for bug #251, somhc(session-oriented message-header cache). 2.0.61

@@ -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    60
+#define VERSION_REVISION    61
 // server info.
 #define RTMP_SIG_SRS_KEY "SRS"
 #define RTMP_SIG_SRS_ROLE "origin/edge server"

@@ -729,6 +729,13 @@ int SrsProtocol::do_send_messages(SrsSharedPtrMessage** msgs, int nb_msgs)
     int c0c3_cache_index = 0;
     char* c0c3_cache = out_c0c3_caches + c0c3_cache_index;
 
+    // the somc(session-oriented message-header cache),
+    // many message header are same, use cache.
+    // @see https://github.com/winlinvip/simple-rtmp-server/issues/251
+    SrsMessageHeader* somhc = NULL;
+    char* somhc_bytes = NULL;
+    int nb_somhc_bytes = 0;
+
     // try to send use the c0c3 header cache,
     // if cache is consumed, try another loop.
     for (int i = 0; i < nb_msgs; i++) {
@@ -755,8 +762,20 @@ int SrsProtocol::do_send_messages(SrsSharedPtrMessage** msgs, int nb_msgs)
         
         // always write the header event payload is empty.
         while (p < pend) {
+            // the first chunk is c0, others is c3.
+            bool is_c0 = p == msg->payload;
+
             // header use iov[0].
-            generate_chunk_header(c0c3_cache, &msg->header, p == msg->payload, iov);
+            generate_chunk_header(somhc, somhc_bytes, nb_somhc_bytes,
+                c0c3_cache, SRS_CONSTS_C0C3_HEADERS_MAX - c0c3_cache_index,
+                &msg->header, is_c0, iov);
+
+            // set somhc to the first header.
+            if (!somhc) {
+                somhc = &msg->header;
+                somhc_bytes = (char*)iov[0].iov_base;
+                nb_somhc_bytes = iov[0].iov_len;
+            }
             
             // payload use iov[1].
             int payload_size = pend - p;
@@ -898,8 +917,10 @@ int SrsProtocol::do_send_and_free_packet(SrsPacket* packet, int stream_id)
     return ret;
 }
 
-void SrsProtocol::generate_chunk_header(char* cache, SrsMessageHeader* mh, bool c0, iovec* iov)
-{
+void SrsProtocol::generate_chunk_header(
+    SrsMessageHeader* somhc, char* somhc_bytes, int nb_somhc_bytes,
+    char* cache, int nb_cache, SrsMessageHeader* mh, bool c0, iovec* iov
+) {
     // to directly set the field.
     char* pp = NULL;
     
@@ -910,11 +931,20 @@ void SrsProtocol::generate_chunk_header(char* cache, SrsMessageHeader* mh, bool
     u_int32_t timestamp = (u_int32_t)mh->timestamp;
     
     if (c0) {
+        // if cached header, copy it.
+        if (somhc) {
+            srs_assert(nb_cache >= nb_somhc_bytes);
+            memcpy(cache, somhc_bytes, nb_somhc_bytes);
+        }
+
         // write new chunk stream header, fmt is 0
         *p++ = 0x00 | (mh->perfer_cid & 0x3F);
         
         // chunk message header, 11 bytes
         // timestamp, 3bytes, big-endian
+        if (somhc && somhc->timestamp == mh->timestamp) {
+            p += 3;
+        } else {
             if (timestamp < RTMP_EXTENDED_TIMESTAMP) {
                 pp = (char*)&timestamp;
                 *p++ = pp[2];
@@ -925,22 +955,31 @@ void SrsProtocol::generate_chunk_header(char* cache, SrsMessageHeader* mh, bool
                 *p++ = 0xFF;
                 *p++ = 0xFF;
             }
+        }
         
         // message_length, 3bytes, big-endian
+        if (somhc && somhc->payload_length == mh->payload_length) {
+            p += 3;
+        } else {
             pp = (char*)&mh->payload_length;
             *p++ = pp[2];
             *p++ = pp[1];
             *p++ = pp[0];
+        }
         
         // message_type, 1bytes
         *p++ = mh->message_type;
         
-        // message_length, 3bytes, little-endian
+        // stream_id, 4bytes, little-endian.
+        if (somhc && somhc->stream_id == mh->stream_id) {
+            p += 4;
+        } else {
             pp = (char*)&mh->stream_id;
             *p++ = pp[0];
             *p++ = pp[1];
             *p++ = pp[2];
             *p++ = pp[3];
+        }
     } else {
         // write no message header chunk stream, fmt is 3
         // @remark, if perfer_cid > 0x3F, that is, use 2B/3B chunk header,
@@ -967,12 +1006,16 @@ void SrsProtocol::generate_chunk_header(char* cache, SrsMessageHeader* mh, bool
     // @see: http://blog.csdn.net/win_lin/article/details/13363699
     // TODO: FIXME: extract to outer.
     if (timestamp >= RTMP_EXTENDED_TIMESTAMP) {
+        if (somhc && somhc->payload_length == mh->payload_length) {
+            p += 4;
+        } else {
                 pp = (char*)&timestamp;
                 *p++ = pp[3];
                 *p++ = pp[2];
                 *p++ = pp[1];
                 *p++ = pp[0];
         }
+    }
     
     // always has header
     iov->iov_base = cache;

@@ -84,7 +84,7 @@ public:
     /**
     * 4bytes.
     * Four-byte field that identifies the stream of the message. These
-    * bytes are set in big-endian format.
+    * bytes are set in little-endian format.
     */
     int32_t stream_id;
     
@@ -494,11 +494,16 @@ private:
     virtual int do_send_and_free_packet(SrsPacket* packet, int stream_id);
     /**
     * generate the chunk header for msg.
+    * @param somhc, session-oriented message-header cache.
+    * @param somhc_bytes, the serialized bytes.
+    * @param nb_somhc_bytes, the size of somhc_bytes.
     * @param mh, the header of msg to send.
     * @param c0, whether the first chunk, the c0 chunk.
     * @param iov, output the header and size to iovec.
     */
-    virtual void generate_chunk_header(char* cache, SrsMessageHeader* mh, bool c0, iovec* iov);
+    virtual void generate_chunk_header(
+        SrsMessageHeader* somhc, char* somhc_bytes, int nb_somhc_bytes,
+        char* cache, int nb_cache, SrsMessageHeader* mh, bool c0, iovec* iov);
     /**
     * imp for decode_message
     */