Repository: prometheus/prometheus
File: promql/histogram_stats_iterator.go (Go)

Code before:
// Copyright 2024 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package promql

import (
	"github.com/prometheus/prometheus/model/histogram"
	"github.com/prometheus/prometheus/model/value"
	"github.com/prometheus/prometheus/tsdb/chunkenc"
)

type HistogramStatsIterator struct {
	chunkenc.Iterator

	currentH *histogram.Histogram
	lastH    *histogram.Histogram

	currentFH *histogram.FloatHistogram
	lastFH    *histogram.FloatHistogram

	haveReadFromCurrentSeries bool
}

// NewHistogramStatsIterator creates an iterator which returns histogram objects
// which have only their sum and count values populated. The iterator handles
// counter reset detection internally and sets the counter reset hint accordingly
// in each returned histogram objects.
func NewHistogramStatsIterator(it chunkenc.Iterator) *HistogramStatsIterator {
	return &HistogramStatsIterator{
		Iterator:  it,
		currentH:  &histogram.Histogram{},
		currentFH: &histogram.FloatHistogram{},
	}
}

func (f *HistogramStatsIterator) Reset(it chunkenc.Iterator) {
	f.Iterator = it
	f.haveReadFromCurrentSeries = false
}

// AtHistogram returns the next timestamp/histogram pair. The counter reset

Review comment (suggestion):
Now that this is exported, better give it a meaningful doc comment. I would probably recycle most of the stuff that was used for `NewHistogramStatsIterator` below and make the latter much shorter.

Code after:
// Copyright 2024 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package promql

import (
	"github.com/prometheus/prometheus/model/histogram"
	"github.com/prometheus/prometheus/model/value"
	"github.com/prometheus/prometheus/tsdb/chunkenc"
)

// HistogramStatsIterator is an iterator that returns histogram objects
// which have only their sum and count values populated. The iterator handles
// counter reset detection internally and sets the counter reset hint accordingly
// in each returned histogram object.
type HistogramStatsIterator struct {
	chunkenc.Iterator

	currentH *histogram.Histogram
	lastH    *histogram.Histogram

	currentFH *histogram.FloatHistogram
	lastFH    *histogram.FloatHistogram

	currentSeriesRead bool
}

// NewHistogramStatsIterator creates a new HistogramStatsIterator.
func NewHistogramStatsIterator(it chunkenc.Iterator) *HistogramStatsIterator {
	return &HistogramStatsIterator{
		Iterator:  it,
		currentH:  &histogram.Histogram{},
		currentFH: &histogram.FloatHistogram{},
	}
}

// Reset resets this iterator for use with a new underlying iterator, reusing
// objects already allocated where possible.
func (f *HistogramStatsIterator) Reset(it chunkenc.Iterator) {
	f.Iterator = it
	f.currentSeriesRead = false