121 lines
2.6 KiB
Go
121 lines
2.6 KiB
Go
package dgraph
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import (
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"context"
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"encoding/json"
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"fmt"
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"github.com/dgraph-io/dgo/v230/protos/api"
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"next.orly.dev/pkg/encoders/hex"
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)
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// Markers provide metadata key-value storage using Dgraph predicates
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// We store markers as special nodes with type "Marker"
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// SetMarker sets a metadata marker
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func (d *D) SetMarker(key string, value []byte) error {
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// Create or update a marker node
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markerID := "marker_" + key
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valueHex := hex.Enc(value)
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nquads := fmt.Sprintf(`
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_:%s <dgraph.type> "Marker" .
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_:%s <marker.key> %q .
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_:%s <marker.value> %q .
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`, markerID, markerID, key, markerID, valueHex)
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mutation := &api.Mutation{
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SetNquads: []byte(nquads),
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CommitNow: true,
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}
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if _, err := d.Mutate(context.Background(), mutation); err != nil {
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return fmt.Errorf("failed to set marker: %w", err)
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}
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return nil
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}
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// GetMarker retrieves a metadata marker
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func (d *D) GetMarker(key string) (value []byte, err error) {
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query := fmt.Sprintf(`{
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marker(func: eq(marker.key, %q)) {
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marker.value
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}
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}`, key)
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resp, err := d.Query(context.Background(), query)
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if err != nil {
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return nil, fmt.Errorf("failed to get marker: %w", err)
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}
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var result struct {
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Marker []struct {
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Value string `json:"marker.value"`
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} `json:"marker"`
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}
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if err = json.Unmarshal(resp.Json, &result); err != nil {
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return nil, fmt.Errorf("failed to parse marker response: %w", err)
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}
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if len(result.Marker) == 0 {
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return nil, fmt.Errorf("marker not found: %s", key)
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}
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// Decode hex value
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value, err = hex.Dec(result.Marker[0].Value)
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if err != nil {
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return nil, fmt.Errorf("failed to decode marker value: %w", err)
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}
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return value, nil
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}
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// HasMarker checks if a marker exists
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func (d *D) HasMarker(key string) bool {
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_, err := d.GetMarker(key)
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return err == nil
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}
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// DeleteMarker removes a metadata marker
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func (d *D) DeleteMarker(key string) error {
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// Find the marker's UID
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query := fmt.Sprintf(`{
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marker(func: eq(marker.key, %q)) {
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uid
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}
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}`, key)
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resp, err := d.Query(context.Background(), query)
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if err != nil {
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return fmt.Errorf("failed to find marker: %w", err)
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}
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var result struct {
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Marker []struct {
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UID string `json:"uid"`
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} `json:"marker"`
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}
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if err = json.Unmarshal(resp.Json, &result); err != nil {
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return fmt.Errorf("failed to parse marker query: %w", err)
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}
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if len(result.Marker) == 0 {
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return nil // Marker doesn't exist
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}
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// Delete the marker node
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mutation := &api.Mutation{
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DelNquads: []byte(fmt.Sprintf("<%s> * * .", result.Marker[0].UID)),
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CommitNow: true,
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}
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if _, err = d.Mutate(context.Background(), mutation); err != nil {
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return fmt.Errorf("failed to delete marker: %w", err)
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}
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return nil
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}
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