Code won't advance past wait function for conditional variable - c++

Question

So, I've been trying to get a better understand of how condition variables work and I've written the following code that tries to implement reading and writing from the same text file:
#include <iostream>
#include <fstream>
#include <cstdlib>
#include <condition_variable>
#include <mutex>
#include <thread>
using namespace std;
mutex mtx;
condition_variable conditionVariable;
ifstream readFile;
ofstream writeFile;
bool doneReading=false;
bool doneWriting=false;
void readFromFile()
{
string line;
readFile.open("./testFile.txt");
if(readFile.is_open())
{
cout << "Successfully opened file!" << "\n";
}
else
{
cout << "Failed to open file..." << "\n";
}
cout << "The file contents are:" << "\n";
while(getline(readFile,line))
{
unique_lock<mutex> lock(mtx);
conditionVariable.wait(lock, [] () {return doneWriting;});
cout << line << "\n";
doneReading=true;
lock.unlock();
conditionVariable.notify_one();
}
readFile.close();
}
void writeToFile()
{
string input;
writeFile.open("./testFile.txt");
cout << "Enter something you want to write to the text file:" << "\n";
cin >> input;
cout << "Going to write " << input << " to the file" << "\n";
if(writeFile.is_open())
{
cout << "Successfully opened file!" << "\n";
unique_lock<mutex> lock2(mtx);
/////////PROGRAM WON'T ADVANCE PAST THIS LINE/////////////
conditionVariable.wait(lock2, [] () {return doneReading;});
cout << "After calling the wait function for the condition variable" << "\n";
writeFile << input;
doneWriting=true;
lock2.unlock();
conditionVariable.notify_one();
writeFile.close();
}
else
{
cout << "Failed to open file..." << "\n";
}
}
int main()
{
int i;
for(i=0;i<10;i++)
{
thread t1(readFromFile);
thread t2(writeToFile);
t1.join();
t2.join();
}
}
And, I modeled my use of boolean variables after the following example from
cppreference.com (scroll down to the bottom to see the example code). However, it has something do the predicate I am passing to the wait function, and I'm not quite sure what is wrong with it. If someone could give some insight, that would be brilliant. Thanks!

Answer 1

Initial state is:
bool doneReading=false;
bool doneWriting=false;
The first thing readFromFile does to these variables is sit and wait for doneWriting to become true
conditionVariable.wait(lock, [] () {return doneWriting;});
The first thing writeFromFile does to these variables is sit and wait for doneReading to become true
conditionVariable.wait(lock2, [] () {return doneReading;});
Neither condition will become true.
Note that the cppreference example does something very different: one thread begins by executing cv.wait(lk, []{return ready;}); while the other begins by executing ready=true;