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Don't allow cancelled contexts to poison the postings for matchers cache.

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Signed-off-by: Charles Korn <charles.korn@grafana.com>
This commit is contained in:
Charles Korn 2023-10-20 15:45:36 +11:00
parent 8df8db6c73
commit 6dcebc9e25
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1 changed files with 16 additions and 11 deletions
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21
tsdb/postings_for_matchers_cache.go
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@ -78,27 +78,31 @@ func (c *PostingsForMatchersCache) PostingsForMatchers(ctx context.Context, ix I
return c.postingsForMatchers(ctx, ix, ms...) return c.postingsForMatchers(ctx, ix, ms...)
} }
c.expire() c.expire()
return c.postingsForMatchersPromise(ctx, ix, ms)() return c.postingsForMatchersPromise(ix, ms)(ctx)
} }
type postingsForMatcherPromise struct { type postingsForMatcherPromise struct {
sync.WaitGroup done chan struct{}
cloner *index.PostingsCloner cloner *index.PostingsCloner
err error err error
} }
func (p *postingsForMatcherPromise) result() (index.Postings, error) { func (p *postingsForMatcherPromise) result(ctx context.Context) (index.Postings, error) {
p.Wait() select {
case <-ctx.Done():
return nil, ctx.Err()
case <-p.done:
if p.err != nil { if p.err != nil {
return nil, p.err return nil, p.err
} }
return p.cloner.Clone(), nil return p.cloner.Clone(), nil
} }
}
func (c *PostingsForMatchersCache) postingsForMatchersPromise(ctx context.Context, ix IndexPostingsReader, ms []*labels.Matcher) func() (index.Postings, error) { func (c *PostingsForMatchersCache) postingsForMatchersPromise(ix IndexPostingsReader, ms []*labels.Matcher) func(context.Context) (index.Postings, error) {
promise := new(postingsForMatcherPromise) promise := new(postingsForMatcherPromise)
promise.Add(1) promise.done = make(chan struct{})
key := matchersKey(ms) key := matchersKey(ms)
oldPromise, loaded := c.calls.LoadOrStore(key, promise) oldPromise, loaded := c.calls.LoadOrStore(key, promise)
@ -106,9 +110,10 @@ func (c *PostingsForMatchersCache) postingsForMatchersPromise(ctx context.Contex
promise = oldPromise.(*postingsForMatcherPromise) promise = oldPromise.(*postingsForMatcherPromise)
return promise.result return promise.result
} }
defer promise.Done() defer close(promise.done)
if postings, err := c.postingsForMatchers(ctx, ix, ms...); err != nil { // FIXME: do we need to cancel the call to postingsForMatchers if all the callers waiting for the result have cancelled their context?
if postings, err := c.postingsForMatchers(context.Background(), ix, ms...); err != nil {
promise.err = err promise.err = err
} else { } else {
promise.cloner = index.NewPostingsCloner(postings) promise.cloner = index.NewPostingsCloner(postings)