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state.go
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state.go
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/*
Copyright 2022 Nokia.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package state
import "context"
type WorkerEvent struct {
Action WorkerAction
Req any
EventCtx *EventCtx
}
type EventCtx struct {
EpIdx int
Message string // used to indicate failures
Hold bool
SameHost bool // inidcated this ep is on the same host as the peer ep
}
type Event string
const (
CreateEvent Event = "create"
DeleteEvent Event = "delete"
ResolutionFailedEvent Event = "resolutionFailed"
CreatedEvent Event = "created"
DeletedEvent Event = "deleted"
FailedEvent Event = "failed"
)
type WorkerAction string
const (
WorkerActionCreate WorkerAction = "create"
WorkerActionDelete WorkerAction = "delete"
)
type StateCtx struct {
State
EventCtx
}
type StateTransition interface {
Transition(ctx context.Context, newState State, eventCtx *EventCtx, generatedEvents ...WorkerAction)
GetAdditionalState(eventCtx *EventCtx) []StateCtx
}
type State interface {
String() string
HandleEvent(ctx context.Context, event Event, eventCtx *EventCtx, w StateTransition)
}
type Deleting struct{}
func (s *Deleting) String() string { return "Deleting" }
func (s *Deleting) HandleEvent(ctx context.Context, event Event, eventCtx *EventCtx, o StateTransition) {
switch event {
case CreateEvent:
if eventCtx.SameHost {
// do nothing
o.Transition(ctx, &Created{}, eventCtx)
} else {
// action -> trigger create to the daemon
o.Transition(ctx, &Creating{}, eventCtx, "create")
}
case DeleteEvent:
// action -> do nothing as deleting is ongoing
case ResolutionFailedEvent:
o.Transition(ctx, &ResolutionFailed{}, eventCtx)
// action -> based on hold trigger delete event on the other end
if !eventCtx.Hold {
sctxs := o.GetAdditionalState(eventCtx)
for _, sctx := range sctxs {
sctx.State.HandleEvent(ctx, DeleteEvent, &sctx.EventCtx, o)
}
}
case DeletedEvent:
o.Transition(ctx, &Deleted{}, eventCtx)
// action -> do nothing since the delete was successfull, trigger genericEvent
case FailedEvent:
o.Transition(ctx, &Failed{}, eventCtx)
// action -> do nothing, trigger genericEvent
default:
// these events should not happen
// CreatedEvent
}
}
type Deleted struct{}
func (s *Deleted) String() string { return "Deleted" }
func (s *Deleted) HandleEvent(ctx context.Context, event Event, eventCtx *EventCtx, o StateTransition) {
switch event {
case CreateEvent:
if eventCtx.SameHost {
o.Transition(ctx, &Created{}, eventCtx)
} else {
o.Transition(ctx, &Creating{}, eventCtx, "create")
}
// action -> trigger create to the daemon
case DeleteEvent:
// action -> do nothing since we are already deleted
case ResolutionFailedEvent:
o.Transition(ctx, &ResolutionFailed{}, eventCtx)
default:
// these events should not happen
// CreatedEvent, DeletedEvent, FailedEvent
}
}
type Failed struct{} // here we trigger an action on the other end
func (s *Failed) String() string { return "Failed" }
func (s *Failed) HandleEvent(ctx context.Context, event Event, eventCtx *EventCtx, o StateTransition) {
switch event {
case CreateEvent:
if eventCtx.SameHost {
o.Transition(ctx, &Created{}, eventCtx)
} else {
o.Transition(ctx, &Creating{}, eventCtx, "create")
}
// action -> trigger create to the daemon
case DeleteEvent:
if eventCtx.SameHost {
o.Transition(ctx, &Deleted{}, eventCtx)
} else {
o.Transition(ctx, &Deleting{}, eventCtx, "delete")
}
// action -> trigger create to the daemon
case ResolutionFailedEvent:
o.Transition(ctx, &ResolutionFailed{}, eventCtx)
if !eventCtx.Hold {
sctxs := o.GetAdditionalState(eventCtx)
for _, sctx := range sctxs {
sctx.State.HandleEvent(ctx, DeleteEvent, &sctx.EventCtx, o)
}
}
default:
// these events should not happen
// CreatedEvent, DeletedEvent, FailedEvent
}
}
type Creating struct{}
func (s *Creating) String() string { return "Creating" }
func (s *Creating) HandleEvent(ctx context.Context, event Event, eventCtx *EventCtx, o StateTransition) {
switch event {
case CreateEvent:
if eventCtx.SameHost {
o.Transition(ctx, &Created{}, eventCtx)
}
// action -> do nothing as creating is ongoing
case DeleteEvent:
if eventCtx.SameHost {
o.Transition(ctx, &Deleted{}, eventCtx)
} else {
o.Transition(ctx, &Deleting{}, eventCtx, "delete")
}
// action -> trigger delete to the daemon
case ResolutionFailedEvent:
o.Transition(ctx, &ResolutionFailed{}, eventCtx)
if !eventCtx.Hold {
sctxs := o.GetAdditionalState(eventCtx)
for _, sctx := range sctxs {
sctx.State.HandleEvent(ctx, DeleteEvent, &sctx.EventCtx, o)
}
}
case CreatedEvent:
o.Transition(ctx, &Created{}, eventCtx)
// done
case FailedEvent:
o.Transition(ctx, &Failed{}, eventCtx)
// done
default:
// these events should not happen: DeletedEvent
}
}
type Created struct{}
func (s *Created) String() string { return "Created" }
func (s *Created) HandleEvent(ctx context.Context, event Event, eventCtx *EventCtx, o StateTransition) {
switch event {
case CreateEvent:
// do nothing
case DeleteEvent:
if eventCtx.SameHost {
o.Transition(ctx, &Deleted{}, eventCtx)
} else {
o.Transition(ctx, &Deleting{}, eventCtx, "delete")
}
// action -> trigger delete to the daemon
case ResolutionFailedEvent:
o.Transition(ctx, &ResolutionFailed{}, eventCtx)
if !eventCtx.Hold {
sctxs := o.GetAdditionalState(eventCtx)
for _, sctx := range sctxs {
sctx.State.HandleEvent(ctx, DeleteEvent, &sctx.EventCtx, o)
}
/*
otherEpIdx := (eventCtx.EpIdx + 1) % 2
o.EndpointsState[otherEpIdx].HandleEvent(DeleteEvent, &EventCtx{
EpIdx: otherEpIdx,
}, o)
*/
}
default:
// these events should not happen: CreatedEvent, DeletedEvent, FailedEvent
}
}
type ResolutionFailed struct{} // here we can either hold or trigger an action on the other end
func (s *ResolutionFailed) String() string { return "ResolutionFailed" }
func (s *ResolutionFailed) HandleEvent(ctx context.Context, event Event, eventCtx *EventCtx, w StateTransition) {
switch event {
case CreateEvent:
if eventCtx.SameHost {
w.Transition(ctx, &Created{}, eventCtx)
} else {
w.Transition(ctx, &Creating{}, eventCtx, "create")
}
case DeleteEvent:
w.Transition(ctx, &Deleting{}, eventCtx, "delete")
case ResolutionFailedEvent:
// do nothing since we are already in resolution failed
default:
// these events should not happen: CreatedEvent, DeletedEvent, FailedEvent
}
}