safing-portbase/api/modules.go

package api

import (
	"time"

	"github.com/safing/portbase/modules"
)

// ModuleHandler specifies the interface for API endpoints that are bound to a module.
type ModuleHandler interface {
	BelongsTo() *modules.Module
}

const (
	moduleCheckMaxWait      = 10 * time.Second
	moduleCheckTickDuration = 500 * time.Millisecond
)

// moduleIsReady checks if the given module is online and http requests can be
// sent its way. If the module is not online already, it will wait for a short
// duration for it to come online.
func moduleIsReady(m *modules.Module) (ok bool) {
	// Check if we are given a module.
	if m == nil {
		// If no module is given, we assume that the handler has not been linked to
		// a module, and we can safely continue with the request.
		return true
	}

	// Check if the module is online.
	if m.Online() {
		return true
	}

	// Check if the module will come online.
	if m.OnlineSoon() {
		var i time.Duration
		for i = 0; i < moduleCheckMaxWait; i += moduleCheckTickDuration {
			// Wait a little.
			time.Sleep(moduleCheckTickDuration)
			// Check if module is now online.
			if m.Online() {
				return true
			}
		}
	}

	return false
}