src/murmur/ServerDB: Turned db version into static field & added some documentation to init/update process

1 files changed, 23 insertions, 2 deletions

diff --git a/src/murmur/ServerDB.cpp b/src/murmur/ServerDB.cpp
index ac0204a63..9f5402796 100644
--- a/src/murmur/ServerDB.cpp
+++ b/src/murmur/ServerDB.cpp
@@ -215,13 +215,18 @@ ServerDB::ServerDB() {
 
 	int version = 0;
 
+	// Make sure a table called "meta" is present
+	// We use the meta table to keep track of various meta information such as the
+	// database structure version this database conforms to.
 	if (Meta::mp.qsDBDriver == "QSQLITE")
 		SQLDO("CREATE TABLE IF NOT EXISTS `%1meta` (`keystring` TEXT PRIMARY KEY, `value` TEXT)");
 	else if (Meta::mp.qsDBDriver == "QPSQL")
 		SQLQUERY("CREATE TABLE IF NOT EXISTS `%1meta` (`keystring` varchar(255) PRIMARY KEY, `value` varchar(255))");
 	else
+		// MySQL
 		SQLDO("CREATE TABLE IF NOT EXISTS `%1meta`(`keystring` varchar(255) PRIMARY KEY, `value` varchar(255)) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin");
 
+	// Query the database structure version the existing database conforms to
 	SQLDO("SELECT `value` FROM `%1meta` WHERE `keystring` = 'version'");
 
 	if (query.next())
@@ -229,9 +234,17 @@ ServerDB::ServerDB() {
 
 	loadOrSetupMetaPBKDF2IterationCount(query);
 
-	if (version < 6) {
+	// Check if the database structure conforms to what this version of the code expects yb comparing to
+	// DB_STRUCTURE_VERSION. If the queried version is less than that, we might have to perform compatibility
+	// changes or create the tables in the first place.
+	if (version < DB_STRUCTURE_VERSION) {
 		if (version > 0) {
+			// A version > 0 means that there are tables in the DB already but they don't conform to the
+			// most recent structure. That means that we have to update them.
+			// Before doing that though we create backups of the existing tables in case something goes wrong.
 			qWarning("Renaming old tables...");
+			// %s is the table prefix we are using and %2 is the upgrade suffix we defined above.
+			// See ServerDB::query for mor info on the %-notation.
 			SQLQUERY("ALTER TABLE `%1servers` RENAME TO `%1servers%2`");
 			if (version < 2)
 				SQLMAY("ALTER TABLE `%1log` RENAME TO `%1slog`");
@@ -254,6 +267,7 @@ ServerDB::ServerDB() {
 			}
 		}
 
+		// Now we generate new tables that conform to the state-of-the-art structure
 		qWarning("Generating new tables...");
 		if (Meta::mp.qsDBDriver == "QSQLITE") {
 			if (version > 0) {
@@ -438,6 +452,7 @@ ServerDB::ServerDB() {
 			SQLQUERY("CREATE TABLE `%1bans` (`server_id` INTEGER NOT NULL, `base` BYTEA, `mask` INTEGER, `name` varchar(255), `hash` CHAR(40), `reason` TEXT, `start` TIMESTAMP, `duration` INTEGER)");
 			SQLQUERY("ALTER TABLE `%1bans` ADD CONSTRAINT `%1bans_del_server` FOREIGN KEY(`server_id`) REFERENCES `%1servers`(`server_id`) ON DELETE CASCADE");
 		} else {
+			// MySQL
 			if (version > 0) {
 				typedef QPair<QString, QString> qsp;
 				QList<qsp> qlForeignKeys;
@@ -505,9 +520,15 @@ ServerDB::ServerDB() {
 			SQLDO("CREATE TABLE `%1bans` (`server_id` INTEGER NOT NULL, `base` BINARY(16), `mask` INTEGER, `name` varchar(255), `hash` CHAR(40), `reason` TEXT, `start` DATETIME, `duration` INTEGER) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin");
 			SQLDO("ALTER TABLE `%1bans` ADD CONSTRAINT `%1bans_del_server` FOREIGN KEY(`server_id`) REFERENCES `%1servers`(`server_id`) ON DELETE CASCADE");
 		}
+
 		if (version == 0) {
+			// The database was empty until we started populating it so the first (and so far only)
+			// entries in it will be the server ID (we know it must be 1 as there has been no previous
+			// server) as well as the version info about the database structure version.
 			SQLDO("INSERT INTO `%1servers` (`server_id`) VALUES(1)");
-			SQLDO("INSERT INTO `%1meta` (`keystring`, `value`) VALUES('version','6')");
+			// Calling this function is the same as using the SQLDO macro
+			ServerDB::exec(query, QLatin1String("INSERT INTO `%1meta` (`keystring`, `value`) ")
+					+ QLatin1String("VALUES('version','%1')").arg(QString::number(DB_STRUCTURE_VERSION)), true);
 		} else {
 			qWarning("Importing old data...");