system & jobs: Reverse link and acquiring events

- The new version of 'systemd_get_event_loop' dont depends
anymore on jobs but returns a unique systemd event loop
for any threads.

- The event loop of jobs now use system.h function instead
of the opposite.

- The function 'jobs_get_sd_event' is removed

- The function 'jobs_acquire_event_manager' is introduced.
It is designed to that the current thread can manipulate
the single event manager

Change-Id: I31fe48dfe0f2cfa4d468e49338d36fea6e7e8081
Signed-off-by: José Bollo <jose.bollo@iot.bzh>

7 files changed, 81 insertions, 39 deletions

diff --git a/src/afb-api-dbus.c b/src/afb-api-dbus.c
index 8c55ed01..dccfbbd8 100644
--- a/src/afb-api-dbus.c
+++ b/src/afb-api-dbus.c
@@ -45,6 +45,7 @@
 
 #include "verbose.h"
 #include "systemd.h"
+#include "jobs.h"
 
 static const char DEFAULT_PATH_PREFIX[] = "/org/agl/afb/api/";
 
@@ -129,6 +130,7 @@ static struct api_dbus *make_api_dbus_3(int system, const char *path, size_t pat
 	}
 
 	/* choose the bus */
+	jobs_acquire_event_manager();
 	sdbus = (system ? systemd_get_system_bus : systemd_get_user_bus)();
 	if (sdbus == NULL)
 		goto error2;
diff --git a/src/afb-export.c b/src/afb-export.c
index b5a4b9e3..37089566 100644
--- a/src/afb-export.c
+++ b/src/afb-export.c
@@ -315,6 +315,24 @@ static int event_broadcast_cb(struct afb_api_x3 *closure, const char *name, stru
 	return afb_evt_broadcast(event, object);
 }
 
+static struct sd_event *get_event_loop(struct afb_api_x3 *closure)
+{
+	jobs_acquire_event_manager();
+	return systemd_get_event_loop();
+}
+
+static struct sd_bus *get_user_bus(struct afb_api_x3 *closure)
+{
+	jobs_acquire_event_manager();
+	return systemd_get_user_bus();
+}
+
+static struct sd_bus *get_system_bus(struct afb_api_x3 *closure)
+{
+	jobs_acquire_event_manager();
+	return systemd_get_system_bus();
+}
+
 static int rootdir_open_locale_cb(struct afb_api_x3 *closure, const char *filename, int flags, const char *locale)
 {
 	return afb_common_rootdir_open_locale(filename, flags, locale);
@@ -451,21 +469,30 @@ static int hooked_event_broadcast_cb(struct afb_api_x3 *closure, const char *nam
 static struct sd_event *hooked_get_event_loop(struct afb_api_x3 *closure)
 {
 	struct afb_export *export = from_api_x3(closure);
-	struct sd_event *r = systemd_get_event_loop();
+	struct sd_event *r;
+
+	jobs_acquire_event_manager();
+	r = get_event_loop(closure);
 	return afb_hook_api_get_event_loop(export, r);
 }
 
 static struct sd_bus *hooked_get_user_bus(struct afb_api_x3 *closure)
 {
 	struct afb_export *export = from_api_x3(closure);
-	struct sd_bus *r = systemd_get_user_bus();
+	struct sd_bus *r;
+
+	jobs_acquire_event_manager();
+	r = get_user_bus(closure);
 	return afb_hook_api_get_user_bus(export, r);
 }
 
 static struct sd_bus *hooked_get_system_bus(struct afb_api_x3 *closure)
 {
 	struct afb_export *export = from_api_x3(closure);
-	struct sd_bus *r = systemd_get_system_bus();
+	struct sd_bus *r;
+
+	jobs_acquire_event_manager();
+	r = get_system_bus(closure);
 	return afb_hook_api_get_system_bus(export, r);
 }
 
@@ -537,9 +564,9 @@ static const struct afb_daemon_itf_x1 daemon_itf = {
 	.vverbose_v2 = vverbose_cb,
 	.event_make = legacy_event_x1_make_cb,
 	.event_broadcast = event_broadcast_cb,
-	.get_event_loop = systemd_get_event_loop,
-	.get_user_bus = systemd_get_user_bus,
-	.get_system_bus = systemd_get_system_bus,
+	.get_event_loop = get_event_loop,
+	.get_user_bus = get_user_bus,
+	.get_system_bus = get_system_bus,
 	.rootdir_get_fd = afb_common_rootdir_get_fd,
 	.rootdir_open_locale = rootdir_open_locale_cb,
 	.queue_job = queue_job_cb,
@@ -1052,9 +1079,9 @@ static const struct afb_api_x3_itf api_x3_itf = {
 
 	.vverbose = (void*)vverbose_cb,
 
-	.get_event_loop = systemd_get_event_loop,
-	.get_user_bus = systemd_get_user_bus,
-	.get_system_bus = systemd_get_system_bus,
+	.get_event_loop = get_event_loop,
+	.get_user_bus = get_user_bus,
+	.get_system_bus = get_system_bus,
 	.rootdir_get_fd = afb_common_rootdir_get_fd,
 	.rootdir_open_locale = rootdir_open_locale_cb,
 	.queue_job = queue_job_cb,
diff --git a/src/afb-fdev.c b/src/afb-fdev.c
index fa1a402f..a5f95660 100644
--- a/src/afb-fdev.c
+++ b/src/afb-fdev.c
@@ -17,10 +17,12 @@
 
 #include "fdev.h"
 
+#include "jobs.h"
 #include "systemd.h"
 #include "fdev-systemd.h"
 
 struct fdev *afb_fdev_create(int fd)
 {
+	jobs_acquire_event_manager();
 	return fdev_systemd_create(systemd_get_event_loop(), fd);
 }
diff --git a/src/jobs.c b/src/jobs.c
index f30904a8..217c5391 100644
--- a/src/jobs.c
+++ b/src/jobs.c
@@ -34,6 +34,7 @@
 #include "jobs.h"
 #include "sig-monitor.h"
 #include "verbose.h"
+#include "systemd.h"
 
 #define EVENT_TIMEOUT_TOP  	((uint64_t)-1)
 #define EVENT_TIMEOUT_CHILD	((uint64_t)10000)
@@ -783,16 +784,15 @@ static struct sd_event *get_sd_event_locked()
 			goto error1;
 		}
 		/* create the systemd event loop */
-		rc = sd_event_new(&evloop.sdev);
-		if (rc < 0) {
-			ERROR("can't make new event loop");
+		evloop.sdev = systemd_get_event_loop();
+		if (!evloop.sdev) {
+			ERROR("can't make event loop");
 			goto error2;
 		}
 		/* put the eventfd in the event loop */
 		rc = sd_event_add_io(evloop.sdev, NULL, evloop.efd, EPOLLIN, on_evloop_efd, NULL);
 		if (rc < 0) {
 			ERROR("can't register eventfd");
-			sd_event_unref(evloop.sdev);
 			evloop.sdev = NULL;
 error2:
 			close(evloop.efd);
@@ -808,12 +808,10 @@ error1:
 }
 
 /**
- * Gets a sd_event item for the current thread.
- * @return a sd_event or NULL in case of error
+ * Ensure that the current running thread can control the event loop.
  */
-struct sd_event *jobs_get_sd_event()
+void jobs_acquire_event_manager()
 {
-	struct sd_event *result;
 	struct thread lt;
 
 	/* ensure an existing thread environment */
@@ -824,7 +822,7 @@ struct sd_event *jobs_get_sd_event()
 
 	/* process */
 	pthread_mutex_lock(&mutex);
-	result = get_sd_event_locked();
+	get_sd_event_locked();
 	pthread_mutex_unlock(&mutex);
 
 	/* release the faked thread environment if needed */
@@ -843,8 +841,6 @@ struct sd_event *jobs_get_sd_event()
 		evloop_release();
 		current_thread = NULL;
 	}
-
-	return result;
 }
 
 /**
diff --git a/src/jobs.h b/src/jobs.h
index 03d52796..a99c9622 100644
--- a/src/jobs.h
+++ b/src/jobs.h
@@ -48,5 +48,5 @@ extern int jobs_start(
 		void (*start)(int signum, void* arg),
 		void *arg);
 
-struct sd_event;
-extern struct sd_event *jobs_get_sd_event();
+extern void jobs_acquire_event_manager();
+
diff --git a/src/systemd.c b/src/systemd.c
index 1adb75ab..29d626bc 100644
--- a/src/systemd.c
+++ b/src/systemd.c
@@ -25,41 +25,53 @@
 #include <systemd/sd-daemon.h>
 
 #include "systemd.h"
-#include "jobs.h"
 
 static struct sd_bus *sdbusopen(struct sd_bus **p, int (*f)(struct sd_bus **))
 {
-	if (*p == NULL) {
-		int rc = f(p);
-		if (rc < 0) {
-			errno = -rc;
-			*p = NULL;
-		} else {
-			rc = sd_bus_attach_event(*p, systemd_get_event_loop(), 0);
+	int rc;
+	struct sd_bus *r;
+
+	r = *p;
+	if (!r) {
+		rc = f(&r);
+		if (rc >= 0) {
+			rc = sd_bus_attach_event(r, systemd_get_event_loop(), 0);
 			if (rc < 0) {
-				sd_bus_unref(*p);
-				errno = -rc;
-				*p = NULL;
+				sd_bus_unref(r);
+				r = 0;
 			}
 		}
+		if (rc < 0)
+			errno = -rc;
+		*p = r;
 	}
-	return *p;
+	return r;
 }
 
 struct sd_event *systemd_get_event_loop()
 {
-	return jobs_get_sd_event();
+	static struct sd_event *result = 0;
+	int rc;
+
+	if (!result) {
+		rc = sd_event_new(&result);
+		if (rc < 0) {
+			errno = -rc;
+			result = NULL;
+		}
+	}
+	return result;
 }
 
 struct sd_bus *systemd_get_user_bus()
 {
-	static struct sd_bus *result = NULL;
+	static struct sd_bus *result = 0;
 	return sdbusopen((void*)&result, (void*)sd_bus_open_user);
 }
 
 struct sd_bus *systemd_get_system_bus()
 {
-	static struct sd_bus *result = NULL;
+	static struct sd_bus *result = 0;
 	return sdbusopen((void*)&result, (void*)sd_bus_open_system);
 }
 
diff --git a/src/watchdog.c b/src/watchdog.c
index f9afd640..92144ba0 100644
--- a/src/watchdog.c
+++ b/src/watchdog.c
@@ -27,12 +27,15 @@
 #include <systemd/sd-daemon.h>
 
 #include "jobs.h"
+#include "systemd.h"
 
 int watchdog_activate()
 {
 	/* set the watchdog */
-	if (sd_watchdog_enabled(0, NULL))
-		sd_event_set_watchdog(jobs_get_sd_event(), 1);
+	if (sd_watchdog_enabled(0, NULL)) {
+		jobs_acquire_event_manager();
+		sd_event_set_watchdog(systemd_get_event_loop(), 1);
+	}
 	return 0;
 }