From 308903dc9185223e015333c674b419b1ef45cb15 Mon Sep 17 00:00:00 2001
From: Erik Hofman <erik@ehofman.com>
Date: Fri, 24 Jan 2020 13:52:37 +0100
Subject: [PATCH] Revert to c3ae70461061a9546a430147a4aabc8960845d19 until the
 condition_variable problem is solved

---
 simgear/threads/SGThread.cxx | 232 +++++++++++++++++++++++------------
 1 file changed, 153 insertions(+), 79 deletions(-)

diff --git a/simgear/threads/SGThread.cxx b/simgear/threads/SGThread.cxx
index 7da62bb7..6123966d 100644
--- a/simgear/threads/SGThread.cxx
+++ b/simgear/threads/SGThread.cxx
@@ -35,85 +35,6 @@
 #include <chrono>
 #include <climits>
 
-#if _WIN32
-# include <list>
-# include <windows.h>
-#else
-# include <pthread.h>
-# include <cassert>
-# include <cerrno>
-# include <sys/time.h>
-#endif
-
-struct SGWaitCondition::PrivateData {
-    PrivateData(void)
-    {
-    }
-    ~PrivateData(void)
-    {
-    }
-
-    void signal(void)
-    {
-        bool waiter;
-        {
-            std::lock_guard<std::mutex> lock(_mutex);
-            waiter = !ready;
-            ready = true;
-        }
-        if (waiter) {
-            _condition.notify_one();
-        }
-    }
-
-    void broadcast(void)
-    {
-        bool waiter;
-        {
-            std::lock_guard<std::mutex> lock(_mutex);
-            waiter = !ready;
-            ready = true;
-        }
-        if (waiter) {
-            _condition.notify_all();
-        }
-    }
-
-    void wait(std::mutex& mutex)
-    {
-        std::unique_lock<std::mutex> lock(_mutex);
-
-        mutex.unlock();
-        _condition.wait(lock, [this]{ return ready; } );
-        mutex.lock();
-
-        ready = false;
-    }
-
-    bool wait(std::mutex& mutex, unsigned msec)
-    {
-        auto timeout = std::chrono::milliseconds(msec);
-        std::unique_lock<std::mutex> lock(mutex);
-
-        try {
-            mutex.unlock();
-            _condition.wait_for(lock, timeout, [this]{ return ready; } );
-            mutex.lock();
-
-            ready = false;
-        } catch (std::runtime_error &ex) {
-            return false;
-        }
-        return true;
-    }
-
-    std::mutex _mutex;
-    std::condition_variable _condition;
-
-private:
-    bool ready = false;
-};
-
 struct SGThread::PrivateData {
     PrivateData()
     {
@@ -162,6 +83,159 @@ struct SGThread::PrivateData {
     bool _started = false;
 };
 
+#if _WIN32
+
+/////////////////////////////////////////////////////////////////////////////
+/// win32 threads
+/////////////////////////////////////////////////////////////////////////////
+
+#include <list>
+#include <windows.h>
+
+struct SGWaitCondition::PrivateData {
+    ~PrivateData(void)
+    {
+        // The waiters list should be empty anyway
+        _mutex.lock();
+        while (!_pool.empty()) {
+            CloseHandle(_pool.front());
+            _pool.pop_front();
+        }
+        _mutex.unlock();
+    }
+
+    void signal(void)
+    {
+        _mutex.lock();
+        if (!_waiters.empty())
+            SetEvent(_waiters.back());
+        _mutex.unlock();
+    }
+
+    void broadcast(void)
+    {
+        _mutex.lock();
+        for (std::list<HANDLE>::iterator i = _waiters.begin(); i != _waiters.end(); ++i)
+            SetEvent(*i);
+        _mutex.unlock();
+    }
+
+    bool wait(std::mutex& externalMutex, DWORD msec)
+    {
+        _mutex.lock();
+        if (_pool.empty())
+            _waiters.push_front(CreateEvent(NULL, FALSE, FALSE, NULL));
+        else
+            _waiters.splice(_waiters.begin(), _pool, _pool.begin());
+        std::list<HANDLE>::iterator i = _waiters.begin();
+        _mutex.unlock();
+
+        externalMutex.unlock();
+
+        DWORD result = WaitForSingleObject(*i, msec);
+
+        externalMutex.lock();
+
+        _mutex.lock();
+        if (result != WAIT_OBJECT_0)
+            result = WaitForSingleObject(*i, 0);
+        _pool.splice(_pool.begin(), _waiters, i);
+        _mutex.unlock();
+
+        return result == WAIT_OBJECT_0;
+    }
+
+    void wait(std::mutex& externalMutex)
+    {
+        wait(externalMutex, INFINITE);
+    }
+
+    // Protect the list of waiters
+    std::mutex _mutex;
+
+    std::list<HANDLE> _waiters;
+    std::list<HANDLE> _pool;
+};
+
+#else
+/////////////////////////////////////////////////////////////////////////////
+/// posix threads
+/////////////////////////////////////////////////////////////////////////////
+
+#include <pthread.h>
+#include <cassert>
+#include <cerrno>
+#include <sys/time.h>
+
+struct SGWaitCondition::PrivateData {
+    PrivateData(void)
+    {
+        int err = pthread_cond_init(&_condition, NULL);
+        assert(err == 0);
+        (void)err;
+    }
+    ~PrivateData(void)
+    {
+        int err = pthread_cond_destroy(&_condition);
+        assert(err == 0);
+        (void)err;
+    }
+
+    void signal(void)
+    {
+        int err = pthread_cond_signal(&_condition);
+        assert(err == 0);
+        (void)err;
+    }
+
+    void broadcast(void)
+    {
+        int err = pthread_cond_broadcast(&_condition);
+        assert(err == 0);
+        (void)err;
+    }
+
+    void wait(std::mutex& mutex)
+    {
+        int err = pthread_cond_wait(&_condition, mutex.native_handle());
+        assert(err == 0);
+        (void)err;
+    }
+
+    bool wait(std::mutex& mutex, unsigned msec)
+    {
+        struct timespec ts;
+#ifdef HAVE_CLOCK_GETTIME
+        if (0 != clock_gettime(CLOCK_REALTIME, &ts))
+            return false;
+#else
+        struct timeval tv;
+        if (0 != gettimeofday(&tv, NULL))
+            return false;
+        ts.tv_sec = tv.tv_sec;
+        ts.tv_nsec = tv.tv_usec * 1000;
+#endif
+
+        ts.tv_nsec += 1000000*(msec % 1000);
+        if (1000000000 <= ts.tv_nsec) {
+            ts.tv_nsec -= 1000000000;
+            ts.tv_sec += 1;
+        }
+        ts.tv_sec += msec / 1000;
+
+        int evalue = pthread_cond_timedwait(&_condition, mutex.native_handle(), &ts);
+        if (evalue == 0)
+          return true;
+
+        assert(evalue == ETIMEDOUT);
+        return false;
+    }
+
+    pthread_cond_t _condition;
+};
+
+#endif
+
 SGThread::SGThread() :
     _privateData(new PrivateData)
 {