int rc = sqlite3_prepare_v2(db_handle_, sql_stmt.c_str(), -1, &ret_stmt, nullptr);
if (rc!=SQLITE_OK) {
std::cout << "Error : " << sqlite3_errmsg(db_handle_) << std::endl;
return;
}
while ((rc = sqlite3_step(ret_stmt) == SQLITE_ROW)) {
row_count = sqlite3_column_int(ret_stmt, 0);
if (row_count > 0) { //more than one trajectory point exists
avlbl_pos_associations_set.insert(i);
}
}
I have this while loop running where i want to understand what's the meaning of while loop's condition. I understand rc is being assigned the value of sqlite3_step(ret_stmt) == SQLITE_ROW (either true or false) but i don't understand the hoops this condition is running through. Why not just sqlite3_step(ret_stmt) == SQLITE_ROW because that will still be a green or red signal for while loop to execute.
Related
I am trying to implement parts of a Linux based network Tic-Tac-Toe program into a Winsock server program. I am having some issues as the Linux version opens a socket as in integer variable:
int client_sock = 0; however, in the Winsock application a Csocket object is created: m_pClientSocket = new CSocket();
Now obviously when I try to compile the function that sends the players move to the server:
if (!SendStatus(client_sock, MOVE)) {
ServerDisconnected();
}
I get an invalid variable type error as the function is expecting an int and it's receiving a Csock object.
My question is how do I get the functions to work? I have tried getting the socket handle and using that but I'm not sure if that's the right direction and using this SendStatus(this->m_pClientSocket->GetSocketHandle(), WIN); is giving me issues as it's a static function.
Send Status Function:
bool SendStatus(int socket, StatusCode status)
{
char* data = (char*)&status;
size_t left = sizeof(status);
ptrdiff_t rc;
while (left)
{
rc = send(socket, data + sizeof(status) - left, left, 0);
if (rc <= 0) return false;
left -= rc;
}
return true;
}
TakeTurn Function:
bool TakeTurn(TTTBoard& board)
{
bool game_over = false;
bool input_good = false;
int row = 0, col = 0;
// Display the board
board.DrawBoard();
while (!input_good)
{
printf("Enter move (row col): ");
// Make sure two integers were inputted
if (scanf_s("%d %d", &row, &col) == 2)
{
if (row < 0 || row > 2)
printf("Invalid row input. Try again.\n");
else if (col < 0 || col > 2)
printf("Invalid column input. Try again.\n");
else if (!board.IsBlank(row, col))
printf("That cell isn't blank. Try again.\n");
else
input_good = true;
}
else
printf("Invalid move input. Try again.\n");
// flush any data from the internal buffers
int c;
while ((c = getchar()) != '\n' && c != EOF);
}
board.PlayerMakeMove(row, col);
cout << "Sending move to server" << endl;
// Send the move to the server
if (!SendStatus(client_sock, MOVE))
ServerDisconnected();
if (!SendInt(client_sock, row))
ServerDisconnected();
if (!SendInt(client_sock, col))
ServerDisconnected();
// Check for win/draw
if (board.IsWon())
{
cout << "YOU WIN!!!!" << endl;
game_over = true;
SendStatus(client_sock, WIN);
}
else if (board.IsDraw())
{
cout << "You tied ._." << endl;
game_over = true;
SendStatus(client_sock, DRAW);
}
return game_over;
}
Hopefully I have shared enough info, I didn't want to bloat the question, thanks!
TL;DR
I am trying to capture keyboard events (more specifically, the Ctrl+c command) in my own C++ program. I am attempting this through generic keyboard presses in SDL2.
END TL;DR
I have found links on SO and the internet that cover the subject of handling keyboard events with SDL2. I have a few of them listed here.
https://stackoverflow.com/questions/28105533/sdl2-joystick-dont-capture-pressed-event
https://lazyfoo.net/tutorials/SDL/04_key_presses/index.php
http://www.cplusplus.com/forum/windows/182214/
http://gigi.nullneuron.net/gigilabs/handling-keyboard-and-mouse-events-in-sdl2/
The major issue I think is causing the problem is that I am also using an Xbox-style joystick at the same time. I have had no issues whatsoever with capturing joystick events. I have been doing that for a long time now. I am having issues trying to get anything with the keyboard to throw an event. I have tried if(event.type == SDL_KEYDOWN) and then checking which key it was, but that appears to return nothing. I feel like there is some macro that I need to define to allow this since I keep finding the same solutions on the internet.
I have included the entire script that I am running at the moment.
#include <boost/thread.hpp>
// Time library
#include <chrono>
// vector data structure
#include <vector>
// Thread-safe base variables
#include <atomic>
// std::cout
#include <iostream>
// Joystick library
#include <SDL2/SDL.h>
// Counters for printing
std::atomic_int printcounter{ 0 };
// This is every 3 * 1000 milliseconds
const int printer = 300;
// If an event is found, allow for printing.
std::atomic_bool eventupdate{ false };
// This function converts the raw joystick axis from the SDL library to proper double precision floating-point values.
double intToDouble(int input)
{
return (double) input / 32767.0 ;
}
// Prevent joystick values from going outside the physical limit
double clamp(double input)
{
return (input < -1.0) ? -1.0 : ( (input > 1.0) ? 1.0 : input);
}
// SDL library joystick deadband
const int JOYSTICK_DEAD_ZONE = 5000;
// These are the raw read in values from the joystick in XInput (XBox) mode.
//Normalized direction
int leftX = 0;
int leftY = 0;
int rightX = 0;
int rightY = 0;
int leftTrigger = -32768;
int rightTrigger = -32768;
// Button array
uint buttons[11] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
// Tbe pov hat is only 4 bits - 1, 2, 4, 8
int povhat = 0;
// These are the rectified joystick values
double leftstickx = 0;
double leftsticky = 0;
double rightstickx = 0;
double rightsticky = 0;
double lefttrigger = 0;
double righttrigger = 0;
// These are the rectified boolean buttons
bool leftstickbut = false;
bool rightstickbut = false;
bool xbutton = false;
bool ybutton = false;
bool abutton = false;
bool bbutton = false;
bool rightbut = false;
bool leftbut = false;
bool startbut = false;
bool backbut = false;
bool centbut = false;
// This is the boolean that controls running the robot.
std::atomic_bool quitrobot{false};
// Joystick values
static double joyvalues[6] = { 0, 0, 0, 0, 0, 0};
static bool joybuttons[11] = { false };
// Sleep function
void wait(int milliseconds)
{
boost::this_thread::sleep_for(boost::chrono::milliseconds{milliseconds});
}
// Now the main code
int main(int argc, char** argv)
{
// Now the robot goes through the looping code until a quit flag is set to true
while ( ! quitrobot)
{
// Now we look for an Xbox-style joystick
std::cout << "Looking for gamepad..." << std::endl;
while(true)
{
// Now the program waits until an Xbox-style joystick is plugged in.
// resetting SDL makes things more stable
SDL_Quit();
// restart SDL with the expectation that a jostick is required.
SDL_Init(SDL_INIT_JOYSTICK);
// SDL_HINT_GRAB_KEYBOARD
// check for a joystick
int res = SDL_NumJoysticks();
if (res > 0) { break; } // Here a joystick has been detected.
if (res < 0)
{
std::cout << "Joystick detection error: " << std::to_string(res) << std::endl;
}
// we don't want the program running super fast when detecting hardware.
wait(20);
}
// Now we check to make sure that the joystick is valid.
// Open the joystick for reading and store its handle in the joy variable
SDL_Joystick *joy = SDL_JoystickOpen(0);
if (joy == NULL) {
/* back to top of while loop */
continue;
}
// Get information about the joystick
const char *name = SDL_JoystickName(joy);
const int num_axes = SDL_JoystickNumAxes(joy);
const int num_buttons = SDL_JoystickNumButtons(joy);
const int num_hats = SDL_JoystickNumHats(joy);
printf("Now reading from joystick '%s' with:\n"
"%d axes\n"
"%d buttons\n"
"%d hats\n\n",
name,
num_axes,
num_buttons,
num_hats);
/* I'm using a logitech F350 wireless in X mode.
If num axis is 4, then gamepad is in D mode, so neutral drive and wait for X mode.
[SAFETY] This means 'D' becomes our robot-disable button.
This can be removed if that's not the goal. */
if (num_axes < 5) {
/* back to top of while loop */
continue;
}
// This is the read joystick and drive robot loop.
while(true)
{
// poll for disconnects or bad things
SDL_Event e;
if (SDL_PollEvent(&e)) {
// SDL generated quit command
if (e.type == SDL_QUIT) { break; }
// Checking for Ctrl+c on the keyboard
// SDL_Keymod modstates = SDL_GetModState();
// if (modstates & KMOD_CTRL)
// {
// One of the Ctrl keys are being held down
// std::cout << "Pressed Ctrl key." << std::endl;
// }
if(e.key.keysym.scancode == SDLK_RCTRL || e.key.keysym.scancode == SDLK_LCTRL || SDL_SCANCODE_RCTRL == e.key.keysym.scancode || e.key.keysym.scancode == SDL_SCANCODE_LCTRL)
{
std::cout << "Pressed QQQQ." << std::endl;
}
if (e.type == SDL_KEYDOWN)
{
switch(e.key.keysym.sym){
case SDLK_UP:
std::cout << "Pressed up." << std::endl;
break;
case SDLK_RCTRL:
std::cout << "Pressed up." << std::endl;
break;
case SDLK_LCTRL:
std::cout << "Pressed up." << std::endl;
break;
}
// Select surfaces based on key press
switch( e.key.keysym.sym )
{
case SDLK_UP:
std::cout << "Pressed Up." << std::endl;
break;
case SDLK_DOWN:
std::cout << "Pressed Up." << std::endl;
break;
case SDLK_LEFT:
std::cout << "Pressed Up." << std::endl;
break;
case SDLK_RIGHT:
std::cout << "Pressed Up." << std::endl;
break;
}
std::cout << "Pressed blah di blah blah please print me." << std::endl;
}
// Checking which joystick event occured
if (e.jdevice.type == SDL_JOYDEVICEREMOVED) { break; }
// Since joystick is not erroring out, we can
else if( e.type == SDL_JOYAXISMOTION )
{
//Motion on controller 0
if( e.jaxis.which == 0 )
{
// event happened
eventupdate = true;
// Left X axis
if( e.jaxis.axis == 0 )
{
// dead zone check
if( e.jaxis.value > -JOYSTICK_DEAD_ZONE && e.jaxis.value < JOYSTICK_DEAD_ZONE)
{
leftX = 0;
}
else
{
leftX = e.jaxis.value;
}
}
// Right Y axis
else if( e.jaxis.axis == 1 )
{
// dead zone check
if( e.jaxis.value > -JOYSTICK_DEAD_ZONE && e.jaxis.value < JOYSTICK_DEAD_ZONE)
{
leftY = 0;
}
else
{
leftY = e.jaxis.value;
}
}
// Left trigger
else if ( e.jaxis.axis == 2 )
{
// dead zone check
if( e.jaxis.value > -JOYSTICK_DEAD_ZONE && e.jaxis.value < JOYSTICK_DEAD_ZONE)
{
leftTrigger = 0;
}
else
{
leftTrigger = e.jaxis.value;
}
}
// Right X axis
else if( e.jaxis.axis == 3 )
{
// dead zone check
if( e.jaxis.value > -JOYSTICK_DEAD_ZONE && e.jaxis.value < JOYSTICK_DEAD_ZONE)
{
rightX = 0;
}
else
{
rightX = e.jaxis.value;
}
}
// Right Y axis
else if( e.jaxis.axis == 4 )
{
// dead zone check
if( e.jaxis.value > -JOYSTICK_DEAD_ZONE && e.jaxis.value < JOYSTICK_DEAD_ZONE)
{
rightY = 0;
}
else
{
rightY = e.jaxis.value;
}
}
// Right trigger
else if( e.jaxis.axis == 5 )
{
// dead zone check
if( e.jaxis.value > -JOYSTICK_DEAD_ZONE && e.jaxis.value < JOYSTICK_DEAD_ZONE)
{
rightTrigger = 0;
}
else
{
rightTrigger = e.jaxis.value;
}
}
}
}
else if ( e.type == SDL_JOYBUTTONUP || e.type == SDL_JOYBUTTONDOWN )
{
// now we are looking for button events.
if (e.jbutton.which == 0)
{
// event happened
eventupdate = true;
// buttons[e.jbutton.button] = e.jbutton.state;
if (e.jbutton.button == 0)
{
buttons[0] = e.jbutton.state;
}
if (e.jbutton.button == 1)
{
buttons[1] = e.jbutton.state;
}
if (e.jbutton.button == 2)
{
buttons[2] = e.jbutton.state;
}
if (e.jbutton.button == 3)
{
buttons[3] = e.jbutton.state;
}
if (e.jbutton.button == 4)
{
buttons[4] = e.jbutton.state;
}
if (e.jbutton.button == 5)
{
buttons[5] = e.jbutton.state;
}
if (e.jbutton.button == 6)
{
buttons[6] = e.jbutton.state;
}
if (e.jbutton.button == 7)
{
buttons[7] = e.jbutton.state;
}
if (e.jbutton.button == 8)
{
buttons[8] = e.jbutton.state;
}
if (e.jbutton.button == 9)
{
buttons[9] = e.jbutton.state;
}
if (e.jbutton.button == 10)
{
buttons[10] = e.jbutton.state;
}
if (e.jbutton.button == 11)
{
buttons[11] = e.jbutton.state;
}
}
}
else if ( e.type == SDL_JOYHATMOTION)
{
if (e.jhat.which == 0)
{
// event happened
eventupdate = true;
povhat = e.jhat.value;
}
}
}
// Now that we have read in the values directly from the joystick we need top convert the values properly.
leftstickx = clamp(intToDouble(leftX));
leftsticky = clamp(intToDouble(leftY));
rightstickx = clamp(intToDouble(rightX));
rightsticky = clamp(intToDouble(rightY));
lefttrigger = clamp(intToDouble(leftTrigger));
righttrigger = clamp(intToDouble(rightTrigger));
// rectify the buttons to become boolean values instead of integers.
abutton = buttons[0] > 0;
bbutton = buttons[1] > 0;
xbutton = buttons[2] > 0;
ybutton = buttons[3] > 0;
//
rightbut = buttons[4] > 0;
leftbut = buttons[5] > 0;
//
centbut = buttons[8] > 0;
startbut = buttons[7] > 0;
backbut = buttons[6] > 0;
//
leftstickbut = buttons[9] > 0;
rightstickbut = buttons[10] > 0;
// Transfer axis to the array.
joyvalues[0] = leftstickx;
joyvalues[1] = leftsticky;
joyvalues[2] = rightstickx;
joyvalues[3] = rightsticky;
joyvalues[4] = lefttrigger;
joyvalues[5] = righttrigger;
// We are using the "B" button to quit the program
if (bbutton)
{
quitrobot = true;
std::cout << "Shutting down program." << std::endl;
break;
}
if (eventupdate)
{
// This section of code is meant for running code that happens when SDL has detected an event.
// This code section can be used for something else as well.
if (e.key.keysym.sym == SDL_SCANCODE_RCTRL || e.key.keysym.sym == SDL_SCANCODE_LCTRL || e.key.keysym.sym == SDLK_LCTRL || e.key.keysym.sym == SDLK_RCTRL)
{
std::cout << "SDL Event: Ctrl pressed.\n" << std::endl;
}
// Simply print the event
eventupdate = false;
} else {}
if ( ! (printcounter = ((printcounter + 1) % printer)))
{
// const Uint8 *state = SDL_GetKeyboardState(NULL);
// if (state[SDL_SCANCODE_RETURN]) {
// printf("<RETURN> is pressed.\n");
// }
}
// Sleep the program for a short bit
wait(5);
}
// Reset SDL since the robot is no longer being actuated.
SDL_JoystickClose(joy);
// We get here only if the joystick has been disconnected.
std::cout << "Gamepad disconnected.\n" << std::endl;
}
// The program then completes.
return 0;
}
The most important part of that huge block of code is lines 129 to 179. I was doing more fooling around trying to get key capture to work but I could not get a response. Everywhere else is logic for the joystick reading (which has worked for me flawlessly). I have been referring to this link for all of the macros available to the programmer. I have not been able to capture the left control button or the right control button. I have also been trying the arrow keys for kicks as well and those are not working either. I know there are remnants of other code snippets thrown in there as I was testing. Given all of my testing, I am just not sure how to capture any keyboard keys, let alone Ctrl+c. None of my desired print statements print.
I am able to run the code on Ubuntu 1804 LTS with the stock GUI manager and window manager. I have a feeling the problem might also have something to do with the operating system not letting SDL2 capture the keyboard, but I don't know what to do to allow only the keyboard or certain keys to be consumed by SDL2.
I am trying to not use platform-specific code since I already have successfully used platform-specific signal interrupts. My goal is to simply make a certain combination of depressed keys result in a program terminating. I figured that, since SDL2 can access all keys on a keyboard, that I should be able to simply
Unless you want to read keyboard input from stdin you need to open a window and focus it to get key events in SDL. Here's an example (note the call to SDL_Init uses SDL_INIT_VIDEO and there's some code in there for rendering a background and handling resize events).
#include <iostream>
#include <SDL2/SDL.h>
int main(int argc, char** argv)
{
if (SDL_Init(SDL_INIT_VIDEO) < 0) { // also initialises the events subsystem
std::cout << "Failed to init SDL.\n";
return -1;
}
SDL_Window *window = SDL_CreateWindow(
"Window", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
680, 480, SDL_WINDOW_SHOWN | SDL_WINDOW_RESIZABLE);
if(!window) {
std::cout << "Failed to create window.\n";
return -1;
}
// Create renderer and select the color for drawing.
SDL_Renderer* renderer = SDL_CreateRenderer(window, -1, 0);
SDL_SetRenderDrawColor(renderer, 200, 200, 200, 255);
while(true)
{
// Clear the entire screen and present.
SDL_RenderClear(renderer);
SDL_RenderPresent(renderer);
SDL_Event event;
while (SDL_PollEvent(&event))
{
if (event.type == SDL_QUIT) {
SDL_Quit();
return 0;
}
if(event.type == SDL_WINDOWEVENT) {
if (event.window.event == SDL_WINDOWEVENT_SIZE_CHANGED) {
int width = event.window.data1;
int height = event.window.data2;
std::cout << "resize event: " << width << "," << height << std::endl;
}
}
if (event.type == SDL_KEYDOWN) {
int key = event.key.keysym.sym;
if (key == SDLK_ESCAPE) {
SDL_Quit();
return 0;
}
std::cout << "key event: " << key << std::endl;
}
}
}
return 0;
}
Key events are sent to the currently focused window and SDL uses the underlying OS to handle this. E.g. In Linux this means SDL calls X11 functions.
edit:
As detailed in this question it appears you can also get a snapshot of the state of the keys. In either case I think a window needs to be opened to receive events even though I've edited this multiple times to come to that conclusion (apologies if that caused any confusion). Your OS may provide functions for polling the state of the keyboard without using events or windows, such as GetAsyncKeyState in Windows.
I'm working on a program that creates a Lua 5.1 environment in an SDL window written with a mix of C and C++. I've set up an event system that queues SDL events so that Lua can pop events off the queue. One of the events is sent when a printable character is typed. When the event is detected it pushes the string into a new lua_State, queues it in an std::queue, and once it's pulled the values in the lua_State get copied into the main coroutine state, where they're then returned by coroutine.yield. But when I compare the string with a constant on the Lua side (ex: ev[2] == "q"), the comparison results in false. If I copy the value to a new string and compare that (ex: "" .. ev[2] == "q"), the comparison results in true.
I've tried using multiple ways of pushing the string (since SDL provides a UTF-8 string instead of an ASCII character), including:
lua_pushstring(L, e.text.text)
to insert the entire string
lua_pushlstring(L, e.text.text, 1)
to insert the first character
char tmp[2]; tmp[0] = e.text.text[0]; tmp[1] = 0; lua_pushstring(L, tmp)
to copy the string and insert that
but none of these fixed the issue.
Here's the basic structure in my C++ code:
const char * termGetEvent(lua_State *L) {
SDL_Event e;
if (SDL_PollEvent(&e)) {
if (e.type == SDL_QUIT) return "die";
else if (e.type == SDL_KEYDOWN && keymap.find(e.key.keysym.scancode) != keymap.end()) {
lua_pushinteger(L, keymap.at(e.key.keysym.scancode));
lua_pushboolean(L, false);
return "key";
} else if (e.type == SDL_KEYUP && keymap.find(e.key.keysym.scancode) != keymap.end()) {
lua_pushinteger(L, keymap.at(e.key.keysym.scancode));
return "key_up";
} else if (e.type == SDL_TEXTINPUT) { // this is the section producing errors
char tmp[2];
tmp[0] = e.text.text[0];
tmp[1] = 0;
lua_pushstring(L, tmp);
return "char";
} else if (e.type == SDL_MOUSEBUTTONDOWN) {
lua_pushinteger(L, buttonConvert(e.button.button));
lua_pushinteger(L, convertX(e.button.x));
lua_pushinteger(L, convertY(e.button.y));
return "mouse_click";
} else if (e.type == SDL_MOUSEBUTTONUP) {
lua_pushinteger(L, buttonConvert(e.button.button));
lua_pushinteger(L, convertX(e.button.x));
lua_pushinteger(L, convertY(e.button.y));
return "mouse_up";
} else if (e.type == SDL_MOUSEWHEEL) {
int x = 0, y = 0;
term->getMouse(&x, &y);
lua_pushinteger(L, e.button.y);
lua_pushinteger(L, convertX(x));
lua_pushinteger(L, convertY(y));
return "mouse_scroll";
} else if (e.type == SDL_MOUSEMOTION && e.motion.state) {
lua_pushinteger(L, buttonConvert2(e.motion.state));
lua_pushinteger(L, convertX(e.motion.x));
lua_pushinteger(L, convertY(e.motion.y));
return "mouse_drag";
} else if (e.type == SDL_WINDOWEVENT && e.window.event == SDL_WINDOWEVENT_RESIZED) {
term->resize();
}
}
return NULL;
}
std::queue<std::pair<const char *, lua_State*> > eventQueue;
int getNextEvent(lua_State *L, const char * filter) {
std::pair<const char *, lua_State*> ev;
do {
while (eventQueue.size() == 0) {
lua_State *param = luaL_newstate();
if (!lua_checkstack(param, 4)) printf("Could not allocate event\n");
const char * name = termGetEvent(param);
if (name != NULL) {
if (strcmp(name, "die") == 0) running = 0;
eventQueue.push(std::make_pair(name, param));
} else if (param) {
lua_pushnil(param);
lua_close(param);
param = NULL;
}
}
ev = eventQueue.front();
eventQueue.pop();
} while (strlen(filter) > 0 && strcmp(std::get<0>(ev), filter) != 0);
// Copy the next event in
lua_State *param = std::get<1>(ev);
int count = lua_gettop(param);
if (!lua_checkstack(L, count + 1)) printf("Could not allocate\n");
lua_pushstring(L, std::get<0>(ev));
lua_xmove(param, L, count);
//lua_close(param);
return count + 1;
}
lua_State *L;
int main() {
int status, result, i;
double sum;
lua_State *coro;
start:
/*
* All Lua contexts are held in this structure. We work with it almost
* all the time.
*/
L = luaL_newstate();
coro = lua_newthread(L);
luaL_openlibs(coro); /* Load Lua libraries */
termInit(); // initializes SDL
/* Load the file containing the script we are going to run */
status = luaL_loadfile(coro, bios_path);
if (status) {
/* If something went wrong, error message is at the top of */
/* the stack */
fprintf(stderr, "Couldn't load file: %s\n", lua_tostring(L, -1));
exit(1);
}
tid = createThread(&termRenderLoop); // stops when running != 1
/* Ask Lua to run our little script */
status = LUA_YIELD;
int narg = 0;
while (status == LUA_YIELD && running == 1) {
status = lua_resume(coro, narg);
if (status == LUA_YIELD) {
if (lua_isstring(coro, -1)) narg = getNextEvent(coro, lua_tostring(coro, -1));
else narg = getNextEvent(coro, "");
} else if (status != 0) {
running = 0;
joinThread(tid);
//usleep(5000000);
termClose();
printf("%s\n", lua_tostring(coro, -1));
lua_close(L);
exit(1);
}
}
joinThread(tid);
termClose();
lua_close(L); /* Cya, Lua */
if (running == 2) {
//usleep(1000000);
goto start;
}
return 0;
}
Here's the Lua script I'm using to test:
while true do
local ev = {coroutine.yield()}
print(table.unpack(ev)) -- provided by previous scripts
if ev[1] == "char" then
print("\"" .. ev[2] .. "\"") -- prints "q" if 'q' was pressed
assert(ev[2] == "q") -- false, even if 'q' was pressed
assert(string.len(ev[2]) == 1) -- true
assert(#ev[2] == 1) -- true
assert(string.len(string.sub(ev[2], 2, 2)) == 0) -- true
assert(string.sub(ev[2], 1, 1) == ev[2]) -- false
assert("" .. ev[2] == "q") -- true if 'q' was pressed
end
if ev[1] == "char" and string.sub(ev[2], 1, 1) == "q" then break end
end
I expect all of the asserts in the script to result in true (assuming 'q' was pressed), but some of them result in false. I had to adjust the statement with the break in it to use only the first character. Why is the string not being compared correctly?
EDIT: I'm not trying to compare the strings on the C++ side, but on the Lua side. I handle string comparisons properly in the C code (strcmp).
After following Egor Skriptunoff's suggestion to replace luaL_newstate with lua_newthread, as well as replacing the lua_close calls with lua_pop, I was able to fix the problem. This post on the lua-users mailing list says you can't close a new thread:
Graham Wakefield wrote:
Hi,
I'm having some hard to understand behavior; I create new threads using lua_newthread, and lua_resume them periodically from C++. However, I may wish to at some point terminate a thread before it has completed; I tried calling lua_close() on the thread's lua_State,
You can't call lua_close() on a thread; only on the main state.
which ended up causing a segmentation fault. Since I was getting excessive memory use otherwise, I ended up replacing lua_close with lua_pop because the state is pushed onto the main stack. After applying these fixes I no longer got any segfaults and the memory usage stays constant.
I'm using portaudio to play a sound. I want to be able to select the output via the UI. I managed it like that :
PaError err = Pa_Initialize();
if( err != paNoError )
return false;
qDebug() <<"Port audio succeed initialization !";
int numDevices;
numDevices = Pa_GetDeviceCount();
if( numDevices <= 0 )
{
qDebug() << "ERROR: Pa_CountDevices returned " << numDevices;
return false;
}
const PaDeviceInfo *deviceInfo;
bool isThereOutput = false;
int i = 0;
while(i < numDevices and !isThereOutput)
{
deviceInfo = Pa_GetDeviceInfo( i );
isThereOutput = (deviceInfo->maxOutputChannels > 0);
i++;
}
if(!isThereOutput)
{
qDebug() << "No output device";
return false;
}
PaError errorOpening;
if(outputDevice != "")
{
PaStreamParameters outputDeviceInfo;
int numDevices = Pa_GetDeviceCount();
const PaDeviceInfo *deviceInfo;
for(int i = 0; i<numDevices; i++ )
{
deviceInfo = Pa_GetDeviceInfo( i );
if(deviceInfo->maxOutputChannels > 0 && deviceInfo->name == outputDevice)
{
outputDeviceInfo.device = i;
outputDeviceInfo.channelCount = 1;
outputDeviceInfo.sampleFormat = paInt8;
outputDeviceInfo.suggestedLatency = deviceInfo->defaultLowOutputLatency;
}
}
if(outputDeviceInfo.channelCount > 1)
{
errorOpening = Pa_OpenStream(&stream, NULL, &outputDeviceInfo, SAMPLE_RATE, FRAME_PER_BUFFER, paNoFlag, audioCallback, this);
}
}
if(outputDevice == "" or errorOpening != paNoError)
{
if(errorOpening != paNoError)
qDebug() << "Can't open selected device ("<< outputDevice <<"), switching to the default one. Error : " << Pa_GetErrorText(errorOpening);
errorOpening = Pa_OpenDefaultStream( &stream,
0, /* no input channels */
1, /* mono output */
paInt8, /* 8 bits output */
SAMPLE_RATE,
FRAME_PER_BUFFER, /* frames per buffer, i.e. the number
of sample frames that PortAudio will
request from the callback. Many apps
may want to use
paFramesPerBufferUnspecified, which
tells PortAudio to pick the best,
possibly changing, buffer size.*/
audioCallback, /* this is your callback function */
this ); /*This is a pointer that will be passed to
your callback*/
}
if(errorOpening != paNoError)
return false;
if(Pa_StartStream( stream ) != paNoError)
return false;
And it fails :
Can't open selected device ( "Sortie intégr" ), switching to the default one. Error : Invalid error code (value greater than zero)
But I can't figure why OpenStream fails with a strange error code and Pa_OpenDefaultStream works like a charm.
So :
Why does it fails ?
Why does it throw a wrong error code ?
I assume you use C++ (though there are several curious and and or in your code.)
If your for loop didn't find any PaDeviceInfo which satisfies eviceInfo->maxOutputChannels > 0 && deviceInfo->name == outputDevice, then your outputDeviceInfo is left un-initialized. That means its channelConnect can have any values including large negative values. Then Pa_OpenStream isn't invoked and your errorOpening is also left un-initialized. I bet that's the reason of Invalid error code (value greater than zero) when you feed it into Pa_GetErrorText().
I am writing a program that uses MySQLe as embedded backend. The database library is owned by an object called "Domain". This Domain object runs within the main thread.
The program launches another thread running a XML-RPC server (boost::thread and xmlrpc_c::serverAbyss). It is linked to the Domain object.
When the XML-RPC server makes the Domain object execute an SQL query the program crashes:
Program received signal: “EXC_BAD_ACCESS”.
[Switching to process 73191]
[Switching to process 73191]
Xcode could not locate source file: regex.cpp (line: 74)
When the master thread calls Domain object's method that executes SQL queries the program still runs.
/*
* Ports listening
*
* - create a Rpc_Server object
* - create a dedicated thread
*/
Rpc_Server server(&domain, &conf_params, &router);
boost::thread server_thread(boost::bind(&Rpc_Server::run, &server)); // This thread makes the server crash
/*
* Domain routine
*
* - Check for ready jobs every minute
*/
while (1) {
v_jobs jobs = domain.get_ready_jobs(conf_params.get_param("node_name")); // This method does NOT make the server crash
sleep(60);
}
Both the Domain object's methods and the Database object's methods lock a mutex to avoid multi access.
bool Mysql::execute(const std::string* query) {
MYSQL_RES* res;
MYSQL_ROW row;
if ( query == NULL )
return false;
this->updates_mutex.lock();
std::cout << query->c_str() << std::endl;
if ( mysql_query(this->mysql, query->c_str()) != 0 ) {
std::cerr << query << std::endl << mysql_error(this->mysql);
UNLOCK_MUTEX;
return false;
}
res = mysql_store_result(this->mysql);
if (res)
while ( ( row = mysql_fetch_row(res) ) )
for ( uint i=0 ; i < mysql_num_fields(res) ; i++ )
std::cout << row[i] << std::endl;
else
if ( mysql_field_count(this->mysql) != 0 ) {
std::cerr << "Erreur : " << mysql_error(this->mysql) << std::endl;
mysql_free_result(res);
this->updates_mutex.unlock();
return false;
}
mysql_free_result(res);
this->updates_mutex.unlock();
return true;
}
bool Domain::add_node(const std::string* running_node, const std::string* n, const int* w) {
std::string query;
this->updates_mutex.lock();
query = "START TRANSACTION;";
if ( this->database.execute(&query) == false ) {
this->updates_mutex.unlock();
return false;
}
query = "REPLACE INTO node (node_name,node_weight) VALUES ('";
query += n->c_str();
query += "','";
query += boost::lexical_cast<std::string>(*w);
query += "');";
if ( this->database.execute(&query) == false ) {
query = "ROLLBACK;";
this->database.execute(&query);
this->updates_mutex.unlock();
return false;
}
query = "COMMIT;"
if ( this->database.execute(&query) == false ) {
this->updates_mutex.unlock();
return false;
} else
this->updates_mutex.unlock();
return true;
}
The MySQLe is created there:
bool Mysql::prepare(const std::string* node_name, const std::string* db_skeleton) {
static char* server_args[] = {"this_program","--datadir=."};
static char* server_groups[] = {"embedded","server","this_program_SERVER",(char *)NULL};
std::string query("CREATE DATABASE IF NOT EXISTS ");
// DB init
if ( mysql_library_init(sizeof(server_args) / sizeof(char *), server_args, server_groups) )
std::cerr << "could not initialize MySQL library" << std::endl;
std::cout << "mysql init..." << std::endl;
if ( (this->mysql = mysql_init(NULL)) == NULL )
std::cerr << mysql_error(this->mysql) << std::endl;
if ( ! mysql_thread_safe() ) {
std::cerr << "MySQL is NOT theadsafe !" << std::endl;
return false;
}
mysql_options(this->mysql, MYSQL_READ_DEFAULT_GROUP, "embedded");
mysql_options(this->mysql, MYSQL_OPT_USE_EMBEDDED_CONNECTION, NULL);
mysql_real_connect(this->mysql, NULL, NULL, NULL, NULL, 0, NULL, 0);
// Creates the schema
query += this->translate_into_db(node_name);
query += ";";
if ( this->execute(&query) == false )
return false;
// Creates the schema
query = "CREATE SCHEMA IF NOT EXISTS ";
query += this->translate_into_db(node_name);
query += " DEFAULT CHARACTER SET latin1;";
this->execute(&query);
// Uses it
query = "USE " + this->translate_into_db(node_name) + ";";
this->execute(&query);
// Loads the skeleton from file
return this->load_file(db_skeleton->c_str());
}
Am I wrong somewhere?
Do you have an example to show me?
I found the solution to my problem. Each thread needs to initialize the MySQL environment. That is to say execute some mysql_* functions.
Here are the modified / new methods :
bool Mysql::atomic_execute(const std::string* query) {
MYSQL_RES* res;
MYSQL_ROW row;
boost::regex empty_string("^\\s+$", boost::regex::perl);
if ( query == NULL )
return false;
if ( query->empty() == true or boost::regex_match(*query, empty_string) == true ) {
std::cerr << "Error : query is empty !" << std::endl;
return false;
}
this->updates_mutex.lock();
if ( mysql_query(this->mysql, query->c_str()) != 0 ) {
std::cerr << query << std::endl << mysql_error(this->mysql);
this->updates_mutex.unlock();;
return false;
}
res = mysql_store_result(this->mysql);
if (res)
while ( ( row = mysql_fetch_row(res) ) )
for ( uint i=0 ; i < mysql_num_fields(res) ; i++ )
std::cout << row[i] << std::endl;
else
if ( mysql_field_count(this->mysql) != 0 ) {
std::cerr << "Erreur : " << mysql_error(this->mysql) << std::endl;
mysql_free_result(res);
this->updates_mutex.unlock();
return false;
}
mysql_free_result(res);
this->updates_mutex.unlock();
return true;
}
bool Mysql::standalone_execute(const v_queries* queries) {
MYSQL* local_mysql = this->init();
std::string query = "START TRANSACTION;";
if ( this->atomic_execute(&query) == false ) {
mysql_close(local_mysql);
return false;
}
BOOST_FOREACH(std::string q, *queries) {
std::cout << q.c_str() << std::endl;
if ( this->atomic_execute(&q) == false ) {
query = "ROLLBACK";
this->atomic_execute(&query);
mysql_close(local_mysql);
return false;
}
}
query = "COMMIT";
if ( this->atomic_execute(&query) == false ) {
mysql_close(local_mysql);
return false;
}
mysql_close(local_mysql);
return true;
}
MYSQL* Mysql::init() {
MYSQL* local_mysql;
local_mysql = mysql_init(this->mysql);
mysql_options(this->mysql, MYSQL_READ_DEFAULT_GROUP, "embedded");
mysql_options(this->mysql, MYSQL_OPT_USE_EMBEDDED_CONNECTION, NULL);
mysql_real_connect(local_mysql, NULL, NULL, NULL, NULL, 0, NULL, 0);
return local_mysql;
}
The atomic_execute method is used to send single queries to the server.
The standalone_execute method initializes a connection and a transaction, then it sends the whole queries to the server using atomic_execute.
I do not know if a ROLLBACK is useful in case of COMMIT's failure...
The code might need some improvements but it works.