discovery-helper: bail out if destination already exists

contrib/perf-utils/discovery-helper.sh

@@ -1,101 +1,105 b''
 #!/bin/bash
 #
 # produces two repositories with different common and missing subsets
 #
 #   $ discovery-helper.sh REPO NBHEADS DEPT
 #
 # The Goal is to produce two repositories with some common part and some
 # exclusive part on each side. Provide a source repository REPO, it will
 # produce two repositories REPO-left and REPO-right.
 #
 # Each repository will be missing some revisions exclusive to NBHEADS of the
 # repo topological heads. These heads and revisions exclusive to them (up to
 # DEPTH depth) are stripped.
 #
 # The "left" repository will use the NBHEADS first heads (sorted by
 # description). The "right" use the last NBHEADS one.
 #
 # To find out how many topological heads a repo has, use:
 #
 #   $ hg heads -t -T '{rev}\n' | wc -l
 #
 # Example:
 #
 #  The `pypy-2018-09-01` repository has 192 heads. To produce two repositories
 #  with 92 common heads and ~50 exclusive heads on each side.
 #
 #    $ ./discovery-helper.sh pypy-2018-08-01 50 10
 
 set -euo pipefail
 
 printusage () {
      echo "usage: `basename $0` REPO NBHEADS DEPTH [left|right]" >&2
 }
 
 if [ $# -lt 3 ]; then
     printusage
     exit 64
 fi
 
 repo="$1"
 shift
 
 nbheads="$1"
 shift
 
 depth="$1"
 shift
 
 doleft=1
 doright=1
 if [ $# -gt 1 ]; then
     printusage
     exit 64
 elif [ $# -eq 1 ]; then
     if [ "$1" == "left" ]; then
         doleft=1
         doright=0
     elif [ "$1" == "right" ]; then
         doleft=0
         doright=1
     else
         printusage
         exit 64
     fi
 fi
 
 leftrepo="${repo}-${nbheads}h-${depth}d-left"
 rightrepo="${repo}-${nbheads}h-${depth}d-right"
 
 left="first(sort(heads(all()), 'desc'), $nbheads)"
 right="last(sort(heads(all()), 'desc'), $nbheads)"
 
 leftsubset="ancestors($left, $depth) and only($left, heads(all() - $left))"
 rightsubset="ancestors($right, $depth) and only($right, heads(all() - $right))"
 
 echo '### creating left/right repositories with missing changesets:'
 if [ $doleft -eq 1 ]; then
     echo '# left  revset:' '"'${leftsubset}'"'
 fi
 if [ $doright -eq 1 ]; then
     echo '# right revset:' '"'${rightsubset}'"'
 fi
 
 buildone() {
-    side=$1
-    dest=$2
-    revset=$3
+    side="$1"
+    dest="$2"
+    revset="$3"
     echo "### building $side repository: $dest"
+    if [ -e "$dest" ]; then
+        echo "destination repo already exists: $dest" >&2
+        exit 1
+    fi
     echo '# cloning'
     hg clone --noupdate "${repo}" "${dest}"
     echo '# stripping' '"'${revset}'"'
     hg -R "${dest}" --config extensions.strip= strip --rev "$revset" --no-backup
 }
 
 if [ $doleft -eq 1 ]; then
-    buildone left $leftrepo $leftsubset
+    buildone left "$leftrepo" "$leftsubset"
 fi
 
 if [ $doright -eq 1 ]; then
-    buildone right $rightrepo $rightsubset
+    buildone right "$rightrepo" "$rightsubset"
 fi