89 lines
3.2 KiB
C++
89 lines
3.2 KiB
C++
|
// fig18_02.cpp
|
||
|
|
// Setting up the concurrencpp::runtime and scheduling tasks with it.
|
||
|
|
#include <chrono>
|
||
|
|
#include <concurrencpp/concurrencpp.h>
|
||
|
|
#include <fmt/format.h>
|
||
|
|
#include <iostream>
|
||
|
|
#include <random>
|
||
|
|
#include <sstream>
|
||
|
|
#include <thread>
|
||
|
|
#include <vector>
|
||
|
|
|
||
|
|
// get current thread's ID as a string
|
||
|
|
std::string id() {
|
||
|
|
std::ostringstream out;
|
||
|
|
out << std::this_thread::get_id();
|
||
|
|
return out.str();
|
||
|
|
}
|
||
|
|
|
||
|
|
// Function printTask sleeps for a specified period in milliseconds.
|
||
|
|
// When it continues executing, it prints its name and completes.
|
||
|
|
void printTask(std::string name, std::chrono::milliseconds sleep) {
|
||
|
|
std::cout << fmt::format(
|
||
|
|
"{} (thread ID: {}) going to sleep for {} ms\n",
|
||
|
|
name, id(), sleep.count());
|
||
|
|
|
||
|
|
// put the calling thread to sleep for sleep milliseconds
|
||
|
|
std::this_thread::sleep_for(sleep);
|
||
|
|
|
||
|
|
std::cout << fmt::format("{} (thread ID: {}) done sleeping\n",
|
||
|
|
name, id());
|
||
|
|
}
|
||
|
|
|
||
|
|
int main() {
|
||
|
|
// set up the concurrencpp runtime for scheduling tasks to execute
|
||
|
|
concurrencpp::runtime runtime;
|
||
|
|
|
||
|
|
std::cout << fmt::format("main's thread ID: {}\n\n", id());
|
||
|
|
|
||
|
|
// set up random number generation for random sleep times
|
||
|
|
std::random_device rd;
|
||
|
|
std::default_random_engine engine{rd()};
|
||
|
|
std::uniform_int_distribution ints{0, 5000};
|
||
|
|
|
||
|
|
// stores the tasks so we can wait for them to complete later;
|
||
|
|
// concurrencpp::result<void> indicates that each task returns void
|
||
|
|
std::vector<concurrencpp::result<void>> results;
|
||
|
|
|
||
|
|
std::cout << "STARTING THREE CONCURRENCPP TASKS\n";
|
||
|
|
|
||
|
|
// schedule three tasks
|
||
|
|
for (int i{1}; i < 4; ++i) {
|
||
|
|
std::chrono::milliseconds sleepTime{ints(engine)};
|
||
|
|
std::string name{fmt::format("Task {}", i)};
|
||
|
|
|
||
|
|
// use a concurrencpp thread_pool_executor to schedule a call
|
||
|
|
// to printTask with name and sleepTime as its arguments
|
||
|
|
results.push_back(runtime.thread_pool_executor()->submit(
|
||
|
|
printTask, name, sleepTime));
|
||
|
|
}
|
||
|
|
|
||
|
|
std::cout << "\nALL TASKS STARTED\n";
|
||
|
|
std::cout << "\nWAITING FOR TASKS TO COMPLETE\n";
|
||
|
|
|
||
|
|
// wait for each task to complete
|
||
|
|
for (auto& result : results) {
|
||
|
|
result.get(); // wait for each task to return its result
|
||
|
|
}
|
||
|
|
|
||
|
|
std::cout << fmt::format("main's thread ID: {}\nMAIN ENDS\n", id());
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
/**************************************************************************
|
||
|
|
* (C) Copyright 1992-2021 by Deitel & Associates, Inc. and *
|
||
|
|
* Pearson Education, Inc. All Rights Reserved. *
|
||
|
|
* *
|
||
|
|
* DISCLAIMER: The authors and publisher of this book have used their *
|
||
|
|
* best efforts in preparing the book. These efforts include the *
|
||
|
|
* development, research, and testing of the theories and programs *
|
||
|
|
* to determine their effectiveness. The authors and publisher make *
|
||
|
|
* no warranty of any kind, expressed or implied, with regard to these *
|
||
|
|
* programs or to the documentation contained in these books. The authors *
|
||
|
|
* and publisher shall not be liable in any event for incidental or *
|
||
|
|
* consequential damages in connection with, or arising out of, the *
|
||
|
|
* furnishing, performance, or use of these programs. *
|
||
|
|
**************************************************************************/
|