func ReadAt(fd int, off int64, size int) ([]byte, error) {
idx := <-idle_event
retch := aio_result_map[idx]
defer func() { idle_event <- idx }()
var cb *C.struct_iocb = &cbs[idx]
var read_buf unsafe.Pointer
C.posix_memalign(&read_buf, pagesize, C.size_t(size))
defer C.free(read_buf)
C.io_prep_pread(cb, C.int(fd), read_buf, C.size_t(size), C.longlong(off))
cbs[idx].data = unsafe.Pointer(&idx)
aio_lock.Lock()
rt := C.io_submit(ctx, 1, &cb)
if int(rt) < 0 {
aio_lock.Unlock()
return nil, errors.New("io submit failed")
}
aiocount++
aio_lock.Unlock()
select {
case have_aio_event <- 0:
default:
}
ret := <-retch
return ret.buf, ret.err
}
// The function allocates size bytes. The address of the allocated memory will
// be a multiple of alignment, which must be a power of two and a multiple of
// sizeof(void *). Alignment or size must not be 0 or the method will
// intentionally panic.
func NewAlignedBuffer(alignment int64, size int) (AlignedBuffer, error) {
if alignment == 0 || size == 0 {
panic(error(syscall.EINVAL))
}
// Allocate memory
var ptr unsafe.Pointer
pbuff := &ptr
rv := C.posix_memalign(pbuff, (C.size_t)(alignment), (C.size_t)(size))
if rv < 0 {
err := (syscall.Errno)(rv)
return nil, err
}
// Create a slice on top of allocated memory
return &_AlignedBuffer{uintptr(ptr), size}, nil
}
func WriteAt(fd int, off int64, buf []byte) (int, error) {
size := len(buf)
if size == 0 {
return 0, nil
}
idx := <-idle_event
retch := aio_result_map[idx]
defer func() { idle_event <- idx }()
var cb *C.struct_iocb = &cbs[idx]
var write_buf unsafe.Pointer
C.posix_memalign(&write_buf, pagesize, C.size_t(size))
defer C.free(write_buf)
for i := 0; i < size; i++ {
*(*byte)(unsafe.Pointer(uintptr(write_buf) + uintptr(i))) = buf[i]
}
C.io_prep_pwrite(cb, C.int(fd), write_buf, C.size_t(size), C.longlong(off))
cbs[idx].data = unsafe.Pointer(&idx)
aio_lock.Lock()
rt := C.io_submit(ctx, 1, &cb)
if int(rt) < 0 {
aio_lock.Unlock()
return 0, errors.New("io submit failed")
}
aiocount++
aio_lock.Unlock()
select {
case have_aio_event <- 0:
default:
}
ret := <-retch
return ret.size, ret.err
}
func posixMemalign(alignment uint64, size uint64) []byte {
var ptr C.void
ptr2 := unsafe.Pointer(&ptr)
writesize := C.posix_memalign(&ptr2, C.size_t(uintptr(alignment)), C.size_t(uintptr(size)))
return []byte(C.GoBytes(unsafe.Pointer(&ptr), writesize))
}