commit 928fefb9a542b816d7c0418077def2b3874d1b0f
author Nan Zhou <nanzhoumails@gmail.com> Mon Mar 28 08:45:00 2022 -0700
committer Nan Zhou <nanzhoumails@gmail.com> Mon Apr 11 15:42:31 2022 +0000
tree fbbf2c8924b3ffbab4159ce54b9a7c3f1b7e71c6
parent a6b9125ff91500afed34dc923e9bafb90da75ec4

sensor collection: implement efficient expand handler

This change adds an efficient expand handler for $levels=1 expand at the
sensors collection.
Instead of Query one sensor at time, it reuses existing codes for
Thermal and Power (which has AutoExpand), and queries the whole sensor at
one query. It's more efficient than the default expand handler as well
since the default handler stills query all the sensors and filter other
sensors when querying a single sensor.

Performance improves dramatically on a real hardware with 220+ sensors:

Before this change,
time wget -qO-
'http://localhost/redfish/v1/Chassis/xxx/Sensors?$expand=.($levels=1)'
> /tmp/log_slow.json

real	0m33.786s
user	0m0.000s
sys	0m0.000s

After this change
time wget -qO-
'http://localhost/redfish/v1/Chassis/xxx/Sensors?$expand=.($levels=1)'
> /tmp/log_fast.json

real	0m0.769s
user	0m0.010s
sys	0m0.010s

TESTED::
1. QEMU Redfish/IPMI passed
2. Validator passed (though it doesn't support query paramters)
3. Tested on real hardware.

{
  "@odata.id": "/redfish/v1/Chassis/xxx/Sensors",
  "@odata.type": "#SensorCollection.SensorCollection",
  "Description": "Collection of Sensors for this Chassis",
  "Members": [
     {
      "@odata.id": "/redfish/v1/Chassis/xxx/Sensors/abc",
      "@odata.type": "#Sensor.v1_0_0.Sensor",
      "Id": "abc",
      "Name": "abc",
      "Reading": 3.133,
      "ReadingRangeMax": 5.8500060148599005,
      "ReadingRangeMin": 0.0,
      "ReadingType": "Voltage",
      "ReadingUnits": "V",
      "Status": {
        "Health": "OK",
        "State": "Enabled"
      },
      "Thresholds": {
        "LowerCritical": {
          "Reading": 2.205
        },
        "UpperCritical": {
          "Reading": 3.507
        }
      }
    },
  ],
  "Members@odata.count": 225,
  "Name": "Sensors"
}

Signed-off-by: Nan Zhou <nanzhoumails@gmail.com>
Change-Id: I745a31d6fe8d0aac08d532ea976bfc1a4a40b19c