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

balancer/autosharding/autosharding.go

@@ -0,0 +1,112 @@
+/*
+ *
+ * Copyright 2026 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 autosharding implements the autosharding load balancing policy.
+package autosharding
+
+import (
+	"encoding/json"
+	"fmt"
+	"time"
+
+	"google.golang.org/grpc/balancer"
+	"google.golang.org/grpc/balancer/endpointsharding"
+	iserviceconfig "google.golang.org/grpc/internal/serviceconfig"
+	"google.golang.org/grpc/resolver"
+	"google.golang.org/grpc/serviceconfig"
+)
+
+// Name is the name of the autosharding balancer.
+const Name = "autosharding_experimental"
+
+func init() {
+	balancer.Register(bb{})
+}
+
+// lbConfig is the balancer config for the autosharding balancer.
+type lbConfig struct {
+	serviceconfig.LoadBalancingConfig `json:"-"`
+
+	ChannelFactoryKey        string                  `json:"channelFactoryKey,omitempty"`
+	AutoShardingTarget       string                  `json:"autoshardingTarget,omitempty"`
+	KeyHeaderName            string                  `json:"keyHeaderName,omitempty"`
+	EnableFallback           bool                    `json:"enableFallback,omitempty"`
+	InitialAssignmentTimeout iserviceconfig.Duration `json:"initialAssignmentTimeout,omitempty"`
+}
+
+type bb struct{}
+
+func (bb) Name() string {
+	return Name
+}
+
+func (bb) ParseConfig(s json.RawMessage) (serviceconfig.LoadBalancingConfig, error) {
+	lbConfig := &lbConfig{InitialAssignmentTimeout: iserviceconfig.Duration(60 * time.Second)}
+	if err := json.Unmarshal(s, lbConfig); err != nil {
+		return nil, fmt.Errorf("autosharding: unable to unmarshal LBConfig: %v", err)
+	}
+	if lbConfig.ChannelFactoryKey == "" {
+		return nil, fmt.Errorf("autosharding: channelFactoryKey field is required")
+	}
+	if lbConfig.AutoShardingTarget == "" {
+		return nil, fmt.Errorf("autosharding: autoshardingTarget field is required")
+	}
+	if lbConfig.KeyHeaderName == "" {
+		return nil, fmt.Errorf("autosharding: keyHeaderName field is required")
+	}
+	return lbConfig, nil
+}
+
+func (bb) Build(balancer.ClientConn, balancer.BuildOptions) balancer.Balancer {
+	return &autoshardingBalancer{}
+}
+
+// slice represents a key range and its assigned endpoints.
+//
+//lint:ignore U1000 Struct fields planned for future implementation
+type slice struct {
+	startKey  []byte // Inclusive start key of the key-range
+	endKey    []byte // Exclusive, nil for sentinel/infinity
+	endpoints []int  // Indices into assignment.endpointNames
+}
+
+// assignment represents a complete snapshot of sharding assignments, and is
+// expected to cover the entire key range.
+type assignment struct {
+	slices        []slice  // Sorted by startKey
+	endpointNames []string // Complete list of endpoint names
+	generation    int64
+}
+
+// endpointState represents the state associated with an endpoint in the LB policy.
+//
+//lint:ignore U1000 Struct fields planned for future implementation
+type endpointState struct {
+	index      int                         // Index of the endpoint within the NR update
+	endpoint   resolver.Endpoint           // The actual endpoint returned by the NR
+	childState endpointsharding.ChildState // State as reported by the child policy
+}
+
+// endpointMap maps from endpoint hostname to endpoint state.
+type endpointMap struct {
+	m map[string]*endpointState
+}
+
+type autoshardingBalancer struct {
+	balancer.Balancer
+}