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antipode.go
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antipode.go
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package antipode
import (
"context"
"fmt"
)
type Datastore_type interface {
write(context.Context, string, string, AntiObj) error
read(context.Context, string, string) (AntiObj, error)
barrier(context.Context, []WriteIdentifier, string) error
}
type AntiObj struct {
Version string
Lineage []WriteIdentifier
}
type WriteIdentifier struct {
Dtstid string
TableId string
Key string
Version string
}
type contextKey string
func Write(ctx context.Context, datastoreType Datastore_type, datastore_ID string, table string, key string, value string) (context.Context, error) {
//extract lineage from ctx
lineage := ctx.Value(contextKey("lineage")).([]WriteIdentifier)
if lineage == nil {
err := fmt.Errorf("Lineage not found inside context")
return ctx, err
}
//update lineage
lineage = append(lineage, WriteIdentifier{Dtstid: datastore_ID, Key: key, Version: value, TableId: table})
//initialize AntiObj
obj := AntiObj{value, lineage}
err := datastoreType.write(ctx, table, key, obj)
if err != nil {
return ctx, err
}
//update ctx with the updated lineage
ctx = context.WithValue(ctx, contextKey("lineage"), lineage)
return ctx, nil
}
func Read(ctx context.Context, datastoreType Datastore_type, table string, key string) (string, []WriteIdentifier, error) {
obj, err := datastoreType.read(ctx, table, key)
return obj.Version, obj.Lineage, err
}
func Barrier(ctx context.Context, datastoreType Datastore_type, datastore_ID string) error {
//extract lineage from ctx
lineage := ctx.Value(contextKey("lineage")).([]WriteIdentifier)
if lineage == nil {
err := fmt.Errorf("Lineage not found inside context")
return err
}
return datastoreType.barrier(ctx, lineage, datastore_ID)
}
func Transfer(ctx context.Context, lineage []WriteIdentifier) (context.Context, error) {
//extract lineage from ctx
oldLineage := ctx.Value(contextKey("lineage")).([]WriteIdentifier)
if oldLineage == nil {
err := fmt.Errorf("Lineage not found inside context")
return ctx, err
}
newLineage := append(oldLineage, lineage...)
ctx = context.WithValue(ctx, contextKey("lineage"), newLineage)
return ctx, nil
}
func GetLineage(ctx context.Context) ([]WriteIdentifier, error) {
lineage := ctx.Value(contextKey("lineage"))
if lineage == nil {
err := fmt.Errorf("Lineage not found inside context")
return []WriteIdentifier{}, err
}
return lineage.([]WriteIdentifier), nil
}
func InitCtx(ctx context.Context) context.Context {
var lineage []WriteIdentifier = []WriteIdentifier{}
ctx = context.WithValue(ctx, contextKey("lineage"), lineage)
return ctx
}