dat_ep_set_watermark

- set high watermark on Endpoint

Synopsis

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

DAT_RETURN
    dat_ep_set_watermark (
    IN      DAT_EP_HANDLE      ep_handle,
    IN      DAT_COUNT          soft_high_watermark,
    IN      DAT_COUNT          hard_high_watermark
    )

Parameters

ep_handle

The handle for an instance of an Endpoint.

soft_high_watermark

The soft high watermark for the number of Recv buffers consumed by the Endpoint.

hard_high_watermark

The hard high watermark for the number of Recv buffers consumed by the Endpoint.

Description

The dat_ep_set_watermark() function sets the soft and hard high watermark values for EP and arms EP for generating asynchronous events for high watermarks. An asynchronous event will be generated for IA async_evd when the number of Recv buffers at EP exceeds the soft high watermark for the first time. A connection broken event will be generated for EP connect_evd when the number of Recv buffers at EP exceeds the hard high watermark. These can occur during this call or when EP takes a buffer from the SRQ or EP RQ. The soft and hard high watermark asynchronous event generation and setting are independent of each other.

The asynchronous event for a soft high watermark is generated only once per setting. Once an event is generated, no new asynchronous events for the soft high watermark is generated until the EP is again set for the soft high watermark. If the Consumer is once again interested in the event, the Consumer should again set the soft high watermark.

If the Consumer is not interested in a soft or hard high watermark, the value of DAT_WATERMARK_INFINITE can be specified for the case that is the default value. This value specifies that a non-asynchronous event will be generated for a high watermark EP attribute for which this value is set. It does not prevent generation of a connection broken event for EP when no Recv buffer is available for a message arrived on the EP connection.

The operation is supported for all states of Endpoint.

Return Values

DAT_SUCCESS

The operation was successful.

DAT_INVALID_HANDLE

The ep_handle argument is an invalid DAT handle.

DAT_INVALID_PARAMETER

One of the parameters is invalid.

DAT_MODEL_NOT_SUPPORTED

The requested Model was not supported by the Provider. The Provider does not support EP Soft or Hard High Watermarks.

Usage

For a hard high watermark, the Provider is ready to generate a connection broken event as soon as the connection is established.

If the asynchronous event for a soft or hard high watermark has not yet been generated, this call simply modifies the values for these attributes. The Provider remains armed for generation of these asynchronous events.

Regardless of whether an asynchronous event for the soft and hard high watermark has been generated, this operation will set the generation of an asynchronous event with the Consumer-provided high watermark values. If the new high watermark values are below the current number of Receive DTOs at EP, an asynchronous event will be generated immediately. Otherwise the old soft or hard (or both) high watermark values are simply replaced with the new ones.

Attributes

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

See Also

dat_ep_create(3DAT), dat_ep_recv_query(3DAT), dat_srq_create(3DAT), dat_srq_free(3DAT), dat_srq_post_recv(3DAT), dat_srq_query(3DAT), dat_srq_resize(3DAT), dat_srq_set_lw(3DAT), libdat(3LIB), attributes(5)