feat(system_monitor): check UDP network errors

[iwatake2222]

Description

Why this PR is needed

• UDP packet drops make Autoware unstable. Therefore, this is an important indicator for determining whether Autoware is functioning correctly
• There are several causes of UDP packet drops, but the primary reason is drops in the send/receive buffer. This is particularly true in the case of the loopback network

What this PR changs

• Monitor UDP recv buffer errors and UDP send buffer errors

Related links

None

How was this PR tested?

• total UDP rcv buf errors and total UDP snd buf errors are monitored, and they are retrieved from /proc/net/snmp
• When errors per unit time is greater than threshold (>=1), status becomes warning
• The CPU usage of system_monitor doesn't change
  • Without this PR: 13.6% / 1600%
  • With this PR: 12.6% / 1600%
  • (the CPU usage of system_monitor in 16-core ECU)

How to cause UDP buf errors

Run the following scripts

import socket
import time

sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

# To cause snd buf error, enable the following line and run the following command
# $> sudo tc qdisc add dev lo root netem delay 100ms
# $> sudo tc qdisc del dev lo root    # fix setting
sock.setsockopt(socket.SOL_SOCKET, socket.SO_SNDBUF, 4)

target_ip = "127.0.0.1"
target_port = 12345

while True:
    sock.sendto(b"a" * 1024, (target_ip, target_port))
    time.sleep(0.00001)

import socket

sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
sock.setsockopt(socket.SOL_SOCKET, socket.SO_RCVBUF, 1)
sock.bind(("0.0.0.0", 12345))

while True:
    try:
        data, addr = sock.recvfrom(1024)
    except Exception as e:
        print(f"Error: {e}")

Notes for reviewers

None.

Interface changes

Topic changes

Additions and removals

None

Modifications

A new member named net_monitor: UDP Buf Errors is added into /diagnostics topic

ROS Parameter Changes

Additions and removals

system/system_monitor/config/net_monitor.param.yaml

Version	Parameter Name	Type	Default Value	Description
New	udp_buf_errors_check_duration	int	1	UDP buf errors check duration
New	udp_buf_errors_check_count	int	1	Generates warning when count of UDP buf errors during udp_buf_errors_check_duration reaches a specified value or higher

Modifications

None

Effects on system behavior

None.

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[iwatake2222]

@ito-san @TetsuKawa
Could you review this PR?
Also, please re-add run-build-and-test-differential label to run worflows (some workflows are stuck for some reasons...)