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  • 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/logforwarder/tracker.go
 
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// Copyright 2016 Canonical Ltd.
 
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// Licensed under the AGPLv3, see LICENCE file for details.
 
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package logforwarder
 
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import (
 
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        "github.com/juju/errors"
 
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        "gopkg.in/juju/names.v2"
 
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        "github.com/juju/juju/api/base"
 
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        logfwdapi "github.com/juju/juju/api/logfwd"
 
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        "github.com/juju/juju/logfwd"
 
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        "github.com/juju/juju/logfwd/syslog"
 
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)
 
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// TrackingSinkArgs holds the args to OpenTrackingSender.
 
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type TrackingSinkArgs struct {
 
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        // AllModels indicates that the tracker is handling all models.
 
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        AllModels bool
 
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        // Config is the logging config that will be used.
 
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        Config *syslog.RawConfig
 
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        // Caller is the API caller that will be used.
 
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        Caller base.APICaller
 
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        // Name is the name given to the log sink.
 
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        Name string
 
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        // OpenSink is the function that opens the underlying log sink that
 
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        // will be wrapped.
 
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        OpenSink LogSinkFn
 
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}
 
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// OpenTrackingSink opens a log record sender to use with a worker.
 
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// The sender also tracks records that were successfully sent.
 
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func OpenTrackingSink(args TrackingSinkArgs) (*LogSink, error) {
 
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        sink, err := args.OpenSink(args.Config)
 
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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 &LogSink{
 
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                &trackingSender{
 
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                        SendCloser: sink,
 
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                        tracker:    newLastSentTracker(args.Name, args.Caller),
 
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                },
 
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        }, nil
 
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}
 
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type trackingSender struct {
 
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        SendCloser
 
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        tracker   *lastSentTracker
 
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        allModels bool
 
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}
 
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// Send implements Sender.
 
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func (s *trackingSender) Send(records []logfwd.Record) error {
 
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        if err := s.SendCloser.Send(records); err != nil {
 
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                return errors.Trace(err)
 
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        }
 
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        if err := s.tracker.setLastSent(s.allModels, records); err != nil {
 
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                return errors.Trace(err)
 
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        }
 
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        return nil
 
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}
 
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type lastSentTracker struct {
 
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        sink   string
 
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        client *logfwdapi.LastSentClient
 
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}
 
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func newLastSentTracker(sink string, caller base.APICaller) *lastSentTracker {
 
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        client := logfwdapi.NewLastSentClient(func(name string) logfwdapi.FacadeCaller {
 
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                return base.NewFacadeCaller(caller, name)
 
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        })
 
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        return &lastSentTracker{
 
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                sink:   sink,
 
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                client: client,
 
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        }
 
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}
 
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func (lst lastSentTracker) setLastSent(allModels bool, records []logfwd.Record) error {
 
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        // The records are received and sent in order, so we only need to
 
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        // call SetLastSent for the last record.
 
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        if len(records) == 0 {
 
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                return nil
 
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        }
 
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        rec := records[len(records)-1]
 
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        model := rec.Origin.ModelUUID
 
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        if allModels {
 
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                model = ""
 
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        }
 
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        var modelTag names.ModelTag
 
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        if model != "" {
 
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                if !names.IsValidModel(model) {
 
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                        return errors.Errorf("bad model UUID %q", model)
 
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                }
 
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                modelTag = names.NewModelTag(model)
 
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        }
 
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        results, err := lst.client.SetLastSent([]logfwdapi.LastSentInfo{{
 
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                LastSentID: logfwdapi.LastSentID{
 
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                        Model: modelTag,
 
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                        Sink:  lst.sink,
 
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                },
 
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                RecordID:        rec.ID,
 
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                RecordTimestamp: rec.Timestamp,
 
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        }})
 
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        if err != nil {
 
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                return errors.Trace(err)
 
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        }
 
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        if err := results[0].Error; err != nil {
 
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                return errors.Trace(err)
 
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        }
 
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        return nil
 
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}