consul/state: basic k/v operations

consul/state/state_store.go

@@ -702,3 +702,55 @@ func (s *StateStore) parseNodes(
 	}
 	return lindex, results, nil
 }
+
+// KVSSet is used to store a key/value pair.
+func (s *StateStore) KVSSet(idx uint64, entry *structs.DirEntry) error {
+	tx := s.db.Txn(true)
+	defer tx.Abort()
+	return s.kvsSetTxn(idx, entry, tx)
+}
+
+// kvsSetTxn is used to insert or update a key/value pair in the state
+// store. It is the inner method used and handles only the actual storage.
+func (s *StateStore) kvsSetTxn(
+	idx uint64, entry *structs.DirEntry,
+	tx *memdb.Txn) error {
+
+	// Retrieve an existing KV pair
+	existing, err := tx.First("kvs", "id", entry.Key)
+	if err != nil {
+		return fmt.Errorf("failed key lookup: %s", err)
+	}
+
+	// Set the indexes
+	if existing != nil {
+		entry.CreateIndex = existing.(*structs.DirEntry).CreateIndex
+		entry.ModifyIndex = idx
+	} else {
+		entry.CreateIndex = idx
+		entry.ModifyIndex = idx
+	}
+
+	// Store the kv pair in the state store and update the index
+	if err := tx.Insert("kvs", entry); err != nil {
+		return fmt.Errorf("failed inserting kv entry: %s", err)
+	}
+	if err := tx.Insert("index", &IndexEntry{"kvs", idx}); err != nil {
+		return fmt.Errorf("failed updating index: %s", err)
+	}
+
+	tx.Commit()
+	return nil
+}
+
+// KVSGet is used to retrieve a key/value pair from the state store.
+func (s *StateStore) KVSGet(key string) (*structs.DirEntry, error) {
+	tx := s.db.Txn(false)
+	defer tx.Abort()
+
+	entry, err := tx.First("kvs", "id", key)
+	if err != nil {
+		return nil, fmt.Errorf("failed key lookup: %s", err)
+	}
+	return entry.(*structs.DirEntry), nil
+}

consul/state/state_store_test.go

@@ -775,3 +775,56 @@ func TestStateStore_NodeInfo_NodeDump(t *testing.T) {
 		t.Fatalf("bad: %#v", dump[0].Services[0])
 	}
 }
+
+func TestStateStore_KVSSet(t *testing.T) {
+	s := testStateStore(t)
+
+	// Write a new K/V entry to the store
+	entry := &structs.DirEntry{
+		Key:   "foo",
+		Value: []byte("bar"),
+	}
+	if err := s.KVSSet(1, entry); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	// Retrieve the K/V entry again
+	result, err := s.KVSGet("foo")
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	if result == nil {
+		t.Fatalf("expected k/v pair, got nothing")
+	}
+
+	// Check that the index was injected into the result
+	if result.CreateIndex != 1 || result.ModifyIndex != 1 {
+		t.Fatalf("bad index: %d, %d", result.CreateIndex, result.ModifyIndex)
+	}
+
+	// Check that the value matches
+	if v := string(result.Value); v != "bar" {
+		t.Fatalf("expected 'bar', got: '%s'", v)
+	}
+
+	// Updating the entry works and changes the index
+	update := &structs.DirEntry{
+		Key:   "foo",
+		Value: []byte("baz"),
+	}
+	if err := s.KVSSet(2, update); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	// Fetch the kv pair and check
+	result, err = s.KVSGet("foo")
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	if result.CreateIndex != 1 || result.ModifyIndex != 2 {
+		t.Fatalf("bad index: %d, %d", result.CreateIndex, result.ModifyIndex)
+	}
+	if v := string(result.Value); v != "baz" {
+		t.Fatalf("expected 'baz', got '%s'", v)
+	}
+}

consul/structs/structs.go

@@ -348,13 +348,13 @@ type IndexedNodeDump struct {
 // DirEntry is used to represent a directory entry. This is
 // used for values in our Key-Value store.
 type DirEntry struct {
-	CreateIndex uint64
-	ModifyIndex uint64
-	LockIndex   uint64
-	Key         string
-	Flags       uint64
-	Value       []byte
-	Session     string `json:",omitempty"`
+	LockIndex uint64
+	Key       string
+	Flags     uint64
+	Value     []byte
+	Session   string `json:",omitempty"`
+
+	RaftIndex
 }
 type DirEntries []*DirEntry