inotify-run

#!/usr/bin/bash

# Wrapper around inotifywait for easier usage.

usage() {
  echo "$0 <inotifywait-args>... -- <cmd>..."
}

inotifywait_args=()
while [[ -n "$1" && "$1" != "--" ]]; do
  inotifywait_args+=("$1")
  shift
done
if [[ "$1" != "--" ]]; then
  echo "Missing command." >&2
  usage
  exit 64
fi
shift
cmd=("$@")

title() {
  printf '\e]1;%s\a' "$*"
  printf '\e]2;%s\a' "$*"
}

# A FIFO to communicate the child pid from the sub-shell.
child_pid_pipe=$(mktemp --dry-run)
mkfifo "$child_pid_pipe"

wrapper_pid=

# Required to "wait" in EXIT handler, where pid is not considered to be part of
# the shell with "wait" anymore.
wait_for_pid() {
  pid="$1"
  if ! kill -0 "$pid" 2>/dev/null; then
    return 0
  fi
  echo -n "Waiting for $pid to terminate" >&2
  while kill -0 "$pid" 2>/dev/null; do
    echo -n '.' >&2
    sleep 0.5 || break
  done
  echo >&2
}

kill_child() {
  pid="$1"

  # Send SIGTERM after 3s.
  (
    sleep 3
    if kill -0 "$pid" 2>/dev/null; then
      # Forcefully kill child after additional 3s.
      (
        sleep 3 || true
        if kill -0 "$pid" 2>/dev/null; then
          echo "Forcefully killing $pid" >&2
          kill -KILL "$pid"
        fi
      ) &
      wait_timeout_pid=$!

      kill -TERM "$pid"
      wait_for_pid "$pid"
    else
      wait_timeout_pid=
    fi
  ) &
  wait_timeout_pid=$!
  wait "$wait_timeout_pid"
}

sigint() {
  ret=$?
  if [[ "$got_sigint" == 1 ]]; then
    exit "$ret"
  fi
  got_sigint=1
}
cleanup() {
  if [[ -n "$child_pid" ]]; then
    kill_child "$child_pid"

  elif [ -n "$wrapper_pid" ] && kill -0 "$wrapper_pid" 2>/dev/null; then
    echo "Killing previous run (PID $wrapper_pid)"
    kill "$wrapper_pid"
    wait "$wrapper_pid"
  fi

  rm "$child_pid_pipe"
  # rm "$child_ret_pipe"
}

trap 'sigint' INT
trap 'cleanup' EXIT

got_sigint=0
while true; do
  child_pid=
  title "… $*"

  # Run command in subshell.
  (
    set +e
    inner_ret=

    inner_cleanup() {
      if [[ -z "$inner_ret" ]]; then
        kill_child "$child_pid"
      fi
      # Handle pdb.set_trace being killed.
      # Ref: https://github.com/antocuni/pdb/issues/28#issuecomment-456385762
      # At least for inner_ret=143 (SIGTERM).
      reset -I
    }
    trap 'inner_cleanup' EXIT

    echo "=== running: $*"
    "${cmd[@]}" &
    child_pid=$!

    echo "$child_pid" > "$child_pid_pipe"
    # echo "waiting for child pid: $child_pid"
    wait $child_pid
    inner_ret=$?
    echo "child:exit:$inner_ret"

    # if [[ "$inner_ret" != 143 ]]; then  # SIGTERM
      if [ "$inner_ret" = 0 ]; then
        title "✔ $*"
      else
        title "✘ $* (ret:$inner_ret)"
      fi
    # fi
  ) </dev/tty &
  wrapper_pid=$!

  # Wait for child to have started.
  child_pid=$(< "$child_pid_pipe")

  # shellcheck disable=SC2086
  inotify_cmd=(inotifywait -e close_write \
    --exclude '/(__pycache__/|\.)|.*@neomake_.*' \
    --format '%w%f' "${inotifywait_args[*]}")  #| grep 'Watches established.'
  echo "=== running: inotify_cmd: ${inotify_cmd[*]}" >&2
  # shellcheck disable=SC2086
  ${inotify_cmd[*]}

  if kill -0 "$child_pid" 2>/dev/null; then
    echo "=== killing/restarting child ($child_pid)"
    kill_child "$child_pid"
  fi

  got_sigint=0
done