142 lines
3.7 KiB
Go
142 lines
3.7 KiB
Go
package appdata
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import (
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"context"
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"sync"
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)
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// AsyncListenerOptions are options for async listeners and listener mux's.
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type AsyncListenerOptions struct {
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// Context is the context whose Done() channel listeners use will use to listen for completion to close their
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// goroutine. If it is nil, then context.Background() will be used and goroutines may be leaked.
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Context context.Context
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// BufferSize is the buffer size of the channels to use. It defaults to 0.
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BufferSize int
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// DoneWaitGroup is an optional wait-group that listener goroutines will notify via Add(1) when they are started
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// and Done() after they are canceled and completed.
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DoneWaitGroup *sync.WaitGroup
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}
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// AsyncListenerMux is a convenience function that calls AsyncListener for each listener
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// with the provided options and combines them using ListenerMux.
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func AsyncListenerMux(opts AsyncListenerOptions, listeners ...Listener) Listener {
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asyncListeners := make([]Listener, len(listeners))
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for i, l := range listeners {
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asyncListeners[i] = AsyncListener(opts, l)
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}
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return ListenerMux(asyncListeners...)
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}
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// AsyncListener returns a listener that forwards received events to the provided listener listening in asynchronously
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// in a separate go routine. The listener that is returned will return nil for all methods including Commit and
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// an error or nil will only be returned when the callback returned by Commit is called.
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// Thus Commit() can be used as a synchronization and error checking mechanism. The go routine
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// that is being used for listening will exit when context.Done() returns and no more events will be received by the listener.
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// bufferSize is the size of the buffer for the channel that is used to send events to the listener.
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func AsyncListener(opts AsyncListenerOptions, listener Listener) Listener {
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commitChan := make(chan error)
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packetChan := make(chan Packet, opts.BufferSize)
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res := Listener{}
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ctx := opts.Context
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if ctx == nil {
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ctx = context.Background()
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}
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done := ctx.Done()
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go func() {
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if opts.DoneWaitGroup != nil {
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opts.DoneWaitGroup.Add(1)
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}
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var err error
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for {
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select {
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case packet := <-packetChan:
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if err != nil {
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// if we have an error, don't process any more packets
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// and return the error and finish when it's time to commit
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if _, ok := packet.(CommitData); ok {
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commitChan <- err
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return
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}
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} else {
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// process the packet
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err = listener.SendPacket(packet)
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// if it's a commit
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if _, ok := packet.(CommitData); ok {
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commitChan <- err
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if err != nil {
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return
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}
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}
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}
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case <-done:
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close(packetChan)
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if opts.DoneWaitGroup != nil {
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opts.DoneWaitGroup.Done()
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}
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return
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}
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}
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}()
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if listener.InitializeModuleData != nil {
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res.InitializeModuleData = func(data ModuleInitializationData) error {
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packetChan <- data
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return nil
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}
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}
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if listener.StartBlock != nil {
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res.StartBlock = func(data StartBlockData) error {
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packetChan <- data
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return nil
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}
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}
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if listener.OnTx != nil {
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res.OnTx = func(data TxData) error {
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packetChan <- data
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return nil
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}
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}
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if listener.OnEvent != nil {
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res.OnEvent = func(data EventData) error {
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packetChan <- data
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return nil
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}
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}
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if listener.OnKVPair != nil {
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res.OnKVPair = func(data KVPairData) error {
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packetChan <- data
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return nil
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}
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}
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if listener.OnObjectUpdate != nil {
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res.OnObjectUpdate = func(data ObjectUpdateData) error {
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packetChan <- data
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return nil
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}
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}
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res.Commit = func(data CommitData) (func() error, error) {
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packetChan <- data
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return func() error {
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return <-commitChan
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}, nil
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}
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res.onBatch = func(batch PacketBatch) error {
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packetChan <- batch
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return nil
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}
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return res
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}
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