clean up concurrency example a bit
parent
9f593eebd1
commit
d6c03be4cd
|
@ -3,69 +3,73 @@
|
|||
|
||||
using namespace ostd;
|
||||
|
||||
/* have an array, split it in two halves and sum each half in a separate
|
||||
* task, which may or may not run in parallel with the other one depending
|
||||
* on the scheduler currently in use - several schedulers are shown
|
||||
*/
|
||||
|
||||
/* this version uses Go-style channels to exchange data; multiple
|
||||
* tasks can put data into channels, the channel itself is a thread
|
||||
* safe queue; it goes the other way around too, multiple tasks can
|
||||
* wait on a channel for some data to be received
|
||||
*/
|
||||
static void test_channel() {
|
||||
auto arr = { 150, 38, 76, 25, 67, 18, -15, 215, 25, -10 };
|
||||
|
||||
auto c = make_channel<int>();
|
||||
auto f = [](auto c, auto half) {
|
||||
c.put(foldl(half, 0));
|
||||
};
|
||||
spawn(f, c, iter(arr).slice(0, arr.size() / 2));
|
||||
spawn(f, c, iter(arr).slice(arr.size() / 2));
|
||||
|
||||
int a = c.get();
|
||||
int b = c.get();
|
||||
writefln(" %s + %s = %s", a, b, a + b);
|
||||
}
|
||||
|
||||
/* this version uses future-style tid objects that represent the tasks
|
||||
* themselves including the return value of the task; the return value
|
||||
* can be retrieved using .get(), which will wait for the value to be
|
||||
* stored unless it already is, becoming invalid after retrieval of
|
||||
* the value; the tid also intercepts any possible exceptions thrown
|
||||
* by the task and propagates them in .get(), allowing the user to
|
||||
* perform safe exception handling across tasks
|
||||
*
|
||||
* keep in mind that unlike the above, this will always wait for t1
|
||||
* first (though t2 can still run in parallel to it depending on the
|
||||
* scheduler currently in use), so a will always come from t1 and b
|
||||
* from t2; in the above test, a can come from either task
|
||||
*/
|
||||
static void test_tid() {
|
||||
auto arr = { 150, 38, 76, 25, 67, 18, -15, 215, 25, -10 };
|
||||
|
||||
auto f = [](auto half) {
|
||||
return foldl(half, 0);
|
||||
};
|
||||
auto t1 = spawn(f, iter(arr).slice(0, arr.size() / 2));
|
||||
auto t2 = spawn(f, iter(arr).slice(arr.size() / 2));
|
||||
|
||||
int a = t1.get();
|
||||
int b = t2.get();
|
||||
writefln(" %s + %s = %s", a, b, a + b);
|
||||
}
|
||||
|
||||
static void test_all() {
|
||||
writeln(" testing channels...");
|
||||
test_channel();
|
||||
writeln(" testing futures...");
|
||||
test_tid();
|
||||
}
|
||||
|
||||
int main() {
|
||||
/* have an array, split it in two halves and sum each half in a separate
|
||||
* task, which may or may not run in parallel with the other one depending
|
||||
* on the scheduler currently in use - several schedulers are shown
|
||||
*/
|
||||
|
||||
/* this version uses Go-style channels to exchange data; multiple
|
||||
* tasks can put data into channels, the channel itself is a thread
|
||||
* safe queue; it goes the other way around too, multiple tasks can
|
||||
* wait on a channel for some data to be received
|
||||
*/
|
||||
auto foo = []() {
|
||||
auto arr = { 150, 38, 76, 25, 67, 18, -15, 215, 25, -10 };
|
||||
|
||||
auto c = make_channel<int>();
|
||||
auto f = [](auto c, auto half) {
|
||||
c.put(foldl(half, 0));
|
||||
};
|
||||
spawn(f, c, iter(arr).slice(0, arr.size() / 2));
|
||||
spawn(f, c, iter(arr).slice(arr.size() / 2));
|
||||
|
||||
int a = c.get();
|
||||
int b = c.get();
|
||||
writefln(" %s + %s = %s", a, b, a + b);
|
||||
};
|
||||
|
||||
/* this version uses future-style tid objects that represent the tasks
|
||||
* themselves including the return value of the task; the return value
|
||||
* can be retrieved using .get(), which will wait for the value to be
|
||||
* stored unless it already is, becoming invalid after retrieval of
|
||||
* the value; the tid also intercepts any possible exceptions thrown
|
||||
* by the task and propagates them in .get(), allowing the user to
|
||||
* perform safe exception handling across tasks
|
||||
*/
|
||||
auto bar = []() {
|
||||
auto arr = { 150, 38, 76, 25, 67, 18, -15, 215, 25, -10 };
|
||||
|
||||
auto f = [](auto half) {
|
||||
return foldl(half, 0);
|
||||
};
|
||||
auto t1 = spawn(f, iter(arr).slice(0, arr.size() / 2));
|
||||
auto t2 = spawn(f, iter(arr).slice(arr.size() / 2));
|
||||
|
||||
int a = t1.get();
|
||||
int b = t2.get();
|
||||
writefln("%s + %s = %s", a, b, a + b);
|
||||
};
|
||||
|
||||
/* tries both examples above */
|
||||
auto baz = [&foo, &bar]() {
|
||||
writeln(" testing channels...");
|
||||
foo();
|
||||
writeln(" testing futures...");
|
||||
foo();
|
||||
};
|
||||
|
||||
/* using thread_scheduler results in an OS thread spawned per task,
|
||||
* implementing a 1:1 (kernel-level) scheduling - very expensive on
|
||||
* Windows, less expensive on Unix-likes (but more than coroutines)
|
||||
*/
|
||||
thread_scheduler{}.start([&baz]() {
|
||||
thread_scheduler{}.start([]() {
|
||||
writeln("(1) 1:1 scheduler: starting...");
|
||||
baz();
|
||||
test_all();
|
||||
writeln("(1) 1:1 scheduler: finishing...");
|
||||
});
|
||||
writeln();
|
||||
|
@ -74,9 +78,9 @@ int main() {
|
|||
* per task, implementing N:1 (user-level) scheduling - very cheap
|
||||
* and portable everywhere but obviously limited to only one thread
|
||||
*/
|
||||
simple_coroutine_scheduler{}.start([&baz]() {
|
||||
simple_coroutine_scheduler{}.start([]() {
|
||||
writeln("(2) N:1 scheduler: starting...");
|
||||
baz();
|
||||
test_all();
|
||||
writeln("(2) N:1 scheduler: finishing...");
|
||||
});
|
||||
writeln();
|
||||
|
@ -86,9 +90,9 @@ int main() {
|
|||
* a hybrid M:N approach - this benefits from multicore systems and
|
||||
* also is relatively cheap (you can create a big number of tasks)
|
||||
*/
|
||||
coroutine_scheduler{}.start([&baz]() {
|
||||
coroutine_scheduler{}.start([]() {
|
||||
writeln("(3) M:N scheduler: starting...");
|
||||
baz();
|
||||
test_all();
|
||||
writeln("(3) M:N scheduler: finishing...");
|
||||
});
|
||||
}
|
||||
|
|
Loading…
Reference in New Issue