jochen
59f4d486b1
The controller acted only on what its events consumer handed it, so a merge the bus skipped left modules behind with nothing said. The stream is now read back every five minutes on a single-filter consumer, and any merge that would still move a module after ten minutes is said and acted on.
80 lines
2.8 KiB
Go
80 lines
2.8 KiB
Go
package link
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import (
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"context"
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"encoding/json"
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"errors"
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"fmt"
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"sort"
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"time"
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"github.com/nats-io/nats.go"
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"github.com/novox/mesh-controller/internal/broker"
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)
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// AnnouncedMerge is one merge the forge announced, as the events stream holds it: what it said, and
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// when the bus took it.
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type AnnouncedMerge struct {
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SourceMoved
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// At is when the bus took the announcement — the stream's own time, not the forge's.
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At time.Time
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// Seq is its place in the events stream.
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Seq uint64
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}
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// MergedSubject is where the forge's merges land: the controller's own follow of them.
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var MergedSubject = broker.ControllerFollows[3]
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// readQuiet is how long a read of the stream waits for one more message before it takes the stream
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// as read to its end. The stream answers at once when it holds something; this is only the wait at
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// the end.
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const readQuiet = 2 * time.Second
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// AnnouncedMerges is every merge the forge announced since a moment, oldest first, read back from
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// the events stream (novox/hq issue 266).
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//
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// **Read on a consumer of its own, filtered on the one subject.** The controller's durable consumer
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// carries several filters, and the bus server the mesh ran when this was written (2.10) skips a
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// message now and then on a consumer with more than one filter: it moves its delivered pointer past
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// the message without ever handing it over, so the controller never hears of it and nothing says so.
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// A consumer filtered on a single subject reads the stream another way and was not seen to skip. This
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// one is ordered, ephemeral and acknowledges nothing, so reading it changes nothing on the bus.
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func (s *Server) AnnouncedMerges(ctx context.Context, since time.Time) ([]AnnouncedMerge, error) {
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if s.js == nil {
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return nil, errors.New("this control plane is not on the bus, so it cannot read what the forge announced")
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}
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sub, err := s.js.Context().SubscribeSync(MergedSubject, nats.OrderedConsumer(), nats.StartTime(since))
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if err != nil {
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return nil, fmt.Errorf("reading the forge's merges from the events stream: %w", err)
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}
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defer func() { _ = sub.Unsubscribe() }()
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var out []AnnouncedMerge
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for {
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wait, cancel := context.WithTimeout(ctx, readQuiet)
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msg, err := sub.NextMsgWithContext(wait)
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cancel()
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if err != nil {
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if ctx.Err() != nil {
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return nil, ctx.Err()
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}
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// Nothing more within the quiet wait: the stream has been read to its end.
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break
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}
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meta, err := msg.Metadata()
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if err != nil {
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continue
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}
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var moved SourceMoved
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if json.Unmarshal(msg.Data, &moved) == nil && moved.Commit != "" && moved.Repo != "" {
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out = append(out, AnnouncedMerge{SourceMoved: moved, At: meta.Timestamp, Seq: meta.Sequence.Stream})
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}
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if meta.NumPending == 0 {
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break
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}
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}
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sort.Slice(out, func(i, j int) bool { return out[i].Seq < out[j].Seq })
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return out, nil
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}
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