YT-24537: Prioritize writers in TReaderWriterSpinLock

commit_hash:94fee5363799655628bd7e2c144a7869a9d89002

1 files changed, 56 insertions, 0 deletions

diff --git a/library/cpp/yt/threading/unittests/rw_spin_lock_ut.cpp b/library/cpp/yt/threading/unittests/rw_spin_lock_ut.cpp
new file mode 100644
index 00000000000..653772604ce
--- /dev/null
+++ b/library/cpp/yt/threading/unittests/rw_spin_lock_ut.cpp
@@ -0,0 +1,56 @@
+#include <library/cpp/testing/gtest/gtest.h>
+
+#include <library/cpp/yt/threading/rw_spin_lock.h>
+
+#include <util/thread/pool.h>
+
+#include <latch>
+#include <thread>
+
+namespace NYT::NThreading {
+namespace {
+
+////////////////////////////////////////////////////////////////////////////////
+
+TEST(TReaderWriterSpinLockTest, WriterPriority)
+{
+    int readerThreads = 10;
+    std::latch latch(readerThreads + 1);
+    std::atomic<size_t> finishedCount = {0};
+
+    TReaderWriterSpinLock lock;
+
+    volatile std::atomic<ui32> x = {0};
+
+    auto readerTask = [&latch, &lock, &finishedCount, &x] () {
+        latch.arrive_and_wait();
+        while (true) {
+            {
+                auto guard = ReaderGuard(lock);
+                // do some stuff
+                for (ui32 i = 0; i < 10'000u; ++i) {
+                    x.fetch_add(i);
+                }
+            }
+            if (finishedCount.fetch_add(1) > 20'000) {
+                break;
+            }
+        }
+    };
+
+    auto readerPool = CreateThreadPool(readerThreads);
+    for (int i = 0; i < readerThreads; ++i) {
+        readerPool->SafeAddFunc(readerTask);
+    }
+
+    latch.arrive_and_wait();
+    while (finishedCount.load() == 0);
+    auto guard = WriterGuard(lock);
+    EXPECT_LE(finishedCount.load(), 1'000u);
+    DoNotOptimizeAway(x);
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+} // namespace
+} // namespace NYT::NConcurrency