forked from cockroachdb/cockroach
/
db.go
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/
db.go
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// Copyright 2014 The Cockroach Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
// implied. See the License for the specific language governing
// permissions and limitations under the License. See the AUTHORS file
// for names of contributors.
//
// Author: Spencer Kimball (spencer.kimball@gmail.com)
// Author: Andrew Bonventre (andybons@gmail.com)
package structured
import (
"github.com/cockroachdb/cockroach/client"
"github.com/cockroachdb/cockroach/proto"
"github.com/cockroachdb/cockroach/storage/engine"
)
// A DB interface provides methods to access a datastore
// using a structured data API.
type DB interface {
PutSchema(*Schema) error
DeleteSchema(*Schema) error
GetSchema(string) (*Schema, error)
}
// A structuredDB satisfies the DB interface using the
// Cockroach kv client API.
type structuredDB struct {
// kvDB is a client to the monolithic key-value map.
kvDB *client.KV
}
// NewDB returns a key-value datastore client which connects to the
// Cockroach cluster via the supplied gossip instance.
func NewDB(kvDB *client.KV) DB {
return &structuredDB{kvDB: kvDB}
}
// PutSchema inserts s into the kv store for subsequent
// usage by clients.
func (db *structuredDB) PutSchema(s *Schema) error {
if err := s.Validate(); err != nil {
return err
}
k := engine.MakeKey(engine.KeySchemaPrefix, proto.Key(s.Key))
return db.kvDB.PutI(k, s)
}
// DeleteSchema removes s from the kv store.
func (db *structuredDB) DeleteSchema(s *Schema) error {
return db.kvDB.Call(proto.Delete, &proto.DeleteRequest{
RequestHeader: proto.RequestHeader{
Key: engine.MakeKey(engine.KeySchemaPrefix, proto.Key(s.Key)),
},
}, &proto.DeleteResponse{})
}
// GetSchema returns the Schema with the given key, or nil if
// one does not exist. A nil error is returned when a schema
// with the given key cannot be found.
func (db *structuredDB) GetSchema(key string) (*Schema, error) {
s := &Schema{}
k := engine.MakeKey(engine.KeySchemaPrefix, proto.Key(key))
found, _, err := db.kvDB.GetI(k, s)
if err != nil || !found {
s = nil
}
return s, err
}