Re: [dpdk-dev] [PATCH] usertools/dpdk-telemetry: print name of app when connected

["Burakov, Anatoly" <anatoly.burakov@intel.com>]

On 16-Feb-21 9:44 AM, Bruce Richardson wrote:
> When the dpdk-telemetry client connects to a DPDK instance, we can use the
> PID provided in the initial connection message to query from /proc the name
> of the process we are connected to, and display that to the user. We use
> the "cmdline" procfs entry for the query since that is available on both
> Linux and FreeBSD (assuming procfs is mounted on the BSD instance).
> 
> Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
> ---
>   usertools/dpdk-telemetry.py | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/usertools/dpdk-telemetry.py b/usertools/dpdk-telemetry.py
> index 181859658f..82b91f346f 100755
> --- a/usertools/dpdk-telemetry.py
> +++ b/usertools/dpdk-telemetry.py
> @@ -45,6 +45,11 @@ def handle_socket(path):
>           return
>       json_reply = read_socket(sock, 1024)
>       output_buf_len = json_reply["max_output_len"]
> +    pid = json_reply["pid"]
> +    if os.path.exists('/proc/' + str(pid) + '/cmdline'):
> +        with open('/proc/' + str(pid) + '/cmdline') as f:

First of all, this is better done using os.path.join:

path = os.path.join('/proc', str(pid), 'cmdline')
if os.path.exists(path):
     with open(path) as f:
         ...

More importantly this isn't terribly Pythonic as it's not over-using 
exceptions :) IMO a better way would be:

try:
     with open(path) as f:
         ...
except IOError as e:
     # ignore if doesn't exist
     if e.errno != errno.ENOENT:
         raise

> +            argv0 = f.read(1024).split('\0')[0]
> +            print("Connected to application: '" + os.path.basename(argv0) + "'")

Also, formatting is better than concatenation, e.g. at least:

bname = os.path.basename(argv0)
print("Connected to application: '{}'".format(bname))

>   
>       # get list of commands for readline completion
>       sock.send("/".encode())
> 


-- 
Thanks,
Anatoly