intermediate changes

ref:cde9a383711a11544ce7e107a78147fb96cc4029

1 files changed, 61 insertions, 0 deletions

diff --git a/util/generic/singleton.cpp b/util/generic/singleton.cpp
new file mode 100644
index 00000000000..eb5a0662f8d
--- /dev/null
+++ b/util/generic/singleton.cpp
@@ -0,0 +1,61 @@
+#include "singleton.h"
+
+#include <util/system/spinlock.h>
+#include <util/system/thread.h>
+#include <util/system/sanitizers.h>
+
+#include <cstring>
+
+namespace {
+    static inline bool MyAtomicTryLock(TAtomic& a, TAtomicBase v) noexcept {
+        return AtomicCas(&a, v, 0);
+    }
+
+    static inline bool MyAtomicTryAndTryLock(TAtomic& a, TAtomicBase v) noexcept {
+        return (AtomicGet(a) == 0) && MyAtomicTryLock(a, v);
+    }
+
+    static inline TAtomicBase MyThreadId() noexcept {
+        const TAtomicBase ret = TThread::CurrentThreadId();
+
+        if (ret) {
+            return ret;
+        }
+
+        //clash almost impossible, ONLY if we have threads with ids 0 and 1!
+        return 1;
+    }
+}
+
+void NPrivate::FillWithTrash(void* ptr, size_t len) {
+#if defined(NDEBUG)
+    Y_UNUSED(ptr);
+    Y_UNUSED(len);
+#else
+    if constexpr (NSan::TSanIsOn()) {
+        Y_UNUSED(ptr);
+        Y_UNUSED(len);
+    } else {
+        memset(ptr, 0xBA, len);
+    }
+#endif
+}
+
+void NPrivate::LockRecursive(TAtomic& lock) noexcept {
+    const TAtomicBase id = MyThreadId();
+
+    Y_VERIFY(AtomicGet(lock) != id, "recursive singleton initialization");
+
+    if (!MyAtomicTryLock(lock, id)) {
+        TSpinWait sw;
+
+        do {
+            sw.Sleep();
+        } while (!MyAtomicTryAndTryLock(lock, id));
+    }
+}
+
+void NPrivate::UnlockRecursive(TAtomic& lock) noexcept {
+    Y_VERIFY(AtomicGet(lock) == MyThreadId(), "unlock from another thread?!?!");
+    AtomicUnlock(&lock);
+}