This Future implementation is modeled after std::future with additional features, including:
SchedInterface through template parameters, enabling usage in coroutine environments such as bthread. A practical example of combining this with bthread can be found in example/use-with-bthread.on_finish/then functionalities to enable asynchronous chaining of tasks.#include <babylon/future.h>
using ::babylon::Future;
using ::babylon::Promise;
{
Promise<int> promise;
auto future = promise.get_future();
::std::thread thread([&]() {
// Perform some asynchronous operations
...
// Set the final value
promise.set_value(10086);
});
future.get(); // Waits for set_value, result == 10086
}
{
// Example using an XSchedInterface coroutine mechanism for synchronization
Promise<int, XSchedInterface> promise;
auto future = promise.get_future();
XThread thread([&]() {
// Perform some asynchronous operations
...
// Set the final value
promise.set_value(10086);
});
future.get(); // Waits for set_value (using XSchedInterface for coroutine
// synchronization without occupying pthread workers), result
// == 10086
}
{
Promise<int> promise;
auto future = promise.get_future();
// Move-capture promise to avoid destruction out of scope
::std::thread thread([promise = ::std::move(promise)]() mutable {
// Perform some asynchronous operations
...
// Set the final value
promise.set_value(10086);
});
Promise<int> promise2;
auto future2 = promise2.get_future();
future.on_finish([promise2 = ::std::move(promise2)](int&& value) {
// Called by set_value, with value == 10086
promise2.set_value(value + 10010);
});
// After on_finish, future is no longer available, cannot be ready or get
future2.get(); // Waits for set_value, result == 20096
}
// For further details, see comments and test cases
// Unit tests: test/test_future.cpp
#include <babylon/future.h>
using ::babylon::CountDownLatch;
{
// Expecting to join 10 asynchronous results
CountDownLatch<> latch(10);
auto future = latch.get_future();
::std::vector<::std::thread> threads;
for (size_t i = 0; i < 10; ++i) {
threads.emplace_back([&] () {
// Each asynchronous result reports completion with count_down
latch.count_down();
});
}
future.get(); // Waits until the count decrements to 0
future.on_finish([] (int) {
// It's also a future, so you can chain further asynchronous tasks
});
}