From 929b4f539bd0c0423f5c77ab17a0ebe84ad10d31 Mon Sep 17 00:00:00 2001
From: Barak Michener <me@barakmich.com>
Date: Thu, 24 Jul 2014 16:59:38 -0400
Subject: [PATCH] update the triplestore interface and local replication

---
 graph/triplestore.go |  8 ++++++++
 replication/local.go | 13 +++++++++----
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/graph/triplestore.go b/graph/triplestore.go
index a640b1d..e72c09d 100644
--- a/graph/triplestore.go
+++ b/graph/triplestore.go
@@ -70,6 +70,14 @@ type TripleStore interface {
 	// Returns the number of triples currently stored.
 	Size() int64
 
+	// The last replicated transaction ID that this triplestore has verified.
+	Horizon() int64
+
+	// Inform the triplestore of a new replication strategy. Happens at startup and,
+	// perhaps in the future, if replication changes mid-run. Writes without any replication
+	// strategy are not allowed.
+	SetReplication(Replication)
+
 	// Creates a fixed iterator which can compare Values
 	FixedIterator() FixedIterator
 
diff --git a/replication/local.go b/replication/local.go
index 0749d55..6f7d684 100644
--- a/replication/local.go
+++ b/replication/local.go
@@ -15,8 +15,9 @@
 package local
 
 import (
-	"github.com/google/cayley/graph"
 	"sync"
+
+	"github.com/google/cayley/graph"
 )
 
 type LocalReplication struct {
@@ -25,7 +26,7 @@ type LocalReplication struct {
 	mut    sync.Mutex
 }
 
-func NewLocalReplication(ts graph.TripleStore, opts graph.Options) (*LocalReplication, error) {
+func NewLocalReplication(ts graph.TripleStore, opts graph.Options) (graph.Replication, error) {
 	rep := &LocalReplication{lastId: ts.Horizon(), ts: ts}
 	ts.SetReplication(rep)
 	return rep, nil
@@ -44,8 +45,12 @@ func (l *LocalReplication) GetLastId() int64 {
 	return l.lastId
 }
 
-func (l *LocalReplication) Replicate([]*graph.Transaction)       {}
-func (l *LocalReplication) RequestTransactionRange(int64, int64) {}
+func (l *LocalReplication) Replicate([]*graph.Transaction) {
+	// Noop, single-machines don't replicate out anywhere.
+}
+func (l *LocalReplication) RequestTransactionRange(int64, int64) {
+	// Single machines also can't catch up.
+}
 
 func init() {
 	graph.RegisterReplication("local", NewLocalReplication)