Tribblix: manual page: dat_ep_post

DAT_EP_POST_RECV(3DAT) Direct Access Transport Library Functions

NAME

dat_ep_post_recv - receive data over the connection of the Endpoint

SYNOPSIS

cc [ flag... ] file... -ldat [ library... ]
#include <dat/udat.h>

DAT_RETURN
dat_ep_post_recv (
IN DAT_EP_HANDLE ep_handle,
IN DAT_COUNT num_segments,
IN DAT_LMR_TRIPLET *local_iov,
IN DAT_DTO_COOKIE user_cookie,
IN DAT_COMPLETION_FLAGS completion_flags
)

PARAMETERS

ep_handle
Handle for an instance of the Endpoint.

num_segments
Number of lmr_triplets in local_iov. Can be 0 for
receiving a 0 size message.

local_iov
I/O Vector that specifies the local buffer to be
filled. Can be NULL for receiving a 0 size
message.

user_cookie:
User-provided cookie that is returned to the
Consumer at the completion of the Receive DTO.
Can be NULL.

completion_flags
Flags for posted Receive. The default
DAT_COMPLETION_DEFAULT_FLAG is 0x00. Other values
are as follows:

Notification of Completion
DAT_COMPLETION_UNSIGNALLED_FLAG

0x04
Non-
notification
completion.
Local
Endpoint
must be
configured
for
Unsignaled
CompletionNotification
Suppression.

DESCRIPTION

The dat_ep_post_recv() function requests the receive of the data over
the connection of the ep_handle Endpoint of the incoming message into
the local_iov.

The num_segments parameter specifies the number of segments in the
local_iov. The local_iov segments are filled in the I/O Vector order
until the whole message is received. This ensures that all the
"front" segments of the local_iov I/O Vector are completely filled,
only one segment is partially filled, if needed, and all segments
that follow it are not filled at all.

The user_cookie allows Consumers to have unique identifiers for each
DTO. These identifiers are completely under user control and are
opaque to the Provider. There is no requirement on the Consumer that
the value user_cookie should be unique for each DTO. The user_cookie
is returned to the Consumer in the Completion event for the posted
Receive.

The completion of the posted Receive is reported to the Consumer
asynchronously through a DTO Completion event based on the
configuration of the connection for Solicited Wait and the specified
completion_flags value for the matching Send. The value of
DAT_COMPLETION _UNSIGNALLED_FLAG is only valid if the Endpoint Recv
Completion Flags DAT_COMPLETION_UNSIGNALLED_FLAG. Otherwise,
DAT_INVALID_PARAMETER is returned.

A Consumer must not modify the local_iov or its content until the DTO
is completed. When a Consumer does not adhere to this rule, the
behavior of the Provider and the underlying Transport is not defined.
Providers that allow Consumers to get ownership of the local_iov but
not the memory it specified back after the dat_ep_post_recv() returns
should document this behavior and also specify its support in
Provider attributes. This behavior allows Consumer full control of
the local_iov content after dat_ep_post_recv() returns. Because this
behavior is not guaranteed by all Providers, portable Consumers
should not rely on this behavior. Consumers should not rely on the
Provider copying local_iov information.

The DAT_SUCCESS return of the dat_ep_post_recv() is at least the
equivalent of posting a Receive operation directly by native
Transport. Providers should avoid resource allocation as part of
dat_ep_post_recv() to ensure that this operation is nonblocking and
thread safe for an UpCall.

If the size of an incoming message is larger than the size of the
local_iov, the reported status of the posted Receive DTO in the
corresponding Completion DTO event is DAT_DTO_LENGTH_ERROR. If the
reported status of the Completion DTO event corresponding to the
posted Receive DTO is not DAT_DTO_SUCCESS, the content of the
local_iov is not defined.

The operation is valid for all states of the Endpoint. The actual
data transfer does not take place until the Endpoint is in the
DAT_EP_STATE_CONNECTED state. The operation on the Endpoint in
DAT_EP_STATE_DISCONNECTED is allowed. If the operation returns
successfully, the posted Recv is immediately flushed to
recv_evd_handle.

RETURN VALUES

DAT_SUCCESS
The operation was successful.

DAT_INSUFFICIENT_RESOURCES
The operation failed due to resource
limitations.

DAT_INVALID_PARAMETER
Invalid parameter. For example, one of
the IOV segments pointed to a memory
outside its LMR.

DAT_INVALID_HANDLE
The ep_handle parameter is invalid.

DAT_PROTECTION_VIOLATION
Protection violation for local or
remote memory access. Protection Zone
mismatch between an LMR of one of the
local_iov segments and the local
Endpoint.

DAT_PRIVILEGES_VIOLATION
Privileges violation for local or
remote memory access. One of the LMRs
used in local_iov was either invalid or
did not have the local read privileges.

USAGE

For best Recv operation performance, the Consumer should align each
buffer segment of local_iov to the Optimal Buffer Alignment attribute
of the Provider. For portable applications, the Consumer should align
each buffer segment of local_iov to the DAT_OPTIMAL_ALIGNMENT.

ATTRIBUTES