util.go

package helpers

import (
	"context"
	"fmt"
	"math"
	"time"

	. "github.com/onsi/gomega"
	"github.com/solo-io/solo-kit/pkg/api/v1/clients"
	"github.com/solo-io/solo-kit/pkg/api/v1/resources"
	"github.com/solo-io/solo-kit/pkg/api/v1/resources/core"
	skerrors "github.com/solo-io/solo-kit/pkg/errors"
)

// PatchResource mutates an existing persisted resource, retrying if a resourceVersionError is encountered
// The mutator method must return the full object that will be persisted, any side effects from the mutator will be ignored
func PatchResource(ctx context.Context, resourceRef *core.ResourceRef, mutator func(resource resources.Resource) resources.Resource, client clients.ResourceClient) error {
	return PatchResourceWithOffset(1, ctx, resourceRef, mutator, client)
}

// PatchResourceWithOffset mutates an existing persisted resource, retrying if a resourceVersionError is encountered
// The mutator method must return the full object that will be persisted, any side effects from the mutator will be ignored
func PatchResourceWithOffset(offset int, ctx context.Context, resourceRef *core.ResourceRef, mutator func(resource resources.Resource) resources.Resource, client clients.ResourceClient) error {
	// There is a potential bug in our resource writing implementation that leads to test flakes
	// https://github.com/solo-io/gloo/issues/7044
	// This is a temporary solution to ensure that tests do not flake

	var patchErr error

	EventuallyWithOffset(offset+1, func(g Gomega) {
		resource, err := client.Read(resourceRef.GetNamespace(), resourceRef.GetName(), clients.ReadOpts{Ctx: ctx})
		g.Expect(err).NotTo(HaveOccurred())
		resourceVersion := resource.GetMetadata().GetResourceVersion()

		mutatedResource := mutator(resource)
		mutatedResource.GetMetadata().ResourceVersion = resourceVersion

		_, patchErr = client.Write(mutatedResource, clients.WriteOpts{Ctx: ctx, OverwriteExisting: true})
		g.Expect(skerrors.IsResourceVersion(patchErr)).To(BeFalse())
	}, time.Second*5, time.Second).ShouldNot(HaveOccurred())

	return patchErr
}

// PercentileIndex returns the index of percentile pct for a slice of length len
// The Nearest Rank Method is used to determine percentiles (https://en.wikipedia.org/wiki/Percentile#The_nearest-rank_method)
// Valid inputs for pct are 0 < n <= 100, any other input will cause panic
func PercentileIndex(len, pct int) int {
	if pct <= 0 || pct > 100 {
		panic(fmt.Sprintf("percentile must be > 0 and <= 100, given %d", pct))
	}

	return int(math.Ceil(float64(len)*(float64(pct)/float64(100)))) - 1
}