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Introduce select_wrapper_t

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select_wrapper_t wraps up the annoying bits of using select(): keeping
track of the max fd, passing null for boring parameters, and
constructing the timeout. Introduce a wrapper struct for this and
replace the existing uses of select() with the wrapper.
This commit is contained in:
ridiculousfish
2021-04-10 16:45:26 -07:00
parent 0dd24c8f74
commit e8a61ef4aa
11 changed files with 119 additions and 99 deletions
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46
src/input_common.cpp
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@@ -44,40 +44,30 @@ void input_common_init(interrupt_func_t func) { interrupt_handler = func; }
/// Internal function used by input_common_readch to read one byte from fd 0. This function should
/// only be called by input_common_readch().
char_event_t input_event_queue_t::readb() {
select_wrapper_t fdset;
for (;;) {
fd_set fdset;
int fd_max = in_;
int ioport = iothread_port();
int res;
fdset.clear();
fdset.add(in_);
FD_ZERO(&fdset);
FD_SET(in_, &fdset);
int ioport = iothread_port();
if (ioport > 0) {
FD_SET(ioport, &fdset);
fd_max = std::max(fd_max, ioport);
fdset.add(ioport);
}
// Get our uvar notifier.
universal_notifier_t& notifier = universal_notifier_t::default_notifier();
// Get the notification fd (possibly none).
int notifier_fd = notifier.notification_fd();
if (notifier_fd > 0) {
FD_SET(notifier_fd, &fdset);
fd_max = std::max(fd_max, notifier_fd);
fdset.add(notifier_fd);
}
// Get its suggested delay (possibly none).
struct timeval tv = {};
const unsigned long usecs_delay = notifier.usec_delay_between_polls();
if (usecs_delay > 0) {
unsigned long usecs_per_sec = 1000000;
tv.tv_sec = static_cast<int>(usecs_delay / usecs_per_sec);
tv.tv_usec = static_cast<int>(usecs_delay % usecs_per_sec);
uint64_t timeout_usec = select_wrapper_t::kNoTimeout;
if (auto notifier_usec_delay = notifier.usec_delay_between_polls()) {
timeout_usec = notifier_usec_delay;
}
res = select(fd_max + 1, &fdset, nullptr, nullptr, usecs_delay > 0 ? &tv : nullptr);
if (res == -1) {
int res = fdset.select(timeout_usec);
if (res < 0) {
if (errno == EINTR || errno == EAGAIN) {
// Some uvar notifiers rely on signals - see #7671.
if (notifier.poll()) {
@@ -98,7 +88,7 @@ char_event_t input_event_queue_t::readb() {
// Check to see if we want a universal variable barrier.
bool barrier_from_poll = notifier.poll();
bool barrier_from_readability = false;
if (notifier_fd > 0 && FD_ISSET(notifier_fd, &fdset)) {
if (notifier_fd > 0 && fdset.test(notifier_fd)) {
barrier_from_readability = notifier.notification_fd_became_readable(notifier_fd);
}
if (barrier_from_poll || barrier_from_readability) {
@@ -110,7 +100,7 @@ char_event_t input_event_queue_t::readb() {
}
}
if (FD_ISSET(in_, &fdset)) {
if (fdset.test(in_)) {
unsigned char arr[1];
if (read_blocked(in_, arr, 1) != 1) {
// The teminal has been closed.
@@ -123,7 +113,7 @@ char_event_t input_event_queue_t::readb() {
// Check for iothread completions only if there is no data to be read from the stdin.
// This gives priority to the foreground.
if (ioport > 0 && FD_ISSET(ioport, &fdset)) {
if (ioport > 0 && fdset.test(ioport)) {
iothread_service_main();
if (auto mc = pop_discard_timeouts()) {
return *mc;
@@ -214,11 +204,9 @@ char_event_t input_event_queue_t::readch_timed(bool dequeue_timeouts) {
if (has_lookahead()) {
result = pop();
} else {
fd_set fds;
FD_ZERO(&fds);
FD_SET(in_, &fds);
struct timeval tm = {wait_on_escape_ms / 1000, 1000 * (wait_on_escape_ms % 1000)};
if (select(in_ + 1, &fds, nullptr, nullptr, &tm) > 0) {
const uint64_t usec_per_msec = 1000;
uint64_t timeout_usec = static_cast<uint64_t>(wait_on_escape_ms) * usec_per_msec;
if (select_wrapper_t::is_fd_readable(in_, timeout_usec)) {
result = readch();
}
}