demi_push - Asynchronously pushes a scatter-gather array to an I/O queue.
#include <demi/libos.h>
int demi_push(demi_qtoken_t *qt_out, int qd, const demi_sgarray_t *sga);demi_push() asynchronously pushes a scatter-gather array to an I/O queue.
The qd parameter is the I/O queue descriptor that is associated with the target I/O queue.
The sga parameter points to the scatter-gather array that is being pushed. For information on scatter-gather arrays,
see demi_sgaalloc().
The qt_out parameter points to the location where the queue token for the demi_push() operation should be stored.
An application may use this queue token with demi_wait() or demi_wait_any() to block until the operation effectively
completes.
The push operation that is performed depends on the type of the underlying I/O queue. If it is network queue, the scatter-gather array is sent over the concerned socket.
demi_push() avoids copying, so the application must not modify or free any memory referenced in the scatter-gather
array, until the asynchronous push operation completes. Some libOSes offer free-protection, which ensures memory
referenced by the scatter-gather array is not released until the operation completes, even if the application releases
that memory area. However, applications should not rely on this feature.
On success, zero is returned. On error, a positive error code is returned.
On error, one of the following positive error codes is returned:
EINVAL- Thesgaargument does not point to a valid scatter-gather array.EINVAL- The scatter-gather array pointed to bysgarefers to a zero-length buffer.EBADF- The I/O queue descriptorqddoes not refer to a valid I/O queue.EAGAIN- Demikernel failed to create an asynchronous co-routine to handle thedemi_push()operation.
Error codes are conformant to POSIX.1-2017.
Demikernel may fail with error codes that are not listed in this manual page.
Any behavior that is not documented in this manual page is unintentional and should be reported.
demi_sgaalloc(), demi_wait() and demi_wait_any().