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116 lines
2.9 KiB
116 lines
2.9 KiB
// Copyright 2014 The Cayley Authors. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package graph
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// Defines the interface for consistent replication of a graph instance.
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//
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// Separate from the backend, this dictates how individual quads get
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// identified and replicated consistently across (potentially) multiple
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// instances. The simplest case is to keep an append-only log of quad
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// changes.
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import (
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"errors"
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"flag"
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"time"
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"github.com/google/cayley/quad"
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)
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type Procedure int8
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// The different types of actions a transaction can do.
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const (
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Add Procedure = +1
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Delete Procedure = -1
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)
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type Delta struct {
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ID PrimaryKey
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Quad quad.Quad
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Action Procedure
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Timestamp time.Time
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}
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type Handle struct {
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QuadStore
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QuadWriter
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}
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type IgnoreOpts struct {
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IgnoreDup, IgnoreMissing bool
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}
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func (h *Handle) Close() {
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h.QuadStore.Close()
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h.QuadWriter.Close()
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}
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var (
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ErrQuadExists = errors.New("quad exists")
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ErrQuadNotExist = errors.New("quad does not exist")
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)
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var (
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IgnoreDup = flag.Bool("ignoredup", false, "Don't stop loading on duplicated key on add")
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IgnoreMissing = flag.Bool("ignoremissing", false, "Don't stop loading on missing key on delete")
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)
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type QuadWriter interface {
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// Add a quad to the store.
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AddQuad(quad.Quad) error
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// TODO(barakmich): Deprecate in favor of transaction.
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// Add a set of quads to the store, atomically if possible.
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AddQuadSet([]quad.Quad) error
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// Removes a quad matching the given one from the database,
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// if it exists. Does nothing otherwise.
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RemoveQuad(quad.Quad) error
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// Apply a set of quad changes
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ApplyTransaction(*Transaction) error
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// Cleans up replication and closes the writing aspect of the database.
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Close() error
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}
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type NewQuadWriterFunc func(QuadStore, Options) (QuadWriter, error)
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var writerRegistry = make(map[string]NewQuadWriterFunc)
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func RegisterWriter(name string, newFunc NewQuadWriterFunc) {
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if _, found := writerRegistry[name]; found {
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panic("already registered QuadWriter " + name)
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}
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writerRegistry[name] = newFunc
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}
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func NewQuadWriter(name string, qs QuadStore, opts Options) (QuadWriter, error) {
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newFunc, hasNew := writerRegistry[name]
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if !hasNew {
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return nil, errors.New("replication: name '" + name + "' is not registered")
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}
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return newFunc(qs, opts)
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}
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func WriterMethods() []string {
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t := make([]string, 0, len(writerRegistry))
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for n := range writerRegistry {
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t = append(t, n)
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}
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return t
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}
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