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/* Self tests for parallel_for_each
Copyright (C) 2021-2025 Free Software Foundation, Inc.
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include "gdbsupport/selftest.h"
#include "gdbsupport/parallel-for.h"
#if CXX_STD_THREAD
#include "gdbsupport/thread-pool.h"
namespace selftests {
namespace parallel_for {
struct save_restore_n_threads
{
save_restore_n_threads ()
: n_threads (gdb::thread_pool::g_thread_pool->thread_count ())
{
}
~save_restore_n_threads ()
{
gdb::thread_pool::g_thread_pool->set_thread_count (n_threads);
}
int n_threads;
};
using foreach_callback_t = gdb::function_view<void (int first, int last)>;
using do_foreach_t = gdb::function_view<void (int first, int last,
foreach_callback_t)>;
static void
test_one (int n_threads, do_foreach_t do_foreach)
{
save_restore_n_threads saver;
gdb::thread_pool::g_thread_pool->set_thread_count (n_threads);
{
constexpr int upper_bound = 1000;
std::atomic<int> counter (0);
do_foreach (0, upper_bound,
[&] (int start, int end) { counter += end - start; });
SELF_CHECK (counter == upper_bound);
}
{
std::atomic<int> counter (0);
do_foreach (0, 0, [&] (int start, int end) { counter += end - start; });
SELF_CHECK (counter == 0);
}
{
/* Check that if there are fewer tasks than threads, then we won't
end up with a null result. */
std::vector<std::unique_ptr<int>> intresults;
std::atomic<bool> any_empty_tasks (false);
do_foreach (0, 1,
[&] (int start, int end)
{
if (start == end)
any_empty_tasks = true;
return std::make_unique<int> (end - start);
});
SELF_CHECK (!any_empty_tasks);
SELF_CHECK (std::all_of (intresults.begin (), intresults.end (),
[] (const std::unique_ptr<int> &entry)
{ return entry != nullptr; }));
}
}
static void
test_parallel_for_each ()
{
const std::vector<do_foreach_t> for_each_functions
{
[] (int start, int end, foreach_callback_t callback)
{ gdb::parallel_for_each<1> (start, end, callback); },
[] (int start, int end, foreach_callback_t callback)
{ gdb::sequential_for_each (start, end, callback);}
};
for (int n_threads : { 0, 1, 3 })
for (const auto &for_each_function : for_each_functions)
test_one (n_threads, for_each_function);
}
} /* namespace parallel_for */
} /* namespace selftests */
#endif /* CXX_STD_THREAD */
INIT_GDB_FILE (parallel_for_selftests)
{
#ifdef CXX_STD_THREAD
selftests::register_test ("parallel_for",
selftests::parallel_for::test_parallel_for_each);
#endif /* CXX_STD_THREAD */
}
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