Initial commit

packages/leann-backend-diskann/third_party/DiskANN/include/windows_slim_lock.h

@@ -0,0 +1,73 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT license.
+#pragma once
+
+#ifndef WIN32_LEAN_AND_MEAN
+#define WIN32_LEAN_AND_MEAN
+#endif
+#include "Windows.h"
+
+namespace diskann
+{
+// A thin C++ wrapper around Windows exclusive functionality of Windows
+// SlimReaderWriterLock.
+//
+// The SlimReaderWriterLock is simpler/more lightweight than std::mutex
+// (8 bytes vs 80 bytes), which is useful in the scenario where DiskANN has
+// one lock per vector in the index. It does not support recursive locking and
+// requires Windows Vista or later.
+//
+// Full documentation can be found at.
+// https://msdn.microsoft.com/en-us/library/windows/desktop/aa904937(v=vs.85).aspx
+class windows_exclusive_slim_lock
+{
+  public:
+    windows_exclusive_slim_lock() : _lock(SRWLOCK_INIT)
+    {
+    }
+
+    // The lock is non-copyable. This also disables move constructor/operator=.
+    windows_exclusive_slim_lock(const windows_exclusive_slim_lock &) = delete;
+    windows_exclusive_slim_lock &operator=(const windows_exclusive_slim_lock &) = delete;
+
+    void lock()
+    {
+        return AcquireSRWLockExclusive(&_lock);
+    }
+
+    bool try_lock()
+    {
+        return TryAcquireSRWLockExclusive(&_lock) != FALSE;
+    }
+
+    void unlock()
+    {
+        return ReleaseSRWLockExclusive(&_lock);
+    }
+
+  private:
+    SRWLOCK _lock;
+};
+
+// An exclusive lock over a SlimReaderWriterLock.
+class windows_exclusive_slim_lock_guard
+{
+  public:
+    windows_exclusive_slim_lock_guard(windows_exclusive_slim_lock &p_lock) : _lock(p_lock)
+    {
+        _lock.lock();
+    }
+
+    // The lock is non-copyable. This also disables move constructor/operator=.
+    windows_exclusive_slim_lock_guard(const windows_exclusive_slim_lock_guard &) = delete;
+    windows_exclusive_slim_lock_guard &operator=(const windows_exclusive_slim_lock_guard &) = delete;
+
+    ~windows_exclusive_slim_lock_guard()
+    {
+        _lock.unlock();
+    }
+
+  private:
+    windows_exclusive_slim_lock &_lock;
+};
+} // namespace diskann