node-lmdb // cursor memory leak – The transaction is wrapped in a setImmediate loop

example4-cursors.js

var lmdb = require('./build/Release/node-lmdb');
var env = new lmdb.Env();
env.open({
    // Path to the environment
    path: "./testdata",
    // Maximum number of databases
    maxDbs: 10
});

// Ensure that the database is empty
var dbi = env.openDbi({
   name: "mydb4",
   create: true
});
dbi.drop();
dbi = env.openDbi({
   name: "mydb4",
   create: true
});

// Write test values

var write = function () {
  var txn0 = env.beginTxn();
  txn0.putString(dbi, "a", "Helló1");
  txn0.putString(dbi, "b", "Hello2");
  txn0.putNumber(dbi, "c", 43);
  /* key 'd' is omitted intentionally */
  txn0.putBinary(dbi, "e", new Buffer("öüóőúéáű"));
  txn0.putBoolean(dbi, "f", false);
  txn0.putString(dbi, "g", "Hello6");
  txn0.commit();
  txn0 = null;
  console.log("wrote initial values");
}

var printFunc = function(key, data) {
    console.log("----->  key:", key);
    console.log("-----> data:", data);
}

var runner = function () {
  write();

  // Begin transaction
  var txn = env.beginTxn();

  // Create cursor
  var cursor = new lmdb.Cursor(txn, dbi);

  console.log("first (expected a)");
  cursor.goToFirst();
  cursor.getCurrentString(printFunc);

  console.log("next (expected b)");
  cursor.goToNext();
  cursor.getCurrentString(printFunc);

  console.log("next (expected c)");
  cursor.goToNext();
  cursor.getCurrentNumber(printFunc);


  console.log("next (expected e)");
  cursor.goToNext();
  cursor.getCurrentBinary(printFunc);


  console.log("prev (expected c)");
  cursor.goToPrev();
  cursor.getCurrentNumber(printFunc);


  console.log("last (expected g)");
  cursor.goToLast();
  cursor.getCurrentString(printFunc);


  console.log("prev (expected f)");
  cursor.goToPrev();
  cursor.getCurrentBoolean(printFunc);


  console.log("go to key 'b' (expected b)");
  cursor.goToKey('b');
  cursor.getCurrentString(printFunc);


  console.log("go to range 'd' (expected e)");
  cursor.goToRange('d');
  cursor.getCurrentBinary(printFunc);


  console.log("del (expected f)");
  cursor.del();
  cursor.getCurrentBoolean(printFunc);

  console.log("");
  console.log("now iterating through all the keys");

  for (var found = cursor.goToFirst(); found; found = cursor.goToNext()) {
      console.log("-----> key:", found);
  }

  // Close cursor
  cursor.close();

  // Commit transaction
  txn.commit();

  cursor = null;
  txn = null;

  // restart the loop
  setImmediate(runner);
};

// kick things off
runner();



process.once('exit', function () {
  dbi.close();
  env.close();
});