Implements maxAvailableComponentSets for accurate estimator

[mszacillo]

What type of PR is this?
/kind feature

What this PR does / why we need it:
Implements maxAvailableComponentSets for the accurate estimator. I have a follow-up commented as a TODO in the implementation for the conversion of the node resource estimation into a plugin.

Which issue(s) this PR fixes:
Part of #6734

Special notes for your reviewer:
Tested E2E using code from #6857. At the moment the estimator returns 0 for the component set estimation, but this is expected since I have not linked this together with the resourcequota plugin (which is under review).

I1027 02:35:43.329736       1 server.go:240] Begin calculating available component sets of resource(kind=FlinkDeployment, name=s-spaaseng/a-5-ticker-demo), request: pb.MaxAvailableComponentSetsRequest{
    Cluster:    "spaas-kaas-tt-dev",
    Components: {
        {
            Name:                "jobmanager",
            ReplicaRequirements: pb.ReplicaRequirements{
                NodeClaim: &pb.NodeClaim{
                    NodeAffinity: (*v1.NodeSelector)(nil),
                    NodeSelector: {},
                    Tolerations:  {
                        {
                            Key:               "node.kubernetes.io/unreachable",
                            Operator:          "Exists",
                            Value:             "",
                            Effect:            "NoExecute",
                            TolerationSeconds: &int64(5),
                        },
                        {
                            Key:               "node.kubernetes.io/not-ready",
                            Operator:          "Exists",
                            Value:             "",
                            Effect:            "NoExecute",
                            TolerationSeconds: &int64(5),
                        },
                    },
                },
                ResourceRequest: {
                    "cpu": {
                        i:      resource.int64Amount{value:500, scale:-3},
                        d:      resource.infDecAmount{},
                        s:      "500m",
                        Format: "DecimalSI",
                    },
                    "memory": {
                        i:      resource.int64Amount{value:2048, scale:-3},
                        d:      resource.infDecAmount{},
                        s:      "2.048",
                        Format: "DecimalSI",
                    },
                },
                Namespace:         "s-spaaseng",
                PriorityClassName: "",
            },
            Replicas: 1,
        },
        {
            Name:                "taskmanager",
            ReplicaRequirements: pb.ReplicaRequirements{
                NodeClaim: &pb.NodeClaim{
                    NodeAffinity: (*v1.NodeSelector)(nil),
                    NodeSelector: {},
                    Tolerations:  {
                        {
                            Key:               "node.kubernetes.io/unreachable",
                            Operator:          "Exists",
                            Value:             "",
                            Effect:            "NoExecute",
                            TolerationSeconds: &int64(5),
                        },
                        {
                            Key:               "node.kubernetes.io/not-ready",
                            Operator:          "Exists",
                            Value:             "",
                            Effect:            "NoExecute",
                            TolerationSeconds: &int64(5),
                        },
                    },
                },
                ResourceRequest: {
                    "cpu": {
                        i:      resource.int64Amount{value:500, scale:-3},
                        d:      resource.infDecAmount{},
                        s:      "500m",
                        Format: "DecimalSI",
                    },
                    "memory": {
                        i:      resource.int64Amount{value:2048, scale:-3},
                        d:      resource.infDecAmount{},
                        s:      "2.048",
                        Format: "DecimalSI",
                    },
                },
                Namespace:         "s-spaaseng",
                PriorityClassName: "",
            },
            Replicas: 1,
        },
    },
}
I1027 02:35:43.330091       1 server.go:247] Finish calculating cluster available component sets of resource(kind=FlinkDeployment, name=s-spaaseng/a-5-ticker-demo), max component sets: 0, time elapsed: 1.688997ms

Does this PR introduce a user-facing change?:

`karmada-scheduler`/`karmada-scheduler-estimator`: Implemented maxAvailableComponentSets for the accurate estimator.

[gemini-code-assist]

Summary of Changes

Hello @mszacillo, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces a significant feature to the estimator, allowing it to accurately determine the maximum number of multi-component sets that can be scheduled across various clusters. This enhancement is crucial for advanced resource allocation and scheduling decisions, providing a more granular and comprehensive view of cluster capacity beyond single replica estimations.

Highlights

• Feature Implementation: This pull request implements the maxAvailableComponentSets functionality for the accurate estimator, enabling it to calculate the maximum number of complete multi-component sets a cluster can host.
• Client-Side Logic: The client-side (pkg/estimator/client/accurate.go) now includes the MaxAvailableComponentSets method, which orchestrates concurrent estimation requests across multiple clusters and handles the conversion of API types to protobuf messages for gRPC communication.
• Server-Side Estimation: On the server-side (pkg/estimator/server/estimate.go and pkg/estimator/server/server.go), new functions EstimateComponents and estimateComponents have been added to process incoming requests, update the scheduler cache snapshot, and run estimation plugins to determine the maximum component sets.
• Metrics Integration: A new metric type, EstimatingTypeMaxAvailableComponentSets, has been introduced in pkg/estimator/server/metrics/metrics.go to track the performance and usage of this new estimation capability.

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[gemini-code-assist]

Code Review

This pull request implements the maxAvailableComponentSets functionality for the accurate estimator, which is a great addition. The changes are well-structured, with corresponding client and server implementations, as well as metrics.

My review focuses on a couple of points in the server-side estimation logic. I've identified a potential bug where the estimation would always return zero, and a minor naming issue that could affect code clarity. The proposed suggestions aim to fix the bug and improve maintainability. Overall, this is a solid contribution.

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Codecov Report

❌ Patch coverage is 0% with 98 lines in your changes missing coverage. Please review.
✅ Project coverage is 46.14%. Comparing base (f60f341) to head (621f845).
⚠️ Report is 4 commits behind head on master.

Files with missing lines	Patch %	Lines
pkg/estimator/client/accurate.go	0.00%	53 Missing ⚠️
pkg/estimator/server/estimate.go	0.00%	23 Missing ⚠️
pkg/estimator/server/server.go	0.00%	22 Missing ⚠️
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Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6876      +/-   ##
==========================================
- Coverage   46.24%   46.14%   -0.11%     
==========================================
  Files         692      692              
  Lines       47194    47288      +94     
==========================================
- Hits        21826    21819       -7     
- Misses      23715    23816     +101     
  Partials     1653     1653              

Flag	Coverage Δ
unittests	46.14% <0.00%> (-0.11%)	⬇️

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[mszacillo]

@RainbowMango @zhzhuang-zju @seanlaii Should be ready for review!

[RainbowMango]

/assign

[RainbowMango]

/lgtm

[RainbowMango]

This is correct and not a blocker. But we should give it another look at the definition of the gRPC data structure. The conversion should be more straightforward.

@seanlaii Do you have any idea?

[RainbowMango]

PS:
I added a follow-up task to #6734 for revising the design here.

[RainbowMango]

/lgtm
/approve

[karmada-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: RainbowMango

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[RainbowMango]

@zhzhuang-zju Can you help look at the failing tests?

[zhzhuang-zju]

Failed Test Scenario:
After deploying a Deployment requesting cpu:10 to member cluster member1, the test checks whether the allUsed field of the quota equals cpu:10, but it is actually empty.

Event Timeline from Logs:

1. The federated-resource-quota-enforcement-controller receives the FederatedResourceQuota (FRQ) creation event. It lists all ResourceBindings (RBs) in the namespace, but at this moment rb.spec.clusters is empty, so it attempts to update the quota’s allUsed to an empty value.
2. Concurrently, the webhook tries to update the quota’s allUsed to cpu:10.
3. The webhook succeeds first:

   2025-10-28T04:28:10.639030322Z stderr F {"ts":1761625690638.9297,"caller":"resourcebinding/validating.go:237","msg":"Updating status of FRQ karmadatest-hxsjh/frq-6pnxg with OverallUsed: map[cpu:{{10 -3} {<nil>}  DecimalSI}] for RB karmadatest-hxsjh/deploy-ctz9t-deployment","v":4}
   2025-10-28T04:28:10.650167067Z stderr F {"ts":1761625690650.0215,"caller":"resourcebinding/validating.go:250","msg":"Successfully updated status of FRQ karmadatest-hxsjh/frq-6pnxg for RB karmadatest-hxsjh/deploy-ctz9t-deployment.","v":2}

4. The federated-resource-quota-enforcement-controller then fails with a conflict error and retries. During the retry, it fetches an outdated version of the ResourceBinding, and thus updates the quota’s allUsed back to empty:

   2025-10-28T04:28:10.533934235Z stderr F {"ts":1761625690140.0073,"caller":"federatedresourcequota/federated_resource_quota_enforcement_controller.go:69","msg":"QuotaEnforcementController reconciling","v":4,"namespacedName":"karmadatest-hxsjh/frq-6pnxg"}
   2025-10-28T04:28:10.631017162Z stderr F {"ts":1761625690630.2998,"caller":"federatedresourcequota/federated_resource_quota_enforcement_controller.go:240","msg":"Collecting FederatedResourceQuota status using ResourceBindings.","v":4}
   2025-10-28T04:28:10.688433682Z stderr F {"ts":1761625690686.8625,"caller":"federatedresourcequota/federated_resource_quota_enforcement_controller.go:86","msg":"Failed to collect status for FederatedResourceQuota","federatedResourceQuota":"karmadatest-hxsjh/frq-6pnxg","err":"Operation cannot be fulfilled on federatedresourcequotas.policy.karmada.io \"frq-6pnxg\": the object has been modified; please apply your changes to the latest version and try again"}
   2025-10-28T04:28:10.69834722Z stderr F {"ts":1761625690698.286,"caller":"federatedresourcequota/federated_resource_quota_enforcement_controller.go:69","msg":"QuotaEnforcementController reconciling","v":4,"namespacedName":"karmadatest-hxsjh/frq-6pnxg"}
   2025-10-28T04:28:10.698493112Z stderr F {"ts":1761625690698.436,"caller":"federatedresourcequota/federated_resource_quota_enforcement_controller.go:240","msg":"Collecting FederatedResourceQuota status using ResourceBindings.","v":4}

5. At this point, the CI checks the quota and observes that allUsed does not match the expected value, causing the test to fail.

  In [BeforeEach] at: /home/runner/work/karmada/karmada/test/e2e/suites/base/federatedresourcequota_test.go:349 @ 10/28/25 04:28:13.927

Summary:
This is a very low-probability race condition that occurs only when both the webhook and the federated-resource-quota-enforcement-controller are triggered almost simultaneously, and the controller happens to read an outdated version of the ResourceBinding.

Is this a bug?
I don't think so. The quota system is eventually consistent, and this issue is resolved automatically by the recalculation mechanism. Kubernetes’ native ResourceQuota exhibits similar behavior (see: kubernetes/kubernetes#123434 (comment)).

Can the test be hardened?
Yes. The e2e test can wait until the federated-resource-quota-enforcement-controller has successfully updated the quota before proceeding to deploy the workload.

/retest