Add CLIENT INFO filter

[sungming2]

Issue: #1699

Problem

The CLIENT INFO command currently returns all client details, which can be excessive. This proposal suggests adding an optional parameter to request specific fields, reducing unnecessary output and improving usability.

CLIENT INFO output:

id=5 addr=127.0.0.1:33448 laddr=127.0.0.1:6379 fd=11 name= age=118 idle=0 flags=N db=8 sub=0 psub=0 ssub=0 multi=-1 watch=0 qbuf=0 qbuf-free=0 argv-mem=10 multi-mem=0 rbs=1024 rbp=0 obl=0 oll=0 omem=0 tot-mem=1562 events=r cmd=client|info user=default redir=-1 resp=2 lib-name= lib-ver= tot-net-in=131 tot-net-out=214470 tot-cmds=4

Proposal

Enhance CLIENT INFO command by adding an optional parameter to specify the fields users want to retrieve.

CLIENT INFO [field1] [field2] [...]

Example

1. Default behavior (no parameters) remains unchanged:

client info

Output:

id=2 addr=127.0.0.1:12345 laddr=127.0.0.1:6379 fd=8 name= age=3000 idle=10 ...

---

2. Retrieve specific fields:

client info id addr

Output:

id=2 addr=127.0.0.1:12345

---

3. Retrieve a single field (No parsing required):

client info id

Output:

2

[sungming2]

I wanted to avoid these repetitive conditions but it seems C doesn't have a graceful way to handle it such as

attribute_map attribute_handlers[] = {
    {"id", () => { return client->id }},
    {"addr", () => { return getClientPeerId() }},
    {"laddr", () => { return getClientSockname() }},
    // Add other attributes...
};

I am open to getting any other suggestions if it doesn't look good

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 71.14%. Comparing base (bd951e6) to head (4f9a180).
Report is 1 commits behind head on unstable.

Additional details and impacted files

@@             Coverage Diff              @@
##           unstable    #1776      +/-   ##
============================================
+ Coverage     71.10%   71.14%   +0.04%     
============================================
  Files           123      123              
  Lines         65552    65615      +63     
============================================
+ Hits          46610    46684      +74     
+ Misses        18942    18931      -11     

Files with missing lines	Coverage Δ
src/commands.def	100.00% <ø> (ø)
src/networking.c	89.00% <100.00%> (+0.15%)	⬆️

... and 12 files with indirect coverage changes

[hpatro]

Just discussed about this in our standup.

Some thought on this.

• Do we really need it?
• I found the regex in the tcl helper to do the job just fine.
• I think @madolson mentioned this, it might be more beneficial for CLIENT LIST rather than CLIENT INFO. CLIENT INFO isn't that heavily used.

Would be good to hear others perspective as well.

[sungming2]

If users don’t actively use CLIENT INFO and if this filter is primarily for testing purposes, I’m fine with closing it.
What do you think? @xbasel

[xbasel]

If users don’t actively use CLIENT INFO and if this filter is primarily for testing purposes, I’m fine with closing it. What do you think? @xbasel

sungming2
I'm not sure how many users actively use this command. I sometimes use CLIENT INFO (and CLIENT LIST) via valkey-cli and find it tedious to visually search for fields. I assume clients especially administrators who run commands interactively, might have the same experience.
No strong opinions either way.

Worth checking whether this is beneficial for CLIENT LIST.