Message-ID: <20241108123816.59521-3-donald.hunter@gmail.com>
Date: Fri,  8 Nov 2024 12:38:16 +0000
From: Donald Hunter <donald.hunter@...il.com>
To: netdev@...r.kernel.org,
	Jakub Kicinski <kuba@...nel.org>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Paolo Abeni <pabeni@...hat.com>,
	Simon Horman <horms@...nel.org>,
	Xiao Liang <shaw.leon@...il.com>,
	Jiri Pirko <jiri@...nulli.us>
Cc: donald.hunter@...hat.com,
	Donald Hunter <donald.hunter@...il.com>
Subject: [PATCH net-next v1 2/2] tools/net/ynl: add async notification handling

The notification handling in ynl is currently very simple, using sleep()
to wait a period of time and then handling all the buffered messages in
a single batch.

This patch adds async notification handling so that messages can be
processed as they are received. This makes it possible to use ynl as a
library that supplies notifications in a timely manner.

- Add poll_ntf() to be a generator that yields 1 notification at a
  time and blocks until a notification is available.
- Add a --duration parameter to the CLI, with --sleep as an alias.

./tools/net/ynl/cli.py \
    --spec <SPEC> --subscribe <TOPIC> [ --duration <SECS> ]

Here is an example python snippet that shows how to use ynl as a library
for receiving notifications:

    ynl = YnlFamily(f"{dir}/rt_route.yaml")
    ynl.ntf_subscribe('rtnlgrp-ipv4-route')

    for event in ynl.poll_ntf():
        handle(event)

Signed-off-by: Donald Hunter <donald.hunter@...il.com>
---
 tools/net/ynl/cli.py     | 14 ++++++--------
 tools/net/ynl/lib/ynl.py | 22 +++++++++++++++++++---
 2 files changed, 25 insertions(+), 11 deletions(-)

diff --git a/tools/net/ynl/cli.py b/tools/net/ynl/cli.py
index b8481f401376..9853fd261ee4 100755
--- a/tools/net/ynl/cli.py
+++ b/tools/net/ynl/cli.py
@@ -4,7 +4,6 @@
 import argparse
 import json
 import pprint
-import time
 
 from lib import YnlFamily, Netlink, NlError
 
@@ -17,7 +16,6 @@ class YnlEncoder(json.JSONEncoder):
             return list(obj)
         return json.JSONEncoder.default(self, obj)
 
-
 def main():
     description = """
     YNL CLI utility - a general purpose netlink utility that uses YAML
@@ -43,7 +41,10 @@ def main():
     group.add_argument('--list-ops', action='store_true')
     group.add_argument('--list-msgs', action='store_true')
 
-    parser.add_argument('--sleep', dest='sleep', type=int)
+    parser.add_argument('--duration', dest='duration', type=int,
+                        help='when subscribed, watch for DURATION seconds')
+    parser.add_argument('--sleep', dest='duration', type=int,
+                        help='alias for duration')
     parser.add_argument('--subscribe', dest='ntf', type=str)
     parser.add_argument('--replace', dest='flags', action='append_const',
                         const=Netlink.NLM_F_REPLACE)
@@ -80,9 +81,6 @@ def main():
     if args.ntf:
         ynl.ntf_subscribe(args.ntf)
 
-    if args.sleep:
-        time.sleep(args.sleep)
-
     if args.list_ops:
         for op_name, op in ynl.ops.items():
             print(op_name, " [", ", ".join(op.modes), "]")
@@ -106,8 +104,8 @@ def main():
         exit(1)
 
     if args.ntf:
-        ynl.check_ntf()
-        output(ynl.async_msg_queue)
+        for msg in ynl.poll_ntf(duration=args.duration):
+            output(msg)
 
 
 if __name__ == "__main__":
diff --git a/tools/net/ynl/lib/ynl.py b/tools/net/ynl/lib/ynl.py
index c22c22bf2cb7..3eca432f5d7b 100644
--- a/tools/net/ynl/lib/ynl.py
+++ b/tools/net/ynl/lib/ynl.py
@@ -12,6 +12,8 @@ import sys
 import yaml
 import ipaddress
 import uuid
+import queue
+import time
 
 from .nlspec import SpecFamily
 
@@ -489,7 +491,7 @@ class YnlFamily(SpecFamily):
         self.sock.setsockopt(Netlink.SOL_NETLINK, Netlink.NETLINK_GET_STRICT_CHK, 1)
 
         self.async_msg_ids = set()
-        self.async_msg_queue = []
+        self.async_msg_queue = queue.Queue()
 
         for msg in self.msgs.values():
             if msg.is_async:
@@ -903,7 +905,7 @@ class YnlFamily(SpecFamily):
 
         msg['name'] = op['name']
         msg['msg'] = attrs
-        self.async_msg_queue.append(msg)
+        self.async_msg_queue.put(msg)
 
     def check_ntf(self):
         while True:
@@ -925,11 +927,25 @@ class YnlFamily(SpecFamily):
 
                 decoded = self.nlproto.decode(self, nl_msg, None)
                 if decoded.cmd() not in self.async_msg_ids:
-                    print("Unexpected msg id done while checking for ntf", decoded)
+                    print("Unexpected msg id while checking for ntf", decoded)
                     continue
 
                 self.handle_ntf(decoded)
 
+    def poll_ntf(self, interval=0.1, duration=None):
+        endtime = time.time() + duration if duration else None
+        while True:
+            try:
+                self.check_ntf()
+                yield self.async_msg_queue.get_nowait()
+            except queue.Empty:
+                try:
+                    time.sleep(interval)
+                except KeyboardInterrupt:
+                    return
+            if endtime and endtime < time.time():
+                return
+
     def operation_do_attributes(self, name):
       """
       For a given operation name, find and return a supported
-- 
2.47.0

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