本文是哲学家就餐问题在 linux 上的程序实现，与windows 平台的实现类似，

程序上稍有不同。

本文是哲学家就餐问题在 linux 上的程序实现，与windows 平台的实现类似，

程序上稍有不同。

PhilosopherDining.cpp

#include

#include

#include

#include

#include

#include "RasUtil.h"

using namespace std;

const unsigned int PHILOSOPHER_NUM=5;

const char THINKING=1;

const char HUNGRY=2;

const char DINING=3;

// each fork has a semaphore

sem_t semph[PHILOSOPHER_NUM];

// Mutex for printing

pthread_mutex_t mutex;

void* philosopherProc(void* param);

int main(int argc, char* argv[])

{

int i;

srand(getpid());

pthread_t philosopherThread[PHILOSOPHER_NUM];

int phId[PHILOSOPHER_NUM];

pthread_mutex_init(&mutex, NULL);

for (i=0; i

{

phId[i] = i;

sem_init(&semph[i], 0, 1);

pthread_create(&philosopherThread[i], NULL, philosopherProc, (void*)(&phId[i]));

usleep(50);

}

sleep(3);

return 0;

}

void* philosopherProc(void* param)

{

int myid;

char idStr[128];

char stateStr[128];

char mystate;

int ret;

unsigned int leftFork;

unsigned int rightFork;

myid = *((int*)(param));

RasUtil::intToStr(myid, idStr);

cout << "philosopher " << myid << " begin......" << endl;

//usleep(10);

// initial state is THINKING

mystate = THINKING;

leftFork = (myid) % PHILOSOPHER_NUM;

rightFork = (myid + 1) % PHILOSOPHER_NUM;

while (true)

{

switch(mystate)

{

case THINKING:

// changing my state

mystate = HUNGRY;

strcpy(stateStr, "HUNGRY");

break;

case HUNGRY:

strcpy(stateStr, "HUNGRY");

// first test the left fork ...

ret = sem_trywait(&semph[leftFork]);

if (ret == 0)

{

// left fork is ok, take it up !

// then test the right fork ...

ret = sem_trywait(&semph[rightFork]);

if (ret == 0)

{

// right fork is also ok !

// changing my state

mystate = DINING;

strcpy(stateStr, "DINING");

}

else

{

// right fork is being used by others, so I must put down

// the left fork.

sem_post(&semph[leftFork]);

}

}

break;

case DINING:

// put down both the left and right fork

sem_post(&semph[leftFork]);

sem_post(&semph[rightFork]);

// changing my state

mystate = THINKING;

strcpy(stateStr, "THINKING");

break;

}

// print my state

pthread_mutex_lock(&mutex);

cout << "philosopher " << myid << " is : " << stateStr << endl;

pthread_mutex_unlock(&mutex);

// sleep a random time : between 1 - 5 s

int sleepTime;

sleepTime = 1 + (int)(5.0*rand()/(RAND_MAX+1.0));

usleep(sleepTime*10);

}

}

RasUtil.h : 完成整数转换为字符串

#ifndef _RasUtil_h_

#define _RasUtil_h_

class RasUtil

{

public:

static inline void intToStr(int i, char* str);

};

inline void RasUtil::intToStr(int i, char* str)

{

int dec;

int sign;

char* p;

p = ecvt(i, 10, &dec, &sign);

strcpy(str, p);

str[dec] = 0;

}

#endif