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Don't allow cancelled contexts to poison the postings for matchers cache.
Signed-off-by: Charles Korn <charles.korn@grafana.com>
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parent
8df8db6c73
commit
6dcebc9e25
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@ -78,27 +78,31 @@ func (c *PostingsForMatchersCache) PostingsForMatchers(ctx context.Context, ix I
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return c.postingsForMatchers(ctx, ix, ms...)
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}
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c.expire()
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return c.postingsForMatchersPromise(ctx, ix, ms)()
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return c.postingsForMatchersPromise(ix, ms)(ctx)
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}
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type postingsForMatcherPromise struct {
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sync.WaitGroup
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done chan struct{}
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cloner *index.PostingsCloner
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err error
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}
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func (p *postingsForMatcherPromise) result() (index.Postings, error) {
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p.Wait()
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if p.err != nil {
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return nil, p.err
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func (p *postingsForMatcherPromise) result(ctx context.Context) (index.Postings, error) {
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select {
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case <-ctx.Done():
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return nil, ctx.Err()
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case <-p.done:
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if p.err != nil {
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return nil, p.err
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}
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return p.cloner.Clone(), nil
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}
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return p.cloner.Clone(), nil
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}
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func (c *PostingsForMatchersCache) postingsForMatchersPromise(ctx context.Context, ix IndexPostingsReader, ms []*labels.Matcher) func() (index.Postings, error) {
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func (c *PostingsForMatchersCache) postingsForMatchersPromise(ix IndexPostingsReader, ms []*labels.Matcher) func(context.Context) (index.Postings, error) {
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promise := new(postingsForMatcherPromise)
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promise.Add(1)
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promise.done = make(chan struct{})
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key := matchersKey(ms)
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oldPromise, loaded := c.calls.LoadOrStore(key, promise)
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@ -106,9 +110,10 @@ func (c *PostingsForMatchersCache) postingsForMatchersPromise(ctx context.Contex
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promise = oldPromise.(*postingsForMatcherPromise)
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return promise.result
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}
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defer promise.Done()
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defer close(promise.done)
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if postings, err := c.postingsForMatchers(ctx, ix, ms...); err != nil {
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// FIXME: do we need to cancel the call to postingsForMatchers if all the callers waiting for the result have cancelled their context?
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if postings, err := c.postingsForMatchers(context.Background(), ix, ms...); err != nil {
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promise.err = err
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} else {
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promise.cloner = index.NewPostingsCloner(postings)
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