ms1,user:u2 secret:s2 muser:mu2 mse
     p.add_argument('-n', '--max', help="""Maximum number of notifications to return in response""", type=int)
     p.set_defaults(func=get_notifications)
 
+    def check_called_name(name):
+        if name in deprecated_aliases:
+            print("{} is deprecated, use {} instead.".format(name, deprecated_aliases[name]), file=sys.stderr)
+
     def call_rpc_func(args):
         try:
             args.func(args)
+            check_called_name(args.called_rpc_name)
         except JSONRPCException as ex:
             print("Exception:")
             print(ex.message)

scripts/rpc/helpers.py

@@ -0,0 +1,16 @@
+import sys
+
+deprecated_aliases = {}
+
+
+def deprecated_alias(old_name):
+    def wrap(f):
+        def old_f(*args, **kwargs):
+            ret = f(*args, **kwargs)
+            print("{} is deprecated, use {} instead.".format(old_name, f.__name__), file=sys.stderr)
+            return ret
+        old_f.__name__ = old_name
+        deprecated_aliases[old_name] = f.__name__
+        setattr(sys.modules[f.__module__], old_name, old_f)
+        return f
+    return wrap