|
| 1 | +package sync |
| 2 | + |
| 3 | +import ( |
| 4 | + "context" |
| 5 | + "sync/atomic" |
| 6 | +) |
| 7 | + |
| 8 | +// ChannelMux is a multiplexer for channels of variable types. |
| 9 | +// It fans all input channels to all output channels. |
| 10 | +type ChannelMux[T any] interface { |
| 11 | + |
| 12 | + // AddInChannel adds given input channel to the list of input channels. |
| 13 | + AddInChannel(<-chan T) |
| 14 | + |
| 15 | + // NewOutChannel returns and adds new output channel to the pods of created addedOutChannels. |
| 16 | + NewOutChannel() <-chan T |
| 17 | + |
| 18 | + // AddOutChannel adds given output channel to the list of added addedOutChannels. |
| 19 | + AddOutChannel(chan<- T) |
| 20 | + |
| 21 | + // Run combines output channel lists and starts multiplexing. |
| 22 | + Run(context.Context) error |
| 23 | +} |
| 24 | + |
| 25 | +type channelMux[T any] struct { |
| 26 | + inChannels []<-chan T |
| 27 | + createdOutChannels []chan<- T |
| 28 | + addedOutChannels []chan<- T |
| 29 | + started atomic.Bool |
| 30 | +} |
| 31 | + |
| 32 | +// NewChannelMux creates new ChannelMux initialized with at least one input channel |
| 33 | +func NewChannelMux[T any](initInChannel <-chan T, inChannels ...<-chan T) ChannelMux[T] { |
| 34 | + return &channelMux[T]{ |
| 35 | + inChannels: append(make([]<-chan T, 0), append(inChannels, initInChannel)...), |
| 36 | + } |
| 37 | +} |
| 38 | + |
| 39 | +func (mux *channelMux[T]) AddInChannel(channel <-chan T) { |
| 40 | + if mux.started.Load() { |
| 41 | + panic("channelMux already started") |
| 42 | + } |
| 43 | + |
| 44 | + mux.inChannels = append(mux.inChannels, channel) |
| 45 | +} |
| 46 | + |
| 47 | +func (mux *channelMux[T]) NewOutChannel() <-chan T { |
| 48 | + if mux.started.Load() { |
| 49 | + panic("channelMux already started") |
| 50 | + } |
| 51 | + |
| 52 | + channel := make(chan T) |
| 53 | + mux.createdOutChannels = append(mux.createdOutChannels, channel) |
| 54 | + |
| 55 | + return channel |
| 56 | +} |
| 57 | + |
| 58 | +func (mux *channelMux[T]) AddOutChannel(channel chan<- T) { |
| 59 | + if mux.started.Load() { |
| 60 | + panic("channelMux already started") |
| 61 | + } |
| 62 | + |
| 63 | + mux.addedOutChannels = append(mux.addedOutChannels, channel) |
| 64 | +} |
| 65 | + |
| 66 | +func (mux *channelMux[T]) Run(ctx context.Context) error { |
| 67 | + mux.started.Store(true) |
| 68 | + |
| 69 | + defer func() { |
| 70 | + for _, channelToClose := range mux.createdOutChannels { |
| 71 | + close(channelToClose) |
| 72 | + } |
| 73 | + }() |
| 74 | + |
| 75 | + outChannels := append(mux.addedOutChannels, mux.createdOutChannels...) |
| 76 | + |
| 77 | + for { |
| 78 | + for _, inChannel := range mux.inChannels { |
| 79 | + select { |
| 80 | + case spread, more := <-inChannel: |
| 81 | + if !more { |
| 82 | + return nil |
| 83 | + } |
| 84 | + |
| 85 | + for _, outChannel := range outChannels { |
| 86 | + select { |
| 87 | + case outChannel <- spread: |
| 88 | + case <-ctx.Done(): |
| 89 | + return ctx.Err() |
| 90 | + } |
| 91 | + } |
| 92 | + case <-ctx.Done(): |
| 93 | + return ctx.Err() |
| 94 | + } |
| 95 | + } |
| 96 | + } |
| 97 | +} |
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