Looking for ways to improve CIMD2 protocol performance

--- c:\diff\smsc_cimd2_orig.c	2007-06-06 00:38:37.090412200 +0300
+++ c:\diff\smsc_cimd2_test.c	2007-06-06 01:27:21.645373200 +0300
@@ -116,7 +116,8 @@
 
     List *outgoing_queue;
     SMSCConn *conn;
-    int io_thread;
+    int i_thread;
+    int o_thread;
     int quitting;
     List *stopped; /* list-trick for suspend/isolate */
 
@@ -2233,6 +2234,125 @@
     }
 }
 
+/*  Output Thread
+*
+ */
+static void o_thread (void *arg)
+{
+    Msg       *msg;
+    SMSCConn  *conn = arg;
+    PrivData *pdata = conn->data;
+    double    sleep = 0.0001;
+
+    /* Make sure we log into our own log-file if defined */
+    log_thread_to(conn->log_idx);
+
+    /* remove messages from SMSC until we are killed */
+    while (!pdata->quitting) {
+    
+        gwlist_consume(pdata->stopped); /* block here if suspended/isolated */
+      
+        /* send messages */
+        do {
+            msg = gwlist_extract_first(pdata->outgoing_queue);
+            if (msg) {
+                sleep = 0;
+                if (cimd2_submit_msg(conn,msg) != 0) break;
+            }
+        } while (msg);
+ 
+        if (sleep > 0) {
+
+            /* note that this implementations means that we sleep even
+             * when we fail connection.. but time is very short, anyway
+             */
+            gwthread_sleep(sleep);
+            /* gradually sleep longer and longer times until something starts to
+             * happen - this of course reduces response time, but that's better than
+             * extensive CPU usage when it is not used
+             */
+            sleep *= 2;
+            if (sleep >= 2.0)
+                sleep = 1.999999;
+        }
+        else {
+            sleep = 0.0001;
+        }
+    }
+}
+
+
+/* Input Thread .
+ * 
+ */
+static void i_thread (void *arg)
+{
+    Msg       *msg;
+    SMSCConn  *conn = arg;
+    PrivData *pdata = conn->data;
+    double    sleep = 0.0001;
+    int conn_active = 0;
+
+    /* Make sure we log into our own log-file if defined */
+    log_thread_to(conn->log_idx);
+
+    /* remove messages from SMSC until we are killed */
+    while (!pdata->quitting) {
+    
+        gwlist_consume(pdata->stopped); /* block here if suspended/isolated */
+      
+        /* check that connection is active */
+        
+        if (conn->status != SMSCCONN_ACTIVE) {
+            if (cimd2_login(conn) != 0) { 
+                error(0, "CIMD2[%s]: Couldn't connect to SMSC (retrying in %ld seconds).",
+                      octstr_get_cstr(conn->id), 
+                      conn->reconnect_delay);
+                gwthread_sleep(conn->reconnect_delay);
+                mutex_lock(conn->flow_mutex);
+                conn->status = SMSCCONN_RECONNECTING; 
+                mutex_unlock(conn->flow_mutex);
+                continue; 
+            } 
+            mutex_lock(conn->flow_mutex);
+            conn->status = SMSCCONN_ACTIVE;
+            conn->connect_time = time(NULL);
+            bb_smscconn_connected(conn);
+            mutex_unlock(conn->flow_mutex);
+            
+			pdata->o_thread = gwthread_create(o_thread, conn);
+        }
+
+        /* receive messages */
+        do { 
+            msg = sms_receive(conn);
+            if (msg) {
+                sleep = 0;
+                debug("bb.sms.cimd2", 0, "CIMD2[%s]: new message received",
+                      octstr_get_cstr(conn->id));
+                bb_smscconn_receive(conn, msg);
+            }
+        } while (msg);
+ 
+        if (sleep > 0) {
+
+            /* note that this implementations means that we sleep even
+             * when we fail connection.. but time is very short, anyway
+             */
+            gwthread_sleep(sleep);
+            /* gradually sleep longer and longer times until something starts to
+             * happen - this of course reduces response time, but that's better than
+             * extensive CPU usage when it is not used
+             */
+            sleep *= 2;
+            if (sleep >= 2.0)
+                sleep = 1.999999;
+        }
+        else {
+            sleep = 0.0001;
+        }
+    }
+}
 
 static int cimd2_add_msg_cb (SMSCConn *conn, Msg *sms)
 {
@@ -2241,7 +2361,11 @@
 
     copy = msg_duplicate(sms);
     gwlist_produce(pdata->outgoing_queue, copy);
-    gwthread_wakeup(pdata->io_thread);
+    
+    /* Modification by Thodoris Kondilis */
+    gwthread_wakeup(pdata->i_thread);
+    gwthread_wakeup(pdata->o_thread);
+    /* End of Modification */
 
     return 0;
 }
@@ -2273,11 +2397,19 @@
         gwlist_remove_producer(pdata->stopped);
         conn->is_stopped = 0;
     }
-
-    if (pdata->io_thread != -1) {
-        gwthread_wakeup(pdata->io_thread);
-        gwthread_join(pdata->io_thread);
+  
+    
+    /* Modification by Thodoris Kondilis */
+    if (pdata->i_thread != -1) {
+        gwthread_wakeup(pdata->i_thread);
+        gwthread_join(pdata->i_thread);
+    }
+    
+    if (pdata->o_thread != -1) {
+        gwthread_wakeup(pdata->o_thread);
+        gwthread_join(pdata->o_thread);
     }
+    /* End of Modofication */
 
     cimd2_close_socket(pdata);
     cimd2_destroy(pdata); 
@@ -2295,7 +2427,12 @@
 
     gwlist_remove_producer(pdata->stopped);
     /* in case there are messages in the buffer already */
-    gwthread_wakeup(pdata->io_thread);
+    
+    /* Modofication by Thodoris Kondilis */ 
+    gwthread_wakeup(pdata->i_thread);
+    gwthread_wakeup(pdata->o_thread);
+    /* End of Modification */
+    
     debug("bb.sms", 0, "SMSCConn CIMD2 %s, start called",
           octstr_get_cstr(conn->id));
 }
@@ -2410,18 +2547,37 @@
                 maxlen);
     }
 
-    pdata->io_thread = gwthread_create(io_thread, conn);
-
-    if (pdata->io_thread == -1) {  
+    
+    /* Modification by Thodoris Kondilis */
+    pdata->i_thread = gwthread_create(i_thread, conn);
+    
+   
+    if (pdata->i_thread == -1) {  
 
-        error(0,"CIMD2[%s]: Couldn't start I/O thread.",
+        error(0,"CIMD2[%s]: Couldn't start Input thread.",
               octstr_get_cstr(conn->id));
         pdata->quitting = 1;
-        gwthread_wakeup(pdata->io_thread);
-        gwthread_join(pdata->io_thread);
+        gwthread_wakeup(pdata->i_thread);
+        gwthread_join(pdata->i_thread);
+        gwthread_wakeup(pdata->o_thread);
+        gwthread_join(pdata->o_thread);
         cimd2_destroy(pdata);
         return -1;  
     } 
+    
+    if (pdata->o_thread == -1) {  
+
+        error(0,"CIMD2[%s]: Couldn't start Output thread.",
+              octstr_get_cstr(conn->id));
+        pdata->quitting = 1;
+        gwthread_wakeup(pdata->i_thread);
+        gwthread_join(pdata->i_thread);
+        gwthread_wakeup(pdata->o_thread);
+        gwthread_join(pdata->o_thread);
+        cimd2_destroy(pdata);
+        return -1;  
+    }
+    /* End of Modofication */
 
     conn->send_msg = cimd2_add_msg_cb;
     conn->shutdown = cimd2_shutdown_cb;