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Simplify AddFast and avoid errgroup Commits in general

This commit is contained in:
Fabian Reinartz 2017-05-18 17:17:56 +02:00
parent fb5c5535fc
commit debfe9b1e5
1 changed files with 32 additions and 22 deletions
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54
db.go
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@ -491,22 +491,13 @@ type dbAppender struct {
samples int
}
func (a *dbAppender) getAppender(ulid string) (*metaAppender, bool) {
for _, h := range a.heads {
if string(h.meta.ULID[:]) == ulid {
return h, true
}
}
return nil, false
}
type metaAppender struct {
meta BlockMeta
app Appender
}
func (a *dbAppender) Add(lset labels.Labels, t int64, v float64) (string, error) {
h, err := a.appenderFor(t)
h, err := a.appenderAt(t)
if err != nil {
return "", err
}
@ -524,9 +515,13 @@ func (a *dbAppender) AddFast(ref string, t int64, v float64) error {
return errors.Wrap(ErrNotFound, "invalid ref length")
}
// The first 16 bytes a ref hold the ULID of the head block.
h, ok := a.getAppender(ref[:16])
if !ok {
return errors.Wrapf(ErrNotFound, "no block for ULID %s", ref[:16])
h, err := a.appenderAt(t)
if err != nil {
return err
}
// Validate the ref points to the same block we got for t.
if string(h.meta.ULID[:]) != ref[:16] {
return ErrNotFound
}
if err := h.app.AddFast(ref[16:], t, v); err != nil {
// The block the ref points to might fit the given timestamp.
@ -543,7 +538,7 @@ func (a *dbAppender) AddFast(ref string, t int64, v float64) error {
// appenderFor gets the appender for the head containing timestamp t.
// If the head block doesn't exist yet, it gets created.
func (a *dbAppender) appenderFor(t int64) (*metaAppender, error) {
func (a *dbAppender) appenderAt(t int64) (*metaAppender, error) {
for _, h := range a.heads {
if intervalContains(h.meta.MinTime, h.meta.MaxTime-1, t) {
return h, nil
@ -590,13 +585,20 @@ func rangeForTimestamp(t int64, width int64) (mint, maxt int64) {
// ensureHead makes sure that there is a head block for the timestamp t if
// it is within or after the currently appendable window.
func (db *DB) ensureHead(t int64) error {
mint, maxt := rangeForTimestamp(t, int64(db.opts.MinBlockDuration))
var (
mint, maxt = rangeForTimestamp(t, int64(db.opts.MinBlockDuration))
addBuffer = len(db.blocks) == 0
last BlockMeta
)
last := db.blocks[len(db.blocks)-1].Meta()
if !addBuffer {
last = db.blocks[len(db.blocks)-1].Meta()
addBuffer = last.MaxTime <= mint-int64(db.opts.MinBlockDuration)
}
// Create another block of buffer in front if the DB is initialized or retrieving
// new data after a long gap.
// This ensures we always have a full block width if append window.
if len(db.blocks) == 0 || last.MaxTime <= mint-int64(db.opts.MinBlockDuration) {
if addBuffer {
if _, err := db.createHeadBlock(mint-int64(db.opts.MinBlockDuration), mint); err != nil {
return err
}
@ -621,14 +623,22 @@ func (a *dbAppender) Commit() error {
// Commits to partial appenders must be concurrent as concurrent appenders
// may have conflicting locks on head appenders.
// XXX(fabxc): is this a leaky abstraction? Should make an effort to catch a multi-error?
var g errgroup.Group
// For high-throughput use cases the errgroup causes significant blocking. Typically,
// we just deal with a single appender and special case it.
var err error
for _, h := range a.heads {
g.Go(h.app.Commit)
switch len(a.heads) {
case 1:
err = a.heads[0].app.Commit()
default:
var g errgroup.Group
for _, h := range a.heads {
g.Go(h.app.Commit)
}
err = g.Wait()
}
if err := g.Wait(); err != nil {
if err != nil {
return err
}
// XXX(fabxc): Push the metric down into head block to account properly