Synopsis
void EVadd_select (
int fd,
void (*function) (char *),
NULL,
char* arg,
int dir );
void EVdel_select (
int type,
int fd,
void (*function) (char *),
NULL,
char* arg,
int dir );
Description
EVadd_select adds an event callback handler of type type .
For all types, function is a pointer to a user-supplied callback function that takes a single pointer argument. The arg parameter specifies the argument.
type can be any of the following:
• EV_SELECT0 or EV_SELECT -- Calls function when the event indicated by the dir parameter occurs in fd , a file descriptor.
Of the two types, EV_SELECT0 is the one you typically specify. EV_SELECT0 specifies that the handler should be invoked only when there are no outstanding push/pop contexts. You should use EV_SELECT0 when the callback uses the routines OMpush_ctx/OMpop_ctx. Otherwise, you can use EV_SELECT. EV_SELECT specifies that the handler can be called in the middle of a push/pop context, but in this case, it should not begin a new context.
• EV_PRE0 or EV_PRE -- Calls function right before waiting for events. The fd and dir parameters have no meaning and should be set to 0.
Of the two types, EV_PRE0 is the one you typically specify. EV_PRE0 specifies that the handler should be invoked only when there are no outstanding push/pop contexts. You should use EV_PRE0 when the callback creates its own push/pop context. Otherwise, you can use EV_PRE. EV_PRE specifies that the handler can be called in the middle of a push/pop context.
• EV_POST -- Calls function right after having waited for events. The fd and dir parameters have no meaning and should be set to 0.
• EV_POLL or EV_TIMEOUT -- Calls function when there are no events. EV_POLL calls the function immediately. EV_TIMEOUT calls the function after a certain number of milliseconds, which you specify with the dir parameter. The fd parameter has no meaning and should be set to 0. For EV_POLL, the dir parameter has no meaning and should be set to 0.
EVdel_select deletes an event callback handler. The parameters to EVdel_select must match those of the EVadd_select that created the handler.
Arguments
type
An event type, as described above:
EV_SELECT0
EV_SELECT
EV_PRE0
EV_PRE
EV_POST
EV_POLL
EV_TIMEOUT
fd
A file descriptor. fd has meaning only when type is EV_SELECT0 or EV_SELECT. Otherwise, it should be 0.
function
A pointer to a user-supplied callback function. The function should take a single pointer argument.
NULL
The fourth argument should be NULL.
arg
The argument passed to function .
dir
When the type is EV_SELECT0 or EV_SELECT, a further refinement of the event type:
• EV_SEL_IN -- The event handler should be invoked when input data is available in fd .
• EV_SEL_OUT -- The event handler should be invoked when output can be sent to fd .
• EV_SEL_EX -- The event handler should be invoked when an exception has occurred in fd .
When the type is EV_TIMEOUT, dir specifies the number of milliseconds to wait before invoking the event handler.
For other types, dir has no meaning and should be 0.