for bug #251, refine the send use cond wait.

@@ -598,6 +598,10 @@ int SrsRtmpConn::do_playing(SrsSource* source, SrsQueueRecvThread* trd)
         // collect elapse for pithy print.
         pithy_print.elapse();
         
+        // wait for message to incoming.
+        // @see https://github.com/winlinvip/simple-rtmp-server/issues/251
+        consumer->wait(SRS_PERF_MW_MIN_MSGS, mw_sleep);
+        
         // get messages from consumer.
         // each msg in msgs.msgs must be free, for the SrsMessageArray never free them.
         int count = 0;
@@ -606,12 +610,9 @@ int SrsRtmpConn::do_playing(SrsSource* source, SrsQueueRecvThread* trd)
             return ret;
         }
         
-        // no message to send, sleep a while.
-        if (count <= 0) {
-            srs_verbose("sleep for no messages to send");
-            st_usleep(mw_sleep * 1000);
-        }
-        srs_info("got %d msgs, mw=%d", count, mw_sleep);
+        // we use wait to get messages, so the count must be positive.
+        srs_assert(count > 0);
+        srs_info("got %d msgs, min=%d, mw=%d", count, SRS_PERF_MW_MIN_MSGS, mw_sleep);
 
         // reportable
         if (pithy_print.can_print()) {

@@ -166,6 +166,16 @@ SrsMessageQueue::~SrsMessageQueue()
     clear();
 }
 
+int SrsMessageQueue::count()
+{
+    return (int)msgs.size();
+}
+
+int SrsMessageQueue::duration()
+{
+    return (int)(av_end_time - av_start_time);
+}
+
 void SrsMessageQueue::set_queue_size(double queue_size)
 {
     queue_size_ms = (int)(queue_size * 1000);
@@ -290,6 +300,11 @@ SrsConsumer::SrsConsumer(SrsSource* _source)
     jitter = new SrsRtmpJitter();
     queue = new SrsMessageQueue();
     should_update_source_id = false;
+    
+    mw_wait = st_cond_new();
+    mw_min_msgs = 0;
+    mw_duration = 0;
+    mw_waiting = false;
 }
 
 SrsConsumer::~SrsConsumer()
@@ -297,6 +312,7 @@ SrsConsumer::~SrsConsumer()
     source->on_consumer_destroy(this);
     srs_freep(jitter);
     srs_freep(queue);
+    st_cond_destroy(mw_wait);
 }
 
 void SrsConsumer::set_queue_size(double queue_size)
@@ -329,6 +345,12 @@ int SrsConsumer::enqueue(SrsSharedPtrMessage* msg, bool atc, int tba, int tbv, S
         return ret;
     }
     
+    // fire the mw when msgs is enough.
+    if (mw_waiting && queue->count() > mw_min_msgs && queue->duration() > mw_duration) {
+        st_cond_signal(mw_wait);
+        mw_waiting = false;
+    }
+    
     return ret;
 }
 
@@ -349,6 +371,22 @@ int SrsConsumer::dump_packets(int max_count, SrsMessage** pmsgs, int& count)
     return queue->dump_packets(max_count, pmsgs, count);
 }
 
+void SrsConsumer::wait(int nb_msgs, int duration)
+{
+    mw_min_msgs = nb_msgs;
+    mw_duration = duration;
+    
+    // already ok, donot wait.
+    if (queue->count() > mw_min_msgs && queue->duration() > mw_duration) {
+        return;
+    }
+    
+    // the enqueue will notify this cond.
+    mw_waiting = true;
+    
+    st_cond_wait(mw_wait);
+}
+
 int SrsConsumer::on_play_client_pause(bool is_pause)
 {
     int ret = ERROR_SUCCESS;

@@ -116,6 +116,14 @@ public:
     virtual ~SrsMessageQueue();
 public:
     /**
+    * get the count of queue.
+    */
+    virtual int count();
+    /**
+    * get duration of queue.
+    */
+    virtual int duration();
+    /**
     * set the queue size
     * @param queue_size the queue size in seconds.
     */
@@ -154,6 +162,12 @@ private:
     bool paused;
     // when source id changed, notice all consumers
     bool should_update_source_id;
+    // the cond wait for mw.
+    // @see https://github.com/winlinvip/simple-rtmp-server/issues/251
+    st_cond_t mw_wait;
+    bool mw_waiting;
+    int mw_min_msgs;
+    int mw_duration;
 public:
     SrsConsumer(SrsSource* _source);
     virtual ~SrsConsumer();
@@ -189,6 +203,12 @@ public:
     */
     virtual int dump_packets(int max_count, SrsMessage** pmsgs, int& count);
     /**
+    * wait for messages incomming, atleast nb_msgs and in duration.
+    * @param nb_msgs the messages count to wait.
+    * @param duration the messgae duration to wait.
+    */
+    virtual void wait(int nb_msgs, int duration);
+    /**
     * when client send the pause message.
     */
     virtual int on_play_client_pause(bool is_pause);

@@ -31,7 +31,7 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 // current release version
 #define VERSION_MAJOR       2
 #define VERSION_MINOR       0
-#define VERSION_REVISION    55
+#define VERSION_REVISION    56
 // server info.
 #define RTMP_SIG_SRS_KEY "SRS"
 #define RTMP_SIG_SRS_ROLE "origin/edge server"

@@ -93,6 +93,11 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 * @remark, recomment to 156.
 */
 #define SRS_PERF_MW_MSGS 156
+/**
+* how many msgs atleast to send.
+* @remark, recomment to 8.
+*/
+#define SRS_PERF_MW_MIN_MSGS 8
 
 /**
 * how many chunk stream to cache, [0, N].