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https://github.com/matrix-org/sliding-sync.git
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8ebb1be2c1
- Randomly move elements 10,000 times in a sliding window. - Fixed a bug as a result which would cause the algorithm to fail to issue a DELETE/INSERT when the room was _inserted_ to the very end of the window range, due to it misfiring with the logic to not issue operations for no-op moves.
37 lines
1.0 KiB
Go
37 lines
1.0 KiB
Go
package testutils
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import "math/rand"
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// Moves a random element in `before`. Returns a new array with the element moved, the item moved,
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// and which index positions it was moved from/to.
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func MoveRandomElement(before []string) (after []string, item string, fromIndex, toIndex int) {
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// randomly choose an element to move
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fromIndex = rand.Intn(len(before))
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item = before[fromIndex]
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// randomly choose a destination location
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toIndex = rand.Intn(len(before))
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// create the after array
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for j := range before {
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if j == fromIndex {
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if j == toIndex {
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after = append(after, before[j]) // no-op move
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}
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continue // skip over before item
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}
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if j == toIndex {
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if j > fromIndex {
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// we've skipped item already, need to make up for it now
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after = append(after, before[toIndex])
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after = append(after, item)
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} else {
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// we will skip over item, need to make up for it now
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after = append(after, item)
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after = append(after, before[toIndex])
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}
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continue
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}
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after = append(after, before[j])
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}
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return
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}
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