mirror of https://github.com/grpc/grpc-go.git
121 lines
3.5 KiB
Go
121 lines
3.5 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 certprovider
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import (
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"fmt"
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"sync"
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)
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// provStore is the global singleton certificate provider store.
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var provStore = &store{
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providers: make(map[storeKey]*wrappedProvider),
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}
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// storeKey acts as the key to the map of providers maintained by the store. A
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// combination of provider name and configuration is used to uniquely identify
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// every provider instance in the store. Go maps need to be indexed by
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// comparable types, so the provider configuration is converted from
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// `interface{}` to string using the ParseConfig method while creating this key.
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type storeKey struct {
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// name of the certificate provider.
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name string
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// configuration of the certificate provider in string form.
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config string
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}
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// wrappedProvider wraps a provider instance with a reference count.
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type wrappedProvider struct {
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Provider
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refCount int
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// A reference to the key and store are also kept here to override the
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// Close method on the provider.
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storeKey storeKey
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store *store
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}
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// store is a collection of provider instances, safe for concurrent access.
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type store struct {
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mu sync.Mutex
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providers map[storeKey]*wrappedProvider
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}
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// GetProvider returns a provider instance corresponding to name and config.
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// name is the registered name of the provider and config is the
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// provider-specific configuration. Implementations of the Builder interface
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// should clearly document the type of configuration accepted by them.
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//
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// If a provider exists for the (name+config) combination, its reference count
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// is incremented before returning. If no provider exists for the (name+config)
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// combination, a new one is created using the registered builder. If no
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// registered builder is found, or the provider configuration is rejected by it,
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// a non-nil error is returned.
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func GetProvider(name string, config interface{}) (Provider, error) {
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provStore.mu.Lock()
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defer provStore.mu.Unlock()
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builder := getBuilder(name)
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if builder == nil {
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return nil, fmt.Errorf("no registered builder for provider name: %s", name)
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}
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stableConfig, err := builder.ParseConfig(config)
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if err != nil {
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return nil, err
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}
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sk := storeKey{
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name: name,
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config: string(stableConfig.Canonical()),
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}
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if wp, ok := provStore.providers[sk]; ok {
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wp.refCount++
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return wp, nil
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}
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provider := builder.Build(stableConfig)
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if provider == nil {
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return nil, fmt.Errorf("certprovider.Build(%v) failed", sk)
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}
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wp := &wrappedProvider{
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Provider: provider,
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refCount: 1,
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storeKey: sk,
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store: provStore,
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}
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provStore.providers[sk] = wp
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return wp, nil
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}
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// Close overrides the Close method of the embedded provider. It releases the
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// reference held by the caller on the underlying provider and if the
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// provider's reference count reaches zero, it is removed from the store, and
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// its Close method is also invoked.
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func (wp *wrappedProvider) Close() {
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ps := wp.store
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ps.mu.Lock()
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defer ps.mu.Unlock()
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wp.refCount--
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if wp.refCount == 0 {
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wp.Provider.Close()
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delete(ps.providers, wp.storeKey)
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}
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}
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