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package kernel
import (
"unsafe"
"fmt"
"gvisor.dev/gvisor/third_party/gvsync"
"reflect"
"strings"
)
// SeqAtomicLoad returns a copy of *ptr, ensuring that the read does not race
// with any writer critical sections in sc.
func SeqAtomicLoadTaskGoroutineSchedInfo(sc *gvsync.SeqCount, ptr *TaskGoroutineSchedInfo) TaskGoroutineSchedInfo {
// This function doesn't use SeqAtomicTryLoad because doing so is
// measurably, significantly (~20%) slower; Go is awful at inlining.
var val TaskGoroutineSchedInfo
for {
epoch := sc.BeginRead()
if gvsync.RaceEnabled {
gvsync.Memmove(unsafe.Pointer(&val), unsafe.Pointer(ptr), unsafe.Sizeof(val))
} else {
val = *ptr
}
if sc.ReadOk(epoch) {
break
}
}
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
// (unspecified, false).
func SeqAtomicTryLoadTaskGoroutineSchedInfo(sc *gvsync.SeqCount, epoch gvsync.SeqCountEpoch, ptr *TaskGoroutineSchedInfo) (TaskGoroutineSchedInfo, bool) {
var val TaskGoroutineSchedInfo
if gvsync.RaceEnabled {
gvsync.Memmove(unsafe.Pointer(&val), unsafe.Pointer(ptr), unsafe.Sizeof(val))
} else {
val = *ptr
}
return val, sc.ReadOk(epoch)
}
func initTaskGoroutineSchedInfo() {
var val TaskGoroutineSchedInfo
typ := reflect.TypeOf(val)
name := typ.Name()
if ptrs := gvsync.PointersInType(typ, name); len(ptrs) != 0 {
panic(fmt.Sprintf("SeqAtomicLoad<%s> is invalid since values %s of type %s contain pointers:\n%s", typ, name, typ, strings.Join(ptrs, "\n")))
}
}
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