Disabled Nagle algorithm in the fault tolerance thread

Consolidated example service installation script into one script for standard and EC2 systems. That script needs some testing though and should be considered an experiment.

inst/scripts/redis-worker-installer.sh

@@ -9,6 +9,12 @@
 # and configures the doRedis init script to start in the usual runlevels.
 # Edit the /etc/doRedis.conf file to point to the right Redis server and
 # to set other configuration parameters.
+#
+# Usage:
+# sudo ./redis-worker-installer.sh
+#
+# On AWS EC2 systems, use:
+# sudo ./redis-worker-installer.sh EC2
 
 echo "Installing /etc/init.d/doRedis script..."
 cat > /etc/init.d/doRedis <<1ZZZ
@@ -33,16 +39,24 @@ DAEMON=/usr/local/bin/doRedis_worker
 DAEMON_ARGS=/etc/doRedis.conf
 PIDFILE=/var/run/doRedis.pid
 SCRIPTNAME=/etc/init.d/doRedis
+EC2=$1
 
 # Define LSB log_* functions.
 # Depend on lsb-base (>= 3.0-6) to ensure that this file is present.
 . /lib/lsb/init-functions
 
 #
-# Function that starts the daemon/service
+# Function that starts the daemon/service, optionally initializing
+# configuration file from EC2 user data.
 #
 do_start()
 {
+  if test "\${EC2}" == "EC2"; then
+    U=\$(wget -O - -q http://169.254.169.254/latest/user-data)
+    if test -n "\${U}";  then
+      echo \${U} > /etc/doRedis.conf
+    fi
+  fi
   sudo -b -n -E -u nobody /usr/local/bin/doRedis_worker /etc/doRedis.conf >/dev/null 2>&1 &
 }
 
@@ -93,14 +107,15 @@ PORT=\$(cat \$CONF | sed -n /^port:/p | tail -n 1 | sed -e "s/.*:[[:blank:]*]//"
 QUEUE=\$(cat \$CONF | sed -n /^queue:/p | tail -n 1 | sed -e "s/.*:[[:blank:]*]//")
 LOG=\$(cat \$CONF | sed -n /^log:/p | tail -n 1 | sed -e "s/.*:[[:blank:]*]//")
 
-[ -z "\${N}" ] && N=1
-[ -z "\${R}" ] && R=R
-[ -z "\${T}" ] && T=5
-[ -z "\${I}" ] && I=Inf
-[ -z "\${HOST}" ] && HOST=localhost
-[ -z "\${PORT}" ] && PORT=6379
+# Set default values
+[ -z "\${N}" ]     && N=2
+[ -z "\${R}" ]     && R=R
+[ -z "\${T}" ]     && T=5
+[ -z "\${I}" ]     && I=Inf
+[ -z "\${HOST}" ]  && HOST=localhost
+[ -z "\${PORT}" ]  && PORT=6379
 [ -z "\${QUEUE}" ] && QUEUE=RJOBS
-[ -z "\${LOG}" ] && LOG=/dev/null
+[ -z "\${LOG}" ]   && LOG=/dev/null
 
 Terminator ()
 {
@@ -136,7 +151,7 @@ cat > /etc/doRedis.conf << 3ZZZ
 # may apper in any order.
 #
 # Set n to the number of workers to start.
-n: 1
+n: 2
 # Set R to the path to R (default assumes 'R' is in the PATH)
 R: R
 # Set timeout to wait period after job queue is deleted before exiting

src/alive.c

@@ -33,6 +33,7 @@
 #else
 #include <sys/types.h>
 #include <sys/socket.h>
+#include <netinet/tcp.h> // TCP_NODELAY
 #include <netinet/in.h>
 #include <netdb.h>
 #include <errno.h>
@@ -111,6 +112,7 @@ void
 tcpconnect (int *s, char *host, int port)
 {
   struct hostent *h;
+  socklen_t len;
   struct sockaddr_in sa;
   int j;
 
@@ -136,6 +138,10 @@ tcpconnect (int *s, char *host, int port)
           return;
         }
     }
+  /* Try to disable Nagle; proceed regardless of success. */
+  j = 1;
+  len = sizeof(j);
+  setsockopt(*s, IPPROTO_TCP, TCP_NODELAY, (const void *)&j, len);
 }
 #endif