NAME
EvmConnCheck(), EvmConnWait(), EvmConnDispatch(), EvmConnFlush() — maintain connection with the EVM daemon
SYNOPSIS
#include <sys/time.h>
#include <evm/evm.h>
EvmStatus_t EvmConnCheck (
EvmConnection_t connection
EvmBoolean_t *IOWaiting );
EvmStatus_t EvmConnWait (
EvmConnection_t connection,
const struct timeval *timeout );
EvmStatus_t EvmConnDispatch (
EvmConnection_t connection );
EvmStatus_t EvmConnFlush (
EvmConnection_t connection,
EvmInt32_t *count );
Library
EVM Support Library
(libevm.so).
Parameters
- connection
The EVM connection that is to be monitored.
See the
EvmConnCreate(3)
manpage.
- IOWaiting
This is the return operand.
Possible values for this operand are the following:
- EvmFALSE
There is no outstanding I/O activity on the connection.
- EvmTRUE
There is outstanding I/O activity on the connection.
The client needs to call
EvmConnDispatch()
to handle the outstanding activity.
- timeout
If the
timeout
value is NULL, it specifies that
EvmConnWait()
is to wait until there is activity on the connection.
If the
timeout
value is not NULL, it specifies the amount of time that
EvmConnWait()
waits for activity on the connection.
- count
Receives a count of messages queued for sending to the EVM daemon.
DESCRIPTION
The
EvmConnCheck()
routine checks whether there is any I/O activity
outstanding on the connection. If there is activity,
IOWaiting
is set to
EvmTRUE.
The program is to then call
EvmConnDispatch()
to handle it. If there is no
outstanding I/O activity,
IOWaiting
is set to
EvmFALSE.
An
EvmTRUE
response from this function does not guarantee that an event has arrived.
An
EvmTRUE
response simply
means that there is a message on the connection that needs to be handled.
The
EvmConnWait()
routine blocks until activity is detected on the connection.
If timeout is not NULL, it specifies the amount of time that
the function waits for activity on the connection before returning
with a status of
EvmERROR_TIMEOUT.
The
EvmConnDispatch()
routine handles one incoming I/O message on the
connection, calling the client's callback function as needed.
If there is no message awaiting processing,
the function returns immediately.
Calling this function is not guaranteed
to invoke the connection's callback function.
If the callback is invoked, it is not necessarily true that
an event has arrived.
The
EvmConnFlush()
routine attempts to send to the EVM daemon any messages
that are queued for output as a result of earlier
EvmEventPost()
calls on a connection that is marked as a non-blocking connection.
The routine continues to send messages from the queue,
until either all messages have been sent or
until the send buffer is full.
On return, if the
count
output parameter is a number greater than zero,
then that number is the number of messages still queued for sending.
EvmConnFlush
returns
EvmERROR_QUEUED.
See
EvmConnControl(3)
for more information.
RETURN VALUE
- EvmERROR_NONE
The operation completed without error.
- EvmERROR_INVALID_ARGUMENT
One of the arguments to the function is invalid.
- EvmERROR_INVALID_VALUE
A value in a structure member is invalid.
- EvmERROR_NO_MEMORY
An operation failed because an attempt to acquire heap memory failed.
- EvmERROR_READ
A read error occurred while reading from the EVM daemon connection.
- EvmERROR_WRITE
A write error occurred while writing to the EVM daemon connection.
- EvmERROR_SELECT
An error occurred on the EVM connection. Invoke
EvmConnDestroy()
to destroy the connection.
- EvmERROR_TIMEOUT
A timeout period expired.
- EvmERROR_SIGNAL
The current operation was interrupted by receipt of a signal.
- EvmERROR_QUEUED
One or more messages is queued for sending to the EVM daemon.
ERRORS
The value of
errno
is not set.
FILES
- /var/evm/sockets/evmd
Default pathname for the domain socket.
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