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| 1 | +package queuelistener |
| 2 | + |
| 3 | +import ( |
| 4 | + "errors" |
| 5 | + "fmt" |
| 6 | + "net" |
| 7 | + "net/http" |
| 8 | + "sync" |
| 9 | + "time" |
| 10 | + |
| 11 | + "github.com/zalando/skipper/logging" |
| 12 | + "github.com/zalando/skipper/metrics" |
| 13 | +) |
| 14 | + |
| 15 | +type stackListener struct { |
| 16 | + log logging.Logger |
| 17 | + metrics metrics.Metrics |
| 18 | + maxConcurrency int64 |
| 19 | + maxQueueSize int64 |
| 20 | + memoryLimitBytes int64 |
| 21 | + connectionBytes int |
| 22 | + queueTimeout time.Duration |
| 23 | + stack *naiveStack[external] |
| 24 | + externalListener net.Listener |
| 25 | + acceptInternal chan external |
| 26 | + quit chan struct{} |
| 27 | + once sync.Once |
| 28 | +} |
| 29 | + |
| 30 | +func StackListener(o Options) (net.Listener, error) { |
| 31 | + nl, err := net.Listen(o.Network, o.Address) |
| 32 | + if err != nil { |
| 33 | + return nil, fmt.Errorf("StackListener failed net.Listen: %w", err) |
| 34 | + } |
| 35 | + |
| 36 | + acceptCH := make(chan external) |
| 37 | + |
| 38 | + if o.Log == nil { |
| 39 | + o.Log = &logging.DefaultLog{} |
| 40 | + } |
| 41 | + |
| 42 | + if o.MemoryLimitBytes <= 0 { |
| 43 | + o.MemoryLimitBytes = defaultMemoryLimitBytes |
| 44 | + } |
| 45 | + |
| 46 | + if o.ConnectionBytes <= 0 { |
| 47 | + o.ConnectionBytes = defaultConnectionBytes |
| 48 | + } |
| 49 | + |
| 50 | + m := o.Metrics |
| 51 | + if m == nil { |
| 52 | + m = metrics.NoMetric{} |
| 53 | + } |
| 54 | + l := &stackListener{ |
| 55 | + log: o.Log, |
| 56 | + metrics: m, |
| 57 | + externalListener: nl, |
| 58 | + maxConcurrency: o.maxConcurrency(), |
| 59 | + maxQueueSize: o.maxQueueSize(), |
| 60 | + memoryLimitBytes: o.MemoryLimitBytes, |
| 61 | + connectionBytes: o.ConnectionBytes, |
| 62 | + queueTimeout: o.QueueTimeout, |
| 63 | + stack: NewStack(), |
| 64 | + acceptInternal: acceptCH, |
| 65 | + quit: make(chan struct{}), |
| 66 | + once: sync.Once{}, |
| 67 | + } |
| 68 | + l.log.Infof("TCP lifo listener config: %s", l) |
| 69 | + |
| 70 | + go l.listenExternal() |
| 71 | + go l.listenInternal() |
| 72 | + return l, nil |
| 73 | +} |
| 74 | + |
| 75 | +func (l *stackListener) String() string { |
| 76 | + return fmt.Sprintf("stackListener concurrency: %d, queue size: %d, memory limit: %d, bytes per connection: %d, queue timeout: %s", l.maxConcurrency, l.maxQueueSize, l.memoryLimitBytes, l.connectionBytes, l.queueTimeout) |
| 77 | +} |
| 78 | + |
| 79 | +func (l *stackListener) Accept() (net.Conn, error) { |
| 80 | + select { |
| 81 | + case <-l.quit: |
| 82 | + return nil, errListenerClosed |
| 83 | + case c := <-l.acceptInternal: |
| 84 | + l.metrics.MeasureSince(acceptLatencyKey, c.accepted) |
| 85 | + d := time.Since(c.accepted) |
| 86 | + if d > l.queueTimeout { |
| 87 | + l.metrics.IncCounter(queueTimeoutKey) |
| 88 | + if c.Conn != nil { |
| 89 | + c.Conn.Close() |
| 90 | + } |
| 91 | + return nil, errAcceptTimeout |
| 92 | + } |
| 93 | + return c, nil |
| 94 | + } |
| 95 | +} |
| 96 | + |
| 97 | +func (l *stackListener) Addr() net.Addr { |
| 98 | + return l.externalListener.Addr() |
| 99 | +} |
| 100 | + |
| 101 | +func (l *stackListener) Close() error { |
| 102 | + l.once.Do(func() { |
| 103 | + close(l.quit) |
| 104 | + l.externalListener.Close() |
| 105 | + close(l.acceptInternal) |
| 106 | + }) |
| 107 | + |
| 108 | + return nil |
| 109 | +} |
| 110 | + |
| 111 | +func (l *stackListener) listenExternal() { |
| 112 | + var ( |
| 113 | + err error |
| 114 | + c net.Conn |
| 115 | + ) |
| 116 | + for { |
| 117 | + select { |
| 118 | + case <-l.quit: |
| 119 | + return |
| 120 | + default: |
| 121 | + } |
| 122 | + |
| 123 | + c, err = l.externalListener.Accept() |
| 124 | + if err != nil { |
| 125 | + if errors.Is(err, http.ErrServerClosed) { |
| 126 | + l.log.Infof("Server closed: %v", err) |
| 127 | + return |
| 128 | + } |
| 129 | + |
| 130 | + // client closed for example |
| 131 | + //l.log.Infof("Failed to accept connection (%T): %v", err, err) |
| 132 | + if c != nil { |
| 133 | + l.log.Info("close connection") |
| 134 | + c.Close() |
| 135 | + } |
| 136 | + continue |
| 137 | + } |
| 138 | + cc := external{c, time.Now()} |
| 139 | + l.stack.Push(&cc) |
| 140 | + } |
| 141 | +} |
| 142 | + |
| 143 | +func (l *stackListener) listenInternal() { |
| 144 | + for { |
| 145 | + select { |
| 146 | + case <-l.quit: |
| 147 | + return |
| 148 | + default: |
| 149 | + } |
| 150 | + cc := l.stack.Pop() |
| 151 | + if cc == nil { |
| 152 | + // reduce cpu usage caused by busywait |
| 153 | + time.Sleep(10 * time.Microsecond) |
| 154 | + continue |
| 155 | + } |
| 156 | + l.metrics.IncCounter(acceptedConnectionsKey) |
| 157 | + l.metrics.UpdateGauge(queuedConnectionsKey, float64(l.stack.top+1)) |
| 158 | + |
| 159 | + l.acceptInternal <- *cc |
| 160 | + } |
| 161 | +} |
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