由std::unique_ptr.release(）引起的间歇性SIGSEGV

我在用C++编写的一个游戏中遇到了一个问题，在这个游戏中，我偶尔会出现一个segfault。以下是我的代码摘录，这是演示该问题所需的最低限度。

它是用以下命令行编译的：

g++ -g3 -std=c++17 -Wall -Wextra -Wpedantic -Weffc++ -o ex ex.cc -lncurses -ltinfo

在Windows11上使用g++10.3.0的WSL下的Ubuntu 20.04上。(您还需要ncurses库(

#include <chrono>
#include <memory>
#include <csignal>
#include <cstdlib>
#include <map>
#include <ncurses.h>
struct Command;
class View {
public:
explicit View();
~View();
void drawStats(int);
Command* handleEvents();
private:
std::map<int, std::unique_ptr<Command>>  keymap_;
};
class Game {
public:
Game();
void delta(const int);
static void end(int);
void render(View&);
void run(View&);
void update();
private:
int delta_;
std::unique_ptr<Command> nextCommand_;
};
struct Command {
virtual ~Command() {}
virtual void execute(Game&)=0;
};
struct MoveCommand : public Command {
explicit MoveCommand(int);
void execute(Game&) override;
private:
int delta_;
};
View::View() : keymap_{
} {
keymap_['['] = std::make_unique<MoveCommand>(-1);;
keymap_[' '] = std::make_unique<MoveCommand>(0);
keymap_[']'] = std::make_unique<MoveCommand>(1);
initscr();
cbreak();
noecho();
nonl();
nodelay(stdscr, TRUE);
intrflush(stdscr, FALSE);
keypad(stdscr, TRUE);
scrollok(stdscr, TRUE);
curs_set(0);
clear();
}
View::~View() {
curs_set(1);
endwin();
}
void View::drawStats(int delta) {
mvprintw(0, 0, "          ");;
mvprintw(0, 0, "Delta = %d", delta);
}
Command* View::handleEvents() {
int c;
if ((c = getch()) != ERR) {
auto command = keymap_.find(c);
if (command != keymap_.end()) {
return command->second.get();
}
}
return nullptr;
}
constexpr static double TICK = 72000000;
volatile bool endflag = false;
Game::Game() : delta_{0}, nextCommand_{} {
struct sigaction act;
act.sa_handler = Game::end;
sigemptyset (&act.sa_mask);
act.sa_flags = 0;
sigaction(SIGHUP, &act, NULL);
sigaction(SIGINT, &act, NULL);
sigaction(SIGTERM, &act, NULL);
}
void Game::delta(const int delta) {
delta_ = delta;
}
void Game::end(int sig) {
switch (sig) {
case SIGINT:
case SIGTERM:
endflag = true;
break;
case SIGHUP:
exit(EXIT_FAILURE);
break;
default:
break;
}
}
void Game::render(View& view) {
view.drawStats(delta_);
}
void Game::run(View& view) {
std::chrono::steady_clock clock;
auto previous = clock.now();
double lag = 0.0;
while (!endflag) {
auto current = clock.now();
auto elapsed = current - previous;
previous = current;
lag += elapsed.count();
auto command = view.handleEvents();
if (command) {
nextCommand_.reset(command);
}
while (lag >= TICK) {
lag -= TICK;
update();
}
render(view);
}
}
void Game::update() {
if (nextCommand_) {
nextCommand_->execute(*this);
nextCommand_.release();
}
}
MoveCommand::MoveCommand(int delta) : delta_{delta} {
}
void MoveCommand::execute(Game& game) {
game.delta(delta_);
}
int main() {
Game game;
View view;
game.run(view);
return EXIT_SUCCESS;
}

运行此程序时，请随机按键([、]和SPACE(。这可能需要一两分钟的时间，但最终你会得到一个segfault。当我运行这个程序在gdb下，我得到以下segfault之后：

Program received signal SIGSEGV, Segmentation fault.

0x0000000000000000 in ?? ()
(gdb) where
#0  0x0000000000000000 in ?? ()
#1  0x0000555555556ae0 in Game::update (this=0x7fffffffd170) at ex.cc:149
#2  0x0000555555556a65 in Game::run (this=0x7fffffffd170, view=...)
at ex.cc:140
#3  0x0000555555556ba1 in main () at ex.cc:165

149行为nextCommand_.release();。我认为正在发生的是当CCD_ 6中的CCD_。所以行if(nextCommand_)成功，但当我们到达nextCommand_->execute(*this);时，它已经不见了，所以在空指针上调用execute()会导致segfault。是这样吗？如果是这样，我应该怎么做才能使执行命令并释放它的操作成为原子操作？如果没有，问题出在哪里？