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Merged
jackc merged 2 commits into from
Apr 26, 2025
Merged

Unsafe to bits #40

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e4eab01
demonstrate that bits.Len64 passes tests
flowchartsman Apr 25, 2025
3f8c490
replace custom log2 impl with bits.Len64
flowchartsman Apr 25, 2025
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32 changes: 0 additions & 32 deletions log.go
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49 changes: 0 additions & 49 deletions log_test.go
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7 changes: 5 additions & 2 deletions pool.go
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@ package puddle
import (
"context"
"errors"
"math/bits"
"sync"
"sync/atomic"
"time"
Expand Down Expand Up @@ -543,12 +544,14 @@ func (p *Pool[T]) TryAcquire(ctx context.Context) (*Resource[T], error) {
// TODO: Replace this with acquireSem.TryAcquireAll() if it gets to
// upstream. https://github.com/golang/sync/pull/19
func acquireSemAll(sem *semaphore.Weighted, num int) int {
if num <= 0 {
panic("aquireSemAll: num <= 0")
}
Comment on lines +547 to +549
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@redloaf redloaf Apr 25, 2025 •
edited
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This is a slight behavior change but is more predictable. If num is negative, sem.TryAcquire can succeed and has the same effect as sem.Release(-num). However, it fails if there are any blocked Acquire calls. Before your changes, this has the potential to result in a sporadic panic for a condition that should probably always result in a panic (as you've written it).

Example and source

if sem.TryAcquire(int64(num)) {
return num
}

var acquired int
for i := int(log2Int(num)); i >= 0; i-- {
for i := bits.Len64(uint64(num)) - 1; i >= 0; i-- {
val := 1 << i
if sem.TryAcquire(int64(val)) {
acquired += val
Expand Down