github.com/axw/juju@v0.0.0-20161005053422-4bd6544d08d4/worker/charmrevision/charmrevisionmanifold/manifold.go (about)

     1  // Copyright 2015 Canonical Ltd.
     2  // Licensed under the AGPLv3, see LICENCE file for details.
     3  
     4  package charmrevisionmanifold
     5  
     6  import (
     7  	"time"
     8  
     9  	"github.com/juju/errors"
    10  	"github.com/juju/utils/clock"
    11  
    12  	"github.com/juju/juju/api/base"
    13  	"github.com/juju/juju/api/charmrevisionupdater"
    14  	"github.com/juju/juju/worker"
    15  	"github.com/juju/juju/worker/charmrevision"
    16  	"github.com/juju/juju/worker/dependency"
    17  )
    18  
    19  // ManifoldConfig describes how to create a worker that checks for updates
    20  // available to deployed charms in an environment.
    21  type ManifoldConfig struct {
    22  
    23  	// The named dependencies will be exposed to the start func as resources.
    24  	APICallerName string
    25  	ClockName     string
    26  
    27  	// The remaining dependencies will be used with the resources to configure
    28  	// and create the worker. The period must be greater than 0; the NewFacade
    29  	// and NewWorker fields must not be nil. charmrevision.NewWorker, and
    30  	// NewAPIFacade, are suitable implementations for most clients.
    31  	Period    time.Duration
    32  	NewFacade func(base.APICaller) (Facade, error)
    33  	NewWorker func(charmrevision.Config) (worker.Worker, error)
    34  }
    35  
    36  // Manifold returns a dependency.Manifold that runs a charm revision worker
    37  // according to the supplied configuration.
    38  func Manifold(config ManifoldConfig) dependency.Manifold {
    39  	return dependency.Manifold{
    40  		Inputs: []string{
    41  			config.APICallerName,
    42  			config.ClockName,
    43  		},
    44  		Start: func(context dependency.Context) (worker.Worker, error) {
    45  			var clock clock.Clock
    46  			if err := context.Get(config.ClockName, &clock); err != nil {
    47  				return nil, errors.Trace(err)
    48  			}
    49  			var apiCaller base.APICaller
    50  			if err := context.Get(config.APICallerName, &apiCaller); err != nil {
    51  				return nil, errors.Trace(err)
    52  			}
    53  			facade, err := config.NewFacade(apiCaller)
    54  			if err != nil {
    55  				return nil, errors.Annotatef(err, "cannot create facade")
    56  			}
    57  
    58  			worker, err := config.NewWorker(charmrevision.Config{
    59  				RevisionUpdater: facade,
    60  				Clock:           clock,
    61  				Period:          config.Period,
    62  			})
    63  			if err != nil {
    64  				return nil, errors.Annotatef(err, "cannot create worker")
    65  			}
    66  			return worker, nil
    67  		},
    68  	}
    69  }
    70  
    71  // NewAPIFacade returns a Facade backed by the supplied APICaller.
    72  func NewAPIFacade(apiCaller base.APICaller) (Facade, error) {
    73  	return charmrevisionupdater.NewState(apiCaller), nil
    74  }
    75  
    76  // Facade has all the controller methods used by the charm revision worker.
    77  type Facade interface {
    78  	charmrevision.RevisionUpdater
    79  }