snapshot of https://github.com/grpc/grpc-go.git (master, 2026-09-15; blobs > 131072B omitted)

internal/hierarchy/hierarchy.go

@@ -0,0 +1,108 @@
+/*
+ *
+ * Copyright 2020 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 hierarchy contains functions to set and get hierarchy string from
+// addresses.
+//
+// This package is experimental.
+package hierarchy
+
+import (
+	"google.golang.org/grpc/resolver"
+)
+
+type pathKeyType string
+
+const pathKey = pathKeyType("grpc.internal.address.hierarchical_path")
+
+type pathValue []string
+
+func (p pathValue) Equal(o any) bool {
+	op, ok := o.(pathValue)
+	if !ok {
+		return false
+	}
+	if len(op) != len(p) {
+		return false
+	}
+	for i, v := range p {
+		if v != op[i] {
+			return false
+		}
+	}
+	return true
+}
+
+// FromEndpoint returns the hierarchical path of endpoint.
+func FromEndpoint(endpoint resolver.Endpoint) []string {
+	path, _ := endpoint.Attributes.Value(pathKey).(pathValue)
+	return path
+}
+
+// SetInEndpoint overrides the hierarchical path in endpoint with path.
+func SetInEndpoint(endpoint resolver.Endpoint, path []string) resolver.Endpoint {
+	endpoint.Attributes = endpoint.Attributes.WithValue(pathKey, pathValue(path))
+	return endpoint
+}
+
+// Group splits a slice of endpoints into groups based on
+// the first hierarchy path. The first hierarchy path will be removed from the
+// result.
+//
+// Input:
+// [
+//
+//	{endpoint0, path: [p0, wt0]}
+//	{endpoint1, path: [p0, wt1]}
+//	{endpoint2, path: [p1, wt2]}
+//	{endpoint3, path: [p1, wt3]}
+//
+// ]
+//
+// Endpoints will be split into p0/p1, and the p0/p1 will be removed from the
+// path.
+//
+// Output:
+//
+//	{
+//	  p0: [
+//	    {endpoint0, path: [wt0]},
+//	    {endpoint1, path: [wt1]},
+//	  ],
+//	  p1: [
+//	    {endpoint2, path: [wt2]},
+//	    {endpoint3, path: [wt3]},
+//	  ],
+//	}
+//
+// If hierarchical path is not set, or has no path in it, the endpoint is
+// dropped.
+func Group(endpoints []resolver.Endpoint) map[string][]resolver.Endpoint {
+	ret := make(map[string][]resolver.Endpoint)
+	for _, endpoint := range endpoints {
+		oldPath := FromEndpoint(endpoint)
+		if len(oldPath) == 0 {
+			continue
+		}
+		curPath := oldPath[0]
+		newPath := oldPath[1:]
+		newEndpoint := SetInEndpoint(endpoint, newPath)
+		ret[curPath] = append(ret[curPath], newEndpoint)
+	}
+	return ret
+}