feat: add initial procmon implementation and test

.gitmodules

@@ -0,0 +1,9 @@
+[submodule "test/bats"]
+	path = test/bats
+	url = https://github.com/bats-core/bats-core.git
+[submodule "test/test_helper/bats-support"]
+	path = test/test_helper/bats-support
+	url = https://github.com/bats-core/bats-support.git
+[submodule "test/test_helper/bats-assert"]
+	path = test/test_helper/bats-assert
+	url = https://github.com/bats-core/bats-assert.git

src/config.bash

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+LIB_SRC=${LIB_SRC:-$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)}
+OUTPUTS=${OUTPUTS:-${LIB_SRC}/../outputs}

src/process_monitor.bash

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+#!/usr/bin/env bash
+
+LIB_SRC=${LIB_SRC:-$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)}
+
+# shellcheck source=./config.bash
+source "${LIB_SRC}/config.bash"
+# shellcheck source=./utils.bash
+source "${LIB_SRC}/utils.bash"
+
+_procmon_output=$(clh_output_folder "procmon")
+_procmon_pid=""
+
+_procmon_init_output() {
+  rm -rf "${_procmon_output}" || true
+  mkdir -p "${_procmon_output}"
+}
+
+clh_start_process_monitor() {
+  _procmon_init_output
+
+  if [ -n "$_procmon_pid" ]; then
+    echoerr "[procmon] process monitor already started"
+    return 1
+  fi
+
+  local pid=$$
+  _pgid=$(ps -o pgid= -p ${pid} | sed 's/ //g')
+  export _pgid
+  export _procmon_output
+
+  echoerr "[procmon] start"
+
+  (
+    shutdown=false
+    while ! $shutdown; do
+      for pid_file in "${_procmon_output}"/*.pid; do
+        [[ -f "${pid_file}" ]] || continue # null glob
+        base_name=$(basename "${pid_file}")
+        pid=${base_name%.pid}
+        if ! kill -0 "${pid}"; then
+          echoerr "[procmon] ${pid} is dead"
+          rm "${pid_file}"
+        fi
+        sleep 1
+      done
+    done
+  ) &
+  _procmon_pid=$!
+  echoerr "[procmon] started with PID $_procmon_pid"
+  return 0
+}
+
+clh_track_last_background_job() {
+  local pid=$!
+  if [ ! -f "${_procmon_output}/${pid}.pid" ]; then
+    touch "${_procmon_output}/${pid}.pid"
+  fi
+}
+
+clh_get_tracked_pids() {
+  result=()
+  for pid_file in "${_procmon_output}"/*.pid; do
+    base_name=$(basename "${pid_file}")
+    pid=${base_name%.pid}
+    result+=("${pid}")
+  done
+}
+
+clh_stop_process_monitor() {
+  if [ -z "$_procmon_pid" ]; then
+    echoerr "[procmon] process monitor not started"
+    return 1
+  fi
+
+  if ! kill -0 "$_procmon_pid"; then
+    echoerr "[procmon] process monitor not running"
+    return 1
+  fi
+
+  if [ "$1" = "monitor_only" ]; then
+    echoerr "[procmon] stop monitor only. Children will be left behind."
+    kill -s TERM "$_procmon_pid"
+    wait "$_procmon_pid"
+    return 0
+  else
+    echoerr "[procmon] stop process group. This will halt the script."
+    kill -s TERM "-$_pgid"
+  fi
+}

src/utils.bash

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+#!/usr/bin/env bash
+
+LIB_SRC=${LIB_SRC:-$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)}
+
+# shellcheck source=./config.bash
+source "${LIB_SRC}/config.bash"
+
+clh_output_folder() {
+  echo "${OUTPUTS}/$1"
+}
+
+echoerr() {
+  echo "$@" >&2
+}

test/bats

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+Subproject commit 941bf35348987999cb510b17f4c59b67486aa818

test/test_helper/bats-assert

@@ -0,0 +1 @@
+Subproject commit 035e99c84759427bf160a6613904e9d57f838ea9

test/test_helper/bats-support

@@ -0,0 +1 @@
+Subproject commit d007fc1f451abbad55204fa9c9eb3e6ed5dc5f61

test/test_process_monitor.bats

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+setup() {
+  bats_require_minimum_version 1.12.0
+
+  export LIB_SRC="${BATS_TEST_DIRNAME}/../src"
+  load "${BATS_TEST_DIRNAME}/test_helper/bats-support/load.bash"
+  load "${BATS_TEST_DIRNAME}/test_helper/bats-assert/load.bash"
+
+  source "${LIB_SRC}/process_monitor.bash"
+}
+
+@test "should not start process monitor twice" {
+  assert clh_start_process_monitor
+  refute clh_start_process_monitor
+  assert clh_stop_process_monitor "monitor_only"
+}
+
+@test "should not stop the process monitor if it wasn't started" {
+  refute clh_stop_process_monitor
+}
+
+# @test "should keep track of process PIDs" {
+#   clh_get_tracked_pids
+#   assert [ ${#result[@]} -eq 0 ]
+
+#   (
+#     while [ ! -f "${OUTPUT_FOLDER}/stop" ]; do
+#       sleep 0.1
+#     done
+#   ) &
+#   clh_track_last_background_job
+
+#   (
+#     while [ ! -f "${OUTPUT_FOLDER}/stop" ]; do
+#       sleep 0.1
+#     done
+#   ) &
+#   clh_track_last_background_job
+
+#   clh_get_tracked_pids
+#   assert [ ${#result[@]} -eq 2 ]
+
+#   touch "${OUTPUT_FOLDER}/stop"
+
+#   clh_get_tracked_pids
+#   assert [ ${#result[@]} -eq 0 ]
+# }