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https://github.com/prometheus/prometheus.git
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3c7de69059
Patterned after `Chunk.Iterator()`: pass the old iterator in so it can be re-used to avoid allocating a new object. (This commit does not do any re-use; it is just changing all the method signatures so re-use is possible in later commits.) Signed-off-by: Bryan Boreham <bjboreham@gmail.com>
105 lines
2.7 KiB
Go
105 lines
2.7 KiB
Go
// Copyright 2021 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 tsdb
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import (
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"context"
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"fmt"
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"math"
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"os"
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"time"
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"github.com/prometheus/prometheus/model/labels"
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"github.com/prometheus/prometheus/tsdb/chunkenc"
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)
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func Example() {
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// Create a random dir to work in. Open() doesn't require a pre-existing dir, but
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// we want to make sure not to make a mess where we shouldn't.
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dir, err := os.MkdirTemp("", "tsdb-test")
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noErr(err)
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// Open a TSDB for reading and/or writing.
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db, err := Open(dir, nil, nil, DefaultOptions(), nil)
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noErr(err)
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// Open an appender for writing.
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app := db.Appender(context.Background())
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series := labels.FromStrings("foo", "bar")
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// Ref is 0 for the first append since we don't know the reference for the series.
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ref, err := app.Append(0, series, time.Now().Unix(), 123)
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noErr(err)
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// Another append for a second later.
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// Re-using the ref from above since it's the same series, makes append faster.
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time.Sleep(time.Second)
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_, err = app.Append(ref, series, time.Now().Unix(), 124)
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noErr(err)
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// Commit to storage.
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err = app.Commit()
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noErr(err)
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// In case you want to do more appends after app.Commit(),
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// you need a new appender.
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app = db.Appender(context.Background())
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// ... adding more samples.
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// Open a querier for reading.
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querier, err := db.Querier(context.Background(), math.MinInt64, math.MaxInt64)
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noErr(err)
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ss := querier.Select(false, nil, labels.MustNewMatcher(labels.MatchEqual, "foo", "bar"))
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for ss.Next() {
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series := ss.At()
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fmt.Println("series:", series.Labels().String())
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it := series.Iterator(nil)
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for it.Next() == chunkenc.ValFloat {
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_, v := it.At() // We ignore the timestamp here, only to have a predictable output we can test against (below)
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fmt.Println("sample", v)
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}
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fmt.Println("it.Err():", it.Err())
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}
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fmt.Println("ss.Err():", ss.Err())
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ws := ss.Warnings()
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if len(ws) > 0 {
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fmt.Println("warnings:", ws)
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}
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err = querier.Close()
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noErr(err)
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// Clean up any last resources when done.
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err = db.Close()
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noErr(err)
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err = os.RemoveAll(dir)
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noErr(err)
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// Output:
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// series: {foo="bar"}
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// sample 123
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// sample 124
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// it.Err(): <nil>
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// ss.Err(): <nil>
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}
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func noErr(err error) {
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if err != nil {
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panic(err)
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}
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}
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