golden/go/tiling/tiling.go

package tiling

import (
	"time"

	"go.skia.org/infra/go/skerr"
	"go.skia.org/infra/golden/go/types"
)

// TraceID helps document when strings should represent ids of traces
type TraceID string

// Commit is information about each Git commit.
// TODO(kjlubick) Why does this need to have its own type? Can't it use one of the other Commit
//   types?
type Commit struct {
	CommitTime time.Time
	Hash       string
	Author     string
	Subject    string
}

// Tile is a config.TILE_SIZE commit slice of data.
//
// The length of the Commits array is the same length as all of the Values
// arrays in all of the Traces.
type Tile struct {
	Traces   map[TraceID]*Trace
	ParamSet map[string][]string
	Commits  []Commit
}

// LastCommitIndex returns the index of the last valid Commit.
func (t *Tile) LastCommitIndex() int {
	for i := len(t.Commits) - 1; i > 0; i-- {
		if !t.Commits[i].CommitTime.IsZero() {
			return i
		}
	}
	return 0
}

// Trim trims the measurements to just the range from [begin, end).
//
// Just like a Go [:] slice this is inclusive of begin and exclusive of end.
// The length on the Traces will then become end-begin.
func (t *Tile) Trim(begin, end int) (*Tile, error) {
	length := end - begin
	if end < begin || end > len(t.Commits) || begin < 0 {
		return nil, skerr.Fmt("Invalid Trim range [%d, %d) of [0, %d]", begin, end, length)
	}
	ret := &Tile{
		Traces:   map[TraceID]*Trace{},
		ParamSet: t.ParamSet,
		Commits:  make([]Commit, length),
	}

	for i := 0; i < length; i++ {
		ret.Commits[i] = t.Commits[i+begin]
	}
	for k, v := range t.Traces {
		t := v.DeepCopy()
		if err := t.Trim(begin, end); err != nil {
			return nil, skerr.Wrapf(err, "trimming trace %s", k)
		}
		ret.Traces[k] = t
	}
	return ret, nil
}

const (
	// MissingDigest is a sentinel value meaning no digest is available at the given commit.
	MissingDigest = types.Digest("")
)

// TracePair represents a single Golden trace and its ID. A slice of TracePair is faster to
// iterate over than a map of TraceID -> Trace
type TracePair struct {
	ID    TraceID
	Trace *Trace
}