mirror of https://github.com/grpc/grpc-go.git
126 lines
3.6 KiB
Go
126 lines
3.6 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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*/
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package xdsclient
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import (
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"fmt"
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"sync"
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"time"
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"google.golang.org/grpc/xds/internal/xdsclient/bootstrap"
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)
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const (
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defaultWatchExpiryTimeout = 15 * time.Second
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defaultIdleAuthorityDeleteTimeout = 5 * time.Minute
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)
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var (
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// This is the client returned by New(). It contains one client implementation,
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// and maintains the refcount.
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singletonClient = &clientRefCounted{}
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// The following functions are no-ops in the actual code, but can be
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// overridden in tests to give them visibility into certain events.
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singletonClientImplCreateHook = func() {}
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singletonClientImplCloseHook = func() {}
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)
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// To override in tests.
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var bootstrapNewConfig = bootstrap.NewConfig
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// onceClosingClient is a thin wrapper around clientRefCounted. The Close()
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// method is overridden such that the underlying reference counted client's
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// Close() is called at most once, thereby making Close() idempotent.
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//
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// This is the type which is returned by New() and NewWithConfig(), making it
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// safe for these callers to call Close() any number of times.
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type onceClosingClient struct {
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XDSClient
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once sync.Once
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}
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func (o *onceClosingClient) Close() {
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o.once.Do(o.XDSClient.Close)
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}
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func newRefCountedWithConfig(config *bootstrap.Config) (XDSClient, error) {
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singletonClient.mu.Lock()
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defer singletonClient.mu.Unlock()
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// If the client implementation was created, increment ref count and return
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// the client.
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if singletonClient.clientImpl != nil {
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singletonClient.refCount++
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return &onceClosingClient{XDSClient: singletonClient}, nil
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}
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// If the passed in config is nil, perform bootstrap to read config.
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if config == nil {
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var err error
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config, err = bootstrapNewConfig()
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if err != nil {
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return nil, fmt.Errorf("xds: failed to read bootstrap file: %v", err)
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}
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}
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// Create the new client implementation.
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c, err := newWithConfig(config, defaultWatchExpiryTimeout, defaultIdleAuthorityDeleteTimeout)
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if err != nil {
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return nil, err
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}
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singletonClient.clientImpl = c
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singletonClient.refCount++
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singletonClientImplCreateHook()
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nodeID := "<unknown>"
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if node, ok := config.XDSServer.NodeProto.(interface{ GetId() string }); ok {
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nodeID = node.GetId()
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}
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logger.Infof("xDS node ID: %s", nodeID)
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return &onceClosingClient{XDSClient: singletonClient}, nil
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}
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// clientRefCounted is ref-counted, and to be shared by the xds resolver and
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// balancer implementations, across multiple ClientConns and Servers.
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type clientRefCounted struct {
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*clientImpl
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// This mu protects all the fields, including the embedded clientImpl above.
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mu sync.Mutex
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refCount int
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}
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// Close closes the client. It does ref count of the xds client implementation,
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// and closes the gRPC connection to the management server when ref count
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// reaches 0.
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func (c *clientRefCounted) Close() {
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c.mu.Lock()
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defer c.mu.Unlock()
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c.refCount--
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if c.refCount == 0 {
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c.clientImpl.Close()
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// Set clientImpl back to nil. So if New() is called after this, a new
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// implementation will be created.
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c.clientImpl = nil
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singletonClientImplCloseHook()
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}
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}
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