Add support for generic events using Linux eventfd

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

API.md

@@ -87,6 +87,11 @@ int uev_signal_init (uev_ctx_t *ctx, uev_t *w, uev_cb_t *cb, void *arg, int sign
 int uev_signal_set  (uev_t *w, int signo);               /* Change signal to wait for */
 int uev_signal_start(uev_t *w);                          /* Restart a stopped signal watcher */
 int uev_signal_stop (uev_t *w);                          /* Stop signal watcher */
+
+/* Generic event watcher, post events for later processing, or from forked child */
+int uev_event_init  (uev_ctx_t *ctx, uev_t *w, uev_cb_t *cb, void *arg);
+int uev_event_post  (uev_t *w);
+int uev_event_stop  (uev_t *w);
 ```
 
 

src/Makefile.am

@@ -1,5 +1,5 @@
 lib_LTLIBRARIES     = libuev.la
-libuev_la_SOURCES   = uev.c uev.h private.h io.c timer.c signal.c cron.c
+libuev_la_SOURCES   = uev.c uev.h private.h io.c timer.c signal.c cron.c event.c
 libuev_la_CPPFLAGS  = -D_GNU_SOURCE -D_TIME_BITS=64
 libuev_la_CFLAGS    = -W -Wall -Wextra -std=gnu11
 libuev_la_LDFLAGS   = $(AM_LDFLAGS) -version-info 3:0:1

src/event.c

@@ -0,0 +1,106 @@
+/* libuEv - Micro event loop library
+ *
+ * Copyright (c) 2012       Flemming Madsen <flemming!madsen()madsensoft!dk>
+ * Copyright (c) 2013-2017  Joachim Nilsson <troglobit()gmail!com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <errno.h>
+#include <sys/eventfd.h>
+#include <unistd.h>		/* close(), read() */
+
+#include "uev.h"
+
+
+/**
+ * Create a generic event watcher
+ * @param ctx    A valid libuEv context
+ * @param w      Pointer to an uev_t watcher
+ * @param cb     Callback when an event is posted
+ * @param arg    Optional callback argument
+ *
+ * @return POSIX OK(0) or non-zero with @param errno set on error.
+ */
+int uev_event_init(uev_ctx_t *ctx, uev_t *w, uev_cb_t *cb, void *arg)
+{
+	int fd;
+
+	if (!w || !ctx) {
+		errno = EINVAL;
+		return -1;
+	}
+	w->fd = -1;
+
+	fd = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);
+	if (fd < 0)
+		return -1;
+
+	return _uev_watcher_init(ctx, w, UEV_EVENT_TYPE, cb, arg, fd, UEV_READ)
+		|| _uev_watcher_start(w);
+}
+
+/**
+ * Post a generic event
+ * @param w  Watcher to post to
+ *
+ * @return POSIX OK(0) or non-zero with @param errno set on error.
+ */
+int uev_event_post(uev_t *w)
+{
+	uint64_t val = 1;
+
+	if (!w || -1 == w->fd) {
+		errno = EINVAL;
+		return -1;
+	}
+
+
+	if (write(w->fd, &val, sizeof(val)) != sizeof(val))
+		return -1;
+
+	return 0;
+}
+
+/**
+ * Stop a generic event watcher
+ * @param w  Watcher to stop
+ *
+ * @return POSIX OK(0) or non-zero with @param errno set on error.
+ */
+int uev_event_stop(uev_t *w)
+{
+	if (!_uev_watcher_active(w))
+		return 0;
+
+	if (_uev_watcher_stop(w))
+		return -1;
+
+	close(w->fd);
+	w->fd = -1;
+
+	return 0;
+}
+
+/**
+ * Local Variables:
+ *  indent-tabs-mode: t
+ *  c-file-style: "linux"
+ * End:
+ */

src/private.h

@@ -66,6 +66,7 @@ typedef enum {
 	UEV_SIGNAL_TYPE,
 	UEV_TIMER_TYPE,
 	UEV_CRON_TYPE,
+	UEV_EVENT_TYPE,
 } uev_type_t;
 
 /* Event mask, used internally only. */

src/uev.c

@@ -257,6 +257,9 @@ int uev_exit(uev_ctx_t *ctx)
 		case UEV_CRON_TYPE:
 			uev_timer_stop(w);
 			break;
+
+		case UEV_EVENT_TYPE:
+			uev_event_stop(w);
 			break;
 		}
 	}
@@ -397,6 +400,11 @@ int uev_run(uev_ctx_t *ctx, int flags)
 				if (!w->u.c.when)
 					uev_timer_stop(w);
 				break;
+
+			case UEV_EVENT_TYPE:
+				if (read(w->fd, &exp, sizeof(exp)) != sizeof(exp))
+					events = UEV_HUP;
+				break;
 			}
 
 			/*

src/uev.h

@@ -50,6 +50,7 @@
 #define uev_signal_active(w) _uev_watcher_active(w)
 #define uev_timer_active(w)  _uev_watcher_active(w)
 #define uev_cron_active(w)   _uev_watcher_active(w)
+#define uev_event_active(w)  _uev_watcher_active(w)
 
 /* Event watcher */
 typedef struct uev {
@@ -100,6 +101,10 @@ int uev_signal_set     (uev_t *w, int signo);
 int uev_signal_start   (uev_t *w);
 int uev_signal_stop    (uev_t *w);
 
+int uev_event_init     (uev_ctx_t *ctx, uev_t *w, uev_cb_t *cb, void *arg);
+int uev_event_post     (uev_t *w);
+int uev_event_stop     (uev_t *w);
+
 #endif /* LIBUEV_UEV_H_ */
 
 /**

tests/.gitignore

@@ -6,3 +6,4 @@ complete
 cronrun
 signal
 timer
+event

tests/Makefile.am

@@ -8,6 +8,7 @@ TESTS          += complete
 TESTS          += cronrun
 TESTS          += signal
 TESTS          += timer
+TESTS          += event
 
 check_PROGRAMS  = $(TESTS)
 

tests/event.c

@@ -0,0 +1,78 @@
+/* Verifies eventfd support
+ *
+ * Copyright (c) 2018  Joachim Nilsson <troglobit@gmail.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "check.h"
+#include <err.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/wait.h>
+
+#define LAPS 10
+pid_t pid;
+
+static void cb(uev_t *w, void *arg, int events)
+{
+	static int num = LAPS;
+
+	num--;
+//	printf("Got event %d ...\n", LAPS - num);
+	if (num == 0) {
+		waitpid(pid, NULL, 0);
+		uev_exit(w->ctx);
+	}
+}
+
+int main(void)
+{
+	uev_ctx_t ctx;
+	uev_t ev;
+	int i;
+
+	/* Initialize libuEv */
+	uev_init(&ctx);
+
+	/* Setup callbacks */
+	uev_event_init(&ctx, &ev, cb, NULL);
+
+	pid = fork();
+	if (-1 == pid)
+		err(1, "fork");
+
+	/* Start event loop */
+	if (pid > 0)
+		return uev_run(&ctx, 0);
+
+	for (i = 0; i < LAPS; i++) {
+		uev_event_post(&ev);
+		usleep(10000);
+	}
+
+	return 0;
+}
+
+/**
+ * Local Variables:
+ *  indent-tabs-mode: t
+ *  c-file-style: "linux"
+ * End:
+ */