svm: queue sub: Add conditional timed wait

On reviece side svm queue only permits blocking and
non-blocking calls. This patch adds timed wait blocking
functionality which returns either on signal/event or
on given time out.

It also preserves the original behavior, so it will not
hurt client applications which are using svm queue.

Change-Id: Ic10632170330a80afb8bc781d4ccddfe4da2c69a
Signed-off-by: Mohsin Kazmi <sykazmi@cisco.com>

2 files changed, 46 insertions, 6 deletions

diff --git a/src/svm/queue.c b/src/svm/queue.c
index aef409277db..96e40fc2aec 100644
--- a/src/svm/queue.c
+++ b/src/svm/queue.c
@@ -26,6 +26,7 @@
 #include <vppinfra/format.h>
 #include <vppinfra/cache.h>
 #include <svm/queue.h>
+#include <vppinfra/time.h>
 #include <signal.h>
 
 /*
@@ -299,12 +300,14 @@ svm_queue_add2 (svm_queue_t * q, u8 * elem, u8 * elem2, int nowait)
  * svm_queue_sub
  */
 int
-svm_queue_sub (svm_queue_t * q, u8 * elem, int nowait)
+svm_queue_sub (svm_queue_t * q, u8 * elem, svm_q_conditional_wait_t cond,
+	       u32 time)
 {
   i8 *headp;
   int need_broadcast = 0;
+  int rc = 0;
 
-  if (nowait)
+  if (cond == SVM_Q_NOWAIT)
     {
       /* zero on success */
       if (pthread_mutex_trylock (&q->mutex))
@@ -317,14 +320,32 @@ svm_queue_sub (svm_queue_t * q, u8 * elem, int nowait)
 
   if (PREDICT_FALSE (q->cursize == 0))
     {
-      if (nowait)
+      if (cond == SVM_Q_NOWAIT)
 	{
 	  pthread_mutex_unlock (&q->mutex);
 	  return (-2);
 	}
-      while (q->cursize == 0)
+      else if (cond == SVM_Q_TIMEDWAIT)
 	{
-	  (void) pthread_cond_wait (&q->condvar, &q->mutex);
+	  struct timespec ts;
+	  ts.tv_sec = unix_time_now () + time;
+	  ts.tv_nsec = 0;
+	  while (q->cursize == 0 && rc == 0)
+	    {
+	      rc = pthread_cond_timedwait (&q->condvar, &q->mutex, &ts);
+	    }
+	  if (rc == ETIMEDOUT)
+	    {
+	      pthread_mutex_unlock (&q->mutex);
+	      return ETIMEDOUT;
+	    }
+	}
+      else
+	{
+	  while (q->cursize == 0)
+	    {
+	      (void) pthread_cond_wait (&q->condvar, &q->mutex);
+	    }
 	}
     }
 
diff --git a/src/svm/queue.h b/src/svm/queue.h
index dc1fc36e002..856c17237d1 100644
--- a/src/svm/queue.h
+++ b/src/svm/queue.h
@@ -36,6 +36,24 @@ typedef struct _svm_queue
   char data[0];
 } svm_queue_t;
 
+typedef enum
+{
+  /**
+   * blocking call
+   */
+  SVM_Q_WAIT = 0,
+
+  /**
+   * non-blocking call
+   */
+  SVM_Q_NOWAIT,
+
+  /**
+   * blocking call, return on signal or time-out
+   */
+  SVM_Q_TIMEDWAIT,
+} svm_q_conditional_wait_t;
+
 svm_queue_t *svm_queue_init (int nels,
 			     int elsize,
 			     int consumer_pid,
@@ -43,7 +61,8 @@ svm_queue_t *svm_queue_init (int nels,
 void svm_queue_free (svm_queue_t * q);
 int svm_queue_add (svm_queue_t * q, u8 * elem, int nowait);
 int svm_queue_add2 (svm_queue_t * q, u8 * elem, u8 * elem2, int nowait);
-int svm_queue_sub (svm_queue_t * q, u8 * elem, int nowait);
+int svm_queue_sub (svm_queue_t * q, u8 * elem, svm_q_conditional_wait_t cond,
+		   u32 time);
 int svm_queue_sub2 (svm_queue_t * q, u8 * elem);
 void svm_queue_lock (svm_queue_t * q);
 void svm_queue_unlock (svm_queue_t * q);