/
watcher.go
740 lines (674 loc) · 19.9 KB
/
watcher.go
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// Copyright 2012-2015 Canonical Ltd.
// Licensed under the AGPLv3, see LICENCE file for details.
package remotestate
import (
"sync"
"time"
"github.com/juju/errors"
"github.com/juju/loggo"
"gopkg.in/juju/names.v2"
"github.com/juju/juju/apiserver/params"
"github.com/juju/juju/core/leadership"
"github.com/juju/juju/watcher"
"github.com/juju/juju/worker"
"github.com/juju/juju/worker/catacomb"
)
var logger = loggo.GetLogger("juju.worker.uniter.remotestate")
// RemoteStateWatcher collects unit, service, and service config information
// from separate state watchers, and updates a Snapshot which is sent on a
// channel upon change.
type RemoteStateWatcher struct {
st State
unit Unit
service Application
relations map[names.RelationTag]*relationUnitsWatcher
relationUnitsChanges chan relationUnitsChange
storageAttachmentWatchers map[names.StorageTag]*storageAttachmentWatcher
storageAttachmentChanges chan storageAttachmentChange
leadershipTracker leadership.Tracker
updateStatusChannel func() <-chan time.Time
commandChannel <-chan string
retryHookChannel <-chan struct{}
catacomb catacomb.Catacomb
out chan struct{}
mu sync.Mutex
current Snapshot
}
// WatcherConfig holds configuration parameters for the
// remote state watcher.
type WatcherConfig struct {
State State
LeadershipTracker leadership.Tracker
UpdateStatusChannel func() <-chan time.Time
CommandChannel <-chan string
RetryHookChannel <-chan struct{}
UnitTag names.UnitTag
}
// NewWatcher returns a RemoteStateWatcher that handles state changes pertaining to the
// supplied unit.
func NewWatcher(config WatcherConfig) (*RemoteStateWatcher, error) {
w := &RemoteStateWatcher{
st: config.State,
relations: make(map[names.RelationTag]*relationUnitsWatcher),
relationUnitsChanges: make(chan relationUnitsChange),
storageAttachmentWatchers: make(map[names.StorageTag]*storageAttachmentWatcher),
storageAttachmentChanges: make(chan storageAttachmentChange),
leadershipTracker: config.LeadershipTracker,
updateStatusChannel: config.UpdateStatusChannel,
commandChannel: config.CommandChannel,
retryHookChannel: config.RetryHookChannel,
// Note: it is important that the out channel be buffered!
// The remote state watcher will perform a non-blocking send
// on the channel to wake up the observer. It is non-blocking
// so that we coalesce events while the observer is busy.
out: make(chan struct{}, 1),
current: Snapshot{
Relations: make(map[int]RelationSnapshot),
Storage: make(map[names.StorageTag]StorageSnapshot),
},
}
err := catacomb.Invoke(catacomb.Plan{
Site: &w.catacomb,
Work: func() error {
return w.loop(config.UnitTag)
},
})
if err != nil {
return nil, errors.Trace(err)
}
return w, nil
}
// Kill is part of the worker.Worker interface.
func (w *RemoteStateWatcher) Kill() {
w.catacomb.Kill(nil)
}
// Wait is part of the worker.Worker interface.
func (w *RemoteStateWatcher) Wait() error {
return w.catacomb.Wait()
}
func (w *RemoteStateWatcher) RemoteStateChanged() <-chan struct{} {
return w.out
}
func (w *RemoteStateWatcher) Snapshot() Snapshot {
w.mu.Lock()
defer w.mu.Unlock()
snapshot := w.current
snapshot.Relations = make(map[int]RelationSnapshot)
for id, relationSnapshot := range w.current.Relations {
relationSnapshotCopy := RelationSnapshot{
Life: relationSnapshot.Life,
Members: make(map[string]int64),
}
for name, version := range relationSnapshot.Members {
relationSnapshotCopy.Members[name] = version
}
snapshot.Relations[id] = relationSnapshotCopy
}
snapshot.Storage = make(map[names.StorageTag]StorageSnapshot)
for tag, storageSnapshot := range w.current.Storage {
snapshot.Storage[tag] = storageSnapshot
}
snapshot.Actions = make([]string, len(w.current.Actions))
copy(snapshot.Actions, w.current.Actions)
snapshot.Commands = make([]string, len(w.current.Commands))
copy(snapshot.Commands, w.current.Commands)
return snapshot
}
func (w *RemoteStateWatcher) ClearResolvedMode() {
w.mu.Lock()
w.current.ResolvedMode = params.ResolvedNone
w.mu.Unlock()
}
func (w *RemoteStateWatcher) CommandCompleted(completed string) {
w.mu.Lock()
defer w.mu.Unlock()
for i, id := range w.current.Commands {
if id != completed {
continue
}
w.current.Commands = append(
w.current.Commands[:i],
w.current.Commands[i+1:]...,
)
break
}
}
func (w *RemoteStateWatcher) setUp(unitTag names.UnitTag) (err error) {
// TODO(dfc) named return value is a time bomb
// TODO(axw) move this logic.
defer func() {
cause := errors.Cause(err)
if params.IsCodeNotFoundOrCodeUnauthorized(cause) {
err = worker.ErrTerminateAgent
}
}()
if w.unit, err = w.st.Unit(unitTag); err != nil {
return errors.Trace(err)
}
w.service, err = w.unit.Application()
if err != nil {
return errors.Trace(err)
}
return nil
}
func (w *RemoteStateWatcher) loop(unitTag names.UnitTag) (err error) {
if err := w.setUp(unitTag); err != nil {
return errors.Trace(err)
}
var requiredEvents int
var seenUnitChange bool
unitw, err := w.unit.Watch()
if err != nil {
return errors.Trace(err)
}
if err := w.catacomb.Add(unitw); err != nil {
return errors.Trace(err)
}
requiredEvents++
var seenServiceChange bool
servicew, err := w.service.Watch()
if err != nil {
return errors.Trace(err)
}
if err := w.catacomb.Add(servicew); err != nil {
return errors.Trace(err)
}
requiredEvents++
var seenConfigChange bool
configw, err := w.unit.WatchConfigSettings()
if err != nil {
return errors.Trace(err)
}
if err := w.catacomb.Add(configw); err != nil {
return errors.Trace(err)
}
requiredEvents++
var seenRelationsChange bool
relationsw, err := w.service.WatchRelations()
if err != nil {
return errors.Trace(err)
}
if err := w.catacomb.Add(relationsw); err != nil {
return errors.Trace(err)
}
requiredEvents++
var seenAddressesChange bool
addressesw, err := w.unit.WatchAddresses()
if err != nil {
return errors.Trace(err)
}
if err := w.catacomb.Add(addressesw); err != nil {
return errors.Trace(err)
}
requiredEvents++
var seenStorageChange bool
storagew, err := w.unit.WatchStorage()
if err != nil {
return errors.Trace(err)
}
if err := w.catacomb.Add(storagew); err != nil {
return errors.Trace(err)
}
requiredEvents++
var seenLeaderSettingsChange bool
leaderSettingsw, err := w.service.WatchLeadershipSettings()
if err != nil {
return errors.Trace(err)
}
if err := w.catacomb.Add(leaderSettingsw); err != nil {
return errors.Trace(err)
}
requiredEvents++
var seenActionsChange bool
actionsw, err := w.unit.WatchActionNotifications()
if err != nil {
return errors.Trace(err)
}
if err := w.catacomb.Add(actionsw); err != nil {
return errors.Trace(err)
}
requiredEvents++
var seenLeadershipChange bool
// There's no watcher for this per se; we wait on a channel
// returned by the leadership tracker.
requiredEvents++
var eventsObserved int
observedEvent := func(flag *bool) {
if !*flag {
*flag = true
eventsObserved++
}
}
// fire will, once the first event for each watcher has
// been observed, send a signal on the out channel.
fire := func() {
if eventsObserved != requiredEvents {
return
}
select {
case w.out <- struct{}{}:
default:
}
}
// Check the initial leadership status, and then we can flip-flop
// waiting on leader or minion to trigger the changed event.
var waitLeader, waitMinion <-chan struct{}
claimLeader := w.leadershipTracker.ClaimLeader()
select {
case <-w.catacomb.Dying():
return w.catacomb.ErrDying()
case <-claimLeader.Ready():
isLeader := claimLeader.Wait()
w.leadershipChanged(isLeader)
if isLeader {
waitMinion = w.leadershipTracker.WaitMinion().Ready()
} else {
waitLeader = w.leadershipTracker.WaitLeader().Ready()
}
observedEvent(&seenLeadershipChange)
}
for {
select {
case <-w.catacomb.Dying():
return w.catacomb.ErrDying()
case _, ok := <-unitw.Changes():
logger.Debugf("got unit change")
if !ok {
return errors.New("unit watcher closed")
}
if err := w.unitChanged(); err != nil {
return errors.Trace(err)
}
observedEvent(&seenUnitChange)
case _, ok := <-servicew.Changes():
logger.Debugf("got service change")
if !ok {
return errors.New("service watcher closed")
}
if err := w.serviceChanged(); err != nil {
return errors.Trace(err)
}
observedEvent(&seenServiceChange)
case _, ok := <-configw.Changes():
logger.Debugf("got config change: ok=%t", ok)
if !ok {
return errors.New("config watcher closed")
}
if err := w.configChanged(); err != nil {
return errors.Trace(err)
}
observedEvent(&seenConfigChange)
case _, ok := <-addressesw.Changes():
logger.Debugf("got address change: ok=%t", ok)
if !ok {
return errors.New("addresses watcher closed")
}
if err := w.addressesChanged(); err != nil {
return errors.Trace(err)
}
observedEvent(&seenAddressesChange)
case _, ok := <-leaderSettingsw.Changes():
logger.Debugf("got leader settings change: ok=%t", ok)
if !ok {
return errors.New("leader settings watcher closed")
}
if err := w.leaderSettingsChanged(); err != nil {
return errors.Trace(err)
}
observedEvent(&seenLeaderSettingsChange)
case actions, ok := <-actionsw.Changes():
logger.Debugf("got action change: %v ok=%t", actions, ok)
if !ok {
return errors.New("actions watcher closed")
}
if err := w.actionsChanged(actions); err != nil {
return errors.Trace(err)
}
observedEvent(&seenActionsChange)
case keys, ok := <-relationsw.Changes():
logger.Debugf("got relations change: ok=%t", ok)
if !ok {
return errors.New("relations watcher closed")
}
if err := w.relationsChanged(keys); err != nil {
return errors.Trace(err)
}
observedEvent(&seenRelationsChange)
case keys, ok := <-storagew.Changes():
logger.Debugf("got storage change: %v ok=%t", keys, ok)
if !ok {
return errors.New("storage watcher closed")
}
if err := w.storageChanged(keys); err != nil {
return errors.Trace(err)
}
observedEvent(&seenStorageChange)
case <-waitMinion:
logger.Debugf("got leadership change: minion")
if err := w.leadershipChanged(false); err != nil {
return errors.Trace(err)
}
waitMinion = nil
waitLeader = w.leadershipTracker.WaitLeader().Ready()
case <-waitLeader:
logger.Debugf("got leadership change: leader")
if err := w.leadershipChanged(true); err != nil {
return errors.Trace(err)
}
waitLeader = nil
waitMinion = w.leadershipTracker.WaitMinion().Ready()
case change := <-w.storageAttachmentChanges:
logger.Debugf("storage attachment change %v", change)
if err := w.storageAttachmentChanged(change); err != nil {
return errors.Trace(err)
}
case change := <-w.relationUnitsChanges:
logger.Debugf("got a relation units change: %v", change)
if err := w.relationUnitsChanged(change); err != nil {
return errors.Trace(err)
}
case <-w.updateStatusChannel():
logger.Debugf("update status timer triggered")
if err := w.updateStatusChanged(); err != nil {
return errors.Trace(err)
}
case id, ok := <-w.commandChannel:
if !ok {
return errors.New("commandChannel closed")
}
logger.Debugf("command enqueued: %v", id)
if err := w.commandsChanged(id); err != nil {
return err
}
case _, ok := <-w.retryHookChannel:
if !ok {
return errors.New("retryHookChannel closed")
}
logger.Debugf("retry hook timer triggered")
if err := w.retryHookTimerTriggered(); err != nil {
return err
}
}
// Something changed.
fire()
}
}
// updateStatusChanged is called when the update status timer expires.
func (w *RemoteStateWatcher) updateStatusChanged() error {
w.mu.Lock()
w.current.UpdateStatusVersion++
w.mu.Unlock()
return nil
}
// commandsChanged is called when a command is enqueued.
func (w *RemoteStateWatcher) commandsChanged(id string) error {
w.mu.Lock()
w.current.Commands = append(w.current.Commands, id)
w.mu.Unlock()
return nil
}
// retryHookTimerTriggered is called when the retry hook timer expires.
func (w *RemoteStateWatcher) retryHookTimerTriggered() error {
w.mu.Lock()
w.current.RetryHookVersion++
w.mu.Unlock()
return nil
}
// unitChanged responds to changes in the unit.
func (w *RemoteStateWatcher) unitChanged() error {
if err := w.unit.Refresh(); err != nil {
return errors.Trace(err)
}
resolved, err := w.unit.Resolved()
if err != nil {
return errors.Trace(err)
}
w.mu.Lock()
defer w.mu.Unlock()
w.current.Life = w.unit.Life()
w.current.ResolvedMode = resolved
return nil
}
// serviceChanged responds to changes in the service.
func (w *RemoteStateWatcher) serviceChanged() error {
if err := w.service.Refresh(); err != nil {
return errors.Trace(err)
}
url, force, err := w.service.CharmURL()
if err != nil {
return errors.Trace(err)
}
ver, err := w.service.CharmModifiedVersion()
if err != nil {
return errors.Trace(err)
}
w.mu.Lock()
w.current.CharmURL = url
w.current.ForceCharmUpgrade = force
w.current.CharmModifiedVersion = ver
w.mu.Unlock()
return nil
}
func (w *RemoteStateWatcher) configChanged() error {
w.mu.Lock()
w.current.ConfigVersion++
w.mu.Unlock()
return nil
}
func (w *RemoteStateWatcher) addressesChanged() error {
w.mu.Lock()
w.current.ConfigVersion++
w.mu.Unlock()
return nil
}
func (w *RemoteStateWatcher) leaderSettingsChanged() error {
w.mu.Lock()
w.current.LeaderSettingsVersion++
w.mu.Unlock()
return nil
}
func (w *RemoteStateWatcher) leadershipChanged(isLeader bool) error {
w.mu.Lock()
w.current.Leader = isLeader
w.mu.Unlock()
return nil
}
// relationsChanged responds to service relation changes.
func (w *RemoteStateWatcher) relationsChanged(keys []string) error {
w.mu.Lock()
defer w.mu.Unlock()
for _, key := range keys {
relationTag := names.NewRelationTag(key)
rel, err := w.st.Relation(relationTag)
if params.IsCodeNotFoundOrCodeUnauthorized(err) {
// If it's actually gone, this unit cannot have entered
// scope, and therefore never needs to know about it.
if ruw, ok := w.relations[relationTag]; ok {
worker.Stop(ruw)
delete(w.relations, relationTag)
delete(w.current.Relations, ruw.relationId)
}
} else if err != nil {
return errors.Trace(err)
} else {
if _, ok := w.relations[relationTag]; ok {
relationSnapshot := w.current.Relations[rel.Id()]
relationSnapshot.Life = rel.Life()
w.current.Relations[rel.Id()] = relationSnapshot
continue
}
ruw, err := w.st.WatchRelationUnits(relationTag, w.unit.Tag())
if err != nil {
return errors.Trace(err)
}
// Because of the delay before handing off responsibility to
// newRelationUnitsWatcher below, add to our own catacomb to
// ensure errors get picked up if they happen.
if err := w.catacomb.Add(ruw); err != nil {
return errors.Trace(err)
}
if err := w.watchRelationUnits(rel, relationTag, ruw); err != nil {
return errors.Trace(err)
}
}
}
return nil
}
// watchRelationUnits starts watching the relation units for the given
// relation, waits for its first event, and records the information in
// the current snapshot.
func (w *RemoteStateWatcher) watchRelationUnits(
rel Relation, relationTag names.RelationTag, ruw watcher.RelationUnitsWatcher,
) error {
relationSnapshot := RelationSnapshot{
Life: rel.Life(),
Members: make(map[string]int64),
}
select {
case <-w.catacomb.Dying():
return w.catacomb.ErrDying()
case change, ok := <-ruw.Changes():
if !ok {
return errors.New("relation units watcher closed")
}
for unit, settings := range change.Changed {
relationSnapshot.Members[unit] = settings.Version
}
}
innerRUW, err := newRelationUnitsWatcher(rel.Id(), ruw, w.relationUnitsChanges)
if err != nil {
return errors.Trace(err)
}
if err := w.catacomb.Add(innerRUW); err != nil {
return errors.Trace(err)
}
w.current.Relations[rel.Id()] = relationSnapshot
w.relations[relationTag] = innerRUW
return nil
}
// relationUnitsChanged responds to relation units changes.
func (w *RemoteStateWatcher) relationUnitsChanged(change relationUnitsChange) error {
w.mu.Lock()
defer w.mu.Unlock()
snapshot, ok := w.current.Relations[change.relationId]
if !ok {
return nil
}
for unit, settings := range change.Changed {
snapshot.Members[unit] = settings.Version
}
for _, unit := range change.Departed {
delete(snapshot.Members, unit)
}
return nil
}
// storageAttachmentChanged responds to storage attachment changes.
func (w *RemoteStateWatcher) storageAttachmentChanged(change storageAttachmentChange) error {
w.mu.Lock()
w.current.Storage[change.Tag] = change.Snapshot
w.mu.Unlock()
return nil
}
func (w *RemoteStateWatcher) actionsChanged(actions []string) error {
w.mu.Lock()
defer w.mu.Unlock()
w.current.Actions = append(w.current.Actions, actions...)
return nil
}
// storageChanged responds to unit storage changes.
func (w *RemoteStateWatcher) storageChanged(keys []string) error {
tags := make([]names.StorageTag, len(keys))
for i, key := range keys {
tags[i] = names.NewStorageTag(key)
}
ids := make([]params.StorageAttachmentId, len(keys))
for i, tag := range tags {
ids[i] = params.StorageAttachmentId{
StorageTag: tag.String(),
UnitTag: w.unit.Tag().String(),
}
}
results, err := w.st.StorageAttachmentLife(ids)
if err != nil {
return errors.Trace(err)
}
w.mu.Lock()
defer w.mu.Unlock()
for i, result := range results {
tag := tags[i]
if result.Error == nil {
if storageSnapshot, ok := w.current.Storage[tag]; ok {
// We've previously started a watcher for this storage
// attachment, so all we needed to do was update the
// lifecycle state.
storageSnapshot.Life = result.Life
w.current.Storage[tag] = storageSnapshot
continue
}
// We haven't seen this storage attachment before, so start
// a watcher now; add it to our catacomb in case of mishap;
// and wait for the initial event.
saw, err := w.st.WatchStorageAttachment(tag, w.unit.Tag())
if err != nil {
return errors.Annotate(err, "watching storage attachment")
}
if err := w.catacomb.Add(saw); err != nil {
return errors.Trace(err)
}
if err := w.watchStorageAttachment(tag, result.Life, saw); err != nil {
return errors.Trace(err)
}
} else if params.IsCodeNotFound(result.Error) {
if watcher, ok := w.storageAttachmentWatchers[tag]; ok {
// already under catacomb management, any error tracked already
worker.Stop(watcher)
delete(w.storageAttachmentWatchers, tag)
}
delete(w.current.Storage, tag)
} else {
return errors.Annotatef(
result.Error, "getting life of %s attachment",
names.ReadableString(tag),
)
}
}
return nil
}
// watchStorageAttachment starts watching the storage attachment with
// the specified storage tag, waits for its first event, and records
// the information in the current snapshot.
func (w *RemoteStateWatcher) watchStorageAttachment(
tag names.StorageTag,
life params.Life,
saw watcher.NotifyWatcher,
) error {
var storageSnapshot StorageSnapshot
select {
case <-w.catacomb.Dying():
return w.catacomb.ErrDying()
case _, ok := <-saw.Changes():
if !ok {
return errors.New("storage attachment watcher closed")
}
var err error
storageSnapshot, err = getStorageSnapshot(w.st, tag, w.unit.Tag())
if params.IsCodeNotProvisioned(err) {
// If the storage is unprovisioned, we still want to
// record the attachment, but we'll mark it as
// unattached. This allows the uniter to wait for
// pending storage attachments to be provisioned.
storageSnapshot = StorageSnapshot{Life: life}
} else if err != nil {
return errors.Annotatef(err, "processing initial storage attachment change")
}
}
innerSAW, err := newStorageAttachmentWatcher(
w.st, saw, w.unit.Tag(), tag, w.storageAttachmentChanges,
)
if err != nil {
return errors.Trace(err)
}
w.current.Storage[tag] = storageSnapshot
w.storageAttachmentWatchers[tag] = innerSAW
return nil
}