49 lines
1.6 KiB
Go
49 lines
1.6 KiB
Go
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package events
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import (
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"github.com/gammazero/workerpool"
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"reflect"
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)
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type CallbackPool struct {
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callbacks []*func(Event)
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pool *workerpool.WorkerPool
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}
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// Pushes a new callback into the array of listeners for the pool.
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func (cp *CallbackPool) Add(callback *func(Event)) {
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if cp.index(reflect.ValueOf(callback)) < 0 {
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cp.callbacks = append(cp.callbacks, callback)
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}
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}
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// Removes a callback from the array of registered callbacks if it exists.
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func (cp *CallbackPool) Remove(callback *func(Event)) {
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i := cp.index(reflect.ValueOf(callback))
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// If i < 0 it means there was no index found for the given callback, meaning it was
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// never registered or was already unregistered from the listeners. Also double check
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// that we didn't somehow escape the length of the topic callback (not sure how that
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// would happen, but lets avoid a panic condition).
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if i < 0 || i >= len(cp.callbacks) {
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return
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}
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// We can assume that the topic still exists at this point since we acquire an exclusive
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// lock on the process, and the "e.index" function cannot return a value >= 0 if there is
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// no topic already existing.
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cp.callbacks = append(cp.callbacks[:i], cp.callbacks[i+1:]...)
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}
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// Finds the index of a given callback in the topic by comparing all of the registered callback
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// pointers to the passed function. This function does not aquire a lock as it should only be called
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// within the confines of a function that has already acquired a lock for the duration of the lookup.
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func (cp *CallbackPool) index(v reflect.Value) int {
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for i, handler := range cp.callbacks {
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if reflect.ValueOf(handler).Pointer() == v.Pointer() {
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return i
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}
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}
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return -1
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}
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