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//===----------------------------------------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// UNSUPPORTED: libcpp-has-no-threads
//
// <memory>
//
// class shared_ptr
//
// This test attempts to create a race condition surrounding use_count()
// with the hope that TSAN will diagnose it.
#include <memory>
#include <atomic>
#include <thread>
#include <cassert>
typedef std::shared_ptr<int> Ptr;
typedef std::weak_ptr<int> WeakPtr;
std::atomic_bool Start;
std::atomic_bool KeepRunning;
struct TestRunner {
TestRunner(Ptr xx) : x(xx) {}
void operator()() {
while (Start == false) {}
while (KeepRunning) {
// loop to prevent always checking the atomic.
for (int i=0; i < 100000; ++i) {
Ptr x2 = x; // increment shared count
WeakPtr x3 = x; // increment weak count
Ptr x4 = x3.lock(); // increment shared count via lock
WeakPtr x5 = x3; // increment weak count
}
}
}
Ptr x;
};
void run_test(Ptr p) {
Start = false;
KeepRunning = true;
assert(p.use_count() == 2);
TestRunner r(p);
assert(p.use_count() == 3);
std::thread t1(r); // Start the test thread.
assert(p.use_count() == 4);
Start = true;
// Run until we witness 25 use count changes via both
// shared and weak pointer methods.
WeakPtr w = p;
int shared_changes_count = 0;
int weak_changes_count = 0;
while (shared_changes_count < 25 && weak_changes_count < 25) {
// check use_count on the shared_ptr
int last = p.use_count();
int new_val = p.use_count();
assert(last >= 4);
assert(new_val >= 4);
if (last != new_val) ++shared_changes_count;
// Check use_count on the weak_ptr
last = w.use_count();
new_val = w.use_count();
assert(last >= 4);
assert(new_val >= 4);
if (last != new_val) ++weak_changes_count;
}
// kill the test thread.
KeepRunning = false;
t1.join();
assert(p.use_count() == 3);
}
int main() {
{
// Test with out-of-place shared_count.
Ptr p(new int(42));
run_test(p);
assert(p.use_count() == 1);
}
{
// Test with in-place shared_count.
Ptr p = std::make_shared<int>(42);
run_test(p);
assert(p.use_count() == 1);
}
}
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