73 lines
2.2 KiB
C++
73 lines
2.2 KiB
C++
#include <ostd/io.hh>
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#include <ostd/concurrency.hh>
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using namespace ostd;
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int main() {
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/* have an array, split it in two halves and sum each half in a separate
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* task, which may or may not run in parallel with the other one depending
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* on the scheduler currently in use - several schedulers are shown
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*/
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auto foo = []() {
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auto arr = ostd::iter({ 150, 38, 76, 25, 67, 18, -15, 215, 25, -10 });
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auto c = make_channel<int>();
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auto f = [](auto c, auto half) {
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c.put(foldl(half, 0));
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};
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spawn(f, c, arr.slice(0, arr.size() / 2));
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spawn(f, c, arr + (arr.size() / 2));
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int a = c.get();
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int b = c.get();
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writefln("%s + %s = %s", a, b, a + b);
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};
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/* using thread_scheduler results in an OS thread spawned per task,
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* implementing a 1:1 (kernel-level) scheduling - very expensive on
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* Windows, less expensive on Unix-likes (but more than coroutines)
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*/
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thread_scheduler{}.start([&foo]() {
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writeln("(1) 1:1 scheduler: starting...");
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foo();
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writeln("(1) 1:1 scheduler: finishing...");
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});
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writeln();
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/* using simple_coroutine_scheduler results in a coroutine spawned
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* per task, implementing N:1 (user-level) scheduling - very cheap
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* and portable everywhere but obviously limited to only one thread
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*/
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simple_coroutine_scheduler{}.start([&foo]() {
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writeln("(2) N:1 scheduler: starting...");
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foo();
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writeln("(2) N:1 scheduler: finishing...");
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});
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writeln();
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/* using coroutine_scheduler results in a coroutine spawned per
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* task, but mapped onto a certain number of OS threads, implementing
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* a hybrid M:N approach - this benefits from multicore systems and
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* also is relatively cheap (you can create a big number of tasks)
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*/
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coroutine_scheduler{}.start([&foo]() {
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writeln("(3) M:N scheduler: starting...");
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foo();
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writeln("(3) M:N scheduler: finishing...");
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});
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}
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/*
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(1) 1:1 scheduler: starting...
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356 + 233 = 589
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(1) 1:1 scheduler: finishing...
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(2) N:1 scheduler: starting...
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356 + 233 = 589
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(2) N:1 scheduler: finishing...
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(3) M:N scheduler: starting...
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356 + 233 = 589
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(3) M:N scheduler: finishing...
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*/
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