NAME

EvmConnCheck, EvmConnWait, EvmConnDispatch, EvmConnFlush − Maintains connection with the EVM daemon

LIBRARY

EVM Support Library (libevm.so, libevm.a)

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);

OPERANDS

connectionThe EVM connection that is to be monitored. 

IOWaitingThis is the return parameter.  Possible values for this parameter are the following:

EvmFALSEThere is no outstanding I/O activity on the connection. 

EvmTRUEThere is outstanding I/O activity on the connection.  The client should call EvmConnDispatch() to handle the outstanding activity. 

timeoutIf this value is NULL, it specifies that EvmConnWait() should wait until there is activity on the connection.  If this value is not NULL, it specifies the amount of time that EvmConnWait() should wait for activity on the connection. 

countReceives 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, IOWaiting is set to EvmTRUE.  The program should then call EvmConnDispatch() to handle it.  If there is no outstanding I/O activity, IOWaiting is set to EvmFALSE.  A response EvmTRUE from this function does not guarantee that an event has arrived; simply 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 should wait for activity on the connection before returning with a status of EvmERROR_TIMEOUT. 

The EvmConnDispatch() routine will handle 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, and 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 the send buffer is full.  On return, the count output parameter holds the number of messages still queued for sending; if this number is more than zero, EvmConnFlush returns EvmERROR_QUEUED.   See the EvmConnControl(3) reference page for more information. 

RETURN VALUES

EvmERROR_NONE
A value in a structure member is invalid.

EvmERROR_INVALID_ARGUMENT
One of the arguments to the function was 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

None

FILES

/var/evm/sockets/evmd
Default pathname for the domain socket.

SEE ALSO

Functions: connect(2), select(2), socket(2)

Routines: EvmConnControl(3), EvmConnCreate(3), EvmConnDestroy(3) EvmEventPost(3)

Event Management: EVM(5)

Event Callback: EvmCallback(5)

Event Connection: EvmConnection(5)

EVM Events: EvmEvent(5)