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


See attributes(5) for descriptions of the following attributes:


+--------------------+---------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+---------------------------+
|Interface Stability | Standard: uDAPL, 1.1, 1.2 |
+--------------------+---------------------------+
|MT-Level | Unsafe |
+--------------------+---------------------------+

SEE ALSO


libdat(3LIB), attributes(5)


July 16, 2004 DAT_EP_POST_RECV(3DAT)