tvl-depot/third_party/gerrit-queue/gerrit/series.go
Vincent Ambo 59f97332b3 subtree(3p/gerrit-queue): Vendor at commit '24f5a642'
Imported from github/tvlfyi/gerrit-queue, originally from
github/tweag/gerrit-queue but that upstream is unmaintained.

git-subtree-dir: third_party/gerrit-queue
git-subtree-mainline: ff10b7ab83
git-subtree-split: 24f5a642af
Change-Id: I307cc38185ab9e25eb102c95096298a150ae13a2
2021-12-09 16:13:56 +03:00

126 lines
3.7 KiB
Go

package gerrit
import (
"sort"
"github.com/apex/log"
)
// AssembleSeries consumes a list of `Changeset`, and groups them together to series
//
// We initially put every Changeset in its own Serie
//
// As we have no control over the order of the passed changesets,
// we maintain a lookup table, mapLeafToSerie,
// which allows to lookup a serie by its leaf commit id
// We concat series in a fixpoint approach
// because both appending and prepending is much more complex.
// Concatenation moves changesets of the later changeset in the previous one
// in a cleanup phase, we remove orphaned series (those without any changesets inside)
// afterwards, we do an integrity check, just to be on the safe side.
func AssembleSeries(changesets []*Changeset, logger *log.Logger) ([]*Serie, error) {
series := make([]*Serie, 0)
mapLeafToSerie := make(map[string]*Serie, 0)
for _, changeset := range changesets {
l := logger.WithField("changeset", changeset.String())
l.Debug("creating initial serie")
serie := &Serie{
ChangeSets: []*Changeset{changeset},
}
series = append(series, serie)
mapLeafToSerie[changeset.CommitID] = serie
}
// Combine series using a fixpoint approach, with a max iteration count.
logger.Debug("glueing together phase")
for i := 1; i < 100; i++ {
didUpdate := false
logger.Debugf("at iteration %d", i)
for j, serie := range series {
l := logger.WithFields(log.Fields{
"i": i,
"j": j,
"serie": serie.String(),
})
parentCommitIDs, err := serie.GetParentCommitIDs()
if err != nil {
return series, err
}
if len(parentCommitIDs) != 1 {
// We can't append merge commits to other series
l.Infof("No single parent, skipping.")
continue
}
parentCommitID := parentCommitIDs[0]
l.Debug("Looking for a predecessor.")
// if there's another serie that has this parent as a leaf, glue together
if otherSerie, ok := mapLeafToSerie[parentCommitID]; ok {
if otherSerie == serie {
continue
}
l = l.WithField("otherSerie", otherSerie)
myLeafCommitID, err := serie.GetLeafCommitID()
if err != nil {
return series, err
}
// append our changesets to the other serie
l.Debug("Splicing together.")
otherSerie.ChangeSets = append(otherSerie.ChangeSets, serie.ChangeSets...)
delete(mapLeafToSerie, parentCommitID)
mapLeafToSerie[myLeafCommitID] = otherSerie
// orphan our serie
serie.ChangeSets = []*Changeset{}
// remove the orphaned serie from the lookup table
delete(mapLeafToSerie, myLeafCommitID)
didUpdate = true
} else {
l.Debug("Not found.")
}
}
series = removeOrphanedSeries(series)
if !didUpdate {
logger.Infof("converged after %d iterations", i)
break
}
}
// Check integrity, just to be on the safe side.
for _, serie := range series {
l := logger.WithField("serie", serie.String())
l.Debugf("checking integrity")
err := serie.CheckIntegrity()
if err != nil {
l.Errorf("checking integrity failed: %s", err)
}
}
return series, nil
}
// removeOrphanedSeries removes all empty series (that contain zero changesets)
func removeOrphanedSeries(series []*Serie) []*Serie {
newSeries := []*Serie{}
for _, serie := range series {
if len(serie.ChangeSets) != 0 {
newSeries = append(newSeries, serie)
}
}
return newSeries
}
// SortSeries sorts a list of series by the number of changesets in each serie, descending
func SortSeries(series []*Serie) []*Serie {
newSeries := make([]*Serie, len(series))
copy(newSeries, series)
sort.Slice(newSeries, func(i, j int) bool {
// the weight depends on the amount of changesets series changeset size
return len(series[i].ChangeSets) > len(series[j].ChangeSets)
})
return newSeries
}