ci: add a helper for retrying shell command

tools/ci/executable-list.txt

@@ -56,6 +56,7 @@ tools/ci/get_supported_examples.sh
 tools/ci/mirror-submodule-update.sh
 tools/ci/multirun_with_pyenv.sh
 tools/ci/push_to_github.sh
+tools/ci/retry_failed.sh
 tools/ci/test_build_system.sh
 tools/ci/test_build_system_cmake.sh
 tools/ci/test_configure_ci_environment.sh

tools/ci/retry_failed.sh

@@ -0,0 +1,45 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+#
+# Retries a command RETRY_ATTEMPTS times in case of failure
+#
+# Inspired by https://stackoverflow.com/a/8351489
+#
+
+max_attempts=${RETRY_ATTEMPTS-3}
+RETRY_TIMEWAIT=${RETRY_TIMEWAIT-1}
+attempt=1
+exitCode=0
+whole_start=$(date +%s)
+attempt_start=whole_start
+
+while true; do
+  if "$@" ; then
+    exitCode=0
+    break
+  else
+    exitCode=$?
+  fi
+
+  if (( $attempt >= $max_attempts )) ; then
+    break
+  fi
+
+  echo "Failed! ("$@") Spent time $(( $(date '+%s') - ${attempt_start} )) sec. Retrying in ${RETRY_TIMEWAIT}..." 1>&2
+  sleep $RETRY_TIMEWAIT
+  attempt=$(( attempt + 1 ))
+  RETRY_TIMEWAIT=$(( RETRY_TIMEWAIT * 2 ))
+  attempt_start=$(date +%s)
+done
+
+if [[ $exitCode != 0 ]] ; then
+  echo -n "Totally failed! ("$@")" 1>&2
+else
+  echo -n "Done ("$@")" 1>&2
+fi
+
+echo " Spent time $(( $(date '+%s') - ${whole_start} )) sec in total" 1>&2
+
+exit $exitCode