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sched: add support for handling exceptions on descriptors

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This commit is contained in:
Miroslav Lichvar 2016-09-26 12:16:42 +02:00
parent 411f4697ca
commit c169ad3f58
2 changed files with 34 additions and 8 deletions
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41
sched.c
View file

@ -522,12 +522,25 @@ dispatch_timeouts(struct timespec *now) {
/* nfd is the number of bits set in all fd_sets */
static void
dispatch_filehandlers(int nfd, fd_set *read_fds, fd_set *write_fds)
dispatch_filehandlers(int nfd, fd_set *read_fds, fd_set *write_fds, fd_set *except_fds)
{
FileHandlerEntry *ptr;
int fd;
for (fd = 0; nfd && fd < one_highest_fd; fd++) {
if (except_fds && FD_ISSET(fd, except_fds)) {
/* This descriptor has an exception, dispatch its handler */
ptr = (FileHandlerEntry *)ARR_GetElement(file_handlers, fd);
(ptr->handler)(fd, SCH_FILE_EXCEPTION, ptr->arg);
nfd--;
/* Don't try to read from it now */
if (read_fds && FD_ISSET(fd, read_fds)) {
FD_CLR(fd, read_fds);
nfd--;
}
}
if (read_fds && FD_ISSET(fd, read_fds)) {
/* This descriptor can be read from, dispatch its handler */
ptr = (FileHandlerEntry *)ARR_GetElement(file_handlers, fd);
@ -582,15 +595,15 @@ handle_slew(struct timespec *raw,
/* ================================================== */
static void
fill_fd_sets(fd_set **read_fds, fd_set **write_fds)
fill_fd_sets(fd_set **read_fds, fd_set **write_fds, fd_set **except_fds)
{
FileHandlerEntry *handlers;
fd_set *rd, *wr;
fd_set *rd, *wr, *ex;
int i, n, events;
n = ARR_GetSize(file_handlers);
handlers = ARR_GetElements(file_handlers);
rd = wr = NULL;
rd = wr = ex = NULL;
for (i = 0; i < n; i++) {
events = handlers[i].events;
@ -613,12 +626,22 @@ fill_fd_sets(fd_set **read_fds, fd_set **write_fds)
}
FD_SET(i, wr);
}
if (events & SCH_FILE_EXCEPTION) {
if (!ex) {
ex = *except_fds;
FD_ZERO(ex);
}
FD_SET(i, ex);
}
}
if (!rd)
*read_fds = NULL;
if (!wr)
*write_fds = NULL;
if (!ex)
*except_fds = NULL;
}
/* ================================================== */
@ -680,7 +703,8 @@ check_current_time(struct timespec *prev_raw, struct timespec *raw, int timeout,
void
SCH_MainLoop(void)
{
fd_set read_fds, write_fds, *p_read_fds, *p_write_fds;
fd_set read_fds, write_fds, except_fds;
fd_set *p_read_fds, *p_write_fds, *p_except_fds;
int status, errsv;
struct timeval tv, saved_tv, *ptv;
struct timespec ts, now, saved_now, cooked;
@ -712,14 +736,15 @@ SCH_MainLoop(void)
p_read_fds = &read_fds;
p_write_fds = &write_fds;
fill_fd_sets(&p_read_fds, &p_write_fds);
p_except_fds = &except_fds;
fill_fd_sets(&p_read_fds, &p_write_fds, &p_except_fds);
/* if there are no file descriptors being waited on and no
timeout set, this is clearly ridiculous, so stop the run */
if (!ptv && !p_read_fds && !p_write_fds)
LOG_FATAL(LOGF_Scheduler, "Nothing to do");
status = select(one_highest_fd, p_read_fds, p_write_fds, NULL, ptv);
status = select(one_highest_fd, p_read_fds, p_write_fds, p_except_fds, ptv);
errsv = errno;
LCL_ReadRawTime(&now);
@ -741,7 +766,7 @@ SCH_MainLoop(void)
}
} else if (status > 0) {
/* A file descriptor is ready for input or output */
dispatch_filehandlers(status, p_read_fds, p_write_fds);
dispatch_filehandlers(status, p_read_fds, p_write_fds, p_except_fds);
} else {
/* No descriptors readable, timeout must have elapsed.
Therefore, tv must be non-null */

1
sched.h
View file

@ -54,6 +54,7 @@ extern void SCH_Finalise(void);
/* File events */
#define SCH_FILE_INPUT 1
#define SCH_FILE_OUTPUT 2
#define SCH_FILE_EXCEPTION 4
/* Register a handler for when select goes true on a file descriptor */
extern void SCH_AddFileHandler(int fd, int events, SCH_FileHandler handler, SCH_ArbitraryArgument arg);