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If applicable, add the following below this CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your own identifying information: Portions Copyright [yyyy] [name of copyright owner] .TH DAT_EVD_WAIT 3DAT "Jul 16, 2004" .SH NAME dat_evd_wait \- remove first event from the Event Dispatcher event queue .SH SYNOPSIS .LP .nf cc [ \fIflag\fR\&.\|.\|. ] \fIfile\fR\&.\|.\|. \fB-ldat\fR [ \fIlibrary\fR\&.\|.\|. ] #include <\fBdat/udat.h\fR> DAT_RETURN dat_evd_wait( IN DAT_EVD_HANDLE \fIevd_handle\fR, IN DAT_TIMEOUT \fItimeout\fR, IN DAT_COUNT \fIthreshold\fR, OUT DAT_EVENT *\fIevent\fR, OUT DAT_COUNT *\fInmore\fR ) .fi .SH PARAMETERS .sp .ne 2 .na \fB\fIevd_handle\fR\fR .ad .RS 14n Handle for an instance of the Event Dispatcher. .RE .sp .ne 2 .na \fB\fItimeout\fR\fR .ad .RS 14n The duration of time, in microseconds, that the Consumer is willing to wait for the event. .RE .sp .ne 2 .na \fB\fIthreshold\fR\fR .ad .RS 14n The number of events that should be on the EVD queue before the operation should return with \fBDAT_SUCCESS\fR. The threshold must be at least 1. .RE .sp .ne 2 .na \fB\fIevent\fR\fR .ad .RS 14n Pointer to the Consumer-allocated structure that the Provider fills with the event data. .RE .sp .ne 2 .na \fB\fInmore\fR\fR .ad .RS 14n The snapshot of the queue size at the time of the operation return. .RE .SH DESCRIPTION .sp .LP The \fBdat_evd_wait()\fR function removes the first event from the Event Dispatcher event queue and fills the Consumer-allocated \fIevent\fR structure with event data. The first element in this structure provides the type of the event; the rest provides the event type-specific parameters. The Consumer should allocate an event structure big enough to hold any event that the Event Dispatcher can deliver. .sp .LP For all events, the Provider fills the \fIdat_event\fR that the Consumer allocates. Therefore, for all events, all fields of \fIdat_event\fR are OUT from the Consumer point of view. For \fBDAT_CONNECTION_REQUEST_EVENT\fR, the Provider creates a Connection Request whose \fIcr_handle\fR is returned to the Consumer in \fBDAT_CR_ARRIVAL_EVENT_DATA\fR. That object is destroyed by the Provider as part of \fBdat_cr_accept\fR(3DAT), \fBdat_cr_reject\fR(3DAT), or \fBdat_cr_handoff\fR(3DAT). The Consumer should not use \fIcr_handle\fR or any of its parameters, including \fIprivate_data\fR, after one of these operations destroys the Connection Request. .sp .LP For \fBDAT_CONNECTION_EVENT_ESTABLISHED\fR for the Active side of connection establishment, the Provider returns the pointer for \fIprivate_data\fR and the \fIprivate_data_size\fR. For the Passive side, \fBDAT_CONNECTION_EVENT_ESTABLISHED\fR event \fIprivate_data\fR is not defined and \fIprivate_data_size\fR returns zero. The Provider is responsible for the memory allocation and deallocation for \fIprivate_data\fR. The \fIprivate_data\fR is valid until the Active side Consumer destroys the connected Endpoint (\fBdat_ep_free\fR(3DAT)), or transitions the Endpoint into Unconnected state so it is ready for the next connection. So, while the Endpoint is in Connected, Disconnect Pending, or Disconnected state, the \fIprivate_data\fR of \fBDAT_CONNECTION_REQUEST_EVENT\fR is still valid for Active side Consumers. .sp .LP Provider must pass to the Consumer the entire Private Data that the remote Consumer provided for \fBdat_ep_connect\fR(3DAT), \fBdat_ep_dup_connect\fR(3DAT), and \fBdat_cr_accept()\fR. If the Consumer provides more data than the Provider and Transport can support (larger than IA Attribute of \fImax_private_data_size\fR), \fBDAT_INVALID_PARAMETER\fR is returned for that operation. .sp .LP A Consumer that blocks performing a \fBdat_evd_wait()\fR on an Event Dispatcher effectively takes exclusive ownership of that Event Dispatcher. Any other dequeue operation (\fBdat_evd_wait()\fR or \fBdat_evd_dequeue\fR(3DAT)) on the Event Dispatcher is rejected with a \fBDAT_INVALID_STATE\fR error code. .sp .LP The CNO associated with the \fBevd_handle()\fR is not triggered upon event arrival if there is a Consumer blocked on \fBdat_evd_wait()\fR on this Event Dispatcher. .sp .LP The \fItimeout\fR allows the Consumer to restrict the amount of time it is blocked waiting for the event arrival. The value of \fBDAT_TIMEOUT_INFINITE\fR indicates that the Consumer waits indefinitely for an event arrival. Consumers should use extreme caution in using this value. .sp .LP When \fItimeout\fR value is reached and the number of events on the EVD queue is below the \fIthreshold\fR value, the operation fails and returns \fBDAT_TIMEOUT_EXPIRED\fR. In this case, no event is dequeued from the EVD and the return value for the \fIevent\fR argument is undefined. However, an \fInmore\fR value is returned that specifies the snapshot of the number of the events on the EVD queue that is returned. .sp .LP The \fIthreshold\fR allows the Consumer to wait for a requested number of event arrivals prior to waking the Consumer. If the value of the \fIthreshold\fR is larger than the Event Dispatcher queue length, the operation fails with the return \fBDAT_INVALID_PARAMETER\fR. If a non-positive value is specified for \fIthreshold\fR, the operation fails and returns \fBDAT_INVALID_PARAMETER\fR. .sp .LP If EVD is used by an Endpoint for a DTO completion stream that is configured for a Consumer-controlled event Notification (\fBDAT_COMPLETION_UNSIGNALLED_FLAG\fR or \fBDAT_COMPLETION_SOLICITED_WAIT_FLAG\fR for Receive Completion Type for Receives; \fBDAT_COMPLETION_UNSIGNALLED_FLAG\fR for Request Completion Type for Send, RDMA Read, RDMA Write and RMR Bind), the \fIthreshold\fR value must be 1. An attempt to specify some other value for \fIthreshold\fR for this case results in \fBDAT_INVALID_STATE\fR. .sp .LP The returned value of \fInmore\fR indicates the number of events left on the Event Dispatcher queue after the \fBdat_evd_wait()\fR returns. If the operation return value is \fBDAT_SUCCESS\fR, the \fInmore\fR value is at least the value of (\fIthreshold\fR -1). Notice that \fInmore\fR is only a snapshot and the number of events can be changed by the time the Consumer tries to dequeue events with \fBdat_evd_wait()\fR with timeout of zero or with \fBdat_evd_dequeue()\fR. .sp .LP For returns other than \fBDAT_SUCCESS\fR, \fBDAT_TIMEOUT_EXPIRED\fR, and \fBDAT_INTERRUPTED_CALL\fR, the returned value of \fInmore\fR is undefined. .sp .LP The returned event that was posted from an Event Stream guarantees Consumers that all events that were posted from the same Event Stream prior to the returned event were already returned to a Consumer directly through a \fBdat_evd_dequeue()\fR or \fBdat_evd_wait()\fR operation. .sp .LP If the return value is neither \fBDAT_SUCCESS\fR nor \fBDAT_TIMEOUT_EXPIRED\fR, then returned values of \fInmore\fR and event are undefined. If the return value is \fBDAT_TIMEOUT_EXPIRED\fR, then the return value of event is undefined, but the return value of \fInmore\fR is defined. If the return value is \fBDAT_SUCCESS\fR, then the return values of \fInmore\fR and \fIevent\fR are defined. .sp .LP If this function is called on an EVD in an unwaitable state, or if \fBdat_evd_set_unwaitable\fR(3DAT) is called on an EVD on which a thread is blocked in this function, the function returns with \fBDAT_INVALID_STATE\fR. .sp .LP The ordering of events dequeued by overlapping calls to \fBdat_evd_wait()\fR or \fBdat_evd_dequeue()\fR is not specified. .SH RETURN VALUES .sp .ne 2 .na \fB\fBDAT_SUCCESS\fR\fR .ad .RS 25n The operation was successful. An event was returned to a Consumer. .RE .sp .ne 2 .na \fB\fBDAT_INVALID_HANDLE\fR\fR .ad .RS 25n The \fIevd_handle\fR parameter is invalid. .RE .sp .ne 2 .na \fB\fBDAT_INVALID_PARAMETER\fR\fR .ad .RS 25n The \fItimeout\fR or \fIthreshold\fR parameter is invalid. For example, \fIthreshold\fR is larger than the EVD's \fIevd_min_qlen\fR. .RE .sp .ne 2 .na \fB\fBDAT_ABORT\fR\fR .ad .RS 25n The operation was aborted because IA was closed or EVD was destroyed .RE .sp .ne 2 .na \fB\fBDAT_INVALID_STATE\fR\fR .ad .RS 25n One of the parameters was invalid for this operation. There is already a waiter on the EVD, or the EVD is in an unwaitable state. .RE .sp .ne 2 .na \fB\fBDAT_TIMEOUT_EXPIRED\fR\fR .ad .RS 25n The operation timed out. .RE .sp .ne 2 .na \fB\fBDAT_INTERRUPTED_CALL\fR\fR .ad .RS 25n The operation was interrupted by a signal. .RE .SH USAGE .sp .LP Consumers should be cautioned against using threshold combined with infinite \fItimeout\fR. .sp .LP Consumers should not mix different models for control of unblocking a waiter. If the Consumer uses Notification Suppression or Solicited Wait to control the Notification events for unblocking a waiter, the \fIthreshold\fR must be set to 1. If the Consumer uses \fIthreshold\fR to control when a waiter is unblocked, \fBDAT_COMPLETION_UNSIGNALLED_FLAG\fR locally and \fBDAT_COMPLETION_SOLICITED_WAIT\fR remotely shall not be used. By default, all completions are Notification events. .SH ATTRIBUTES .sp .LP See \fBattributes\fR(7) for descriptions of the following attributes: .sp .sp .TS box; c | c l | l . ATTRIBUTE TYPE ATTRIBUTE VALUE _ Interface Stability Standard: uDAPL, 1.1, 1.2 _ MT-Level Safe .TE .SH SEE ALSO .sp .LP .BR dat_cr_accept (3DAT), .BR dat_cr_handoff (3DAT), .BR dat_cr_reject (3DAT), .BR dat_ep_connect (3DAT), .BR dat_ep_dup_connect (3DAT), .BR dat_ep_free (3DAT), .BR dat_evd_dequeue (3DAT), .BR dat_evd_set_unwaitable (3DAT), .BR libdat (3LIB), .BR attributes (7)