2 files changed, 64 insertions, 45 deletions

diff --git a/xmrstak/backend/globalStates.cpp b/xmrstak/backend/globalStates.cpp
index e60db8f..6058b7a 100644
--- a/xmrstak/backend/globalStates.cpp
+++ b/xmrstak/backend/globalStates.cpp
@@ -35,57 +35,18 @@ namespace xmrstak
 
 void globalStates::consume_work( miner_work& threadWork, uint64_t& currentJobId)
 {
-	/* Only the executer thread which updates the job is ever setting iConsumeCnt
-	 * to 1000. In this case each consumer must wait until the job is fully updated.
-	 */
-	uint64_t numConsumer = 0;
-
-	/* Take care that we not consume a job if the job is updated.
-	 * If we leave the loop we have increased iConsumeCnt so that
-	 * the job will not be updated until we leave the method.
-	 */
-	do{
-		numConsumer = iConsumeCnt.load(std::memory_order_relaxed);
-		if(numConsumer < 1000)
-		{
-			// register that thread try consume job data
-			numConsumer = ++iConsumeCnt;
-			if(numConsumer >= 1000)
-			{
-				iConsumeCnt--;
-				// 11 is a arbitrary chosen prime number
-				std::this_thread::sleep_for(std::chrono::milliseconds(11));
-			}
-		}
-		else
-		{
-			// an other thread is preparing a new job, 11 is a arbitrary chosen prime number
-			std::this_thread::sleep_for(std::chrono::milliseconds(11));
-		}
-	}
-	while(numConsumer >= 1000);
+	jobLock.rdlock();
 
 	threadWork = oGlobalWork;
 	currentJobId = iGlobalJobNo.load(std::memory_order_relaxed);
 	
-	// signal that thread consumed work
-	iConsumeCnt--;
+	jobLock.unlock();
 }
 
 void globalStates::switch_work(miner_work& pWork, pool_data& dat)
 {
-	/* 1000 is used to notify that the the job will be updated as soon
-	 * as all consumer (which currently coping oGlobalWork has copied
-	 * all data)
-	 */
-	iConsumeCnt += 1000;
-	// wait until all threads which entered consume_work are finished
-	while (iConsumeCnt.load(std::memory_order_relaxed) > 1000)
-	{
-		// 7 is a arbitrary chosen prime number which is smaller than the consumer waiting time
-		std::this_thread::sleep_for(std::chrono::milliseconds(7));
-	}
-	// BEGIN CRITICAL SECTION
+	jobLock.wrlock();
+	
 	// this notifies all threads that the job has changed
 	iGlobalJobNo++; 
 
@@ -100,8 +61,8 @@ void globalStates::switch_work(miner_work& pWork, pool_data& dat)
 	 */
 	dat.iSavedNonce = iGlobalNonce.exchange(dat.iSavedNonce, std::memory_order_relaxed);
 	oGlobalWork = pWork;
-	// END CRITICAL SECTION: allow job consume
-	iConsumeCnt -= 1000;
+	
+	jobLock.unlock();
 }
 
 } // namespace xmrstak
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