Removing rocksdb write lock mutexes as store::write_queue serializes …

…write transactions.

nano/store/rocksdb/rocksdb.cpp

@@ -117,11 +117,6 @@ nano::store::rocksdb::component::component (nano::logger & logger_a, std::filesy
 		db.reset (nullptr);
 	}
 
-	if (!open_read_only_a)
-	{
-		construct_column_family_mutexes ();
-	}
-
 	if (is_fully_upgraded)
 	{
 		open (error, path_a, open_read_only_a, options, create_column_families ());
@@ -422,24 +417,10 @@ std::vector<rocksdb::ColumnFamilyDescriptor> nano::store::rocksdb::component::cr
 	return column_families;
 }
 
-nano::store::write_transaction nano::store::rocksdb::component::tx_begin_write (std::vector<nano::tables> const & tables_requiring_locks_a, std::vector<nano::tables> const & tables_no_locks_a)
+nano::store::write_transaction nano::store::rocksdb::component::tx_begin_write (std::vector<nano::tables> const &, std::vector<nano::tables> const &)
 {
-	std::unique_ptr<nano::store::rocksdb::write_transaction_impl> txn;
 	release_assert (db != nullptr);
-	if (tables_requiring_locks_a.empty () && tables_no_locks_a.empty ())
-	{
-		// Use all tables if none are specified
-		txn = std::make_unique<nano::store::rocksdb::write_transaction_impl> (transaction_db, all_tables (), tables_no_locks_a, write_lock_mutexes);
-	}
-	else
-	{
-		txn = std::make_unique<nano::store::rocksdb::write_transaction_impl> (transaction_db, tables_requiring_locks_a, tables_no_locks_a, write_lock_mutexes);
-	}
-
-	// Tables must be kept in alphabetical order. These can be used for mutex locking, so order is important to prevent deadlocking
-	debug_assert (std::is_sorted (tables_requiring_locks_a.begin (), tables_requiring_locks_a.end ()));
-
-	return store::write_transaction{ std::move (txn) };
+	return store::write_transaction{ std::make_unique<nano::store::rocksdb::write_transaction_impl> (transaction_db) };
 }
 
 nano::store::read_transaction nano::store::rocksdb::component::tx_begin_read () const
@@ -743,14 +724,6 @@ int nano::store::rocksdb::component::clear (::rocksdb::ColumnFamilyHandle * colu
 	return status.code ();
 }
 
-void nano::store::rocksdb::component::construct_column_family_mutexes ()
-{
-	for (auto table : all_tables ())
-	{
-		write_lock_mutexes.emplace (std::piecewise_construct, std::forward_as_tuple (table), std::forward_as_tuple ());
-	}
-}
-
 rocksdb::Options nano::store::rocksdb::component::get_db_options ()
 {
 	::rocksdb::Options db_options;

nano/store/rocksdb/rocksdb.hpp

@@ -108,7 +108,6 @@ class component : public nano::store::component
 	::rocksdb::TransactionDB * transaction_db = nullptr;
 	std::unique_ptr<::rocksdb::DB> db;
 	std::vector<std::unique_ptr<::rocksdb::ColumnFamilyHandle>> handles;
-	std::unordered_map<nano::tables, nano::mutex> write_lock_mutexes;
 	nano::rocksdb_config rocksdb_config;
 	unsigned const max_block_write_batch_num_m;
 
@@ -152,7 +151,6 @@ class component : public nano::store::component
 	void upgrade_v22_to_v23 (store::write_transaction &);
 	void upgrade_v23_to_v24 (store::write_transaction &);
 
-	void construct_column_family_mutexes ();
 	::rocksdb::Options get_db_options ();
 	::rocksdb::BlockBasedTableOptions get_table_options () const;
 	::rocksdb::ColumnFamilyOptions get_cf_options (std::string const & cf_name_a) const;

nano/store/rocksdb/transaction.cpp

@@ -32,13 +32,9 @@ void * nano::store::rocksdb::read_transaction_impl::get_handle () const
 	return (void *)&options;
 }
 
-nano::store::rocksdb::write_transaction_impl::write_transaction_impl (::rocksdb::TransactionDB * db_a, std::vector<nano::tables> const & tables_requiring_locks_a, std::vector<nano::tables> const & tables_no_locks_a, std::unordered_map<nano::tables, nano::mutex> & mutexes_a) :
-	db (db_a),
-	tables_requiring_locks (tables_requiring_locks_a),
-	tables_no_locks (tables_no_locks_a),
-	mutexes (mutexes_a)
+nano::store::rocksdb::write_transaction_impl::write_transaction_impl (::rocksdb::TransactionDB * db_a) :
+	db (db_a)
 {
-	lock ();
 	::rocksdb::TransactionOptions txn_options;
 	txn_options.set_snapshot = true;
 	txn = db->BeginTransaction (::rocksdb::WriteOptions (), txn_options);
@@ -48,7 +44,6 @@ nano::store::rocksdb::write_transaction_impl::~write_transaction_impl ()
 {
 	commit ();
 	delete txn;
-	unlock ();
 }
 
 void nano::store::rocksdb::write_transaction_impl::commit ()
@@ -74,23 +69,7 @@ void * nano::store::rocksdb::write_transaction_impl::get_handle () const
 	return txn;
 }
 
-void nano::store::rocksdb::write_transaction_impl::lock ()
-{
-	for (auto table : tables_requiring_locks)
-	{
-		mutexes.at (table).lock ();
-	}
-}
-
-void nano::store::rocksdb::write_transaction_impl::unlock ()
-{
-	for (auto table : tables_requiring_locks)
-	{
-		mutexes.at (table).unlock ();
-	}
-}
-
 bool nano::store::rocksdb::write_transaction_impl::contains (nano::tables table_a) const
 {
-	return (std::find (tables_requiring_locks.begin (), tables_requiring_locks.end (), table_a) != tables_requiring_locks.end ()) || (std::find (tables_no_locks.begin (), tables_no_locks.end (), table_a) != tables_no_locks.end ());
+	return true;
 }

nano/store/rocksdb/transaction_impl.hpp

@@ -26,7 +26,7 @@ class read_transaction_impl final : public store::read_transaction_impl
 class write_transaction_impl final : public store::write_transaction_impl
 {
 public:
-	write_transaction_impl (::rocksdb::TransactionDB * db_a, std::vector<nano::tables> const & tables_requiring_locks_a, std::vector<nano::tables> const & tables_no_locks_a, std::unordered_map<nano::tables, nano::mutex> & mutexes_a);
+	write_transaction_impl (::rocksdb::TransactionDB * db_a);
 	~write_transaction_impl ();
 	void commit () override;
 	void renew () override;
@@ -36,12 +36,6 @@ class write_transaction_impl final : public store::write_transaction_impl
 private:
 	::rocksdb::Transaction * txn;
 	::rocksdb::TransactionDB * db;
-	std::vector<nano::tables> tables_requiring_locks;
-	std::vector<nano::tables> tables_no_locks;
-	std::unordered_map<nano::tables, nano::mutex> & mutexes;
 	bool active{ true };
-
-	void lock ();
-	void unlock ();
 };
 }