Fix Transaction memory leak

Summary:
- Make sure we clean up recovered_transactions_ on DBImpl destructor
- delete leaked txns and env in TransactionTest

Test Plan: Run transaction_test under valgrind

Reviewers: sdong, andrewkr, yhchiang, horuff

Reviewed By: horuff

Subscribers: andrewkr, dhruba

Differential Revision: https://reviews.facebook.net/D58263

db/db_impl.cc

@@ -460,6 +460,10 @@ DBImpl::~DBImpl() {
   // so the cache can be safely destroyed.
   table_cache_->EraseUnRefEntries();
 
+  for (auto& txn_entry : recovered_transactions_) {
+    delete txn_entry.second;
+  }
+
   // versions need to be destroyed before table_cache since it can hold
   // references to table_cache.
   versions_.reset();

utilities/transactions/transaction_test.cc

@@ -57,6 +57,7 @@ class TransactionTest : public testing::Test {
   ~TransactionTest() {
     delete db;
     DestroyDB(dbname, options);
+    delete env_;
   }
 
   Status ReOpenNoDelete() {
@@ -442,6 +443,8 @@ TEST_F(TransactionTest, TwoPhaseRollbackTest) {
   // try rollback again
   s = txn->Rollback();
   ASSERT_EQ(s, Status::InvalidArgument());
+
+  delete txn;
 }
 
 TEST_F(TransactionTest, PersistentTwoPhaseTransactionTest) {
@@ -495,6 +498,7 @@ TEST_F(TransactionTest, PersistentTwoPhaseTransactionTest) {
   s = db->Get(read_options, Slice("foo"), &value);
   ASSERT_TRUE(s.IsNotFound());
 
+  delete txn;
   // kill and reopen
   s = ReOpenNoDelete();
   ASSERT_OK(s);
@@ -735,6 +739,8 @@ TEST_F(TransactionTest, TwoPhaseDoubleRecoveryTest) {
   s = txn->Commit();
   ASSERT_OK(s);
 
+  delete txn;
+
   // kill and reopen
   env_->SetFilesystemActive(false);
   ReOpenNoDelete();