[chore] update latest deps, ensure readme up to date (#1873)

* [chore] update latest deps, ensure readme up to date

* remove double entry

vendor/google.golang.org/grpc/internal/grpcsync/callback_serializer.go

@@ -0,0 +1,65 @@
+/*
+ *
+ * Copyright 2022 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 grpcsync
+
+import (
+	"context"
+
+	"google.golang.org/grpc/internal/buffer"
+)
+
+// CallbackSerializer provides a mechanism to schedule callbacks in a
+// synchronized manner. It provides a FIFO guarantee on the order of execution
+// of scheduled callbacks. New callbacks can be scheduled by invoking the
+// Schedule() method.
+//
+// This type is safe for concurrent access.
+type CallbackSerializer struct {
+	callbacks *buffer.Unbounded
+}
+
+// NewCallbackSerializer returns a new CallbackSerializer instance. The provided
+// context will be passed to the scheduled callbacks. Users should cancel the
+// provided context to shutdown the CallbackSerializer. It is guaranteed that no
+// callbacks will be executed once this context is canceled.
+func NewCallbackSerializer(ctx context.Context) *CallbackSerializer {
+	t := &CallbackSerializer{callbacks: buffer.NewUnbounded()}
+	go t.run(ctx)
+	return t
+}
+
+// Schedule adds a callback to be scheduled after existing callbacks are run.
+//
+// Callbacks are expected to honor the context when performing any blocking
+// operations, and should return early when the context is canceled.
+func (t *CallbackSerializer) Schedule(f func(ctx context.Context)) {
+	t.callbacks.Put(f)
+}
+
+func (t *CallbackSerializer) run(ctx context.Context) {
+	for ctx.Err() == nil {
+		select {
+		case <-ctx.Done():
+			return
+		case callback := <-t.callbacks.Get():
+			t.callbacks.Load()
+			callback.(func(ctx context.Context))(ctx)
+		}
+	}
+}