drop_collection_not_blocked_by_txn.js

/**
 * Test that drop collection only takes database IX lock and will not be blocked by transactions.
 *
 * @tags: [uses_transactions, requires_db_locking, assumes_unsharded_collection]
 */

let dbName = 'drop_collection_not_blocked_by_txn';
let mydb = db.getSiblingDB(dbName);

assert.commandWorked(mydb.runCommand({insert: "a", documents: [{x: 1}]}));
assert.commandWorked(mydb.runCommand({insert: "b", documents: [{x: 1}]}));

const session = mydb.getMongo().startSession();
const sessionDb = session.getDatabase(dbName);

session.startTransaction();
// This holds a database IX lock and a collection IX lock on "a".
sessionDb.a.insert({y: 1});

// This only requires database IX lock.
assert.commandWorked(mydb.runCommand({drop: "b"}));

assert.commandWorked(session.commitTransaction_forTesting());