uncloud/pkg/client/deploy/scheduler/service.go

package scheduler

import (
	"context"
	"errors"
	"fmt"

	"github.com/psviderski/uncloud/internal/machine/api/pb"
	"github.com/psviderski/uncloud/pkg/api"
)

type ServiceScheduler struct {
	machines    []*Machine
	spec        api.ServiceSpec
	constraints []Constraint
}

func NewServiceSchedulerWithClient(ctx context.Context, cli Client, spec api.ServiceSpec) (*ServiceScheduler, error) {
	machines, err := InspectMachines(ctx, cli)
	if err != nil {
		return nil, fmt.Errorf("inspect machines: %w", err)
	}

	return NewServiceSchedulerWithMachines(machines, spec), nil
}

// NewServiceSchedulerWithMachines creates a new ServiceScheduler with the given machines and service specification.
func NewServiceSchedulerWithMachines(machines []*Machine, spec api.ServiceSpec) *ServiceScheduler {
	constraints := constraintsFromSpec(spec)

	return &ServiceScheduler{
		machines:    machines,
		spec:        spec,
		constraints: constraints,
	}
}

// EligibleMachines returns a list of machines that satisfy all constraints for the next scheduled container.
func (s *ServiceScheduler) EligibleMachines() ([]*Machine, error) {
	var available []*Machine
	for _, machine := range s.machines {
		if s.evaluateConstraints(machine) {
			available = append(available, machine)
		}
	}
	if len(available) == 0 {
		return nil, errors.New("no machines available that satisfy all constraints")
	}
	return available, nil
}

func (s *ServiceScheduler) evaluateConstraints(machine *Machine) bool {
	for _, c := range s.constraints {
		if !c.Evaluate(machine) {
			return false
		}
	}
	return true
}

func (s *ServiceScheduler) ScheduleContainer() ([]*pb.MachineInfo, error) {
	// TODO: organise machines in a heap and supply a sort function from the strategy. Each scheduled container
	//  should update the machine and reorder it in the heap.
	return nil, errors.New("not implemented")
}