github.com/axw/juju@v0.0.0-20161005053422-4bd6544d08d4/worker/logforwarder/tracker.go (about)

     1  // Copyright 2016 Canonical Ltd.
     2  // Licensed under the AGPLv3, see LICENCE file for details.
     3  
     4  package logforwarder
     5  
     6  import (
     7  	"github.com/juju/errors"
     8  	"gopkg.in/juju/names.v2"
     9  
    10  	"github.com/juju/juju/api/base"
    11  	logfwdapi "github.com/juju/juju/api/logfwd"
    12  	"github.com/juju/juju/logfwd"
    13  	"github.com/juju/juju/logfwd/syslog"
    14  )
    15  
    16  // TrackingSinkArgs holds the args to OpenTrackingSender.
    17  type TrackingSinkArgs struct {
    18  	// AllModels indicates that the tracker is handling all models.
    19  	AllModels bool
    20  
    21  	// Config is the logging config that will be used.
    22  	Config *syslog.RawConfig
    23  
    24  	// Caller is the API caller that will be used.
    25  	Caller base.APICaller
    26  
    27  	// Name is the name given to the log sink.
    28  	Name string
    29  
    30  	// OpenSink is the function that opens the underlying log sink that
    31  	// will be wrapped.
    32  	OpenSink LogSinkFn
    33  }
    34  
    35  // OpenTrackingSink opens a log record sender to use with a worker.
    36  // The sender also tracks records that were successfully sent.
    37  func OpenTrackingSink(args TrackingSinkArgs) (*LogSink, error) {
    38  	sink, err := args.OpenSink(args.Config)
    39  	if err != nil {
    40  		return nil, errors.Trace(err)
    41  	}
    42  
    43  	return &LogSink{
    44  		&trackingSender{
    45  			SendCloser: sink,
    46  			tracker:    newLastSentTracker(args.Name, args.Caller),
    47  		},
    48  	}, nil
    49  }
    50  
    51  type trackingSender struct {
    52  	SendCloser
    53  	tracker   *lastSentTracker
    54  	allModels bool
    55  }
    56  
    57  // Send implements Sender.
    58  func (s *trackingSender) Send(records []logfwd.Record) error {
    59  	if err := s.SendCloser.Send(records); err != nil {
    60  		return errors.Trace(err)
    61  	}
    62  	if err := s.tracker.setLastSent(s.allModels, records); err != nil {
    63  		return errors.Trace(err)
    64  	}
    65  	return nil
    66  }
    67  
    68  type lastSentTracker struct {
    69  	sink   string
    70  	client *logfwdapi.LastSentClient
    71  }
    72  
    73  func newLastSentTracker(sink string, caller base.APICaller) *lastSentTracker {
    74  	client := logfwdapi.NewLastSentClient(func(name string) logfwdapi.FacadeCaller {
    75  		return base.NewFacadeCaller(caller, name)
    76  	})
    77  	return &lastSentTracker{
    78  		sink:   sink,
    79  		client: client,
    80  	}
    81  }
    82  
    83  func (lst lastSentTracker) setLastSent(allModels bool, records []logfwd.Record) error {
    84  	// The records are received and sent in order, so we only need to
    85  	// call SetLastSent for the last record.
    86  	if len(records) == 0 {
    87  		return nil
    88  	}
    89  	rec := records[len(records)-1]
    90  	model := rec.Origin.ModelUUID
    91  	if allModels {
    92  		model = ""
    93  	}
    94  	var modelTag names.ModelTag
    95  	if model != "" {
    96  		if !names.IsValidModel(model) {
    97  			return errors.Errorf("bad model UUID %q", model)
    98  		}
    99  		modelTag = names.NewModelTag(model)
   100  	}
   101  	results, err := lst.client.SetLastSent([]logfwdapi.LastSentInfo{{
   102  		LastSentID: logfwdapi.LastSentID{
   103  			Model: modelTag,
   104  			Sink:  lst.sink,
   105  		},
   106  		RecordID:        rec.ID,
   107  		RecordTimestamp: rec.Timestamp,
   108  	}})
   109  	if err != nil {
   110  		return errors.Trace(err)
   111  	}
   112  	if err := results[0].Error; err != nil {
   113  		return errors.Trace(err)
   114  	}
   115  	return nil
   116  }