rename to quads

graph/quadwriter.go

@@ -0,0 +1,83 @@
+// Copyright 2014 The Cayley Authors. All rights reserved.
+//
+// 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.
+
+package graph
+
+// Defines the interface for consistent replication of a graph instance.
+//
+// Separate from the backend, this dictates how individual triples get
+// identified and replicated consistently across (potentially) multiple
+// instances. The simplest case is to keep an append-only log of triple
+// changes.
+
+import (
+	"errors"
+	"time"
+
+	"github.com/google/cayley/quad"
+)
+
+type Procedure byte
+
+// The different types of actions a transaction can do.
+const (
+	Add Procedure = iota
+	Delete
+)
+
+type Delta struct {
+	ID        int64
+	Quad      *quad.Quad
+	Action    Procedure
+	Timestamp time.Time
+}
+
+type QuadWriter interface {
+	// Add a triple to the store.
+	AddQuad(*quad.Quad) error
+
+	// Add a set of triples to the store, atomically if possible.
+	AddQuadSet([]*quad.Quad) error
+
+	// Removes a triple matching the given one  from the database,
+	// if it exists. Does nothing otherwise.
+	RemoveQuad(*quad.Quad) error
+}
+
+type NewQuadWriterFunc func(TripleStore, Options) (QuadWriter, error)
+
+var writerRegistry = make(map[string]NewQuadWriterFunc)
+
+func RegisterWriter(name string, newFunc NewQuadWriterFunc) {
+	if _, found := writerRegistry[name]; found {
+		panic("already registered TripleWriter " + name)
+	}
+	writerRegistry[name] = newFunc
+}
+
+func NewQuadWriter(name string, ts TripleStore, opts Options) (QuadWriter, error) {
+	newFunc, hasNew := writerRegistry[name]
+	if !hasNew {
+		return nil, errors.New("replication: name '" + name + "' is not registered")
+	}
+	return newFunc(ts, opts)
+}
+
+func WriterMethods() []string {
+	t := make([]string, 0, len(writerRegistry))
+	for n := range writerRegistry {
+		t = append(t, n)
+	}
+	return t
+}