180ff682d9
Signed-off-by: Adrian Cole <adrian@tetrate.io> Co-authored-by: Takeshi Yoneda <takeshi@tetrate.io>
43 lines
1.8 KiB
Go
43 lines
1.8 KiB
Go
package sysfs
|
|
|
|
import (
|
|
"github.com/tetratelabs/wazero/experimental/sys"
|
|
"github.com/tetratelabs/wazero/internal/platform"
|
|
)
|
|
|
|
// _select waits until one or more of the file descriptors become ready for
|
|
// reading or writing.
|
|
//
|
|
// # Parameters
|
|
//
|
|
// The `timeoutMillis` parameter is how long to block for an event, or
|
|
// interrupted, in milliseconds. There are two special values:
|
|
// - zero returns immediately
|
|
// - any negative value blocks any amount of time
|
|
//
|
|
// A zero sys.Errno is success. The below are expected otherwise:
|
|
// - sys.ENOSYS: the implementation does not support this function.
|
|
// - sys.EINTR: the call was interrupted prior to an event.
|
|
//
|
|
// # Impact of blocking
|
|
//
|
|
// Because this is a blocking syscall, it will also block the carrier thread of the goroutine,
|
|
// preventing any means to support context cancellation directly.
|
|
//
|
|
// There are ways to obviate this issue. We outline here one idea, that is however not currently implemented.
|
|
// A common approach to support context cancellation is to add a signal file descriptor to the set,
|
|
// e.g. the read-end of a pipe or an eventfd on Linux.
|
|
// When the context is canceled, we may unblock a Select call by writing to the fd, causing it to return immediately.
|
|
// This however requires to do a bit of housekeeping to hide the "special" FD from the end-user.
|
|
//
|
|
// # Notes
|
|
//
|
|
// - This is like `select` in POSIX except it returns if any are ready
|
|
// instead of a specific file descriptor. See
|
|
// https://pubs.opengroup.org/onlinepubs/9699919799/functions/select.html
|
|
// - This is named _select to avoid collision on the select keyword, while
|
|
// not exporting the function.
|
|
func _select(n int, r, w, e *platform.FdSet, timeoutNanos int32) (ready bool, errno sys.Errno) {
|
|
return syscall_select(n, r, w, e, timeoutNanos)
|
|
}
|