mirror of https://github.com/grpc/grpc-go.git
95 lines
2.6 KiB
Go
95 lines
2.6 KiB
Go
/*
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*
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* Copyright 2023 gRPC authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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*/
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package clusterresolver
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import (
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"sync"
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"google.golang.org/grpc/internal/grpcsync"
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"google.golang.org/grpc/xds/internal/xdsclient/xdsresource"
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)
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type edsResourceWatcher interface {
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WatchEndpoints(string, func(xdsresource.EndpointsUpdate, error)) func()
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}
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type edsDiscoveryMechanism struct {
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cancelWatch func()
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topLevelResolver topLevelResolver
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stopped *grpcsync.Event
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mu sync.Mutex
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update xdsresource.EndpointsUpdate
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updateReceived bool
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}
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func (er *edsDiscoveryMechanism) lastUpdate() (interface{}, bool) {
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er.mu.Lock()
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defer er.mu.Unlock()
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if !er.updateReceived {
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return nil, false
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}
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return er.update, true
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}
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func (er *edsDiscoveryMechanism) resolveNow() {
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}
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// The definition of stop() mentions that implementations must not invoke any
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// methods on the topLevelResolver once the call to `stop()` returns.
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func (er *edsDiscoveryMechanism) stop() {
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// Canceling a watch with the xDS client can race with an xDS response
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// received around the same time, and can result in the watch callback being
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// invoked after the watch is canceled. Callers need to handle this race,
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// and we fire the stopped event here to ensure that a watch callback
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// invocation around the same time becomes a no-op.
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er.stopped.Fire()
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er.cancelWatch()
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}
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func (er *edsDiscoveryMechanism) handleEndpointsUpdate(update xdsresource.EndpointsUpdate, err error) {
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if er.stopped.HasFired() {
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return
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}
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if err != nil {
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er.topLevelResolver.onError(err)
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return
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}
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er.mu.Lock()
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er.update = update
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er.updateReceived = true
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er.mu.Unlock()
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er.topLevelResolver.onUpdate()
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}
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// newEDSResolver returns an implementation of the endpointsResolver interface
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// that uses EDS to resolve the given name to endpoints.
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func newEDSResolver(nameToWatch string, watcher edsResourceWatcher, topLevelResolver topLevelResolver) *edsDiscoveryMechanism {
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ret := &edsDiscoveryMechanism{
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topLevelResolver: topLevelResolver,
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stopped: grpcsync.NewEvent(),
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}
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ret.cancelWatch = watcher.WatchEndpoints(nameToWatch, ret.handleEndpointsUpdate)
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return ret
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}
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