Attempt to wget boost up to 20 times during installation. (ray-projec…

…t#927)

src/thirdparty/build_boost.sh

@@ -9,7 +9,16 @@ TP_DIR=$(cd "$(dirname "${BASH_SOURCE:-$0}")"; pwd)
 
 # Download and compile boost if it isn't already present.
 if [ ! -d $TP_DIR/boost ]; then
-  wget --no-check-certificate http://downloads.sourceforge.net/project/boost/boost/1.60.0/boost_1_60_0.tar.gz -O $TP_DIR/boost_1_60_0.tar.gz
+  # The wget command frequently fails, so retry up to 20 times.
+  for COUNT in {1..20}; do
+    # Attempt to wget boost and break from the retry loop if it succeeds.
+    wget --no-check-certificate http://downloads.sourceforge.net/project/boost/boost/1.60.0/boost_1_60_0.tar.gz -O $TP_DIR/boost_1_60_0.tar.gz && break
+    # If none of the retries succeeded at getting boost, then fail.
+    if [[ $COUNT == 20 ]]; then
+      exit 1
+    fi
+  done
+
   tar xf $TP_DIR/boost_1_60_0.tar.gz -C $TP_DIR/
   rm -rf $TP_DIR/boost_1_60_0.tar.gz