go.temporal.io/server@v1.23.0/common/metrics/otel_options.go (about)

     1  // The MIT License
     2  //
     3  // Copyright (c) 2020 Temporal Technologies Inc.  All rights reserved.
     4  //
     5  // Copyright (c) 2020 Uber Technologies, Inc.
     6  //
     7  // Permission is hereby granted, free of charge, to any person obtaining a copy
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     9  // in the Software without restriction, including without limitation the rights
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    14  // The above copyright notice and this permission notice shall be included in
    15  // all copies or substantial portions of the Software.
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    17  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    18  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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    20  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    21  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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    23  // THE SOFTWARE.
    24  
    25  package metrics
    26  
    27  import (
    28  	"go.opentelemetry.io/otel/metric"
    29  )
    30  
    31  type (
    32  	// optionSet represents a slice of metric options. We need it to be able to add options of the
    33  	// [metric.InstrumentOption] type to slices which may be of any other type implemented by metric.InstrumentOption.
    34  	// Normally, you could do something like `T metric.InstrumentOption` here, but the type dependency here is reversed.
    35  	// We need a generic type T that is implemented *by* metric.InstrumentOption, not the other way around.
    36  	// This is the only solution which avoids duplicating all the logic of the addOptions function without relying on
    37  	// reflection, an error-prone type assertion, or a type switch with a runtime error for unhandled cases.
    38  	optionSet[T any] interface {
    39  		addOption(option metric.InstrumentOption) T
    40  	}
    41  	counterOptions   []metric.Int64CounterOption
    42  	gaugeOptions     []metric.Float64ObservableGaugeOption
    43  	histogramOptions []metric.Int64HistogramOption
    44  )
    45  
    46  func addOptions[T optionSet[T]](omp *otelMetricsHandler, opts T, metricName string) T {
    47  	metricDef, ok := omp.catalog.getMetric(metricName)
    48  	if !ok {
    49  		return opts
    50  	}
    51  
    52  	if description := metricDef.description; description != "" {
    53  		opts = opts.addOption(metric.WithDescription(description))
    54  	}
    55  
    56  	if unit := metricDef.unit; unit != "" {
    57  		opts = opts.addOption(metric.WithUnit(string(unit)))
    58  	}
    59  
    60  	return opts
    61  }
    62  
    63  func (opts counterOptions) addOption(option metric.InstrumentOption) counterOptions {
    64  	return append(opts, option)
    65  }
    66  
    67  func (opts gaugeOptions) addOption(option metric.InstrumentOption) gaugeOptions {
    68  	return append(opts, option)
    69  }
    70  
    71  func (opts histogramOptions) addOption(option metric.InstrumentOption) histogramOptions {
    72  	return append(opts, option)
    73  }