着名的过山车问题。假设有n名乘客和 一辆过山车。乘客反复等待乘车 在车上。该车具有C座的容量，C <100。 ñ，但是 cheapskate车主不会让汽车离开车站直到它 充分。编写程序来模拟此问题的解决方案。每 乘客必须是一个等待乘坐的线程，等待直到 骑行完成，从骑行出发并离开。
汽车应该是等待C乘客进入汽车的线程 骑车，然后绕轨道走一段固定的时间 （一些固定的睡眠时间），然后让乘客下船。确实如此 直到没有更多的乘客想要乘坐。
你的main（）线程将在汽车线程上执行pthread_join（）。 当没有更多等待的乘客线程时，汽车线程退出 因此main（）线程将打印信息并退出。
因此，假设汽车和每位乘客都是分开的 线程。你会如何编写一个可以模拟这个系统的程序 并满足以下要求：
汽车总是乘坐C乘客;
汽车行驶时，没有乘客会从车上跳下来;
汽车行驶时，没有乘客会跳上车;
线程将通过“监视器”进行同步（记住，它 使用互斥锁和条件变量来保证互斥 它有三个操作：takeRide，loadCustomers和 unloadCustomers。第一次行动由乘客召集;一个电话 在乘客乘坐并准备好之前不会返回 离开。最后两个操作由汽车线程调用。你可以 添加任何其他内容以帮助您的设计工作。
我的问题：这些是要传递给线程的函数。 takeRide传递给乘客线程，加载和卸载传递到汽车线程。首先，乘客和汽车容量的组合是行不通的。例如，汽车和7名乘客的容量为2。这将被困在最后一位乘客身上。其次，unboarding不能正常工作。我没有看到“乘客x左车”。我如何解决这个问题并不适用于每个乘客/容量组合？我需要另一个mutex吗？另外，为什么它会像下面的示例输出一样随机停止运行？为什么carUnload无法正常工作？
示例死锁输出：容量= 2，乘客= 6
Passenger 5 is waiting for car.
Passenger 4 is waiting for car.
Passenger 3 is waiting for car.
Passenger 2 is waiting for car.
Passenger 1 is waiting for car.
Passenger 0 is waiting for car.
Car is waiting for passengers.
Passenger 4 will take ride in the car
Passenger 3 will take ride in the car
Passenger 2 is waiting for car.
Passenger 1 is waiting for car.
Passenger 5 is waiting for car.
Passenger 0 is waiting for car.
·H
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <stdbool.h>
int cap, numPass;
int passengersInCar;
bool carIsWaiting; //true if car is waiting for passengers
pthread_mutex_t rollerCoasterLock;
pthread_cond_t carLoad;
pthread_cond_t carUnload;
pthread_cond_t carFull;
.C
void takeRide(const int passenger_id);
void load();
void unload();
void takeRide(const int passenger_id){
pthread_mutex_lock(&rollerCoasterLock);
while(!carIsWaiting || passengersInCar==cap){
printf("Passenger %d is waiting for car.\n", passenger_id);
pthread_cond_wait(&carLoad, &rollerCoasterLock);
}
// numPass--;
passengersInCar++;
printf("Passenger %d will take ride in the car\n", passenger_id);
if (passengersInCar == cap){
pthread_cond_broadcast(&carFull);
// passengersInCar=0;
}
pthread_cond_wait(&carFull, &rollerCoasterLock);
pthread_cond_wait(&carUnload, &rollerCoasterLock);
printf("Passenger %d left car.\n", passenger_id);
pthread_mutex_unlock(&rollerCoasterLock);
pthread_exit(0);
}
void load(){
pthread_mutex_lock(&rollerCoasterLock);
// if(numPass==0)
// pthread_exit(NULL);
while(passengersInCar>0){
pthread_cond_wait(&carUnload, &rollerCoasterLock);
}
carIsWaiting = true;
pthread_cond_broadcast(&carLoad);
printf("Car is waiting for passengers.\n");
pthread_cond_wait(&carFull, &rollerCoasterLock);
carIsWaiting = false;
pthread_cond_broadcast(&carFull);
printf("Car is full. Going around...\n" );
pthread_mutex_unlock(&rollerCoasterLock);
}
void unload(){
pthread_mutex_lock(&rollerCoasterLock);
pthread_cond_broadcast(&carUnload);
puts("unloading...");
passengersInCar=0;
pthread_mutex_unlock(&rollerCoasterLock);
// pthread_exit(0);
}
主要
#include <pthread.h>
#include <unistd.h>
#include "rollerCoaster.h"
void* carThreadFunction();
void* passengerThreadFunction(int passenger_id);
void testRollerCoasterOneCar(int carCapacity, int numPassengers);
int cap, numPass;
pthread_attr_t threadAttributes;
int main(int argc, char *argv[]) {
passengersInCar = 0;
carIsWaiting = false;
pthread_mutex_init(&rollerCoasterLock, NULL);
pthread_cond_init(&carLoad, NULL);
pthread_cond_init(&carUnload, NULL);
pthread_cond_init(&carFull, NULL);
//check command line args
if (argc != 3){
puts("Please enter (car-capacity-num) and (num-of-passengers).\n");
exit(0);
} else {
cap = atoi(argv[1]);
numPass = atoi(argv[2]);
}
pthread_attr_init(&threadAttributes);
pthread_attr_setscope(&threadAttributes, PTHREAD_SCOPE_SYSTEM);
testRollerCoasterOneCar(cap, numPass);
pthread_join(carThread, NULL);
puts("done");
return 0;
}
void testRollerCoasterOneCar(int carCapacity, int numPassengers) {
// rollerCoasterOneCar = new RollerCoasterOneCar(carCapacity);
pthread_t carThread;
pthread_create(&carThread, &threadAttributes, (void*) carThreadFunction, (void*) NULL);
pthread_t passengersThreads[numPassengers];
for (int i = 0; i < numPassengers; i++) {
pthread_create(&passengersThreads[i], &threadAttributes, (void*) passengerThreadFunction, (void*)i);
}
}
void* carThreadFunction(){
while(true){
load();
usleep(100000);
unload();
}
return NULL;
}
void* passengerThreadFunction(int passenger_id){
while(true){
takeRide(passenger_id);
}
return NULL;
}