1 files changed, 57 insertions, 0 deletions
diff --git a/libs/usvfs/src/usvfs_dll/semaphore.cpp b/libs/usvfs/src/usvfs_dll/semaphore.cpp
new file mode 100644
index 0000000..609b2f5
--- /dev/null
+++ b/libs/usvfs/src/usvfs_dll/semaphore.cpp
@@ -0,0 +1,57 @@
+#include "semaphore.h"
+#include "exceptionex.h"
+
+RecursiveBenaphore::RecursiveBenaphore() : m_Counter(0), m_OwnerId(0UL), m_Recursion(0)
+{
+  m_Semaphore = ::CreateSemaphore(nullptr, 1, 1, nullptr);
+}
+
+RecursiveBenaphore::~RecursiveBenaphore()
+{
+  ::CloseHandle(m_Semaphore);
+}
+
+void RecursiveBenaphore::wait(DWORD timeout)
+{
+  DWORD tid = ::GetCurrentThreadId();
+
+  if (::_InterlockedIncrement(&m_Counter) > 1) {
+    if (tid != m_OwnerId) {
+      int tries = 3;
+      while (::WaitForSingleObject(m_Semaphore, timeout) != WAIT_OBJECT_0) {
+        HANDLE owner = ::OpenThread(SYNCHRONIZE, FALSE, m_OwnerId);
+        ON_BLOCK_EXIT([owner]() {
+          ::CloseHandle(owner);
+        });
+        if ((tries <= 0) || (::WaitForSingleObject(owner, 0) == WAIT_OBJECT_0)) {
+          // owner has quit without releasing the semaphore!
+          m_Recursion = 0;
+          spdlog::get("usvfs")->error("thread {} never released the mutex", m_OwnerId);
+          break;
+        } else {
+          --tries;
+        }
+      }
+    }
+  }
+  m_OwnerId = tid;
+  ++m_Recursion;
+}
+
+void RecursiveBenaphore::signal()
+{
+  if (m_Recursion == 0) {
+    return;
+  }
+  // no validation the signaling thread is the one owning the lock
+  DWORD recursion = --m_Recursion;
+  if (recursion == 0) {
+    m_OwnerId = 0;
+  }
+  DWORD result = ::_InterlockedDecrement(&m_Counter);
+  if (result > 0) {
+    if (recursion == 0) {
+      ::ReleaseSemaphore(m_Semaphore, 1, nullptr);
+    }
+  }
+}