gistfile1.txt

package gobgp

import (
	"fmt"

	v2alpha1api "github.com/cilium/cilium/pkg/k8s/apis/cilium.io/v2alpha1"
)

// workDiff is a helper structure which provides fields and a method set
// for computing a diff of work to achieve a given
// *v2alpha1api.CiliumBGPPeeringPolicy
type workDiff struct {
	// incoming CiliumBGPPeeringConfigurations mapped by their
	// local ASN.
	seen map[int]*v2alpha1api.CiliumBGPPeeringConfiguration
	// Local ASNs which BgpServers must be instantiated, configured,
	// and added to the manager. Lookup peering configuration via `map`
	// field.
	add []int
	// Local ASNs which BgpServers exist for but current policy has marked
	// for removal. Lookup peering configuration va Manager's LocalASNMap
	remove []int
	// Local ASNs which BgpServers exist for but policy associated with server
	// may have been updated and needs further evaluation. Lookup peering configuration
	// via `map` field.
	eval []int
}

// Diff computes the work diff for given an incoming *v2alpha1api.CiliumBGPPeeringPolicy and
// the current LocalASNMap state.
//
// Once Diff is invoked the appropriate field will contain BgpServers to add, remove, or re-evaluate
// in the workDiff's respective fields.
func (wd *workDiff) Diff(m LocalASNMap, policy *v2alpha1api.CiliumBGPPeeringPolicy) error {
	if err := wd.addDiff(m, policy); err != nil {
		return fmt.Errorf("encountered error creating work diff (add): %v", err)
	}
	if err := wd.removeDiff(m, policy); err != nil {
		return fmt.Errorf("encountered error creating work diff (remove): %v", err)
	}
	return nil
}

// addDiff will populate the `seen` field of the workDiff, compute BgpServers which must be
// created, configured, and registered, and mark existing BgpServers for re-evaluation of their
// configuration.
//
// since addDiff populates the `seen` field of a diff, this method should always be called first
// when computing a work diff.
func (wd *workDiff) addDiff(m LocalASNMap, policy *v2alpha1api.CiliumBGPPeeringPolicy) error {
	for _, config := range policy.Spec.Peers {
		if _, ok := wd.seen[config.LocalASN]; !ok {
			wd.seen[config.LocalASN] = &config
		} else {
			return fmt.Errorf("encountered duplicate local ASNs")
		}
		if _, ok := m[config.LocalASN]; !ok {
			wd.add = append(wd.add, config.LocalASN)
		} else {
			wd.eval = append(wd.eval, config.LocalASN)
		}
	}
	return nil
}

// removeDiff will populate the `remove` field of a work diff, indicating which existing
// BgpServers must disconnected and removed from the Manager.
func (wd *workDiff) removeDiff(m LocalASNMap, policy *v2alpha1api.CiliumBGPPeeringPolicy) error {
	for k, _ := range m {
		if _, ok := wd.seen[k]; !ok {
			wd.remove = append(wd.remove, k)
		}
	}
	return nil
}