forked from mirror/client_golang
47 lines
2.0 KiB
Go
47 lines
2.0 KiB
Go
// Copyright 2015 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 metric
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import dto "github.com/prometheus/client_model/go"
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// A Metric models a single sample value with its meta data being exported to
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// Prometheus. Implementers of Metric in this package include Gauge, Counter,
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// Untyped, and Summary. Users can implement their own Metric types, but that
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// should be rarely needed.
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type Metric interface {
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// Desc returns the descriptor for the Metric. This method idempotently
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// returns the same descriptor throughout the lifetime of the Metric. A
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// Metric unable to describe itself must return an invalid descriptor
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// (created with NewInvalidDesc).
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Desc() Desc
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// Write encodes the Metric into a "Metric" Protocol Buffer data
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// transmission object.
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//
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// Implementers of custom Metric types must observe concurrency safety
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// as reads of this metric may occur at any time, and any blocking
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// occurs at the expense of total performance of rendering all
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// registered metrics. Ideally Metric implementations should support
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// concurrent readers.
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//
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// The caller may minimize memory allocations by providing a
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// pre-existing reset dto.Metric pointer. The caller may recycle the
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// dto.Metric proto message, so Metric implementations should just
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// populate the provided dto.Metric and then should not keep any
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// reference to it.
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//
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// While populating dto.Metric, labels must be sorted lexicographically.
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// (Implementers may find LabelPairSorter useful for that.)
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Write(*dto.Metric) error
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}
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