From 409eda21a4287078d209e05ac37ed0c8fa57573a Mon Sep 17 00:00:00 2001
From: loonycyborg <loonycyborg@gmail.com>
Date: Mon, 6 Feb 2017 15:43:41 +0300
Subject: [PATCH] Reimplement autoreconnect if sql server lost functionality

---
 src/server/forum_user_handler.cpp | 28 ++++++++++++++++++++++------
 src/server/forum_user_handler.hpp |  2 ++
 2 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/src/server/forum_user_handler.cpp b/src/server/forum_user_handler.cpp
index a42c9313fe79..6ccf29528fea 100644
--- a/src/server/forum_user_handler.cpp
+++ b/src/server/forum_user_handler.cpp
@@ -116,7 +116,7 @@ bool fuh::user_exists(const std::string& name) {
 
 	// Make a test query for this username
 	try {
-		return prepared_statement<bool>(conn, "SELECT 1 FROM `" + db_users_table_ + "` WHERE UPPER(username)=UPPER(?)", name);
+		return prepared_statement<bool>("SELECT 1 FROM `" + db_users_table_ + "` WHERE UPPER(username)=UPPER(?)", name);
 	} catch (sql_error& e) {
 		ERR_UH << "Could not execute test query for user '" << name << "' :" << e.message << std::endl;
 		// If the database is down just let all usernames log in
@@ -246,9 +246,25 @@ void fuh::set_lastlogin(const std::string& user, const time_t& lastlogin) {
 	}
 }
 
+template<typename T, typename... Args>
+inline T fuh::prepared_statement(const std::string& sql, Args&&... args)
+{
+	try {
+		return ::prepared_statement<T>(conn, sql, std::forward<Args>(args)...);
+	} catch (sql_error&) {
+		WRN_UH << "caught sql error, trying to reconnect and retry..." << std::endl;
+		//Try to reconnect and execute query again
+		if(!mysql_real_connect(conn, db_host_.c_str(),  db_user_.c_str(), db_password_.c_str(), db_name_.c_str(), 0, nullptr, 0)) {
+			ERR_UH << "Could not connect to database: " << mysql_errno(conn) << ": " << mysql_error(conn) << std::endl;
+			throw sql_error("Error querying database.");
+		}
+	}
+	return ::prepared_statement<T>(conn, sql, std::forward<Args>(args)...);
+}
+
 template<typename T>
 T fuh::get_detail_for_user(const std::string& name, const std::string& detail) {
-	return prepared_statement<T>(conn,
+	return prepared_statement<T>(
 		"SELECT `" + detail + "` FROM `" + db_users_table_ + "` WHERE UPPER(username)=UPPER(?)",
 		name);
 }
@@ -256,7 +272,7 @@ T fuh::get_detail_for_user(const std::string& name, const std::string& detail) {
 template<typename T>
 T fuh::get_writable_detail_for_user(const std::string& name, const std::string& detail) {
 	if(!extra_row_exists(name)) throw sql_error("row doesn't exist");
-	return prepared_statement<T>(conn,
+	return prepared_statement<T>(
 		"SELECT `" + detail + "` FROM `" + db_extra_table_ + "` WHERE UPPER(username)=UPPER(?)",
 		name);
 }
@@ -267,9 +283,9 @@ void fuh::write_detail(const std::string& name, const std::string& detail, T&& v
 		// Check if we do already have a row for this user in the extra table
 		if(!extra_row_exists(name)) {
 			// If not create the row
-			prepared_statement<void>(conn, "INSERT INTO `" + db_extra_table_ + "` VALUES(?,?,'0')", name, std::forward<T>(value));
+			prepared_statement<void>("INSERT INTO `" + db_extra_table_ + "` VALUES(?,?,'0')", name, std::forward<T>(value));
 		}
-		prepared_statement<void>(conn, "UPDATE `" + db_extra_table_ + "` SET " + detail + "=? WHERE UPPER(username)=UPPER(?)", std::forward<T>(value), name);
+		prepared_statement<void>("UPDATE `" + db_extra_table_ + "` SET " + detail + "=? WHERE UPPER(username)=UPPER(?)", std::forward<T>(value), name);
 	} catch (sql_error& e) {
 		ERR_UH << "Could not set detail for user '" << name << "': " << e.message << std::endl;
 	}
@@ -279,7 +295,7 @@ bool fuh::extra_row_exists(const std::string& name) {
 
 	// Make a test query for this username
 	try {
-		return prepared_statement<bool>(conn, "SELECT 1 FROM `" + db_extra_table_ + "` WHERE UPPER(username)=UPPER(?)", name);
+		return prepared_statement<bool>("SELECT 1 FROM `" + db_extra_table_ + "` WHERE UPPER(username)=UPPER(?)", name);
 	} catch (sql_error& e) {
 		ERR_UH << "Could not execute test query for user '" << name << "' :" << e.message << std::endl;
 		return false;
diff --git a/src/server/forum_user_handler.hpp b/src/server/forum_user_handler.hpp
index bdb96ef8cc6a..ea2580115692 100644
--- a/src/server/forum_user_handler.hpp
+++ b/src/server/forum_user_handler.hpp
@@ -98,6 +98,8 @@ class fuh : public user_handler {
 
 		MYSQL *conn;
 
+		template<typename T, typename... Args>
+		inline T prepared_statement(const std::string& sql, Args&&...);
 		// Query a detail for a particular user from the database
 		template<typename T>
 		T get_detail_for_user(const std::string& name, const std::string& detail);