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501bc6419e
This PR is a reference implementation of the proposal described in #10420. In addition to what described in #10420, in this PR I've introduced labels.StableHash(). The idea is to offer an hashing function which doesn't change over time, and that's used by query sharding in order to get a stable behaviour over time. The implementation of labels.StableHash() is the hashing function used by Prometheus before stringlabels, and what's used by Grafana Mimir for query sharding (because built before stringlabels was a thing). Follow up work As mentioned in #10420, if this PR is accepted I'm also open to upload another foundamental piece used by Grafana Mimir query sharding to accelerate the query execution: an optional, configurable and fast in-memory cache for the series hashes. Signed-off-by: Marco Pracucci <marco@pracucci.com>
33 lines
1.1 KiB
Go
33 lines
1.1 KiB
Go
// Copyright 2020 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 labels
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import (
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"testing"
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"github.com/stretchr/testify/require"
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)
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// TestStableHash tests that StableHash is stable.
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// The hashes this test asserts should not be changed.
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func TestStableHash(t *testing.T) {
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for expectedHash, lbls := range map[uint64]Labels{
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0xef46db3751d8e999: EmptyLabels(),
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0x347c8ee7a9e29708: FromStrings("hello", "world"),
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0xcbab40540f26097d: FromStrings(MetricName, "metric", "label", "value"),
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} {
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require.Equal(t, expectedHash, StableHash(lbls))
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}
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}
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