MariaDB connection pool is now a stack

src/BSQL/BSQL.h

@@ -11,7 +11,7 @@
 #include <deque>
 #include <map>
 #include <memory>
-#include <queue>
+#include <stack>
 #include <string>
 #include <thread>
 

src/BSQL/MySqlConnection.cpp

@@ -11,7 +11,7 @@ MySqlConnection::~MySqlConnection() {
 	operations.clear();
 	//and release them
 	while (!availableConnections.empty()) {
-		auto front(availableConnections.front());
+		auto front(availableConnections.top());
 		mysql_close(front);
 		if (front == firstSuccessfulConnection)
 			firstSuccessfulConnection = nullptr;
@@ -57,7 +57,7 @@ MYSQL* MySqlConnection::RequestConnection() {
 	if (availableConnections.empty() && !LoadNewConnection())
 		return nullptr;
 
-	auto front(availableConnections.front());
+	auto front(availableConnections.top());
 	availableConnections.pop();
 	if (availableConnections.empty())
 		LoadNewConnection();

src/BSQL/MySqlConnection.h

@@ -10,7 +10,7 @@ class MySqlConnection : public Connection {
 	std::string database;
 	unsigned short port;
 
-	std::queue<MYSQL*> availableConnections;
+	std::stack<MYSQL*> availableConnections;
 	MYSQL* firstSuccessfulConnection;
 	MySqlConnectOperation* newestConnectionAttempt;
 private:

src/DMAPI/BSQL.dm

@@ -39,6 +39,8 @@ Properly quotes a string for use by the database. The connection must be open fo
 Starts an operation for a query
   query: The text of the query. Only one query allowed per invocation, no semicolons
  Returns: A /datum/BSQL_Operation/Query representing the running query and subsequent result set or null if an error occurred
+
+ Note for MariaDB: The underlying connection is pooled. In order to use connection state based properties (i.e. LAST_INSERT_ID()) you can guarantee multiple queries will use the same connection by running BSQL_DEL_CALL(query) on the finished /datum/BSQL_Operation/Query and then creating the next one with another call to BeginQuery() with no sleeps in between
 */
 /datum/BSQL_Connection/proc/BeginQuery(query)
 	return