[VOL-4289] Proto changes for gRPC migration
Change-Id: I317a0a865ccf78d0c37aa229c50d293a3f66c8bb
diff --git a/vendor/google.golang.org/grpc/balancer/roundrobin/roundrobin.go b/vendor/google.golang.org/grpc/balancer/roundrobin/roundrobin.go
new file mode 100644
index 0000000..274eb2f
--- /dev/null
+++ b/vendor/google.golang.org/grpc/balancer/roundrobin/roundrobin.go
@@ -0,0 +1,83 @@
+/*
+ *
+ * Copyright 2017 gRPC 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.
+ *
+ */
+
+// Package roundrobin defines a roundrobin balancer. Roundrobin balancer is
+// installed as one of the default balancers in gRPC, users don't need to
+// explicitly install this balancer.
+package roundrobin
+
+import (
+ "sync"
+
+ "google.golang.org/grpc/balancer"
+ "google.golang.org/grpc/balancer/base"
+ "google.golang.org/grpc/grpclog"
+ "google.golang.org/grpc/internal/grpcrand"
+)
+
+// Name is the name of round_robin balancer.
+const Name = "round_robin"
+
+var logger = grpclog.Component("roundrobin")
+
+// newBuilder creates a new roundrobin balancer builder.
+func newBuilder() balancer.Builder {
+ return base.NewBalancerBuilder(Name, &rrPickerBuilder{}, base.Config{HealthCheck: true})
+}
+
+func init() {
+ balancer.Register(newBuilder())
+}
+
+type rrPickerBuilder struct{}
+
+func (*rrPickerBuilder) Build(info base.PickerBuildInfo) balancer.Picker {
+ logger.Infof("roundrobinPicker: Build called with info: %v", info)
+ if len(info.ReadySCs) == 0 {
+ return base.NewErrPicker(balancer.ErrNoSubConnAvailable)
+ }
+ scs := make([]balancer.SubConn, 0, len(info.ReadySCs))
+ for sc := range info.ReadySCs {
+ scs = append(scs, sc)
+ }
+ return &rrPicker{
+ subConns: scs,
+ // Start at a random index, as the same RR balancer rebuilds a new
+ // picker when SubConn states change, and we don't want to apply excess
+ // load to the first server in the list.
+ next: grpcrand.Intn(len(scs)),
+ }
+}
+
+type rrPicker struct {
+ // subConns is the snapshot of the roundrobin balancer when this picker was
+ // created. The slice is immutable. Each Get() will do a round robin
+ // selection from it and return the selected SubConn.
+ subConns []balancer.SubConn
+
+ mu sync.Mutex
+ next int
+}
+
+func (p *rrPicker) Pick(balancer.PickInfo) (balancer.PickResult, error) {
+ p.mu.Lock()
+ sc := p.subConns[p.next]
+ p.next = (p.next + 1) % len(p.subConns)
+ p.mu.Unlock()
+ return balancer.PickResult{SubConn: sc}, nil
+}