101 lines
2.1 KiB
Go
101 lines
2.1 KiB
Go
package container
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import "github.com/hashicorp/go-memdb"
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const (
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memdbTable = "containers"
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memdbIDField = "ID"
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memdbIDIndex = "id"
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)
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// ViewDB provides an in-memory transactional (ACID) container Store
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type ViewDB interface {
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Snapshot() View
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Save(snapshot *Snapshot) error
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Delete(id string) error
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}
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// View can be used by readers to avoid locking
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type View interface {
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All() ([]Snapshot, error)
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Get(id string) (*Snapshot, error)
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}
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var schema = &memdb.DBSchema{
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Tables: map[string]*memdb.TableSchema{
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memdbTable: {
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Name: memdbTable,
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Indexes: map[string]*memdb.IndexSchema{
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memdbIDIndex: {
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Name: memdbIDIndex,
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Unique: true,
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Indexer: &memdb.StringFieldIndex{Field: memdbIDField},
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},
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},
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},
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},
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}
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type memDB struct {
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store *memdb.MemDB
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}
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// NewViewDB provides the default implementation, with the default schema
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func NewViewDB() (ViewDB, error) {
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store, err := memdb.NewMemDB(schema)
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if err != nil {
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return nil, err
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}
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return &memDB{store: store}, nil
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}
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// Snapshot provides a consistent read-only View of the database
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func (db *memDB) Snapshot() View {
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return &memdbView{db.store.Txn(false)}
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}
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// Save atomically updates the in-memory store
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func (db *memDB) Save(snapshot *Snapshot) error {
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txn := db.store.Txn(true)
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defer txn.Commit()
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return txn.Insert(memdbTable, snapshot)
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}
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// Delete removes an item by ID
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func (db *memDB) Delete(id string) error {
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txn := db.store.Txn(true)
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defer txn.Commit()
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return txn.Delete(memdbTable, &Snapshot{ID: id})
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}
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type memdbView struct {
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txn *memdb.Txn
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}
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// All returns a all items in this snapshot
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func (v *memdbView) All() ([]Snapshot, error) {
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var all []Snapshot
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iter, err := v.txn.Get(memdbTable, memdbIDIndex)
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if err != nil {
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return nil, err
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}
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for {
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item := iter.Next()
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if item == nil {
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break
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}
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snapshot := *(item.(*Snapshot)) // force a copy
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all = append(all, snapshot)
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}
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return all, nil
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}
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//Get returns an item by id
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func (v *memdbView) Get(id string) (*Snapshot, error) {
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s, err := v.txn.First(memdbTable, memdbIDIndex, id)
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if err != nil {
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return nil, err
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}
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snapshot := *(s.(*Snapshot)) // force a copy
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return &snapshot, nil
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}
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