在哪里放置pthread Mutex和con var，以确保激活所有功能

i具有以下程序，该程序应采用"订单"并同步处理它们。我认为其中大多数都起作用，但是关键区域4直到下订单后才能获得静音。将cond_vars放置在哪里，以便区域4在仍在产生订单时获得锁？

#include <pthread.h>
#include <iostream>
#include <unistd.h>
#include <cstdlib>
using namespace std;
#define MAX 10
#define N 4
// Data structure to represent a simplified Order 
// that has an order number and an item number.
struct Order
{
  int order_num;
  int item_num; 
};
Order new_orders [N];       // array of elements of type Order to be used as 
a shared buffer
int num_new_orders = 0;     // count of number of new (i.e., unprocessed)   
orders
int order_num = 0;          // global variable used to generate unique order  
numbers

pthread_mutex_t data_mutex = PTHREAD_MUTEX_INITIALIZER;
pthread_mutex_t console_mutex = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t spaceAvailabe = PTHREAD_COND_INITIALIZER;
pthread_cond_t newOrder = PTHREAD_COND_INITIALIZER;
pthread_cond_t consoleVar = PTHREAD_COND_INITIALIZER;
void* takeOrders(void* arg)
{
  int item;
  int index = 0;
  for(int i = 0; i < MAX; ++i) {
    // Beginning of critical region 1
    pthread_mutex_lock(&console_mutex);
    // Get user input
    cout << "Enter a menu item number between 1 and 50: ";
    cin >> item;
    // Print new order's details
    cout << "Got new order! Order number is " << order_num <<
                " and item number: " << item << std::endl;

    // End of critical region 1
    pthread_mutex_unlock(&console_mutex);
    // Beginning of critical region 2
    pthread_mutex_lock(&data_mutex);
    // Put new order into new orders buffer and update number of new orders
    while(num_new_orders>=MAX){
        pthread_cond_wait(&spaceAvailabe, &console_mutex);
    }
    new_orders[index].order_num = order_num;
    new_orders[index++].item_num = item;
    ++num_new_orders;
    pthread_cond_signal(&newOrder);
    // End of critical region 2
     pthread_mutex_unlock(&data_mutex);
    // Update order number so that next order gets a different number
    ++order_num;

    // If the end of the new orders buffer is reached, wrap back around
    if(index == N)
        index = 0;
}
pthread_exit(NULL);
}
void* processOrders(void* arg)
{
  int item;
  int index = 0;
  int o_num;
for(int i = 0; i < MAX; ++i) {
    // Beginning of critical region 3
    pthread_mutex_lock(&data_mutex);
    // Retrieve new order details from buffer and update number of new orders
   while(num_new_orders==0)
    {
        pthread_cond_wait(&newOrder, &data_mutex);  
    }
    o_num = new_orders[index].order_num;
    item = new_orders[index++].item_num;
    --num_new_orders;
    pthread_cond_signal(&spaceAvailabe);

    // End of critical region 3
    pthread_mutex_unlock(&data_mutex);
    // Beginning of critical region 4
    pthread_mutex_lock(&console_mutex);
     // Print retrieved order's details
    cout << "Processing order number " << o_num << " with item number: " << 
item << std::endl;
    // End of critical region 4
    pthread_mutex_unlock(&console_mutex);
    // Suspend self for 1 second
    sleep(1);
    // If the end of the new orders buffer is reached, wrap back around
    if(index == N)
        index = 0;
  }
  pthread_exit(NULL);
}
int main()
{
  // Create threads to take and process orders
  pthread_t id1, id2;
  pthread_create(&id1, NULL, processOrders, NULL);
  pthread_create(&id2, NULL, takeOrders, NULL);
  pthread_join(id1, NULL);
  pthread_join(id2, NULL);
  // Print goodbye message
  cout << "Phew! Done with orders for today!" << endl;
  pthread_exit(NULL);
}