mirror of https://github.com/grpc/grpc-go.git
108 lines
3.1 KiB
Go
108 lines
3.1 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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"sync/atomic"
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)
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type clusterNameAndServiceName struct {
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clusterName, edsServiceName string
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}
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type clusterRequestsCounter struct {
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mu sync.Mutex
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clusters map[clusterNameAndServiceName]*ClusterRequestsCounter
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}
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var src = &clusterRequestsCounter{
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clusters: make(map[clusterNameAndServiceName]*ClusterRequestsCounter),
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}
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// ClusterRequestsCounter is used to track the total inflight requests for a
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// service with the provided name.
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type ClusterRequestsCounter struct {
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ClusterName string
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EDSServiceName string
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numRequests uint32
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}
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// GetClusterRequestsCounter returns the ClusterRequestsCounter with the
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// provided serviceName. If one does not exist, it creates it.
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func GetClusterRequestsCounter(clusterName, edsServiceName string) *ClusterRequestsCounter {
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src.mu.Lock()
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defer src.mu.Unlock()
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k := clusterNameAndServiceName{
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clusterName: clusterName,
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edsServiceName: edsServiceName,
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}
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c, ok := src.clusters[k]
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if !ok {
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c = &ClusterRequestsCounter{ClusterName: clusterName}
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src.clusters[k] = c
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}
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return c
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}
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// StartRequest starts a request for a cluster, incrementing its number of
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// requests by 1. Returns an error if the max number of requests is exceeded.
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func (c *ClusterRequestsCounter) StartRequest(max uint32) error {
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// Note that during race, the limits could be exceeded. This is allowed:
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// "Since the implementation is eventually consistent, races between threads
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// may allow limits to be potentially exceeded."
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// https://www.envoyproxy.io/docs/envoy/latest/intro/arch_overview/upstream/circuit_breaking#arch-overview-circuit-break.
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if atomic.LoadUint32(&c.numRequests) >= max {
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return fmt.Errorf("max requests %v exceeded on service %v", max, c.ClusterName)
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}
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atomic.AddUint32(&c.numRequests, 1)
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return nil
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}
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// EndRequest ends a request for a service, decrementing its number of requests
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// by 1.
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func (c *ClusterRequestsCounter) EndRequest() {
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atomic.AddUint32(&c.numRequests, ^uint32(0))
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}
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// ClearCounterForTesting clears the counter for the service. Should be only
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// used in tests.
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func ClearCounterForTesting(clusterName, edsServiceName string) {
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src.mu.Lock()
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defer src.mu.Unlock()
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k := clusterNameAndServiceName{
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clusterName: clusterName,
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edsServiceName: edsServiceName,
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}
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c, ok := src.clusters[k]
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if !ok {
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return
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}
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c.numRequests = 0
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}
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// ClearAllCountersForTesting clears all the counters. Should be only used in
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// tests.
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func ClearAllCountersForTesting() {
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src.mu.Lock()
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defer src.mu.Unlock()
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src.clusters = make(map[clusterNameAndServiceName]*ClusterRequestsCounter)
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}
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