Add OnUnloadModule hook to MySQL

git-svn-id: http://svn.inspircd.org/repository/trunk/inspircd@12632 e03df62e-2008-0410-955e-edbf42e46eb7

src/modules/extra/m_mysql.cpp

@@ -67,16 +67,23 @@ class SQLConnection;
 class MySQLresult;
 class DispatcherThread;
 
-struct QueueItem
+struct QQueueItem
 {
 	SQLQuery* q;
 	SQLConnection* c;
-	QueueItem(SQLQuery* Q, SQLConnection* C) : q(Q), c(C) {}
+	QQueueItem(SQLQuery* Q, SQLConnection* C) : q(Q), c(C) {}
+};
+
+struct RQueueItem
+{
+	SQLQuery* q;
+	MySQLresult* r;
+	RQueueItem(SQLQuery* Q, MySQLresult* R) : q(Q), r(R) {}
 };
 
 typedef std::map<std::string, SQLConnection*> ConnMap;
-typedef std::deque<QueueItem> QueryQueue;
+typedef std::deque<QQueueItem> QueryQueue;
-typedef std::deque<MySQLresult*> ResultQueue;
+typedef std::deque<RQueueItem> ResultQueue;
 
 /** MySQL module
  *  */
@@ -84,14 +91,15 @@ class ModuleSQL : public Module
 {
  public:
 	DispatcherThread* Dispatcher;
-	QueryQueue qq;
+	QueryQueue qq;       // MUST HOLD MUTEX
-	ResultQueue rq;
+	ResultQueue rq;      // MUST HOLD MUTEX
-	ConnMap connections;
+	ConnMap connections; // main thread only
 
 	ModuleSQL();
 	void init();
 	~ModuleSQL();
 	void OnRehash(User* user);
+	void OnUnloadModule(Module* mod);
 	Version GetVersion();
 };
 
@@ -115,14 +123,13 @@ class DispatcherThread : public SocketThread
 class MySQLresult : public SQLResult
 {
  public:
-	SQLQuery* query;
 	SQLerror err;
 	int currentrow;
 	int rows;
 	std::vector<std::string> colnames;
 	std::vector<SQLEntries> fieldlists;
 
-	MySQLresult(SQLQuery* q, MYSQL_RES* res, int affected_rows) : query(q), err(SQL_NO_ERROR), currentrow(0), rows(0)
+	MySQLresult(MYSQL_RES* res, int affected_rows) : err(SQL_NO_ERROR), currentrow(0), rows(0)
 	{
 		if (affected_rows >= 1)
 		{
@@ -166,7 +173,7 @@ class MySQLresult : public SQLResult
 		}
 	}
 
-	MySQLresult(SQLQuery* q, SQLerror& e) : query(q), err(e)
+	MySQLresult(SQLerror& e) : err(e)
 	{
 
 	}
@@ -217,11 +224,11 @@ class SQLConnection : public SQLProvider
  public:
 	reference<ConfigTag> config;
 	MYSQL *connection;
-	bool active;
+	Mutex lock;
 
 	// This constructor creates an SQLConnection object with the given credentials, but does not connect yet.
 	SQLConnection(Module* p, ConfigTag* tag) : SQLProvider(p, "SQL/" + tag->getString("id")),
-		config(tag), active(false)
+		config(tag)
 	{
 	}
 
@@ -310,30 +317,23 @@ class SQLConnection : public SQLProvider
 		return (ModuleSQL*)(Module*)creator;
 	}
 
-	void DoBlockingQuery(SQLQuery* req)
+	MySQLresult* DoBlockingQuery(SQLQuery* req)
 	{
+
 		/* Parse the command string and dispatch it to mysql */
 		if (CheckConnection() && !mysql_real_query(connection, req->query.data(), req->query.length()))
 		{
 			/* Successfull query */
 			MYSQL_RES* res = mysql_use_result(connection);
 			unsigned long rows = mysql_affected_rows(connection);
-			MySQLresult* r = new MySQLresult(req, res, rows);
+			return new MySQLresult(res, rows);
-			Parent()->Dispatcher->LockQueue();
-			Parent()->rq.push_back(r);
-			Parent()->Dispatcher->NotifyParent();
-			Parent()->Dispatcher->UnlockQueue();
 		}
 		else
 		{
 			/* XXX: See /usr/include/mysql/mysqld_error.h for a list of
 			 * possible error numbers and error messages */
 			SQLerror e(SQL_QREPLY_FAIL, ConvToStr(mysql_errno(connection)) + std::string(": ") + mysql_error(connection));
-			MySQLresult* r = new MySQLresult(req, e);
+			return new MySQLresult(e);
-			Parent()->Dispatcher->LockQueue();
-			Parent()->rq.push_back(r);
-			Parent()->Dispatcher->NotifyParent();
-			Parent()->Dispatcher->UnlockQueue();
 		}
 	}
 
@@ -359,7 +359,7 @@ class SQLConnection : public SQLProvider
 	void submit(SQLQuery* q)
 	{
 		Parent()->Dispatcher->LockQueue();
-		Parent()->qq.push_back(QueueItem(q, this));
+		Parent()->qq.push_back(QQueueItem(q, this));
 		Parent()->Dispatcher->UnlockQueueWakeup();
 	}
 };
@@ -374,8 +374,8 @@ void ModuleSQL::init()
 	Dispatcher = new DispatcherThread(this);
 	ServerInstance->Threads->Start(Dispatcher);
 
-	Implementation eventlist[] = { I_OnRehash };
+	Implementation eventlist[] = { I_OnRehash, I_OnUnloadModule };
-	ServerInstance->Modules->Attach(eventlist, this, 1);
+	ServerInstance->Modules->Attach(eventlist, this, 2);
 }
 
 ModuleSQL::~ModuleSQL()
@@ -394,7 +394,6 @@ ModuleSQL::~ModuleSQL()
 
 void ModuleSQL::OnRehash(User* user)
 {
-	Dispatcher->LockQueue();
 	ConnMap conns;
 	ConfigTagList tags = ServerInstance->Config->ConfTags("database");
 	for(ConfigIter i = tags.first; i != tags.second; i++)
@@ -415,21 +414,56 @@ void ModuleSQL::OnRehash(User* user)
 			connections.erase(curr);
 		}
 	}
+
+	// now clean up the deleted databases
+	Dispatcher->LockQueue();
+	SQLerror err(SQL_BAD_DBID);
 	for(ConnMap::iterator i = connections.begin(); i != connections.end(); i++)
 	{
-		if (i->second->active)
+		ServerInstance->Modules->DelService(*i->second);
+		// it might be running a query on this database. Wait for that to complete
+		i->second->lock.Lock();
+		i->second->lock.Unlock();
+		// now remove all active queries to this DB
+		for(unsigned int j = qq.size() - 1; j >= 0; j--)
 		{
-			// can't delete it now. Next rehash will try to kill it again
+			if (qq[j].c == i->second)
-			conns.insert(*i);
+			{
+				qq[j].q->OnError(err);
+				delete qq[j].q;
+				qq.erase(qq.begin() + j);
+			}
 		}
-		else
+		// finally, nuke the connection
+		delete i->second;
+	}
+	Dispatcher->UnlockQueue();
+	connections.swap(conns);
+}
+
+void ModuleSQL::OnUnloadModule(Module* mod)
+{
+	SQLerror err(SQL_BAD_DBID);
+	Dispatcher->LockQueue();
+	for(unsigned int i = qq.size() - 1; i >= 0; i--)
+	{
+		if (qq[i].q->creator == mod)
 		{
-			ServerInstance->Modules->DelService(*i->second);
+			if (i == 0)
-			delete i->second;
+			{
+				// need to wait until the query is done
+				// (the result will be discarded)
+				qq[i].c->lock.Lock();
+				qq[i].c->lock.Unlock();
+			}
+			qq[i].q->OnError(err);
+			delete qq[i].q;
+			qq.erase(qq.begin() + i);
 		}
 	}
-	connections.swap(conns);
 	Dispatcher->UnlockQueue();
+	// clean up any result queue entries
+	Dispatcher->OnNotify();
 }
 
 Version ModuleSQL::GetVersion()
@@ -444,13 +478,30 @@ void DispatcherThread::Run()
 	{
 		if (!Parent->qq.empty())
 		{
-			QueueItem i = Parent->qq.front();
+			QQueueItem i = Parent->qq.front();
-			Parent->qq.pop_front();
+			i.c->lock.Lock();
-			i.c->active = true;
 			this->UnlockQueue();
-			i.c->DoBlockingQuery(i.q);
+			MySQLresult* res = i.c->DoBlockingQuery(i.q);
+			i.c->lock.Unlock();
+
+			/*
+			 * At this point, the main thread could be working on:
+			 *  Rehash - delete i.c out from under us. We don't care about that.
+			 *  UnloadModule - delete i.q and the qq item. Need to avoid reporting results.
+			 */
+
 			this->LockQueue();
-			i.c->active = false;
+			if (Parent->qq.front().q == i.q)
+			{
+				Parent->qq.pop_front();
+				Parent->rq.push_back(RQueueItem(i.q, res));
+				NotifyParent();
+			}
+			else
+			{
+				// UnloadModule ate the query
+				delete res;
+			}
 		}
 		else
 		{
@@ -469,13 +520,13 @@ void DispatcherThread::OnNotify()
 	this->LockQueue();
 	for(ResultQueue::iterator i = Parent->rq.begin(); i != Parent->rq.end(); i++)
 	{
-		MySQLresult* res = *i;
+		MySQLresult* res = i->r;
 		if (res->err.id == SQL_NO_ERROR)
-			res->query->OnResult(*res);
+			i->q->OnResult(*res);
 		else
-			res->query->OnError(res->err);
+			i->q->OnError(res->err);
-		delete res->query;
+		delete i->q;
-		delete res;
+		delete i->r;
 	}
 	Parent->rq.clear();
 	this->UnlockQueue();