From c186dfbdbd43f5b51a67812ad48e1df1eacf131e Mon Sep 17 00:00:00 2001
From: =?utf8?q?Jos=C3=A9=20Bollo?= <jose.bollo@iot.bzh>
Date: Thu, 6 Apr 2017 10:31:09 +0200
Subject: [PATCH] Add an easy function for synchronous calls
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The added function, 'jobs_call', allows to call
a job with 'group' sequencing and 'timeout'
handling synchronously.

The difference with 'jobs_enter' is that the
function 'jobs_call' assert that the job is
terminated when 'callback' returns.

Change-Id: I8c01d1cd017787ca0448b03a899305a9069ebb6c
Signed-off-by: José Bollo <jose.bollo@iot.bzh>
---
 src/jobs.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++----
 src/jobs.h |  6 ++++++
 2 files changed, 74 insertions(+), 4 deletions(-)

diff --git a/src/jobs.c b/src/jobs.c
index 1ed20fcb..17deb88e 100644
--- a/src/jobs.c
+++ b/src/jobs.c
@@ -82,6 +82,15 @@ struct thread
 	unsigned waits: 1;     /**< is waiting? */
 };
 
+/**
+ * Description of synchonous callback
+ */
+struct sync
+{
+	void (*callback)(int, void*);	/**< the synchrnous callback */
+	void *arg;			/**< the argument of the callback */
+};
+
 /* synchronisation of threads */
 static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
 static pthread_cond_t  cond = PTHREAD_COND_INITIALIZER;
@@ -451,7 +460,7 @@ int jobs_queue0(
  *                 or the signal number that broke the normal flow.
  *                 The remaining parameter is the parameter 'arg1'
  *                 given here.
- * @param arg1     The second argument for 'callback'
+ * @param arg      The second argument for 'callback'
  * @return 0 in case of success or -1 in case of error
  */
 int jobs_queue(
@@ -569,13 +578,25 @@ error:
 
 /**
  * Enter a synchronisation point: activates the job given by 'callback'
- * @param group the gro
+ * and 'closure' using 'group' and 'timeout' to control sequencing and
+ * execution time.
+ * @param group the group for sequencing jobs
+ * @param timeout the time in seconds allocated to the job
+ * @param callback the callback that will handle the job.
+ *                 it receives 3 parameters: 'signum' that will be 0
+ *                 on normal flow or the catched signal number in case
+ *                 of interrupted flow, the context 'closure' as given and
+ *                 a 'jobloop' reference that must be used when the job is
+ *                 terminated to unlock the current execution flow.
+ * @param closure the context completion closure for the callback
+ * @return 0 on success or -1 in case of error
  */
 int jobs_enter(
 		void *group,
 		int timeout,
 		void (*callback)(int signum, void *closure, struct jobloop *jobloop),
-		void *closure)
+		void *closure
+)
 {
 	
 	struct job *job;
@@ -601,11 +622,16 @@ int jobs_enter(
 	return 0;
 }
 
+/**
+ * Unlocks the execution flow designed by 'jobloop'.
+ * @param jobloop indication of the flow to unlock
+ * @return 0 in case of success of -1 on error
+ */
 int jobs_leave(struct jobloop *jobloop)
 {
 	struct thread *t;
-	pthread_mutex_lock(&mutex);
 
+	pthread_mutex_lock(&mutex);
 	t = threads;
 	while (t && t != (struct thread*)jobloop)
 		t = t->next;
@@ -620,6 +646,44 @@ int jobs_leave(struct jobloop *jobloop)
 	return -!t;
 }
 
+/**
+ * Internal helper function for 'jobs_call'.
+ * @see jobs_call, jobs_enter, jobs_leave
+ */
+static void call_cb(int signum, void *closure, struct jobloop *jobloop)
+{
+	struct sync *sync = closure;
+	sync->callback(signum, sync->arg);
+	jobs_leave(jobloop);
+}
+
+/**
+ * Calls synchronously the job represented by 'callback' and 'arg1'
+ * for the 'group' and the 'timeout' and waits for its completion.
+ * @param group    The group of the job or NULL when no group.
+ * @param timeout  The maximum execution time in seconds of the job
+ *                 or 0 for unlimited time.
+ * @param callback The function to execute for achieving the job.
+ *                 Its first parameter is either 0 on normal flow
+ *                 or the signal number that broke the normal flow.
+ *                 The remaining parameter is the parameter 'arg1'
+ *                 given here.
+ * @param arg      The second argument for 'callback'
+ * @return 0 in case of success or -1 in case of error
+ */
+int jobs_call(
+		void *group,
+		int timeout,
+		void (*callback)(int, void*),
+		void *arg)
+{
+	struct sync sync;
+
+	sync.callback = callback;
+	sync.arg = arg;
+	return jobs_enter(group, timeout, call_cb, &sync);
+}
+
 /**
  * Gets a sd_event item for the current thread.
  * @return a sd_event or NULL in case of error
diff --git a/src/jobs.h b/src/jobs.h
index f508e3c0..a98b27ad 100644
--- a/src/jobs.h
+++ b/src/jobs.h
@@ -54,6 +54,12 @@ extern int jobs_enter(
 
 extern int jobs_leave(struct jobloop *jobloop);
 
+extern int jobs_call(
+		void *group,
+		int timeout,
+		void (*callback)(int, void*),
+		void *arg);
+
 extern struct sd_event *jobs_get_sd_event();
 
 extern void jobs_terminate();
-- 
2.16.6