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Viewing changes to src/github.com/juju/juju/worker/uniter/remotestate/relationunits.go

  • Committer: Nicholas Skaggs
  • Date: 2016-10-24 20:56:05 UTC
  • Revision ID: nicholas.skaggs@canonical.com-20161024205605-z8lta0uvuhtxwzwl
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src/github.com/juju/juju/worker/uniter/remotestate/relationunits.go
 
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// Copyright 2015 Canonical Ltd.
 
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// Licensed under the AGPLv3, see LICENCE file for details.
 
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package remotestate
 
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import (
 
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        "github.com/juju/errors"
 
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        "github.com/juju/juju/watcher"
 
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        "github.com/juju/juju/worker"
 
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        "github.com/juju/juju/worker/catacomb"
 
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)
 
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type relationUnitsWatcher struct {
 
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        catacomb   catacomb.Catacomb
 
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        relationId int
 
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        changes    watcher.RelationUnitsChannel
 
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        out        chan<- relationUnitsChange
 
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}
 
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type relationUnitsChange struct {
 
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        relationId int
 
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        watcher.RelationUnitsChange
 
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}
 
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// newRelationUnitsWatcher creates a new worker that takes values from the
 
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// supplied watcher's Changes chan, annotates them with the supplied relation
 
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// id, and delivers then on the supplied out chan.
 
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//
 
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// The caller releases responsibility for stopping the supplied watcher and
 
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// waiting for errors, *whether or not this method succeeds*.
 
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func newRelationUnitsWatcher(
 
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        relationId int,
 
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        watcher watcher.RelationUnitsWatcher,
 
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        out chan<- relationUnitsChange,
 
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) (*relationUnitsWatcher, error) {
 
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        ruw := &relationUnitsWatcher{
 
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                relationId: relationId,
 
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                changes:    watcher.Changes(),
 
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                out:        out,
 
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        }
 
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        err := catacomb.Invoke(catacomb.Plan{
 
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                Site: &ruw.catacomb,
 
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                Work: ruw.loop,
 
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                Init: []worker.Worker{watcher},
 
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        })
 
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        if err != nil {
 
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                return nil, errors.Trace(err)
 
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        }
 
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        return ruw, nil
 
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}
 
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// Kill is part of the worker.Worker interface.
 
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func (w *relationUnitsWatcher) Kill() {
 
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        w.catacomb.Kill(nil)
 
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}
 
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// Wait is part of the worker.Worker interface.
 
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func (w *relationUnitsWatcher) Wait() error {
 
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        return w.catacomb.Wait()
 
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}
 
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func (w *relationUnitsWatcher) loop() error {
 
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        for {
 
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                select {
 
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                case <-w.catacomb.Dying():
 
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                        return w.catacomb.ErrDying()
 
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                case change, ok := <-w.changes:
 
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                        if !ok {
 
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                                return errors.New("watcher closed channel")
 
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                        }
 
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                        select {
 
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                        case <-w.catacomb.Dying():
 
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                                return w.catacomb.ErrDying()
 
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                        case w.out <- relationUnitsChange{w.relationId, change}:
 
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                        }
 
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                }
 
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        }
 
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}