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sched: add support for output file event

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This allows waiting for non-blocking write operations.
This commit is contained in:
Miroslav Lichvar 2016-06-22 15:14:25 +02:00
parent d8d096aa54
commit 57fc2ff1be
2 changed files with 35 additions and 24 deletions
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58
sched.c
View file

@ -519,28 +519,29 @@ dispatch_timeouts(struct timeval *now) {
/* ================================================== */
/* nfh is the number of bits set in fhs */
/* nfd is the number of bits set in all fd_sets */
static void
dispatch_filehandlers(int nfh, fd_set *fhs)
dispatch_filehandlers(int nfd, fd_set *read_fds, fd_set *write_fds)
{
FileHandlerEntry *ptr;
int fh = 0;
int fd;
while (nfh > 0) {
if (FD_ISSET(fh, fhs)) {
for (fd = 0; nfd && fd < one_highest_fd; fd++) {
if (read_fds && FD_ISSET(fd, read_fds)) {
/* This descriptor can be read from, dispatch its handler */
ptr = (FileHandlerEntry *)ARR_GetElement(file_handlers, fh);
(ptr->handler)(fh, SCH_FILE_INPUT, ptr->arg);
/* Decrement number of readable files still to find */
--nfh;
ptr = (FileHandlerEntry *)ARR_GetElement(file_handlers, fd);
(ptr->handler)(fd, SCH_FILE_INPUT, ptr->arg);
nfd--;
}
++fh;
if (write_fds && FD_ISSET(fd, write_fds)) {
/* This descriptor can be written to, dispatch its handler */
ptr = (FileHandlerEntry *)ARR_GetElement(file_handlers, fd);
(ptr->handler)(fd, SCH_FILE_OUTPUT, ptr->arg);
nfd--;
}
}
}
/* ================================================== */
@ -581,15 +582,15 @@ handle_slew(struct timeval *raw,
/* ================================================== */
static void
fill_fd_sets(fd_set **read_fds)
fill_fd_sets(fd_set **read_fds, fd_set **write_fds)
{
FileHandlerEntry *handlers;
fd_set *rd;
fd_set *rd, *wr;
int i, n, events;
n = ARR_GetSize(file_handlers);
handlers = ARR_GetElements(file_handlers);
rd = NULL;
rd = wr = NULL;
for (i = 0; i < n; i++) {
events = handlers[i].events;
@ -604,10 +605,20 @@ fill_fd_sets(fd_set **read_fds)
}
FD_SET(i, rd);
}
if (events & SCH_FILE_OUTPUT) {
if (!wr) {
wr = *write_fds;
FD_ZERO(wr);
}
FD_SET(i, wr);
}
}
if (!rd)
*read_fds = NULL;
if (!wr)
*write_fds = NULL;
}
/* ================================================== */
@ -667,7 +678,7 @@ check_current_time(struct timeval *prev_raw, struct timeval *raw, int timeout,
void
SCH_MainLoop(void)
{
fd_set read_fds, *p_read_fds;
fd_set read_fds, write_fds, *p_read_fds, *p_write_fds;
int status, errsv;
struct timeval tv, saved_tv, *ptv;
struct timeval now, saved_now, cooked;
@ -699,14 +710,15 @@ SCH_MainLoop(void)
}
p_read_fds = &read_fds;
fill_fd_sets(&p_read_fds);
p_write_fds = &write_fds;
fill_fd_sets(&p_read_fds, &p_write_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)
if (!ptv && !p_read_fds && !p_write_fds)
LOG_FATAL(LOGF_Scheduler, "Nothing to do");
status = select(one_highest_fd, p_read_fds, NULL, NULL, ptv);
status = select(one_highest_fd, p_read_fds, p_write_fds, NULL, ptv);
errsv = errno;
LCL_ReadRawTime(&now);
@ -727,10 +739,8 @@ SCH_MainLoop(void)
LOG_FATAL(LOGF_Scheduler, "select() failed : %s", strerror(errsv));
}
} else if (status > 0) {
/* A file descriptor is ready to read */
dispatch_filehandlers(status, &read_fds);
/* A file descriptor is ready for input or output */
dispatch_filehandlers(status, p_read_fds, p_write_fds);
} else {
/* No descriptors readable, timeout must have elapsed.
Therefore, tv must be non-null */

1
sched.h
View file

@ -53,6 +53,7 @@ extern void SCH_Finalise(void);
/* File events */
#define SCH_FILE_INPUT 1
#define SCH_FILE_OUTPUT 2
/* 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);