add read write lock class

add log class from Will Zhang:

Package: cpputil
Source: https://github.com/willzhang4a58/cpputil
License: MIT License

1 files changed, 58 insertions, 0 deletions

diff --git a/xmrstak/backend/globalStates.hpp b/xmrstak/backend/globalStates.hpp
index 44b6e0b..3add4e4 100644
--- a/xmrstak/backend/globalStates.hpp
+++ b/xmrstak/backend/globalStates.hpp
@@ -6,10 +6,66 @@
 #include "xmrstak/backend/pool_data.hpp"
 
 #include <atomic>
+#include <condition_variable>
 
 namespace xmrstak
 {
 
+
+class RWLock {
+public:
+    RWLock() : _status(0), _waiting_readers(0), _waiting_writers(0) {}
+    RWLock(const RWLock&) = delete;
+    RWLock(RWLock&&) = delete;
+    RWLock& operator = (const RWLock&) = delete;
+    RWLock& operator = (RWLock&&) = delete;
+
+    void rdlock() {
+        std::unique_lock<std::mutex> lck(_mtx);
+        _waiting_readers += 1;
+        _read_cv.wait(lck, [&]() { return _waiting_writers == 0 && _status >= 0; });
+        _waiting_readers -= 1;
+        _status += 1;
+    }
+
+    void wrlock() {
+        std::unique_lock<std::mutex> lck(_mtx);
+        _waiting_writers += 1;
+        _write_cv.wait(lck, [&]() { return _status == 0; });
+        _waiting_writers -= 1;
+        _status = -1;
+    }
+
+    void unlock() {
+        std::unique_lock<std::mutex> lck(_mtx);
+        if (_status == -1) {
+            _status = 0;
+        } else {
+            _status -= 1;
+        }
+        if (_waiting_writers > 0) {
+            if (_status == 0) {
+                _write_cv.notify_one();
+            }
+        } else {
+            _read_cv.notify_all();
+        }
+    }
+
+private:
+    // -1    : one writer
+    // 0     : no reader and no writer
+    // n > 0 : n reader
+    int32_t _status;
+    int32_t _waiting_readers;
+    int32_t _waiting_writers;
+    std::mutex _mtx;
+    std::condition_variable _read_cv;
+    std::condition_variable _write_cv;
+};
+
+
+
 struct globalStates
 {
 	static inline globalStates& inst()
@@ -44,6 +100,8 @@ private:
 	globalStates() : iThreadCount(0), iGlobalJobNo(0), iConsumeCnt(0)
 	{
 	}
+
+	RWLock jobLock;
 };
 
 } // namespace xmrstak