EvmEventPost(3)EvmEventPost(3)NAME
EvmEventPost, EvmEventPostVa - Posts an event
SYNOPSIS
#include <evm/evm.h>
EvmStatus_t EvmEventPost(
EvmConnection_t connection,
const EvmEvent_t event ); EvmStatus_t EvmEventPostVa(
EvmConnection_t connection,
const EvmEvent_t event,
[EvmItemId_t item_id,
const EvmItemValue_t item_id]...,
EvmITEM_NONE );
OPERANDS
The connection through which events are posted. See EvmConnCreate(3).
The event that is to be posted to the specified connection. See
EvmEventCreate(3). The identifier for the event data item to be set.
See EvmItemSet(3) for possible values for this operand, and the data
contained by the data item. The value to be stored in the associated
item indicated by item_id.
DESCRIPTION
An EVM client program uses the routines described on this page to pass
events to the EVM daemon, for distribution to subscribers.
EvmEventPost() posts an event that has already been created with
EvmEventCreate() or EvmEventCreateVa().
EvmEventPostVa() allows you to create, post and destroy an event in a
single call. It first creates a new event, adding to it any data items
supplied in the call. If the event operand is not NULL, the contents of
the supplied event are then merged into the new event, and the new
event is posted. The new event is destroyed before the routine returns,
and the supplied event (if any) is unchanged. See EvmItemSetVa(3) for
details of the item_ids and item_values that may be passed as operands
to this routine.
If you pass NULL as the connection operand to either of these routines
the event is posted to the local daemon, using a temporary connection,
which is destroyed before the routine returns. Because of the overhead
associated with creating and destroying an EVM connection, you should
pass NULL only if your program rarely posts events.
If either routine is unable to pass the event to the daemon, the error
is reported immediately through the return code. If the event is passed
to the daemon, the type of response depends on the response mode speci‐
fied when the connection was created.
NOTES
These routines do not destroy the event passed as the event operand.
You must explicitly call EvmEventDestroy() to destroy the event and
free its memory once it is no longer needed. You should avoid posting
a large number of events in rapid succession, since this may cause the
connection's send buffer to fill, and the posting process to block
until the EVM daemon has relieved some or all of the data. Although
this is a normal part of process synchronization, some high-performance
processes may prefer to block as infrequently as possible. EvmConnCon‐
trol() can be used to increase the size of the send buffer. See Evm‐
ConnControl(3) for more information. If you use extended item_ids to
supply names and values of variable items to EvmEventPostVa(), be sure
to supply the correct number of operands for each. A variable name and
value is required for all such items, and some variable types require
an additional argument. See EvmItemSetVa(3) for more information.
RESTRICTIONS
None
RETURN VALUES
The operation was completed without error. The EVM daemon rejected the
event. The most likely reasons for this to happen are that no template
has been registered for the event, or that the caller is not authorized
to post the event. See evmtemplate(4) and evm.auth(4) for more informa‐
tion. One of the arguments to the function was invalid. A value in a
structure member is invalid. An operation failed because an attempt to
acquire heap memory failed. The connection's output buffer is full,
and the event has been queued in heap space. Another attempt will be
made to flush the queue when the next call is made to EvmEventPost(3),
or when the caller invokes EvmConnFlush(3). This error code is only
returned for connections for which EvmConnControl(3) has been invoked
with the request argument set to EvmCONN_POST_NONBLOCK_SET. A read
error occurred while reading from the EVM daemon connection. The con‐
nection is no longer usable, and the caller should invoke EvmConnDe‐
stroy() to destroy it. A write error occurred while writing to the EVM
daemon connection. The connection is no longer usable, and the caller
should invoke EvmConnDestroy() to destroy it.
ERRORS
None
LIBRARY
EVM Support Library (libevm.so, libevm.a)
FILES
None
SEE ALSO
Routines: EvmConnControl(3), EvmConnCreate(3), EvmConnDestroy(3), Evm‐
ConnRegistrationGet(3), EvmEventCreate(3), EvmEventDestroy(3), EvmItem‐
SetVa(3)
Files: kevm(7)
Event Management: EVM(5)
Event Connection: EvmConnection(5)
EVM Events: EvmEvent(5)EvmEventPost(3)
