fix(mongo_killer): refactor mongo_killer to make more sense

Author: hasezoey

packages/mongodb-memory-server-core/package.json

@@ -88,6 +88,7 @@
     "lint": "npm run eslint && npm run tscheck",
     "eslint": "eslint -c ../../.eslintrc.js 'src/**/*.{js,ts}'",
     "test": "npm run lint && npm run coverage",
+    "test:watch": "npm run watch",
     "tscheck": "tsc --noEmit"
   }
 }

packages/mongodb-memory-server-core/scripts/mongo_killer.js

@@ -7,28 +7,61 @@
     - kill itself
 */
 
+/**
+ * Because since node 4.0.0 the internal util.is* functions got deprecated
+ * @param {any} val Any value to test if null or undefined
+ */
+function isNullOrUndefined(val) {
+  return val === null || val === undefined;
+}
+
+/**
+ * Check if the given Process is still alive
+ * @param {number} pid The Process PID
+ */
+function isAlive(pid) {
+  try {
+    process.kill(pid, 0);
+    return true;
+  } catch (err) {
+    return false;
+  }
+}
+
+// the following line is just to ensure this process gets actually exited
+process.on('SIGINT', () => process.exit(0));
+
 const parentPid = parseInt(process.argv[2], 10);
 const childPid = parseInt(process.argv[3], 10);
 
-if (parentPid && childPid) {
-  setInterval(() => {
-    // if parent dead
+function check() {
+  // if parent dead
+  if (!isAlive(parentPid)) {
+    console.log('mongo_killer: parentPid not alive');
     try {
-      process.kill(parentPid, 0);
-    } catch (e) {
-      try {
-        process.kill(childPid);
-      } catch (ee) {
-        // doesnt matter if it is dead
-      }
-      process.exit();
+      process.kill(childPid);
+    } catch (err) {
+      console.log('mongo_killer: couldnt kill child:', err);
     }
+    process.exit();
+  }
 
-    // if child dead
-    try {
-      process.kill(childPid, 0);
-    } catch (e) {
-      process.exit();
-    }
-  }, 2000);
+  // if child dead
+  if (!isAlive(childPid)) {
+    console.log('mongo_killer: childPid not alive');
+    process.exit();
+  }
+}
+
+if (isNullOrUndefined(parentPid) || Number.isNaN(parentPid)) {
+  console.log('mongo_killer: parentPid is undefined or NaN!');
+  process.exit(-1);
 }
+
+if (isNullOrUndefined(childPid) || Number.isNaN(childPid)) {
+  console.log('mongo_killer: childPid is undefined or NaN!');
+  process.exit(-1);
+}
+
+check(); // run once before the interval
+setInterval(check, 2000);