dat_ep_create

- create an instance of an Endpoint

Synopsis

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

DAT_RETURN
    dat_ep_create (
    IN    DAT_IA_HANDLE    ia_handle,
    IN    DAT_PZ_HANDLE    pz_handle,
    IN    DAT_EVD_HANDLE   recv_evd_handle,
    IN    DAT_EVD_HANDLE   request_evd_handle,
    IN    DAT_EVD_HANDLE   connect_evd_handle,
    IN    DAT_EP_ATTR      *ep_attributes,
    OUT   DAT_EP_HANDLE    *ep_handle
    )

Parameters

ia_handle

Handle for an open instance of the IA to which the created Endpoint belongs.

pz_handle

Handle for an instance of the Protection Zone.

recv_evd_handle

Handle for the Event Dispatcher where events for completions of incoming (receive) DTOs are reported. DAT_HANDLE_NULL specifies that the Consumer is not interested in events for completions of receives.

request_evd_handle

Handle for the Event Dispatcher where events for completions of outgoing (Send, RDMA Write, RDMA Read, and RMR Bind) DTOs are reported. DAT_HANDLE_NULL specifies that the Consumer is not interested in events for completions of requests.

connect_evd_handle

Handle for the Event Dispatcher where Connection events are reported. DAT_HANDLE_NULL specifies that the Consumer is not interested in connection events for now.

ep_attributes

Pointer to a structure that contains Consumer-requested Endpoint attributes. Can be NULL.

ep_handle

Handle for the created instance of an Endpoint.

Description

The dat_ep_create() function creates an instance of an Endpoint that is provided to the Consumer as ep_handle. The value of ep_handle is not defined if the DAT_RETURN is not DAT_SUCCESS.

The Endpoint is created in the Unconnected state.

Protection Zone pz_handle allows Consumers to control what local memory the Endpoint can access for DTOs and what memory remote RDMA operations can access over the connection of a created Endpoint. Only memory referred to by LMRs and RMRs that match the Endpoint Protection Zone can be accessed by the Endpoint.

The recv_evd_handle and request_evd_handle parameters are Event Dispatcher instances where the Consumer collects completion notifications of DTOs. Completions of Receive DTOs are reported in recv_evd_handle Event Dispatcher, and completions of Send, RDMA Read, and RDMA Write DTOs are reported in request_evd_handle Event Dispatcher. All completion notifications of RMR bindings are reported to a Consumer in request_evd_handle Event Dispatcher.

All Connection events for the connected Endpoint are reported to the Consumer through connect_evd_handle Event Dispatcher.

The ep_attributes parameter specifies the initial attributes of the created Endpoint. If the Consumer specifies NULL, the Provider fills it with its default Endpoint attributes. The Consumer might not be able to do any posts to the Endpoint or use the Endpoint in connection establishment until certain Endpoint attributes are set. Maximum Message Size and Maximum Recv DTOs are examples of such attributes.

Return Values

DAT_SUCCESS

The operation was successful.

DAT_INSUFFICIENT_RESOURCES

The operation failed due to resource limitations.

DAT_INVALID_HANDLE

Invalid DAT handle.

DAT_INVALID_PARAMETER

Invalid parameter. One of the requested EP parameters or attributes was invalid or a combination of attributes or parameters is invalid.

DAT_MODEL_NOT_SUPPORTED

The requested Provider Model was not supported.

Usage

The Consumer creates an Endpoint prior to the establishment of a connection. The created Endpoint is in DAT_EP_STATE_UNCONNECTED. Consumers can do the following:

1. Request a connection on the Endpoint through dat_ep_connect(3DAT) or dat_ep_dup_connect(3DAT) for the active side of the connection model.

2. Associate the Endpoint with the Pending Connection Request that does not have an associated local Endpoint for accepting the Pending Connection Request for the passive/server side of the connection model.

3. Create a Reserved Service Point with the Endpoint for the passive/server side of the connection model. Upon arrival of a Connection Request on the Service Point, the Consumer accepts the Pending Connection Request that has the Endpoint associated with it

The Consumer cannot specify a request_evd_handle (recv_evd_handle) with Request Completion Flags (Recv Completion Flags) that do not match the other Endpoint Completion Flags for the DTO/RMR completion streams that use the same EVD. If request_evd_handle (recv_evd_handle) is used for an EVD that is fed by any event stream other than DTO or RMR completion event streams, only DAT_COMPLETION_THRESHOLD is valid for Request/Recv Completion Flags for the Endpoint completion streams that use that EVD. If request_evd_handle (recv_evd_handle) is used for request (recv) completions of an Endpoint whose associated Request (Recv) Completion Flag attribute is DAT_COMPLETION_UNSIGNALLED_FLAG, the Request Completion Flags and Recv Completion Flags for all Endpoint completion streams that use the EVD must specify the same. Analogously, if recv_evd_handle is used for recv completions of an Endpoint whose associated Recv Completion Flags attribute is DAT_COMPLETION_SOLICITED_WAIT, the Recv Completion Flags for all Endpoint Recv completion streams that use the same EVD must specify the same Recv Completion Flags attribute value and the EVD cannot be used for any other event stream types.

If EP is created with NULL attributes, Provider can fill them with its own default values. The Consumer should not rely on the Provider-filled attribute defaults, especially for portable applications. The Consumer cannot do any operations on the created Endpoint except for dat_ep_query(3DAT), dat_ep_get_status(3DAT), dat_ep_modify(3DAT), and dat_ep_free(3DAT), depending on the values that the Provider picks.

The Provider is encouraged to pick up reasonable defaults because unreasonable values might restrict Consumers to the dat_ep_query(), dat_ep_get_status(), dat_ep_modify(), and dat_ep_free() operations. The Consumer should check what values the Provider picked up for the attributes. It is especially important to make sure that the number of posted operations is not too large to avoid EVD overflow. Depending on the values picked up by the Provider, the Consumer might not be able to do any RDMA operations; it might only be able to send or receive messages of very small sizes, or it might not be able to have more than one segment in a buffer. Before doing any operations, except the ones listed above, the Consumer can configure the Endpoint using dat_ep_modify() to the attributes they want.

One reason the Consumer might still want to create an Endpoint with Null attributes is for the Passive side of the connection establishment, where the Consumer sets up Endpoint attributes based on the connection request of the remote side.

Consumers might want to create Endpoints with NULL attributes if Endpoint properties are negotiated as part the Consumer connection establishment protocol.

Consumers that create Endpoints with Provider default attributes should always verify that the Provider default attributes meet their application's requirements with regard to the number of request/receive DTOs that can be posted, maximum message sizes, maximum request/receive IOV sizes, and maximum RDMA sizes.

Attributes

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

See Also

dat_ep_connect(3DAT), dat_ep_dup_connect(3DAT), dat_ep_free(3DAT), dat_ep_get_status(3DAT), dat_ep_modify(3DAT), dat_ep_query(3DAT), libdat(3LIB), attributes(5)