44 lines
1.1 KiB
Go
44 lines
1.1 KiB
Go
package priopool
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// Priority pool based on implementation example from heap package.
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// Priority queue itself is not thread safe.
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// See https://cs.opensource.google/go/go/+/refs/tags/go1.17.2:src/container/heap/example_pq_test.go
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type priorityQueueTask struct {
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value func()
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priority int
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index uint64 // monotonusly increasing index to sort values with same priority
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}
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type priorityQueue struct {
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nextIndex uint64
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tasks []*priorityQueueTask
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}
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func (pq priorityQueue) Len() int { return len(pq.tasks) }
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func (pq priorityQueue) Less(i, j int) bool {
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if pq.tasks[i].priority == pq.tasks[j].priority {
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return pq.tasks[i].index < pq.tasks[j].index
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}
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return pq.tasks[i].priority > pq.tasks[j].priority
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}
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func (pq priorityQueue) Swap(i, j int) {
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pq.tasks[i], pq.tasks[j] = pq.tasks[j], pq.tasks[i]
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}
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func (pq *priorityQueue) Push(x interface{}) {
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item := x.(*priorityQueueTask)
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item.index = pq.nextIndex
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pq.nextIndex++
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pq.tasks = append(pq.tasks, item)
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}
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func (pq *priorityQueue) Pop() interface{} {
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n := len(pq.tasks)
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item := pq.tasks[n-1]
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pq.tasks[n-1] = nil
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pq.tasks = pq.tasks[0 : n-1]
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return item
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}
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