Add env var for server unit test parallelism

We also ensure that for now TravisCI runs server tests serially to avoid
not emitting output for more than ten minutes triggering the TravisCI auto
kill feature.

Author: portante

.travis.yml

@@ -1,26 +1,28 @@
 dist: xenial
 language: perl
 perl:
- - "5.28"
- - "5.26"
- - "5.24"
- - "5.22"
- - "5.20"
- - "5.18"
- - "5.16"
- - "5.10"
+  - "5.28"
+  - "5.26"
+  - "5.24"
+  - "5.22"
+  - "5.20"
+  - "5.18"
+  - "5.16"
+  - "5.10"
 before_install:
- - sudo apt-get update
+  - sudo apt-get update
 install:
- - sudo apt-get install python python-pip bc libjson-perl libswitch-perl realpath
- - sudo pip install configtools elasticsearch
- - sudo apt-get install python-software-properties
- - sudo add-apt-repository ppa:fkrull/deadsnakes -y
- - sudo apt-get update
- - sudo apt-get install python3.6 --force-yes -y
- - sudo wget -O /tmp/get-pip.py https://bootstrap.pypa.io/get-pip.py
- - sudo python3.6 /tmp/get-pip.py
- - sudo pip install 'configtools<0.4.0' elasticsearch
- - sudo ln -sf python3.6 /usr/bin/python3
+  - sudo apt-get install python python-pip bc libjson-perl libswitch-perl realpath
+  - sudo pip install configtools elasticsearch
+  - sudo apt-get install python-software-properties
+  - sudo add-apt-repository ppa:fkrull/deadsnakes -y
+  - sudo apt-get update
+  - sudo apt-get install python3.6 --force-yes -y
+  - sudo wget -O /tmp/get-pip.py https://bootstrap.pypa.io/get-pip.py
+  - sudo python3.6 /tmp/get-pip.py
+  - sudo pip install 'configtools<0.4.0' elasticsearch
+  - sudo ln -sf python3.6 /usr/bin/python3
+env:
+  - PBENCH_UNITTEST_SERVER_MODE=serial
 script:
- - ./run-unittests
+  - ./run-unittests

server/bin/unittests

@@ -644,6 +644,9 @@ declare -A cmds=(
 all_tests_sorted=$(for x in ${!cmds[@]} ;do echo $x ;done | sed 's/\./-/' | sort -n -t '-' -k 3 | sort -n -t '-' -k 2 --stable | sed 's/\(.*-[0-9]\)-\([0-9]\)/\1.\2/')
 
 mode="serial"
+if [[ -n "$PBENCH_UNITTEST_SERVER_MODE" ]]; then
+    mode="$PBENCH_UNITTEST_SERVER_MODE"
+fi
 case $1 in
     --serial)
         shift
@@ -658,6 +661,10 @@ case $1 in
         exit 1
         ;;
 esac
+if [[ "$mode" != "serial" && "$mode" != "parallel" ]]; then
+    printf "Bad server unit test mode \"$mode\", choose either 'serial' or 'parallel'\n" >&2
+    exit 1
+fi
 
 test_args=$*
 if [ -z "$test_args" ] ;then