/
serviceconfig.go
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/
serviceconfig.go
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/*
*
* 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 resolver
import (
"encoding/json"
"fmt"
"sync/atomic"
"time"
"google.golang.org/grpc/codes"
iresolver "google.golang.org/grpc/internal/resolver"
"google.golang.org/grpc/internal/wrr"
"google.golang.org/grpc/status"
"google.golang.org/grpc/xds/internal/balancer/clustermanager"
"google.golang.org/grpc/xds/internal/env"
)
const (
cdsName = "cds_experimental"
xdsClusterManagerName = "xds_cluster_manager_experimental"
)
type serviceConfig struct {
LoadBalancingConfig balancerConfig `json:"loadBalancingConfig"`
}
type balancerConfig []map[string]interface{}
func newBalancerConfig(name string, config interface{}) balancerConfig {
return []map[string]interface{}{{name: config}}
}
type cdsBalancerConfig struct {
Cluster string `json:"cluster"`
}
type xdsChildConfig struct {
ChildPolicy balancerConfig `json:"childPolicy"`
}
type xdsClusterManagerConfig struct {
Children map[string]xdsChildConfig `json:"children"`
}
// pruneActiveClusters deletes entries in r.activeClusters with zero
// references.
func (r *xdsResolver) pruneActiveClusters() {
for cluster, ci := range r.activeClusters {
if atomic.LoadInt32(&ci.refCount) == 0 {
delete(r.activeClusters, cluster)
}
}
}
// serviceConfigJSON produces a service config in JSON format representing all
// the clusters referenced in activeClusters. This includes clusters with zero
// references, so they must be pruned first.
func serviceConfigJSON(activeClusters map[string]*clusterInfo) (string, error) {
// Generate children (all entries in activeClusters).
children := make(map[string]xdsChildConfig)
for cluster := range activeClusters {
children[cluster] = xdsChildConfig{
ChildPolicy: newBalancerConfig(cdsName, cdsBalancerConfig{Cluster: cluster}),
}
}
sc := serviceConfig{
LoadBalancingConfig: newBalancerConfig(
xdsClusterManagerName, xdsClusterManagerConfig{Children: children},
),
}
bs, err := json.Marshal(sc)
if err != nil {
return "", fmt.Errorf("failed to marshal json: %v", err)
}
return string(bs), nil
}
type route struct {
m *compositeMatcher // converted from route matchers
clusters wrr.WRR
maxStreamDuration time.Duration
}
func (r route) String() string {
return fmt.Sprintf("%s -> { clusters: %v, maxStreamDuration: %v }", r.m.String(), r.clusters, r.maxStreamDuration)
}
type configSelector struct {
r *xdsResolver
routes []route
clusters map[string]*clusterInfo
}
var errNoMatchedRouteFound = status.Errorf(codes.Unavailable, "no matched route was found")
func (cs *configSelector) SelectConfig(rpcInfo iresolver.RPCInfo) (*iresolver.RPCConfig, error) {
if cs == nil {
return nil, status.Errorf(codes.Unavailable, "no valid clusters")
}
var rt *route
// Loop through routes in order and select first match.
for _, r := range cs.routes {
if r.m.match(rpcInfo) {
rt = &r
break
}
}
if rt == nil || rt.clusters == nil {
return nil, errNoMatchedRouteFound
}
cluster, ok := rt.clusters.Next().(string)
if !ok {
return nil, status.Errorf(codes.Internal, "error retrieving cluster for match: %v (%T)", cluster, cluster)
}
// Add a ref to the selected cluster, as this RPC needs this cluster until
// it is committed.
ref := &cs.clusters[cluster].refCount
atomic.AddInt32(ref, 1)
config := &iresolver.RPCConfig{
// Communicate to the LB policy the chosen cluster.
Context: clustermanager.SetPickedCluster(rpcInfo.Context, cluster),
OnCommitted: func() {
// When the RPC is committed, the cluster is no longer required.
// Decrease its ref.
if v := atomic.AddInt32(ref, -1); v == 0 {
// This entry will be removed from activeClusters when
// producing the service config for the empty update.
select {
case cs.r.updateCh <- suWithError{emptyUpdate: true}:
default:
}
}
},
}
if env.TimeoutSupport && rt.maxStreamDuration != 0 {
config.MethodConfig.Timeout = &rt.maxStreamDuration
}
return config, nil
}
// stop decrements refs of all clusters referenced by this config selector.
func (cs *configSelector) stop() {
// The resolver's old configSelector may be nil. Handle that here.
if cs == nil {
return
}
// If any refs drop to zero, we'll need a service config update to delete
// the cluster.
needUpdate := false
// Loops over cs.clusters, but these are pointers to entries in
// activeClusters.
for _, ci := range cs.clusters {
if v := atomic.AddInt32(&ci.refCount, -1); v == 0 {
needUpdate = true
}
}
// We stop the old config selector immediately after sending a new config
// selector; we need another update to delete clusters from the config (if
// we don't have another update pending already).
if needUpdate {
select {
case cs.r.updateCh <- suWithError{emptyUpdate: true}:
default:
}
}
}
// A global for testing.
var newWRR = wrr.NewRandom
// newConfigSelector creates the config selector for su; may add entries to
// r.activeClusters for previously-unseen clusters.
func (r *xdsResolver) newConfigSelector(su serviceUpdate) (*configSelector, error) {
cs := &configSelector{
r: r,
routes: make([]route, len(su.routes)),
clusters: make(map[string]*clusterInfo),
}
for i, rt := range su.routes {
clusters := newWRR()
for cluster, weight := range rt.Action {
clusters.Add(cluster, int64(weight))
// Initialize entries in cs.clusters map, creating entries in
// r.activeClusters as necessary. Set to zero as they will be
// incremented by incRefs.
ci := r.activeClusters[cluster]
if ci == nil {
ci = &clusterInfo{refCount: 0}
r.activeClusters[cluster] = ci
}
cs.clusters[cluster] = ci
}
cs.routes[i].clusters = clusters
var err error
cs.routes[i].m, err = routeToMatcher(rt)
if err != nil {
return nil, err
}
if rt.MaxStreamDuration == nil {
cs.routes[i].maxStreamDuration = su.ldsConfig.maxStreamDuration
} else {
cs.routes[i].maxStreamDuration = *rt.MaxStreamDuration
}
}
// Account for this config selector's clusters. Do this after no further
// errors may occur. Note: cs.clusters are pointers to entries in
// activeClusters.
for _, ci := range cs.clusters {
atomic.AddInt32(&ci.refCount, 1)
}
return cs, nil
}
type clusterInfo struct {
// number of references to this cluster; accessed atomically
refCount int32
}