Merge System into Support.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@120298 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Support/Mutex.h

@@ -0,0 +1,154 @@
+//===- llvm/System/Mutex.h - Mutex Operating System Concept -----*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file declares the llvm::sys::Mutex class.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SYSTEM_MUTEX_H
+#define LLVM_SYSTEM_MUTEX_H
+
+#include "llvm/Support/Threading.h"
+#include <cassert>
+
+namespace llvm
+{
+  namespace sys
+  {
+    /// @brief Platform agnostic Mutex class.
+    class MutexImpl
+    {
+    /// @name Constructors
+    /// @{
+    public:
+
+      /// Initializes the lock but doesn't acquire it. if \p recursive is set
+      /// to false, the lock will not be recursive which makes it cheaper but
+      /// also more likely to deadlock (same thread can't acquire more than
+      /// once).
+      /// @brief Default Constructor.
+      explicit MutexImpl(bool recursive = true);
+
+      /// Releases and removes the lock
+      /// @brief Destructor
+      ~MutexImpl();
+
+    /// @}
+    /// @name Methods
+    /// @{
+    public:
+
+      /// Attempts to unconditionally acquire the lock. If the lock is held by
+      /// another thread, this method will wait until it can acquire the lock.
+      /// @returns false if any kind of error occurs, true otherwise.
+      /// @brief Unconditionally acquire the lock.
+      bool acquire();
+
+      /// Attempts to release the lock. If the lock is held by the current
+      /// thread, the lock is released allowing other threads to acquire the
+      /// lock.
+      /// @returns false if any kind of error occurs, true otherwise.
+      /// @brief Unconditionally release the lock.
+      bool release();
+
+      /// Attempts to acquire the lock without blocking. If the lock is not
+      /// available, this function returns false quickly (without blocking). If
+      /// the lock is available, it is acquired.
+      /// @returns false if any kind of error occurs or the lock is not
+      /// available, true otherwise.
+      /// @brief Try to acquire the lock.
+      bool tryacquire();
+
+    //@}
+    /// @name Platform Dependent Data
+    /// @{
+    private:
+      void* data_; ///< We don't know what the data will be
+
+    /// @}
+    /// @name Do Not Implement
+    /// @{
+    private:
+      MutexImpl(const MutexImpl & original);
+      void operator=(const MutexImpl &);
+    /// @}
+    };
+
+
+    /// SmartMutex - A mutex with a compile time constant parameter that
+    /// indicates whether this mutex should become a no-op when we're not
+    /// running in multithreaded mode.
+    template<bool mt_only>
+    class SmartMutex : public MutexImpl {
+      unsigned acquired;
+      bool recursive;
+    public:
+      explicit SmartMutex(bool rec = true) :
+        MutexImpl(rec), acquired(0), recursive(rec) { }
+
+      bool acquire() {
+        if (!mt_only || llvm_is_multithreaded()) {
+          return MutexImpl::acquire();
+        } else {
+          // Single-threaded debugging code.  This would be racy in
+          // multithreaded mode, but provides not sanity checks in single
+          // threaded mode.
+          assert((recursive || acquired == 0) && "Lock already acquired!!");
+          ++acquired;
+          return true;
+        }
+      }
+
+      bool release() {
+        if (!mt_only || llvm_is_multithreaded()) {
+          return MutexImpl::release();
+        } else {
+          // Single-threaded debugging code.  This would be racy in
+          // multithreaded mode, but provides not sanity checks in single
+          // threaded mode.
+          assert(((recursive && acquired) || (acquired == 1)) &&
+                 "Lock not acquired before release!");
+          --acquired;
+          return true;
+        }
+      }
+
+      bool tryacquire() {
+        if (!mt_only || llvm_is_multithreaded())
+          return MutexImpl::tryacquire();
+        else return true;
+      }
+
+      private:
+        SmartMutex(const SmartMutex<mt_only> & original);
+        void operator=(const SmartMutex<mt_only> &);
+    };
+
+    /// Mutex - A standard, always enforced mutex.
+    typedef SmartMutex<false> Mutex;
+
+    template<bool mt_only>
+    class SmartScopedLock  {
+      SmartMutex<mt_only>& mtx;
+
+    public:
+      SmartScopedLock(SmartMutex<mt_only>& m) : mtx(m) {
+        mtx.acquire();
+      }
+
+      ~SmartScopedLock() {
+        mtx.release();
+      }
+    };
+
+    typedef SmartScopedLock<false> ScopedLock;
+  }
+}
+
+#endif