diff options
Diffstat (limited to 'pkg/sync/seqatomic_unsafe.go')
-rw-r--r-- | pkg/sync/seqatomic_unsafe.go | 40 |
1 files changed, 17 insertions, 23 deletions
diff --git a/pkg/sync/seqatomic_unsafe.go b/pkg/sync/seqatomic_unsafe.go index eda6fb131..2184cb5ab 100644 --- a/pkg/sync/seqatomic_unsafe.go +++ b/pkg/sync/seqatomic_unsafe.go @@ -25,41 +25,35 @@ import ( type Value struct{} // SeqAtomicLoad returns a copy of *ptr, ensuring that the read does not race -// with any writer critical sections in sc. -func SeqAtomicLoad(sc *sync.SeqCount, ptr *Value) Value { - // This function doesn't use SeqAtomicTryLoad because doing so is - // measurably, significantly (~20%) slower; Go is awful at inlining. - var val Value +// with any writer critical sections in seq. +// +//go:nosplit +func SeqAtomicLoad(seq *sync.SeqCount, ptr *Value) Value { for { - epoch := sc.BeginRead() - if sync.RaceEnabled { - // runtime.RaceDisable() doesn't actually stop the race detector, - // so it can't help us here. Instead, call runtime.memmove - // directly, which is not instrumented by the race detector. - sync.Memmove(unsafe.Pointer(&val), unsafe.Pointer(ptr), unsafe.Sizeof(val)) - } else { - // This is ~40% faster for short reads than going through memmove. - val = *ptr - } - if sc.ReadOk(epoch) { - break + if val, ok := SeqAtomicTryLoad(seq, seq.BeginRead(), ptr); ok { + return val } } - return val } // SeqAtomicTryLoad returns a copy of *ptr while in a reader critical section -// in sc initiated by a call to sc.BeginRead() that returned epoch. If the read -// would race with a writer critical section, SeqAtomicTryLoad returns +// in seq initiated by a call to seq.BeginRead() that returned epoch. If the +// read would race with a writer critical section, SeqAtomicTryLoad returns // (unspecified, false). -func SeqAtomicTryLoad(sc *sync.SeqCount, epoch sync.SeqCountEpoch, ptr *Value) (Value, bool) { - var val Value +// +//go:nosplit +func SeqAtomicTryLoad(seq *sync.SeqCount, epoch sync.SeqCountEpoch, ptr *Value) (val Value, ok bool) { if sync.RaceEnabled { + // runtime.RaceDisable() doesn't actually stop the race detector, so it + // can't help us here. Instead, call runtime.memmove directly, which is + // not instrumented by the race detector. sync.Memmove(unsafe.Pointer(&val), unsafe.Pointer(ptr), unsafe.Sizeof(val)) } else { + // This is ~40% faster for short reads than going through memmove. val = *ptr } - return val, sc.ReadOk(epoch) + ok = seq.ReadOk(epoch) + return } func init() { |