78 lines
1.8 KiB
Go
78 lines
1.8 KiB
Go
package log
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import (
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"encoding/json"
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"errors"
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"reflect"
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)
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// Metadata is a convenience type for generic maps
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type Metadata map[string]interface{}
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// DeepMerge merges the second Metadata parameter into the first.
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// Nested Metadata are merged recursively. Primitives are over-written.
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func DeepMerge(b, a Metadata) Metadata {
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out := Metadata{}
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for k, v := range b {
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out[k] = v
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}
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for k, v := range a {
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maybe, err := Metadatify(v)
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if err != nil {
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// if the new value is not meta. just overwrite the dest vaue
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if out[k] != nil {
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log.Debugf("Overwriting key: %s, old: %s, new: %s", k, out[k], v)
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}
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out[k] = v
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continue
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}
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// it is meta. What about dest?
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outv, exists := out[k]
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if !exists {
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// the new value is meta, but there's no dest value. just write it
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out[k] = v
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continue
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}
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outMetadataValue, err := Metadatify(outv)
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if err != nil {
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// the new value is meta and there's a dest value, but the dest
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// value isn't meta. just overwrite
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out[k] = v
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continue
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}
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// both are meta. merge them.
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out[k] = DeepMerge(outMetadataValue, maybe)
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}
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return out
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}
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// Loggable implements the Loggable interface.
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func (m Metadata) Loggable() map[string]interface{} {
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// NB: method defined on value to avoid de-referencing nil Metadata
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return m
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}
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// JsonString returns the marshaled JSON string for the metadata.
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func (m Metadata) JsonString() (string, error) {
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// NB: method defined on value
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b, err := json.Marshal(m)
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return string(b), err
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}
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// Metadatify converts maps into Metadata.
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func Metadatify(i interface{}) (Metadata, error) {
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value := reflect.ValueOf(i)
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if value.Kind() == reflect.Map {
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m := map[string]interface{}{}
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for _, k := range value.MapKeys() {
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m[k.String()] = value.MapIndex(k).Interface()
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}
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return Metadata(m), nil
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}
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return nil, errors.New("is not a map")
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}
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