| 提交 | 用户 | age | ||
| a0123f | 1 | // Created by cgo -godefs - DO NOT EDIT |
| Z | 2 | // cgo -godefs sem_linux.go |
| 3 | ||
| 4 | package shm | |
| 5 | ||
| 6 | import ( | |
| 7 | "sync/atomic" | |
| 8 | "syscall" | |
| 9 | "unsafe" | |
| 10 | ||
| 11 | "golang.org/x/sys/unix" | |
| 12 | ) | |
| 13 | ||
| 14 | type Semaphore [32]byte | |
| 15 | ||
| 16 | type newSem struct { | |
| 17 | Value uint32 | |
| 18 | Private int32 | |
| 19 | NWaiters uint64 | |
| 20 | } | |
| 21 | ||
| 22 | func New(value uint) (*Semaphore, error) { | |
| 23 | sem := new(Semaphore) | |
| 24 | ||
| 25 | if err := sem.Init(value); err != nil { | |
| 26 | return nil, err | |
| 27 | } | |
| 28 | ||
| 29 | return sem, nil | |
| 30 | } | |
| 31 | ||
| 32 | func atomicDecrementIfPositive(mem *uint32) uint32 { | |
| 33 | for { | |
| 34 | if old := atomic.LoadUint32(mem); old == 0 || atomic.CompareAndSwapUint32(mem, old, old-1) { | |
| 35 | return old | |
| 36 | } | |
| 37 | } | |
| 38 | } | |
| 39 | ||
| 40 | func (sem *Semaphore) Wait() error { | |
| 41 | isem := (*newSem)(unsafe.Pointer(sem)) | |
| 42 | ||
| 43 | if atomicDecrementIfPositive(&isem.Value) > 0 { | |
| 44 | return nil | |
| 45 | } | |
| 46 | ||
| 47 | atomic.AddUint64(&isem.NWaiters, 1) | |
| 48 | ||
| 49 | for { | |
| 50 | t := syscall.Timeval{3 /*sec*/, 0 /*usec*/} | |
| 51 | if _, _, err := unix.Syscall6(unix.SYS_FUTEX, uintptr(unsafe.Pointer(&isem.Value)), uintptr(0x0), 0, uintptr(unsafe.Pointer(&t)), 0, 0); err != 0 && err != unix.EWOULDBLOCK { | |
| 52 | atomic.AddUint64(&isem.NWaiters, ^uint64(0)) | |
| 53 | return err | |
| 54 | } | |
| 55 | ||
| 56 | if atomicDecrementIfPositive(&isem.Value) > 0 { | |
| 57 | atomic.AddUint64(&isem.NWaiters, ^uint64(0)) | |
| 58 | return nil | |
| 59 | } | |
| 60 | } | |
| 61 | } | |
| 62 | ||
| 63 | func (sem *Semaphore) TryWait() error { | |
| 64 | isem := (*newSem)(unsafe.Pointer(sem)) | |
| 65 | ||
| 66 | if atomicDecrementIfPositive(&isem.Value) > 0 { | |
| 67 | return nil | |
| 68 | } | |
| 69 | ||
| 70 | return unix.EAGAIN | |
| 71 | } | |
| 72 | ||
| 73 | func (sem *Semaphore) Post() error { | |
| 74 | isem := (*newSem)(unsafe.Pointer(sem)) | |
| 75 | ||
| 76 | for { | |
| 77 | cur := atomic.LoadUint32(&isem.Value) | |
| 78 | ||
| 79 | if cur == 0x7fffffff { | |
| 80 | return unix.EOVERFLOW | |
| 81 | } | |
| 82 | ||
| 83 | if atomic.CompareAndSwapUint32(&isem.Value, cur, cur+1) { | |
| 84 | break | |
| 85 | } | |
| 86 | } | |
| 87 | ||
| 88 | if atomic.LoadUint64(&isem.NWaiters) <= 0 { | |
| 89 | return nil | |
| 90 | } | |
| 91 | ||
| 92 | if _, _, err := unix.Syscall6(unix.SYS_FUTEX, uintptr(unsafe.Pointer(&isem.Value)), uintptr(0x1), 1, 0, 0, 0); err != 0 { | |
| 93 | return err | |
| 94 | } | |
| 95 | ||
| 96 | return nil | |
| 97 | } | |
| 98 | ||
| 99 | func (sem *Semaphore) Init(value uint) error { | |
| 100 | if value > 0x7fffffff { | |
| 101 | return unix.EINVAL | |
| 102 | } | |
| 103 | ||
| 104 | isem := (*newSem)(unsafe.Pointer(sem)) | |
| 105 | isem.Value = uint32(value) | |
| 106 | isem.Private = 0 | |
| 107 | isem.NWaiters = 0 | |
| 108 | ||
| 109 | return nil | |
| 110 | } | |
| 111 | ||
| 112 | func (sem *Semaphore) Destroy() error { | |
| 113 | return nil | |
| 114 | } | |
