add option, off by default, to stall each message forward by some time

to better simulate network conditions when testing against local relay.

xwords4/relay/cref.cpp

@@ -96,6 +96,12 @@ CookieRef::ReInit( const char* cookie, const char* connName, CookieID id )
     m_nHostMsgs = 0;
     m_in_handleEvents = false;
 
+    if ( RelayConfigs::GetConfigs()->GetValueFor( "SEND_DELAY_MILLIS", 
+                                                   &m_delayMicros ) ) {
+        m_delayMicros *= 1000;  /* millis->micros */
+    } else {
+        m_delayMicros = 0;
+    }
     RelayConfigs::GetConfigs()->GetValueFor( "HEARTBEAT", &m_heatbeat );
     logf( XW_LOGINFO, "initing cref for cookie %s, connName %s",
           m_cookie.c_str(), m_connName.c_str() );
@@ -882,6 +888,10 @@ CookieRef::forward_or_store( const CRefEvent* evt )
     /* This is an ugly hack!!!! */
     *buf = XWRELAY_MSG_FROMRELAY;
 
+    if ( 0 < m_delayMicros && destSocket != -1 ) {
+        usleep( m_delayMicros );
+    }
+
     if ( (destSocket == -1)
          || !send_with_length( destSocket, buf, buflen, true ) ) {
         store_message( dest, buf, buflen );

xwords4/relay/cref.h

@@ -256,6 +256,8 @@ class CookieRef {
 
     pthread_t m_locking_thread; /* for debugging only */
     bool m_in_handleEvents;     /* for debugging only */
+
+    int m_delayMicros;
 }; /* CookieRef */
 
 #endif

xwords4/relay/xwrelay.conf

@@ -42,3 +42,7 @@ SERVERNAME=eehouse.org
 # 0 means errors only, 1 info, 2 verbose and 3 very verbose.
 LOGLEVEL=0
 LOGFILE_PATH=./xwrelay.log
+
+# Delay sending packets so devices/emulators on the same machine as
+# relay have a bit more natural experience
+# SEND_DELAY_MILLIS=500