add -I interval option

-I INTERVAL option inserts sleep for interval (seconds) between
SSH connection attempts (issue #7).

src/mscp.c

@@ -80,8 +80,6 @@ struct src {
 #define non_null_string(s) (s[0] != '\0')
 
 
-
-
 static int expand_coremask(const char *coremask, int **cores, int *nr_cores)
 {
         int n, *core_list, core_list_len = 0, nr_usable, nr_all;
@@ -203,6 +201,11 @@ static int validate_and_set_defaut_params(struct mscp_opts *o)
 		return -1;
 	}
 
+	if (o->interval > 0) {
+		/* when the interval is set, establish SSH connections sequentially. */
+		o->max_startups = 1;
+	}
+
 	if (o->msg_fd == 0)
 		o->msg_fd = STDOUT_FILENO;
 
@@ -594,7 +597,22 @@ int mscp_join(struct mscp *m)
 	return ret;
 }
 
-/* copy thread related functions */
+/* copy thread-related functions */
+
+static void wait_for_interval(int interval)
+{
+	_Atomic static long next;
+	struct timeval t;
+	long now;
+
+	gettimeofday(&t, NULL);
+	now = t.tv_sec * 1000000 + t.tv_usec;
+
+	if (next - now > 0)
+		usleep(next - now);
+
+	next = now + interval * 1000000;
+}
 
 static void mscp_copy_thread_cleanup(void *arg)
 {
@@ -604,16 +622,17 @@ static void mscp_copy_thread_cleanup(void *arg)
 
 void *mscp_copy_thread(void *arg)
 {
-        sftp_session src_sftp, dst_sftp;
-        struct mscp_thread *t = arg;
+	sftp_session src_sftp, dst_sftp;
+	struct mscp_thread *t = arg;
 	struct mscp *m = t->m;
-        struct chunk *c;
+	struct chunk *c;
+	bool nomore;
+
+        pthread_cleanup_push(mscp_copy_thread_cleanup, t);
 
         if (t->cpu > -1) {
-                if (set_thread_affinity(pthread_self(), t->cpu) < 0) {
-			t->ret = -1;
-                        return NULL;
-		}
+                if (set_thread_affinity(pthread_self(), t->cpu) < 0)
+			goto err_out;
         }
 
 	if (sem_wait(m->sem) < 0) {
@@ -622,9 +641,12 @@ void *mscp_copy_thread(void *arg)
 		goto err_out;
 	}
 
-	mpr_notice(m->msg_fp, "connecting to %s for copy thread:%d...\n",
-		   m->remote, t->id);
-	t->sftp = ssh_init_sftp_session(m->remote, m->ssh_opts);
+	if (!(nomore = chunk_pool_is_empty(&m->cp))) {
+		if (m->opts->interval > 0)
+			wait_for_interval(m->opts->interval);
+		mpr_notice(m->msg_fp, "thread:%d connecting to %s\n", t->id, m->remote);
+		t->sftp = ssh_init_sftp_session(m->remote, m->ssh_opts);
+	}
 
 	if (sem_post(m->sem) < 0) {
 		mscp_set_error("sem_post: %s", strerrno());
@@ -632,8 +654,13 @@ void *mscp_copy_thread(void *arg)
 		goto err_out;
 	}
 
+	if (nomore) {
+		mpr_notice(m->msg_fp, "thread:%d no more connections needed\n", t->id);
+		goto out;
+	}
+
 	if (!t->sftp) {
-		mpr_err(m->msg_fp, "copy thread:%d: %s\n", t->id, mscp_get_error());
+		mpr_err(m->msg_fp, "thread:%d: %s\n", t->id, mscp_get_error());
 		goto err_out;
 	}
 
@@ -650,10 +677,6 @@ void *mscp_copy_thread(void *arg)
                 return NULL; /* not reached */
         }
 
-        pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL);
-        pthread_setcanceltype(PTHREAD_CANCEL_DEFERRED, NULL);
-        pthread_cleanup_push(mscp_copy_thread_cleanup, t);
-
         while (1) {
                 c = chunk_pool_pop(&m->cp);
 		if (c == CHUNK_POP_WAIT) {
@@ -673,8 +696,8 @@ void *mscp_copy_thread(void *arg)
         pthread_cleanup_pop(1);
 
         if (t->ret < 0)
-		mpr_err(m->msg_fp, "copy failed: chunk %s 0x%010lx-0x%010lx\n",
-			c->p->path, c->off, c->off + c->len);
+		mpr_err(m->msg_fp, "thread:%d copy failed: %s 0x%010lx-0x%010lx\n",
+			t->id, c->p->path, c->off, c->off + c->len);
 
         return NULL;
 
@@ -682,10 +705,14 @@ err_out:
 	t->finished = true;
 	t->ret = -1;
 	return NULL;
+out:
+	t->finished = true;
+	t->ret = 0;
+	return NULL;
 }
 
 
-/* cleanup related functions */
+/* cleanup-related functions */
 
 static void free_src(struct list_head *list)
 {
@@ -751,19 +778,20 @@ void mscp_free(struct mscp *m)
 
 void mscp_get_stats(struct mscp *m, struct mscp_stats *s)
 {
+	int nr_finished = 0, nr_threads = 0;
 	struct mscp_thread *t;
-	bool finished = true;
 
 	s->total = m->total_bytes;
 	s->done = 0;
 
 	RWLOCK_READ_ACQUIRE(&m->thread_rwlock);
 	list_for_each_entry(t, &m->thread_list, list) {
+		nr_threads++;
 		s->done += t->done;
-		if (!t->finished)
-			finished = false;
+		if (t->finished)
+			nr_finished++;
 	}
 	RWLOCK_RELEASE();
 
-	s->finished = finished;
+	s->finished = nr_threads > 0 ? (nr_finished == nr_threads) : false;
 }