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resources: Overhaul legacy code around the resource API

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This patch makes a number of changes in the engine surrounding the
resource API. In particular:

* Cleanup of send/read event.
* Cleanup of DoSend (now Event) in the Watch method.
* Events are now more consistently pointers.
* Exiting within Watch is now done in a single place.
* Multiple incoming events will be combined into a single action.
* Events in flight during an action are played back after CheckApply.
* Addition of Close method to API

This gets things ready for rate limiting and semaphore metaparams!
This commit is contained in:
James Shubin
2017-01-04 16:22:19 -05:00
parent 74435aac76
commit 51c83116a2
17 changed files with 268 additions and 222 deletions
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73
resources/resources.go
View File

@@ -26,6 +26,7 @@ import (
"log"
"os"
"path"
"sync"
"time"
// TODO: should each resource be a sub-package?
@@ -129,19 +130,19 @@ type Base interface {
SetKind(string)
Kind() string
Meta() *MetaParams
Events() chan event.Event
Events() chan *event.Event
AssociateData(*Data)
IsWatching() bool
SetWatching(bool)
IsWorking() bool
SetWorking(bool)
Converger() converger.Converger
RegisterConverger()
UnregisterConverger()
ConvergerUID() converger.ConvergerUID
GetState() ResState
SetState(ResState)
DoSend(chan event.Event, string) (bool, error)
SendEvent(event.EventName, bool, bool) bool
ReadEvent(*event.Event) (bool, bool) // TODO: optional here?
Event(chan *event.Event) error
SendEvent(event.EventName, error) error
ReadEvent(*event.Event) (*error, bool)
Refresh() bool // is there a pending refresh to run?
SetRefresh(bool) // set the refresh state of this resource
SendRecv(Res) (map[string]bool, error) // send->recv data passing function
@@ -154,10 +155,10 @@ type Base interface {
GetGroup() []Res // return everyone grouped inside me
SetGroup([]Res)
VarDir(string) (string, error)
Running(chan event.Event) error // notify the engine that Watch started
Started() <-chan struct{} // returns when the resource has started
Running(chan *event.Event) error // notify the engine that Watch started
Started() <-chan struct{} // returns when the resource has started
Starter(bool)
Poll(chan event.Event) error // poll alternative to watching :(
Poll(chan *event.Event) error // poll alternative to watching :(
}
// Res is the minimum interface you need to implement to define a new resource.
@@ -166,8 +167,9 @@ type Res interface {
Default() Res // return a struct with sane defaults as a Res
Validate() error
Init() error
GetUIDs() []ResUID // most resources only return one
Watch(chan event.Event) error // send on channel to signal process() events
Close() error
GetUIDs() []ResUID // most resources only return one
Watch(chan *event.Event) error // send on channel to signal process() events
CheckApply(apply bool) (checkOK bool, err error)
AutoEdges() AutoEdge
Compare(Res) bool
@@ -182,13 +184,14 @@ type BaseRes struct {
Recv map[string]*Send // mapping of key to receive on from value
kind string
events chan event.Event
mutex *sync.Mutex // locks around sending and closing of events channel
events chan *event.Event
converger converger.Converger // converged tracking
cuid converger.ConvergerUID
prefix string // base prefix for this resource
debug bool
state ResState
watching bool // is Watch() loop running ?
working bool // is the Worker() loop running ?
started chan struct{} // closed when worker is started/running
starter bool // does this have indegree == 0 ? XXX: usually?
isStateOK bool // whether the state is okay based on events or not
@@ -244,8 +247,9 @@ func (obj *BaseRes) Init() error {
if obj.kind == "" {
return fmt.Errorf("Resource did not set kind!")
}
obj.events = make(chan event.Event) // unbuffered chan to avoid stale events
obj.started = make(chan struct{}) // closes when started
obj.mutex = &sync.Mutex{}
obj.events = make(chan *event.Event) // unbuffered chan to avoid stale events
obj.started = make(chan struct{}) // closes when started
//dir, err := obj.VarDir("")
//if err != nil {
// return errwrap.Wrapf(err, "VarDir failed in Init()")
@@ -255,6 +259,15 @@ func (obj *BaseRes) Init() error {
return nil
}
// Close shuts down and performs any cleanup.
func (obj *BaseRes) Close() error {
obj.mutex.Lock()
obj.working = false // obj.SetWorking(false)
close(obj.events) // this is where we properly close this channel!
obj.mutex.Unlock()
return nil
}
// GetName is used by all the resources to Get the name.
func (obj *BaseRes) GetName() string {
return obj.Name
@@ -281,7 +294,7 @@ func (obj *BaseRes) Meta() *MetaParams {
}
// Events returns the channel of events to listen on.
func (obj *BaseRes) Events() chan event.Event {
func (obj *BaseRes) Events() chan *event.Event {
return obj.events
}
@@ -292,14 +305,18 @@ func (obj *BaseRes) AssociateData(data *Data) {
obj.debug = data.Debug
}
// IsWatching tells us if the Worker() function is running.
func (obj *BaseRes) IsWatching() bool {
return obj.watching
// IsWorking tells us if the Worker() function is running.
func (obj *BaseRes) IsWorking() bool {
obj.mutex.Lock()
defer obj.mutex.Unlock()
return obj.working
}
// SetWatching stores the status of if the Worker() function is running.
func (obj *BaseRes) SetWatching(b bool) {
obj.watching = b
// SetWorking tracks the state of if Worker() function is running.
func (obj *BaseRes) SetWorking(b bool) {
obj.mutex.Lock()
defer obj.mutex.Unlock()
obj.working = b
}
// Converger returns the converger object used by the system. It can be used to
@@ -455,7 +472,7 @@ func (obj *BaseRes) Started() <-chan struct{} { return obj.started }
func (obj *BaseRes) Starter(b bool) { obj.starter = b }
// Poll is the watch replacement for when we want to poll, which outputs events.
func (obj *BaseRes) Poll(processChan chan event.Event) error {
func (obj *BaseRes) Poll(processChan chan *event.Event) error {
cuid := obj.ConvergerUID() // get the converger uid used to report status
// create a time.Ticker for the given interval
@@ -468,7 +485,7 @@ func (obj *BaseRes) Poll(processChan chan event.Event) error {
}
var send = false
var exit = false
var exit *error
for {
obj.SetState(ResStateWatching)
select {
@@ -479,16 +496,14 @@ func (obj *BaseRes) Poll(processChan chan event.Event) error {
case event := <-obj.Events():
cuid.ResetTimer() // important
if exit, send = obj.ReadEvent(&event); exit {
return nil
if exit, send = obj.ReadEvent(event); exit != nil {
return *exit // exit
}
}
if send {
send = false
if exit, err := obj.DoSend(processChan, ""); exit || err != nil {
return err // we exit or bubble up a NACK...
}
obj.Event(processChan)
}
}
}