mirror of https://github.com/grafana/grafana.git
76 lines
2.2 KiB
Go
76 lines
2.2 KiB
Go
package legacydata
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import (
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"github.com/grafana/grafana-plugin-sdk-go/data"
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jsoniter "github.com/json-iterator/go"
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)
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// DataFrames is an interface for retrieving encoded and decoded data frames.
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//
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// See NewDecodedDataFrames and NewEncodedDataFrames for more information.
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type DataFrames interface {
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// Encoded encodes Frames into a slice of []byte.
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// If an error occurs [][]byte will be nil.
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// The encoded result, if any, will be cached and returned next time Encoded is called.
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Encoded() ([][]byte, error)
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// Decoded decodes a slice of Arrow encoded frames to data.Frames ([]*data.Frame).
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// If an error occurs Frames will be nil.
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// The decoded result, if any, will be cached and returned next time Decoded is called.
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Decoded() (data.Frames, error)
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}
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type dataFrames struct {
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decoded data.Frames
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encoded [][]byte
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}
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// NewDecodedDataFrames instantiates DataFrames from decoded frames.
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//
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// This should be the primary function for creating DataFrames if you're implementing a plugin.
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// In a Grafana alerting scenario it needs to operate on decoded frames, which is why this function is
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// preferrable. When encoded data frames are needed, e.g. returned from Grafana HTTP API, it will
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// happen automatically when MarshalJSON() is called.
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func NewDecodedDataFrames(decodedFrames data.Frames) DataFrames {
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return &dataFrames{
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decoded: decodedFrames,
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}
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}
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func (df *dataFrames) Encoded() ([][]byte, error) {
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if df.encoded == nil {
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encoded, err := df.decoded.MarshalArrow()
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if err != nil {
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return nil, err
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}
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df.encoded = encoded
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}
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return df.encoded, nil
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}
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func (df *dataFrames) Decoded() (data.Frames, error) {
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if df.decoded == nil {
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decoded, err := data.UnmarshalArrowFrames(df.encoded)
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if err != nil {
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return nil, err
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}
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df.decoded = decoded
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}
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return df.decoded, nil
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}
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func (df *dataFrames) MarshalJSON() ([]byte, error) {
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encoded, err := df.Encoded()
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if err != nil {
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return nil, err
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}
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// Use a configuration that's compatible with the standard library
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// to minimize the risk of introducing bugs. This will make sure
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// that map keys is ordered.
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jsonCfg := jsoniter.ConfigCompatibleWithStandardLibrary
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return jsonCfg.Marshal(encoded)
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}
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