1 files changed, 186 insertions, 0 deletions
diff --git a/src/system_wrappers/source/rw_lock_win.cc b/src/system_wrappers/source/rw_lock_win.cc
new file mode 100644
index 0000000000..82cd0ac04f
--- /dev/null
+++ b/src/system_wrappers/source/rw_lock_win.cc
@@ -0,0 +1,186 @@
+/*
+ *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "rw_lock_win.h"
+
+#include "critical_section_wrapper.h"
+#include "condition_variable_wrapper.h"
+#include "trace.h"
+
+// TODO (hellner) why not just use the rw_lock_generic.cc solution if
+//                           native is not supported? Unnecessary redundancy!
+
+namespace webrtc {
+bool RWLockWindows::_winSupportRWLockPrimitive = false;
+static HMODULE library = NULL;
+
+PInitializeSRWLock       _PInitializeSRWLock;
+PAcquireSRWLockExclusive _PAcquireSRWLockExclusive;
+PAcquireSRWLockShared    _PAcquireSRWLockShared;
+PReleaseSRWLockShared    _PReleaseSRWLockShared;
+PReleaseSRWLockExclusive _PReleaseSRWLockExclusive;
+
+RWLockWindows::RWLockWindows()
+    : _critSectPtr(NULL),
+      _readCondPtr(NULL),
+      _writeCondPtr(NULL),
+      _readersActive(0),
+      _writerActive(false),
+      _readersWaiting(0),
+      _writersWaiting(0)
+{
+}
+
+RWLockWindows::~RWLockWindows()
+{
+    delete _writeCondPtr;
+    delete _readCondPtr;
+    delete _critSectPtr;
+}
+
+int RWLockWindows::Init()
+{
+    if(!library)
+    {
+        // Use native implementation if supported (i.e Vista+)
+        library = LoadLibrary(TEXT("Kernel32.dll"));
+        if(library)
+        {
+            WEBRTC_TRACE(kTraceStateInfo, kTraceUtility, -1,
+                         "Loaded Kernel.dll");
+
+            _PInitializeSRWLock =
+                (PInitializeSRWLock)GetProcAddress(
+                    library,
+                    "InitializeSRWLock");
+
+            _PAcquireSRWLockExclusive =
+               (PAcquireSRWLockExclusive)GetProcAddress(
+                   library,
+                   "AcquireSRWLockExclusive");
+            _PReleaseSRWLockExclusive =
+                (PReleaseSRWLockExclusive)GetProcAddress(
+                    library,
+                    "ReleaseSRWLockExclusive");
+            _PAcquireSRWLockShared =
+                (PAcquireSRWLockShared)GetProcAddress(
+                    library,
+                    "AcquireSRWLockShared");
+            _PReleaseSRWLockShared =
+                (PReleaseSRWLockShared)GetProcAddress(
+                    library,
+                    "ReleaseSRWLockShared");
+
+            if( _PInitializeSRWLock &&
+                _PAcquireSRWLockExclusive &&
+                _PReleaseSRWLockExclusive &&
+                _PAcquireSRWLockShared &&
+                _PReleaseSRWLockShared )
+            {
+                WEBRTC_TRACE(kTraceStateInfo, kTraceUtility, -1,
+                            "Loaded Simple RW Lock");
+                _winSupportRWLockPrimitive = true;
+            }
+        }
+    }
+    if(_winSupportRWLockPrimitive)
+    {
+        _PInitializeSRWLock(&_lock);
+    } else {
+        _critSectPtr  = CriticalSectionWrapper::CreateCriticalSection();
+        _readCondPtr  = ConditionVariableWrapper::CreateConditionVariable();
+        _writeCondPtr = ConditionVariableWrapper::CreateConditionVariable();
+    }
+    return 0;
+}
+
+void RWLockWindows::AcquireLockExclusive()
+{
+    if (_winSupportRWLockPrimitive)
+    {
+        _PAcquireSRWLockExclusive(&_lock);
+    } else {
+        _critSectPtr->Enter();
+
+        if (_writerActive || _readersActive > 0)
+        {
+            ++_writersWaiting;
+            while (_writerActive || _readersActive > 0)
+            {
+                _writeCondPtr->SleepCS(*_critSectPtr);
+            }
+            --_writersWaiting;
+        }
+        _writerActive = true;
+        _critSectPtr->Leave();
+    }
+}
+
+void RWLockWindows::ReleaseLockExclusive()
+{
+    if(_winSupportRWLockPrimitive)
+    {
+        _PReleaseSRWLockExclusive(&_lock);
+    } else {
+        _critSectPtr->Enter();
+        _writerActive = false;
+        if (_writersWaiting > 0)
+        {
+            _writeCondPtr->Wake();
+
+        }else if (_readersWaiting > 0) {
+            _readCondPtr->WakeAll();
+        }
+        _critSectPtr->Leave();
+    }
+}
+
+void RWLockWindows::AcquireLockShared()
+{
+    if(_winSupportRWLockPrimitive)
+    {
+        _PAcquireSRWLockShared(&_lock);
+    } else
+    {
+        _critSectPtr->Enter();
+        if (_writerActive || _writersWaiting > 0)
+        {
+            ++_readersWaiting;
+
+            while (_writerActive || _writersWaiting > 0)
+            {
+                _readCondPtr->SleepCS(*_critSectPtr);
+            }
+            --_readersWaiting;
+        }
+        ++_readersActive;
+        _critSectPtr->Leave();
+    }
+}
+
+void RWLockWindows::ReleaseLockShared()
+{
+    if(_winSupportRWLockPrimitive)
+    {
+        _PReleaseSRWLockShared(&_lock);
+    } else
+    {
+        _critSectPtr->Enter();
+
+        --_readersActive;
+
+        if (_readersActive == 0 && _writersWaiting > 0)
+        {
+            _writeCondPtr->Wake();
+        }
+        _critSectPtr->Leave();
+    }
+}
+} // namespace webrtc