命名線程，使用typedef /結構

Question

我正在創建一個程序來練習使用線程。我試圖給他們起個名字，這樣當程序運行時，您可以清楚地看到「航班1正在起飛......」或「航班6正在着陸......」等等。我希望每個線程都有一個flyTime（所以我知道他們將使用跑道的順序），這將隨機生成。我嘗試過，並且使用struct/typedef給每個pthread賦予這些特性有困難，所以我可以說例如flight.flyTime並在整個程序中使用它。這裏是我的代碼的相關部分沒有我的起飛/降落功能：

#include <pthread.h> 
#include <stdio.h> 
#include <cstdlib> 
#include <iostream> 
#include <queue> 

#define NUM_THREADS  8    //8 flights 

pthread_mutex_t runway1lock; 

void *FlightID(void *flightid){ 
    long fid; 
    fid = (long)flightid; 
    pthread_exit(NULL); 
} 

typedef struct{     //each plane has these characteristics 
    long fid; 
    int StartState;  // if start=1 ==> taking off:::if start=2 ==> landing 
    int flyTime;   //fly == randomly generated time (order) 
}FLIGHTS; 

FLIGHTS flights[NUM_THREADS]; 

int StartState(flights[NUM_THREADS]){ 
    int startState; 
    for (int i=0; i<=NUM_THREADS; i++){ 
      startState = rand() % 1+2; 
    } 
    std::string start; 
    if(startState == 1){ 
      start = "Taking off"; 
    } 
    if(startState == 2){ 
      start = "Landing"; 
    } 
    for (int t=0; t<NUM_THREADS; t++){ 
      std::cout << "Start State for Flight# " << FlightID << " is " << start << std::endl; 
    } 
    return startState; 
} 

int main(int argc, char *argv[]){ 
// pthread_t flights[NUM_THREADS]; //pthread_t keeps a thread ID after the thread is created with pthread_create() 
            //it's like an index on a vector of threads 
    int rc; 
    long t; 
    for (t=1; t<=NUM_THREADS; t++){   //loop creates threads(flights) 
      printf("In main: Creating flight %1d\n", t); 
      rc = pthread_create(&flights[t], NULL, FlightID, (void *)t); 
      if (rc){ 
        printf("ERROR: return code from pthread_create() is %d\n", rc); 
        return (-1); 
      } 
      printf("Created flight %1d\n", t); 
      StartState(flights[t]);   //gives every flight a start state 
      if(StartState(flights[t])==1){ 
        std::cout << "Flight # " << &flights[t] << " is listed as waiting at the gate." << std::endl; 
        //go to takeoff function and go through switch case  
      } 
      if(StartState(flights[t])==2){`enter code here` 
        std::cout << "Flight # " << &flights[t] << " is listed as waiting to land." << std::endl; 
        //go to landing function and go through switch case  
      } 
    } 
    pthread_exit(NULL); 
} 

Answer 1

下面有一個代碼片段代表了我將如何實現它。

你也應該看看pthread_key_create，pthread_getspecific和pthread_setspecific。這是一組函數，它們允許您將特定於每個線程的數據存儲在線程的內存上下文中。稍後，它可能會在您的代碼中派上用場。

typedef struct{ 
    long fid; 
    int StartState; 
    int flyTime; 
} FLIGHTS; 

FLIGHTS** flights = new FLIGHTS*[NUM_THREADS]; 
pthread_key_t pkey: 

void *FlightID(void *flightid){ 
    long fid; 
    fid = (long)flightid; 
    FLIGHTS* flight = new FLIGHTS(); 
    flight->fid = fid; 
    flights[fid] = flight; 
    pthread_setspecific(pkey, flight); 

    int startState; 
    for (int i=0; i<=NUM_THREADS; i++){ 
      startState = rand() % 1+2; 
    } 
    std::string start; 
    if(startState == 1){ 
      start = "Taking off"; 
    } 
    if(startState == 2){ 
      start = "Landing"; 
    } 
    for (int t=0; t<NUM_THREADS; t++){ 
      std::cout << "Start State for Flight# " << fid << " is " << start << std::endl; 
    } 

    flight->StartState = startState; 
} 

int main(int argc, char* argv[]) { 
    pthread_key_create(&pkey, NULL); 
    for (t=1; t<=NUM_THREADS; t++){ 
     rc = pthread_create(&flights[t], NULL, FlightID, (void *)t); 
     if (rc){ 
      printf("ERROR: return code from pthread_create() is %d\n", rc); 
      return (-1); 
     } 
     printf("Created flight %1d\n", t); 
    } 
} 

另外，我不知道如果我理解正確的代碼，或者如果你只是有一些關於它的編碼錯誤，所以我離開你的一些問題或意見，可能是錯誤/缺陷：

1）您在開始回調函數調用了pthread_exit：

void *FlightID(void *flightid){ 
    long fid; 
    fid = (long)flightid; 
    pthread_exit(NULL); 
} 

2）你傳遞給< <操作的函數沒有返回值：

std::cout << "Start State for Flight# " << FlightID << " is " << start << std::endl; 

3）爲了得到返回值，你需要調用同一個函數3次。應該不是int state = StartState（flights [i]）然後測試狀態變量值？ StartState（flights [t]）; //給每一個航班開始狀態

if(StartState(flights[t])==1){ 
      std::cout << "Flight # " << &flights[t] << " is listed as waiting at the gate." << std::endl; 
      //go to takeoff function and go through switch case  
    } 
    if(StartState(flights[t])==2){`enter code here` 
      std::cout << "Flight # " << &flights[t] << " is listed as waiting to land." << std::endl; 
      //go to landing function and go through switch case  
    } 

4）你不能這樣定義一個函數：

int StartState(flights[NUM_THREADS]){