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branch_iterator.go
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branch_iterator.go
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package ref
import (
"context"
"errors"
"github.com/treeverse/lakefs/pkg/db"
"github.com/treeverse/lakefs/pkg/graveler"
)
type BranchIterator struct {
db db.Database
ctx context.Context
repositoryID graveler.RepositoryID
value *graveler.BranchRecord
buf []*graveler.BranchRecord
offset string
fetchSize int
err error
state iteratorState
orderByCommitID bool
}
type BranchIteratorOption func(bi *BranchIterator)
func WithOrderByCommitID() BranchIteratorOption {
return func(bi *BranchIterator) {
bi.orderByCommitID = true
}
}
type branchRecord struct {
BranchID graveler.BranchID `db:"id"`
CommitID graveler.CommitID `db:"commit_id"`
StagingToken graveler.StagingToken `db:"staging_token"`
}
func NewBranchIterator(ctx context.Context, db db.Database, repositoryID graveler.RepositoryID, prefetchSize int, opts ...BranchIteratorOption) *BranchIterator {
res := &BranchIterator{
db: db,
ctx: ctx,
repositoryID: repositoryID,
fetchSize: prefetchSize,
buf: make([]*graveler.BranchRecord, 0, prefetchSize),
orderByCommitID: false,
}
for _, opt := range opts {
opt(res)
}
return res
}
func (ri *BranchIterator) Next() bool {
if ri.err != nil {
return false
}
ri.maybeFetch()
// stage a value and increment offset
if len(ri.buf) == 0 {
return false
}
ri.value = ri.buf[0]
ri.buf = ri.buf[1:]
ri.offset = string(ri.value.BranchID)
return true
}
func (ri *BranchIterator) maybeFetch() {
if ri.state == iteratorStateDone {
return
}
if len(ri.buf) > 0 {
return
}
var offsetCondition string
if ri.state == iteratorStateInit {
offsetCondition = iteratorOffsetCondition(true)
ri.state = iteratorStateQuerying
} else {
offsetCondition = iteratorOffsetCondition(false)
}
var buf []*branchRecord
err := ri.db.Select(ri.ctx, &buf, `
SELECT id, staging_token, commit_id
FROM graveler_branches
WHERE repository_id = $1
AND id `+offsetCondition+` $2
ORDER BY `+ri.getOrderBy()+` ASC
LIMIT $3`, ri.repositoryID, ri.offset, ri.fetchSize)
if err != nil {
ri.err = err
return
}
if len(buf) < ri.fetchSize {
ri.state = iteratorStateDone
}
for _, b := range buf {
rec := &graveler.BranchRecord{
BranchID: b.BranchID,
Branch: &graveler.Branch{
CommitID: b.CommitID,
StagingToken: b.StagingToken,
},
}
ri.buf = append(ri.buf, rec)
}
}
func (ri *BranchIterator) SeekGE(id graveler.BranchID) {
if errors.Is(ri.err, ErrIteratorClosed) {
return
}
ri.offset = string(id)
ri.state = iteratorStateInit
ri.buf = ri.buf[:0]
ri.value = nil
ri.err = nil
}
func (ri *BranchIterator) Value() *graveler.BranchRecord {
if ri.err != nil {
return nil
}
return ri.value
}
func (ri *BranchIterator) Err() error {
return ri.err
}
func (ri *BranchIterator) Close() {
ri.err = ErrIteratorClosed
ri.buf = nil
}
func (ri *BranchIterator) getOrderBy() string {
if ri.orderByCommitID {
return "commit_id"
}
return "id"
}