mirror of https://github.com/grpc/grpc-go.git
112 lines
4.0 KiB
Go
112 lines
4.0 KiB
Go
/*
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*
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* Copyright 2020 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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package xdsclient
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import (
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"context"
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"fmt"
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"sync"
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"google.golang.org/grpc/xds/internal/xdsclient/xdsresource"
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)
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// WatchResource uses xDS to discover the resource associated with the provided
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// resource name. The resource type implementation determines how xDS requests
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// are sent out and how responses are deserialized and validated. Upon receipt
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// of a response from the management server, an appropriate callback on the
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// watcher is invoked.
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func (c *clientImpl) WatchResource(rType xdsresource.Type, resourceName string, watcher xdsresource.ResourceWatcher) (cancel func()) {
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// Return early if the client is already closed.
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//
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// The client returned from the top-level API is a ref-counted client which
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// contains a pointer to `clientImpl`. When all references are released, the
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// ref-counted client sets its pointer to `nil`. And if any watch APIs are
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// made on such a closed client, we will get here with a `nil` receiver.
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if c == nil || c.done.HasFired() {
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logger.Warningf("Watch registered for name %q of type %q, but client is closed", rType.TypeName(), resourceName)
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return func() {}
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}
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if err := c.resourceTypes.maybeRegister(rType); err != nil {
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logger.Warningf("Watch registered for name %q of type %q which is already registered", rType.TypeName(), resourceName)
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c.serializer.TrySchedule(func(context.Context) { watcher.OnError(err, xdsresource.NopDoneNotifier{}) })
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return func() {}
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}
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// TODO: Make ParseName return an error if parsing fails, and
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// schedule the OnError callback in that case.
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n := xdsresource.ParseName(resourceName)
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a, unref, err := c.findAuthority(n)
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if err != nil {
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logger.Warningf("Watch registered for name %q of type %q, authority %q is not found", rType.TypeName(), resourceName, n.Authority)
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c.serializer.TrySchedule(func(context.Context) { watcher.OnError(err, xdsresource.NopDoneNotifier{}) })
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return func() {}
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}
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cancelF := a.watchResource(rType, n.String(), watcher)
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return func() {
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cancelF()
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unref()
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}
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}
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// A registry of xdsresource.Type implementations indexed by their corresponding
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// type URLs. Registration of an xdsresource.Type happens the first time a watch
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// for a resource of that type is invoked.
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type resourceTypeRegistry struct {
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mu sync.Mutex
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types map[string]xdsresource.Type
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}
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func newResourceTypeRegistry() *resourceTypeRegistry {
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return &resourceTypeRegistry{types: make(map[string]xdsresource.Type)}
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}
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func (r *resourceTypeRegistry) get(url string) xdsresource.Type {
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r.mu.Lock()
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defer r.mu.Unlock()
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return r.types[url]
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}
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func (r *resourceTypeRegistry) maybeRegister(rType xdsresource.Type) error {
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r.mu.Lock()
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defer r.mu.Unlock()
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url := rType.TypeURL()
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typ, ok := r.types[url]
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if ok && typ != rType {
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return fmt.Errorf("attempt to re-register a resource type implementation for %v", rType.TypeName())
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}
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r.types[url] = rType
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return nil
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}
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func (c *clientImpl) triggerResourceNotFoundForTesting(rType xdsresource.Type, resourceName string) error {
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if c == nil || c.done.HasFired() {
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return fmt.Errorf("attempt to trigger resource-not-found-error for resource %q of type %q, but client is closed", rType.TypeName(), resourceName)
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}
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n := xdsresource.ParseName(resourceName)
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a, unref, err := c.findAuthority(n)
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if err != nil {
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return fmt.Errorf("attempt to trigger resource-not-found-error for resource %q of type %q, but authority %q is not found", rType.TypeName(), resourceName, n.Authority)
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}
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defer unref()
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a.triggerResourceNotFoundForTesting(rType, n.String())
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return nil
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}
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