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// Copyright (c) the JPEG XL Project Authors. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#include <algorithm>
#include <atomic>
#include <cstdint>
#include <vector>
#include "lib/jxl/base/data_parallel.h"
#include "lib/jxl/base/status.h"
#include "lib/jxl/test_utils.h"
#include "lib/jxl/testing.h"
using ::jxl::test::ThreadPoolForTests;
namespace jpegxl {
namespace {
int PopulationCount(uint64_t bits) {
int num_set = 0;
while (bits != 0) {
num_set += bits & 1;
bits >>= 1;
}
return num_set;
}
// Ensures task parameter is in bounds, every parameter is reached,
// pool can be reused (multiple consecutive Run calls), pool can be destroyed
// (joining with its threads), num_threads=0 works (runs on current thread).
TEST(ThreadParallelRunnerTest, TestPool) {
for (int num_threads = 0; num_threads <= 18; ++num_threads) {
ThreadPoolForTests pool(num_threads);
for (int num_tasks = 0; num_tasks < 32; ++num_tasks) {
std::vector<int> mementos(num_tasks);
for (int begin = 0; begin < 32; ++begin) {
std::fill(mementos.begin(), mementos.end(), 0);
const auto do_task = [begin, num_tasks, &mementos](
const int task,
const int thread) -> jxl::Status {
// Parameter is in the given range
EXPECT_GE(task, begin);
EXPECT_LT(task, begin + num_tasks);
// Store mementos to be sure we visited each task.
mementos.at(task - begin) = 1000 + task;
return true;
};
EXPECT_TRUE(RunOnPool(pool.get(), begin, begin + num_tasks,
jxl::ThreadPool::NoInit, do_task, "TestPool"));
for (int task = begin; task < begin + num_tasks; ++task) {
EXPECT_EQ(1000 + task, mementos.at(task - begin));
}
}
}
}
}
// Verify "thread" parameter when processing few tasks.
TEST(ThreadParallelRunnerTest, TestSmallAssignments) {
const int kMaxThreads = 8;
for (int num_threads = 1; num_threads <= kMaxThreads; ++num_threads) {
ThreadPoolForTests pool(num_threads);
// (Avoid mutex because it may perturb the worker thread scheduling)
std::atomic<uint64_t> id_bits{0};
std::atomic<int> num_calls{0};
const auto do_task = [&num_calls, num_threads, &id_bits](
const int task, const int thread) -> jxl::Status {
num_calls.fetch_add(1, std::memory_order_relaxed);
EXPECT_LT(thread, num_threads);
uint64_t bits = id_bits.load(std::memory_order_relaxed);
while (!id_bits.compare_exchange_weak(bits, bits | (1ULL << thread))) {
// lock-free retry-loop
}
return true;
};
EXPECT_TRUE(RunOnPool(pool.get(), 0, num_threads, jxl::ThreadPool::NoInit,
do_task, "TestSmallAssignments"));
// Correct number of tasks.
EXPECT_EQ(num_threads, num_calls.load());
const int num_participants = PopulationCount(id_bits.load());
// Can't expect equality because other workers may have woken up too late.
EXPECT_LE(num_participants, num_threads);
}
}
struct Counter {
Counter() {
// Suppress "unused-field" warning.
(void)padding;
}
void Assimilate(const Counter& victim) { counter += victim.counter; }
int counter = 0;
int padding[31];
};
TEST(ThreadParallelRunnerTest, TestCounter) {
const int kNumThreads = 12;
ThreadPoolForTests pool(kNumThreads);
alignas(128) Counter counters[kNumThreads];
const int kNumTasks = kNumThreads * 19;
const auto count = [&counters](const int task,
const int thread) -> jxl::Status {
counters[thread].counter += task;
return true;
};
EXPECT_TRUE(RunOnPool(pool.get(), 0, kNumTasks, jxl::ThreadPool::NoInit,
count, "TestCounter"));
int expected = 0;
for (int i = 0; i < kNumTasks; ++i) {
expected += i;
}
for (int i = 1; i < kNumThreads; ++i) {
counters[0].Assimilate(counters[i]);
}
EXPECT_EQ(expected, counters[0].counter);
}
} // namespace
} // namespace jpegxl