我正在开发一种测试工具,用于从PC并行端口生成波形。此工具旨在生成任何波形模式,定时精度为ms,因此我使用Lua脚本定义波形模式,当用户单击[开始]按钮时,GUI启动新的QThread以运行脚本。
Lua的以下三个函数实现为C ++全局函数:
当调用pwrite时,写入的数据存储在全局变量中,然后以20ms的间隔更新GUI以更新GUI上的并行端口数据。 (这20ms间隔刷新不是一个好的设计,但我还没弄清楚如何在数据发生变化时使用信号进行GUI更新。)
该工具现在基本上可用了。波形输出没有问题,但并行端口数据更新有一些问题:
当Lua调用msleep时,GUI线程停止,并行端口数据仅在msleep结束后更新。
所以我的问题是:
如何实现sleep方法,以免它停止GUI线程的更新?
如何实现pwrite,以便在写入数据发生变化时GUI可以接收更新并行端口数据的信号?
程序GUI如下链接:
相关代码:
/* common.cpp file */
int L_MSleep(lua_State* l)
{
int milisec=0;
struct timespec req={0, 0};
time_t sec;
milisec=luaL_optint(l,1,0); // obtain parameter
if (milisec==0)
return 0;
sec=(int)(milisec/1000);
milisec=milisec-(sec*1000);
req.tv_sec=sec;
req.tv_nsec=milisec*1000000L;
while(nanosleep(&req,&req)==-1)
continue;
return 1;
}
/* LuaRunner.cpp file */
LuaRunner::LuaRunner(QObject *parent) :
QThread(parent)
{
runlua = false;
}
void LuaRunner::run()
{
QString err = "";
runlua = true;
LUA_RunScript(this->ff, err);
runlua = false;
if(err != "")
{
emit errorMessage(err);
}
}
int LuaRunner::LUA_RunScript(QString ff, QString &err)
{
L = lua_open();
luaL_openlibs(L);
if (luaL_loadfile(L, ff.toAscii()) || lua_pcall(L, 0, 0, 0))
{
err = QString(lua_tostring(L, -1));
return -1;
}
lua_register(L, "ssleep", L_SSleep);
lua_register(L, "msleep", L_MSleep);
lua_register(L, "pwrite", L_PortWrite);
lua_register(L, "print", L_Log);
lua_getglobal(L, "dotest");
if (!lua_isfunction(L, -1))
{
err = QString("Test function(dotest) should be a function");
return -1;
}
if(lua_pcall(L, 0, 0, 0))
{
err = QString(lua_tostring(L, -1));
return -1;
}
lua_close(L);
return 0;
}
答案 0 :(得分:4)
您在专用线程中正确运行Lua脚本。这是正确的方法 - 差不多。每次要运行脚本时都要重新启动线程。那是错的。您还从LUA线程访问GUI线程中的数据,而不进行任何同步。这不好。 Qt以信号和插槽之间的排队连接的形式提供了一种出色的机制。当信号槽调用通过线程边界时,参数将被包装在QEvent
中,并异步传递给目标QObject
。在每个线程中,事件传递是序列化的,因此您不必担心数据损坏等。
以下是应该如何做的:
// LUAObject.h
#include <QObject>
class LUAObject : public QObject
{
Q_OBJECT
public:
LUAObject(QObject * parent = 0);
public slots:
void setScript(const QString &);
void runScript();
void stop();
signals:
void hasError(const QString &);
void finished();
void hasParallelData(int);
void hasMessage(const QString &);
private:
QString script;
bool stop;
}
// LUAObject.cpp
// whatever Lua includes you need etc
LUAObject::LUAObject(QObject* p) : QObject(p)
{}
void LUAObject::stop() { stopped = true; }
void LUAObject::setScript(const QString & scr)
{ script = scr; }
int L_PWrite(lua_State* l)
{
int data = luaL_optint(l, 1, -1);
if (data != -1) {
// access the parallel port HERE, NOT in the GUI thread!
emit hasParallelData(luaL_optint(l, 1, 0));
}
return 0;
}
// returns a bool - true means we are stopped and should exit
int L_MSleep(lua_State* l)
{
int ms = luaL_optint(l, 1, -1);
if (ms == -1) return 0;
QApplication::processEvents(QEventLoop::WaitForMoreEvents, ms);
lua_pushBoolean(l, stopped); // event processing would run the stop() slot call
return 1;
}
int L_SSleep(lua_State* l)
{
int secs = luaL_optint(l, 1, -1);
if (secs == -1) return 0;
QApplication::processEvents(QEventLoop::WaitForMoreEvents, secs*1000);
lua_pushBoolean(l, stopped); // event processing would run the stop() slot call
return 1;
}
int L_Log(lua_State* l)
{
const char * msg = luaL_optstring(l, 1, 0);
if (!msg) return 0;
emit hasMessage(msg);
return 0;
}
class Lua // RAII
{
public:
explicit Lua(lua_state * l) : L(l) {}
~Lua() { lua_close(L); }
operator lua_state*() const { return L; }
private:
lua_state * L;
Q_DISABLE_COPY(LUA)
};
LUAObject::runScript()
{
stopped = false;
Lua L(lua_open());
luaL_openlibs(L);
if (luaL_loadbuffer(L, script.toAscii().constData(), script.length(), "script") || lua_pcall(L, 0, 0, 0))
{
emit hasError(lua_tostring(L, -1));
return;
}
lua_register(L, "ssleep", L_SSleep);
lua_register(L, "msleep", L_MSleep);
lua_register(L, "pwrite", L_PWrite);
lua_register(L, "print", L_Log);
lua_getglobal(L, "dotest");
if (!lua_isfunction(L, -1))
{
emit hasError("Test function(dotest) should be a function");
return;
}
if(lua_pcall(L, 0, 0, 0))
{
emit hasError(lua_tostring(L, -1));
return;
}
emit finished();
}
// main.cpp
#include <QApplication>
#include <QMetaMethod>
#include "LUAObject.h"
...
int main(int argc, char** argv)
{
QApplication(argc, argv);
MainWindow window;
...
QThread thread;
LUAObject lua;
thread.start(QThread::TimeCriticalPriority);
lua.moveToThread(&thread);
...
// NOTE: you can ONLY connect to LUAObject slots, you CANNOT call them
// directly since it runs in a separate thread!
connect(&window, SIGNAL(startClicked()), &lua, SLOT(runScript());
connect(&lua, SIGNAL(hasError(QString)), &window, SLOT(luaError(QString)));
...
window.show();
int rc = qApp->exec();
QMetaObject::invokeMethod(&lua, SLOT(stop())); // cross-thread slot invocation
thread.exit();
thread.wait();
return rc;
}
我将UI的实现留给您的想象力。请注意,它是未经测试的代码。如果我知道的话,它可能会炸毁你的电脑。
答案 1 :(得分:0)
也许您应该使用QT的msleep,因为它是QThread
提供的用途