mirror of https://github.com/grpc/grpc-go.git
115 lines
3.4 KiB
Go
115 lines
3.4 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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"context"
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"sync"
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"google.golang.org/grpc/internal/grpcsync"
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)
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// Distributor makes it easy for provider implementations to furnish new key
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// materials by handling synchronization between the producer and consumers of
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// the key material.
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//
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// Provider implementations which choose to use a Distributor should do the
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// following:
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// - create a new Distributor using the NewDistributor() function.
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// - invoke the Set() method whenever they have new key material or errors to
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// report.
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// - delegate to the distributor when handing calls to KeyMaterial().
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// - invoke the Stop() method when they are done using the distributor.
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type Distributor struct {
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// mu protects the underlying key material.
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mu sync.Mutex
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km *KeyMaterial
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pErr error
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// ready channel to unblock KeyMaterial() invocations blocked on
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// availability of key material.
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ready *grpcsync.Event
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// done channel to notify provider implementations and unblock any
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// KeyMaterial() calls, once the Distributor is closed.
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closed *grpcsync.Event
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}
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// NewDistributor returns a new Distributor.
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func NewDistributor() *Distributor {
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return &Distributor{
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ready: grpcsync.NewEvent(),
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closed: grpcsync.NewEvent(),
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}
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}
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// Set updates the key material in the distributor with km.
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//
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// Provider implementations which use the distributor must not modify the
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// contents of the KeyMaterial struct pointed to by km.
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//
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// A non-nil err value indicates the error that the provider implementation ran
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// into when trying to fetch key material, and makes it possible to surface the
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// error to the user. A non-nil error value passed here causes distributor's
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// KeyMaterial() method to return nil key material.
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func (d *Distributor) Set(km *KeyMaterial, err error) {
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d.mu.Lock()
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d.km = km
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d.pErr = err
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if err != nil {
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// If a non-nil err is passed, we ignore the key material being passed.
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d.km = nil
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}
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d.ready.Fire()
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d.mu.Unlock()
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}
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// KeyMaterial returns the most recent key material provided to the Distributor.
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// If no key material was provided at the time of this call, it will block until
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// the deadline on the context expires or fresh key material arrives.
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func (d *Distributor) KeyMaterial(ctx context.Context) (*KeyMaterial, error) {
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if d.closed.HasFired() {
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return nil, errProviderClosed
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}
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if d.ready.HasFired() {
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return d.keyMaterial()
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}
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select {
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case <-ctx.Done():
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return nil, ctx.Err()
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case <-d.closed.Done():
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return nil, errProviderClosed
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case <-d.ready.Done():
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return d.keyMaterial()
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}
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}
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func (d *Distributor) keyMaterial() (*KeyMaterial, error) {
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d.mu.Lock()
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defer d.mu.Unlock()
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return d.km, d.pErr
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}
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// Stop turns down the distributor, releases allocated resources and fails any
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// active KeyMaterial() call waiting for new key material.
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func (d *Distributor) Stop() {
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d.closed.Fire()
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}
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