jschoubben
316af50da3
view_tiers compares the kept assignment revision whose catalog carries the source revision with the one kept before it, through the seat mesh-wants' verbs revision and difference (view/difference.go, tiers.go Tiers), and reads the tiers and each module's after (module and edge kind) from the answer; the view orders nothing. The manifest invokes the two verbs. Builds: design 47 G §512, §186, A-242
94 lines
3.3 KiB
Go
94 lines
3.3 KiB
Go
package view
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import (
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"encoding/json"
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"fmt"
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"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-contracts/go/seats/meshwants"
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"git.novox.be/novox/mesh-sdk/go/buscalls"
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)
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// The seat mesh-wants' verbs revision and difference as the view's invokes names them: the tiers of a source revision are
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// read through them and worked out nowhere in the view (design 47 G §512, §186, A-242).
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const (
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RevisionVerb = "seat:" + meshwants.Seat + "." + meshwants.VerbRevision
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DifferenceVerb = "seat:" + meshwants.Seat + "." + meshwants.VerbDifference
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)
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// WalkMost is the most kept assignment revisions a source revision's revision is looked for through, newest first.
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const WalkMost = 256
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// callSeat asks verb with body through call and reads its declared answer into out.
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func callSeat(call func(key string, body any) (json.RawMessage, error), verb string, body, out any) error {
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raw, err := call(verb, body)
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if err != nil {
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return fmt.Errorf("%s: %w", verb, err)
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}
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answer, said, ok := buscalls.Unwrap(raw)
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if !ok {
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return fmt.Errorf("%s answered: %s", verb, said)
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}
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if err := json.Unmarshal(answer, out); err != nil {
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return fmt.Errorf("the answer of %s does not read: %w", verb, err)
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}
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return nil
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}
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// AssignmentOf asks the seat for one kept assignment graph revision (0: the trunk's newest).
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func AssignmentOf(call func(key string, body any) (json.RawMessage, error)) func(revision int64) (meshwants.AssignmentRevision, error) {
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return func(revision int64) (meshwants.AssignmentRevision, error) {
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var a meshwants.RevisionAnswer
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err := callSeat(call, RevisionVerb, meshwants.RevisionInput{Revision: revision}, &a)
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return a.Revision, err
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}
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}
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// DifferenceOf asks the seat for the difference of two kept revisions.
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func DifferenceOf(call func(key string, body any) (json.RawMessage, error)) func(from, to int64) (meshwants.Difference, error) {
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return func(from, to int64) (meshwants.Difference, error) {
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var d meshwants.Difference
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err := callSeat(call, DifferenceVerb, meshwants.DifferenceInput{From: from, To: to}, &d)
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return d, err
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}
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}
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// revisionsOf finds the kept assignment revisions that carry the source revision for a watched branch: to the first of them
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// (the one whose change it is) and from the revision kept before it, walking back from the newest. A zero from says there is
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// none before it.
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func (r Reader) revisionsOf(source uint64) (from, to int64, err error) {
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if r.Assignment == nil || r.Difference == nil {
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return 0, 0, fmt.Errorf("the assigner's revisions cannot be read here")
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}
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newest, err := r.Assignment(0)
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if err != nil {
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return 0, 0, fmt.Errorf("the assigner's newest revision: %w", err)
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}
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carries := func(rev meshwants.AssignmentRevision) bool {
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for _, c := range rev.Catalogs {
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if c.Source > 0 && uint64(c.Source) == source {
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return true
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}
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}
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return false
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}
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for n, steps := newest.Revision, 0; n >= 1 && steps < WalkMost; n, steps = n-1, steps+1 {
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rev := newest
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if n != newest.Revision {
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if rev, err = r.Assignment(n); err != nil {
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continue // a revision no longer kept
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}
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}
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if !carries(rev) {
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if to != 0 {
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return rev.Revision, to, nil // the kept revision before the first that carries it
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}
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continue
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}
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to = rev.Revision
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}
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if to == 0 {
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return 0, 0, fmt.Errorf("no kept assignment revision of the assigner carries the source revision %d", source)
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}
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return 0, to, nil
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}
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