docker/swarmkit

package store

import (
    memdb "github.com/hashicorp/go-memdb"
    "github.com/moby/swarmkit/v2/api"
)

// ObjectStoreConfig provides the necessary methods to store a particular object
// type inside MemoryStore.
type ObjectStoreConfig struct {
    Table            *memdb.TableSchema
    Save             func(ReadTx, *api.StoreSnapshot) error
    Restore          func(Tx, *api.StoreSnapshot) error
    ApplyStoreAction func(Tx, api.StoreAction) error
}

// RestoreTable takes a list of new objects of a particular type (e.g. clusters,
// nodes, etc., which conform to the StoreObject interface) and replaces the
// existing objects in the store of that type with the new objects.
func RestoreTable(tx Tx, table string, newObjects []api.StoreObject) error {
    checkType := func(by By) error {
        return nil
    }
    var oldObjects []api.StoreObject
    appendResult := func(o api.StoreObject) {
        oldObjects = append(oldObjects, o)
    }

    err := tx.find(table, All, checkType, appendResult)
    if err != nil {
        return nil
    }

    updated := make(map[string]struct{})

    for _, o := range newObjects {
        objectID := o.GetID()
        if existing := tx.lookup(table, indexID, objectID); existing != nil {
            if err := tx.update(table, o); err != nil {
                return err
            }
            updated[objectID] = struct{}{}
        } else {
            if err := tx.create(table, o); err != nil {
                return err
            }
        }
    }
    for _, o := range oldObjects {
        objectID := o.GetID()
        if _, ok := updated[objectID]; !ok {
            if err := tx.delete(table, objectID); err != nil {
                return err
            }
        }
    }
    return nil
}