LocalRPC: add --timeout arg

To allow running local rpc commands that might take a very long time.
The server-side `processing_timeout` is a bit ugly though... :/

electrumx/server/session.py

@@ -1528,6 +1528,8 @@ def set_request_handlers(self, ptuple):
 class LocalRPC(SessionBase):
     '''A local TCP RPC server session.'''
 
+    processing_timeout = 10**9  # disable timeouts
+
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
         self.client = 'RPC'

electrumx_rpc

@@ -85,6 +85,8 @@ def main():
     )
     main_parser.add_argument('-p', '--port', metavar='port_num', type=int,
                              help='RPC port number')
+    main_parser.add_argument('--timeout', type=int, default=30,
+                             help='timeout for command in seconds')
 
     subparsers = main_parser.add_subparsers(help='sub-command help',
                                             dest='command')
@@ -110,13 +112,15 @@ def main():
     if port is None:
         port = int(environ.get('RPC_PORT', 8000))
     method = args.pop('command')
+    timeout = args.pop('timeout')
 
     # aiorpcX makes this so easy...
     async def send_request():
         try:
-            async with timeout_after(30):
+            async with timeout_after(timeout):
                 async with connect_rs('localhost', port) as session:
                     session.transport._framer.max_size = 0
+                    session.sent_request_timeout = timeout
                     result = await session.send_request(method, args)
                     if method in ('query', ):
                         for line in result: