456b2ef6eb
If there are many listeners to bucket notifications or to the trace subsystem, healing fails to work properly since it suspends itself when the number of concurrent connections is above a certain threshold. These connections are also continuous and not costly (*no disk access*), it is okay to just ignore them in waitForLowHTTPReq().
90 lines
2 KiB
Go
90 lines
2 KiB
Go
/*
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* MinIO Cloud Storage, (C) 2019 MinIO, Inc.
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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 pubsub
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import (
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"sync"
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)
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// Sub - subscriber entity.
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type Sub struct {
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ch chan interface{}
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filter func(entry interface{}) bool
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}
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// PubSub holds publishers and subscribers
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type PubSub struct {
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subs []*Sub
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sync.RWMutex
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}
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// Publish message to the subscribers.
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// Note that publish is always nob-blocking send so that we don't block on slow receivers.
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// Hence receivers should use buffered channel so as not to miss the published events.
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func (ps *PubSub) Publish(item interface{}) {
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ps.RLock()
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defer ps.RUnlock()
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for _, sub := range ps.subs {
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if sub.filter == nil || sub.filter(item) {
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select {
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case sub.ch <- item:
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default:
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}
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}
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}
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}
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// Subscribe - Adds a subscriber to pubsub system
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func (ps *PubSub) Subscribe(subCh chan interface{}, doneCh <-chan struct{}, filter func(entry interface{}) bool) {
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ps.Lock()
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defer ps.Unlock()
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sub := &Sub{subCh, filter}
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ps.subs = append(ps.subs, sub)
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go func() {
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<-doneCh
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ps.Lock()
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defer ps.Unlock()
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for i, s := range ps.subs {
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if s == sub {
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ps.subs = append(ps.subs[:i], ps.subs[i+1:]...)
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}
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}
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}()
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}
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// HasSubscribers returns true if pubsub system has subscribers
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func (ps *PubSub) HasSubscribers() bool {
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return ps.NumSubscribers() > 0
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}
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// NumSubscribers returns the number of current subscribers
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func (ps *PubSub) NumSubscribers() int {
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ps.RLock()
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defer ps.RUnlock()
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return len(ps.subs)
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}
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// New inits a PubSub system
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func New() *PubSub {
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return &PubSub{}
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}
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