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-rw-r--r--lib/containers/syncvalue.go67
1 files changed, 0 insertions, 67 deletions
diff --git a/lib/containers/syncvalue.go b/lib/containers/syncvalue.go
deleted file mode 100644
index 160db3c..0000000
--- a/lib/containers/syncvalue.go
+++ /dev/null
@@ -1,67 +0,0 @@
-// Copyright (C) 2022-2023 Luke Shumaker <lukeshu@lukeshu.com>
-//
-// SPDX-License-Identifier: GPL-2.0-or-later
-
-package containers
-
-import (
- "sync"
-)
-
-// SyncValue is a typed equivalent of sync/atomic.Value.
-//
-// It is not actually a wrapper around sync/atomic.Value for
-// allocation-performance reasons.
-type SyncValue[T comparable] struct {
- mu sync.Mutex
- ok bool
- val T
-}
-
-// This uses a dumb mutex-based solution because
-//
-// 1. Performance is good enough, because in the fast-path mutexes
-// use the same compare-and-swap as sync/atomic.Value; and because
-// all of these methods are short we're unlikely to hit the
-// mutex's slow path.
-//
-// 2. We could use sync/atomic.Pointer[T], which by itself would have
-// the same performance characteristics as sync/atomic.Value but
-// without the benefit of runtime_procPin()/runtime_procUnpin().
-// We want to avoid that because it means we're doing an
-// allocation for every store/swap; avoiding that is our whole
-// reason for not just wraping sync/atomic.Value. So then we'd
-// want to use a SyncPool to reuse allocations; but (1) that adds
-// more sync-overhead, and (2) it also gets trickier because we'd
-// have to be careful about not adding a pointer back to the pool
-// when load has grabbed the pointer but not yet dereferenced it.
-
-func (v *SyncValue[T]) Load() (val T, ok bool) {
- v.mu.Lock()
- defer v.mu.Unlock()
- return v.val, v.ok
-}
-
-func (v *SyncValue[T]) Store(val T) {
- v.mu.Lock()
- defer v.mu.Unlock()
- v.val, v.ok = val, true
-}
-
-func (v *SyncValue[T]) Swap(newV T) (oldV T, oldOK bool) {
- v.mu.Lock()
- defer v.mu.Unlock()
- oldV, oldOK = v.val, v.ok
- v.val, v.ok = newV, true
- return
-}
-
-func (v *SyncValue[T]) CompareAndSwap(oldV, newV T) (swapped bool) {
- v.mu.Lock()
- defer v.mu.Unlock()
- if !v.ok || v.val != oldV {
- return false
- }
- v.val = newV
- return true
-}