// This file is part of Eigen, a lightweight C++ template library // for linear algebra. // // Copyright (C) 2016 Dmitry Vyukov <dvyukov@google.com> // Copyright (C) 2016 Benoit Steiner <benoit.steiner.goog@gmail.com> // // This Source Code Form is subject to the terms of the Mozilla // Public License v. 2.0. If a copy of the MPL was not distributed // with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
// Visual studio doesn't implement a rand_r() function since its // implementation of rand() is already thread safe int rand_reentrant(unsignedint* s) { #ifdef EIGEN_COMP_MSVC_STRICT
EIGEN_UNUSED_VARIABLE(s); return rand(); #else return rand_r(s); #endif
}
// Empty tests that the queue is not claimed to be empty when is is in fact not. // Emptiness property is crucial part of thread pool blocking scheme, // so we go to great effort to ensure this property. We create a queue with // 1 element and then push 1 element (either front or back at random) and pop // 1 element (either front or back at random). So queue always contains at least // 1 element, but otherwise changes chaotically. Another thread constantly tests // that the queue is not claimed to be empty. void test_empty_runqueue()
{
RunQueue<int, 4> q;
q.PushFront(1);
std::atomic<bool> done(false);
std::thread mutator([&q, &done]() { unsigned rnd = 0;
std::vector<int> stolen; for (int i = 0; i < 1 << 18; i++) { if (rand_reentrant(&rnd) % 2)
VERIFY_IS_EQUAL(0, q.PushFront(1)); else
VERIFY_IS_EQUAL(0, q.PushBack(1)); if (rand_reentrant(&rnd) % 2)
VERIFY_IS_EQUAL(1, q.PopFront()); else { for (;;) { if (q.PopBackHalf(&stolen) == 1) {
stolen.clear(); break;
}
VERIFY_IS_EQUAL(0u, stolen.size());
}
}
}
done = true;
}); while (!done) {
VERIFY(!q.Empty()); int size = q.Size();
VERIFY_GE(size, 1);
VERIFY_LE(size, 2);
}
VERIFY_IS_EQUAL(1, q.PopFront());
mutator.join();
}
// Stress is a chaotic random test. // One thread (owner) calls PushFront/PopFront, other threads call PushBack/ // PopBack. Ensure that we don't crash, deadlock, and all sanity checks pass. void test_stress_runqueue()
{ staticconstint kEvents = 1 << 18;
RunQueue<int, 8> q;
std::atomic<int> total(0);
std::vector<std::unique_ptr<std::thread>> threads;
threads.emplace_back(new std::thread([&q, &total]() { int sum = 0; int pushed = 1; int popped = 1; while (pushed < kEvents || popped < kEvents) { if (pushed < kEvents) { if (q.PushFront(pushed) == 0) {
sum += pushed;
pushed++;
}
} if (popped < kEvents) { int v = q.PopFront(); if (v != 0) {
sum -= v;
popped++;
}
}
}
total += sum;
})); for (int i = 0; i < 2; i++) {
threads.emplace_back(new std::thread([&q, &total]() { int sum = 0; for (int j = 1; j < kEvents; j++) { if (q.PushBack(j) == 0) {
sum += j; continue;
}
EIGEN_THREAD_YIELD();
j--;
}
total += sum;
}));
threads.emplace_back(new std::thread([&q, &total]() { int sum = 0;
std::vector<int> stolen; for (int j = 1; j < kEvents;) { if (q.PopBackHalf(&stolen) == 0) {
EIGEN_THREAD_YIELD(); continue;
} while (stolen.size() && j < kEvents) { int v = stolen.back();
stolen.pop_back();
VERIFY_IS_NOT_EQUAL(v, 0);
sum += v;
j++;
}
} while (stolen.size()) { int v = stolen.back();
stolen.pop_back();
VERIFY_IS_NOT_EQUAL(v, 0); while ((v = q.PushBack(v)) != 0) EIGEN_THREAD_YIELD();
}
total -= sum;
}));
} for (size_t i = 0; i < threads.size(); i++) threads[i]->join();
VERIFY(q.Empty());
VERIFY(total.load() == 0);
}
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