kood-scheduler: fix Reservation Score divide by zero

[eahydra]

Signed-off-by: Joseph joseph.t.lee@outlook.com

Ⅰ. Describe what this PR does

fix Reservation Score divide by zero.

Ⅱ. Does this pull request fix one issue?

Ⅲ. Describe how to verify it

1. create a reservation with empty resources as the following:

apiVersion: scheduling.koordinator.sh/v1alpha1
kind: Reservation
metadata:
  name: test
spec:
  allocateOnce: true
  owners:
  - labelSelector:
      matchLabels:
        app: test
  template:
    metadata:
      name: test-55859d896f-8dx9c
      namespace: default
    spec:
      containers:
      - resources:
          limits:
            cpu: "0"
            memory: "0"
          requests:
            cpu: "0"
            memory: "0"
      priority: 9000
      priorityClassName: koord-prod
      restartPolicy: Always
      schedulerName: koord-scheduler
      tolerations:
      - effect: NoExecute
        key: node.kubernetes.io/not-ready
        operator: Exists
        tolerationSeconds: 300
      - effect: NoExecute
        key: node.kubernetes.io/unreachable
        operator: Exists
        tolerationSeconds: 300
  ttl: 30m0s

2. wait the Reservation scheduled by koord-scheduler
3. create a pod with label app=test and pod resources requests defines as the following:

spec:
  containers:
  - resources:
      limits:
        cpu: "0"
        memory: "0"
      requests:
        cpu: "0"
        memory: "0"

5. the koord-scheduler panic

apply the PR, the koord-scheduler schedule successfully.

Ⅳ. Special notes for reviews

V. Checklist

• I have written necessary docs and comments
• I have added necessary unit tests and integration tests
• All checks passed in make test

[eahydra]

/hold
I need to add UT for the case.

[eahydra]

/hold cancel

[codecov]

Codecov Report

Merging #564 (0bd66e5) into main (330680b) will increase coverage by 0.03%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #564      +/-   ##
==========================================
+ Coverage   67.14%   67.18%   +0.03%     
==========================================
  Files         164      164              
  Lines       17760    17762       +2     
==========================================
+ Hits        11925    11933       +8     
+ Misses       4950     4946       -4     
+ Partials      885      883       -2     

Flag	Coverage Δ
unittests	67.18% <100.00%> (+0.03%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
pkg/scheduler/plugins/reservation/rcache.go	89.07% <100.00%> (+0.09%)	⬆️
pkg/scheduler/plugins/reservation/plugin.go	80.21% <0.00%> (+0.63%)	⬆️
pkg/util/httputil/reverseproxy.go	85.10% <0.00%> (+0.79%)	⬆️

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[hormes]

/lgtm
/approve

[koordinator-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hormes

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