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2aefd00c24
The chunkenc.Appender interface's AppendHistogram and AppendFloatHistogram methods used to require a typed previous appender (*HistogramAppender or *FloatHistogramAppender). Callers were forced to type-assert s.app to that concrete type before each call, discarding it (and the cross-chunk counter-reset signal it carries) whenever the actual concrete type didn't match -- for example when a chunk used a different histogram encoding. Change the signature to accept the generic chunkenc.Appender interface and move the concrete-type check inside each implementation, onto the code path that actually needs the previous appender's state (the new-chunk branch where setCounterResetHeader runs). The check goes through small private interfaces -- histogramAppendable and floatHistogramAppendable -- so any appender type that exposes the appropriate appendable() method can serve as prev, and types that don't (xor, xor2, or a histogram appender on the opposite-kind code path) are silently ignored. This prepares the ground for #18609, which introduces *HistogramSTAppender and *FloatHistogramSTAppender. Both embed their non-ST counterparts and will satisfy the new interfaces automatically, so they can be passed as prev without a special case in the caller. Callers in tsdb/head_append.go and tsdb/ooo_head.go are simplified accordingly. The Appender consumers in storage/series.go and tsdb/querier.go were already passing nil and continue to do so unchanged. Signed-off-by: György Krajcsovits <gyorgy.krajcsovits@grafana.com>
42 lines
1.8 KiB
Go
42 lines
1.8 KiB
Go
// Copyright The Prometheus Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package chunkenc
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import "github.com/prometheus/prometheus/model/histogram"
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// histogramAppendable is the subset of an integer-histogram appender's API
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// that AppendHistogram needs from a previous chunk's appender in order to
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// detect counter resets across chunks. It is satisfied by *HistogramAppender
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// and any type that embeds it (e.g. *HistogramSTAppender). The Appender
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// interface itself stays a single type so callers can hand off whichever
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// concrete appender they happen to have without first type-asserting it.
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type histogramAppendable interface {
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appendable(*histogram.Histogram) (
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positiveInserts, negativeInserts,
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backwardPositiveInserts, backwardNegativeInserts []Insert,
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okToAppend bool, counterResetHint CounterResetHeader,
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)
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}
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// floatHistogramAppendable is the float-histogram counterpart of
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// histogramAppendable. Note the asymmetry with the integer version: float
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// histograms surface a bool counter-reset flag rather than the richer
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// CounterResetHeader value used for integer histograms.
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type floatHistogramAppendable interface {
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appendable(*histogram.FloatHistogram) (
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positiveInserts, negativeInserts,
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backwardPositiveInserts, backwardNegativeInserts []Insert,
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okToAppend, counterReset bool,
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)
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}
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