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// Copyright The OpenTelemetry Authors
// SPDX-License-Identifier: Apache-2.0
package log // import "go.opentelemetry.io/otel/sdk/log"
import (
"fmt"
"os"
"strconv"
"time"
"go.opentelemetry.io/otel"
)
// setting is a configuration setting value.
type setting[T any] struct {
Value T
Set bool
}
// newSetting returns a new [setting] with the value set.
func newSetting[T any](value T) setting[T] {
return setting[T]{Value: value, Set: true}
}
// resolver returns an updated setting after applying an resolution operation.
type resolver[T any] func(setting[T]) setting[T]
// Resolve returns a resolved version of s.
//
// It will apply all the passed fn in the order provided, chaining together the
// return setting to the next input. The setting s is used as the initial
// argument to the first fn.
//
// Each fn needs to validate if it should apply given the Set state of the
// setting. This will not perform any checks on the set state when chaining
// function.
func (s setting[T]) Resolve(fn ...resolver[T]) setting[T] {
for _, f := range fn {
s = f(s)
}
return s
}
// clampMax returns a resolver that will ensure a setting value is no greater
// than n. If it is, the value is set to n.
func clampMax[T ~int | ~int64](n T) resolver[T] {
return func(s setting[T]) setting[T] {
if s.Value > n {
s.Value = n
}
return s
}
}
// clearLessThanOne returns a resolver that will clear a setting value and
// change its set state to false if its value is less than 1.
func clearLessThanOne[T ~int | ~int64]() resolver[T] {
return func(s setting[T]) setting[T] {
if s.Value < 1 {
s.Value = 0
s.Set = false
}
return s
}
}
// getenv returns a resolver that will apply an integer environment variable
// value associated with key to a setting value.
//
// If the input setting to the resolver is set, the environment variable will
// not be applied.
//
// If the environment variable value associated with key is not an integer, an
// error will be sent to the OTel error handler and the setting will not be
// updated.
//
// If the setting value is a [time.Duration] type, the environment variable
// will be interpreted as a duration of milliseconds.
func getenv[T ~int | ~int64](key string) resolver[T] {
return func(s setting[T]) setting[T] {
if s.Set {
// Passed, valid, options have precedence.
return s
}
if v := os.Getenv(key); v != "" {
n, err := strconv.Atoi(v)
if err != nil {
otel.Handle(fmt.Errorf("invalid %s value %s: %w", key, v, err))
} else {
switch any(s.Value).(type) {
case time.Duration:
// OTel duration envar are in millisecond.
s.Value = T(time.Duration(n) * time.Millisecond)
default:
s.Value = T(n)
}
s.Set = true
}
}
return s
}
}
// fallback returns a resolve that will set a setting value to val if it is not
// already set.
//
// This is usually passed at the end of a resolver chain to ensure a default is
// applied if the setting has not already been set.
func fallback[T any](val T) resolver[T] {
return func(s setting[T]) setting[T] {
if !s.Set {
s.Value = val
s.Set = true
}
return s
}
}
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