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//
// Copyright 2017 Garrett D'Amore <garrett@damore.org>
//
// This software is supplied under the terms of the MIT License, a
// copy of which should be located in the distribution where this
// file was obtained (LICENSE.txt). A copy of the license may also be
// found online at https://opensource.org/licenses/MIT.
//
// POSIX pipes.
#include "core/nng_impl.h"
#ifdef PLATFORM_POSIX_PIPE
#include <errno.h>
// This implementation of notification pipes works ~everywhere on POSIX,
// as it only relies on pipe() and non-blocking I/O.
#ifdef NNG_USE_EVENTFD
// Linux eventfd. This is lighter weight than pipes, and has better semantics
// to boot. This is far better than say epoll().
#include <fcntl.h>
#include <sys/eventfd.h>
#include <unistd.h>
#ifdef EFD_CLOEXEC
#define NNI_EVENTFD_FLAGS EFD_CLOEXEC
#else
#define NNI_EVENTFD_FLAGS 0
#endif
int
nni_plat_pipe_open(int *wfd, int *rfd)
{
int fd;
if ((fd = eventfd(0, NNI_EVENTFD_FLAGS)) < 0) {
return (nni_plat_errno(errno));
}
(void) fcntl(fd, F_SETFD, FD_CLOEXEC);
(void) fcntl(fd, F_SETFL, O_NONBLOCK);
*wfd = *rfd = fd;
return (0);
}
void
nni_plat_pipe_raise(int wfd)
{
uint64_t one = 1;
(void) write(wfd, &one, sizeof(one));
}
void
nni_plat_pipe_clear(int rfd)
{
uint64_t val;
(void) read(rfd, &val, sizeof(val));
}
void
nni_plat_pipe_close(int wfd, int rfd)
{
NNI_ASSERT(wfd == rfd);
(void) close(wfd);
}
#else // NNG_USE_EVENTFD
#include <fcntl.h>
#include <unistd.h>
int
nni_plat_pipe_open(int *wfd, int *rfd)
{
int fds[2];
if (pipe(fds) < 0) {
return (nni_plat_errno(errno));
}
*wfd = fds[1];
*rfd = fds[0];
(void) fcntl(fds[0], F_SETFD, FD_CLOEXEC);
(void) fcntl(fds[1], F_SETFD, FD_CLOEXEC);
(void) fcntl(fds[0], F_SETFL, O_NONBLOCK);
(void) fcntl(fds[1], F_SETFL, O_NONBLOCK);
return (0);
}
void
nni_plat_pipe_raise(int wfd)
{
char c = 1;
(void) write(wfd, &c, 1);
}
void
nni_plat_pipe_clear(int rfd)
{
char buf[32];
int rv;
for (;;) {
// Completely drain the pipe, but don't wait. This coalesces
// events somewhat.
if (read(rfd, buf, sizeof(buf)) <= 0) {
return;
}
}
}
void
nni_plat_pipe_close(int wfd, int rfd)
{
close(wfd);
close(rfd);
}
#endif // NNG_USE_EVENTFD
#else
// Suppress empty symbols warnings in ranlib.
int nni_posix_pipe_not_used = 0;
#endif // PLATFORM_POSIX_PIPE
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