Initial commit: Final state of the master project

Research/inc/tbb/internal/_mutex_padding.h

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+/*
+    Copyright 2005-2015 Intel Corporation.  All Rights Reserved.
+
+    This file is part of Threading Building Blocks. Threading Building Blocks is free software;
+    you can redistribute it and/or modify it under the terms of the GNU General Public License
+    version 2  as  published  by  the  Free Software Foundation.  Threading Building Blocks is
+    distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the
+    implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+    See  the GNU General Public License for more details.   You should have received a copy of
+    the  GNU General Public License along with Threading Building Blocks; if not, write to the
+    Free Software Foundation, Inc.,  51 Franklin St,  Fifth Floor,  Boston,  MA 02110-1301 USA
+
+    As a special exception,  you may use this file  as part of a free software library without
+    restriction.  Specifically,  if other files instantiate templates  or use macros or inline
+    functions from this file, or you compile this file and link it with other files to produce
+    an executable,  this file does not by itself cause the resulting executable to be covered
+    by the GNU General Public License. This exception does not however invalidate any other
+    reasons why the executable file might be covered by the GNU General Public License.
+*/
+
+#ifndef __TBB_mutex_padding_H
+#define __TBB_mutex_padding_H
+
+// wrapper for padding mutexes to be alone on a cache line, without requiring they be allocated
+// from a pool.  Because we allow them to be defined anywhere they must be two cache lines in size.
+
+
+namespace tbb {
+namespace interface7 {
+namespace internal {
+
+static const size_t cache_line_size = 64;
+
+// Pad a mutex to occupy a number of full cache lines sufficient to avoid false sharing
+// with other data; space overhead is up to 2*cache_line_size-1.
+template<typename Mutex, bool is_rw> class padded_mutex;
+
+template<typename Mutex>
+class padded_mutex<Mutex,false> : tbb::internal::mutex_copy_deprecated_and_disabled {
+    typedef long pad_type;
+    pad_type my_pad[((sizeof(Mutex)+cache_line_size-1)/cache_line_size+1)*cache_line_size/sizeof(pad_type)];
+
+    Mutex *impl() { return (Mutex *)((uintptr_t(this)|(cache_line_size-1))+1);}
+
+public:
+    static const bool is_rw_mutex = Mutex::is_rw_mutex;
+    static const bool is_recursive_mutex = Mutex::is_recursive_mutex;
+    static const bool is_fair_mutex = Mutex::is_fair_mutex;
+
+    padded_mutex() { new(impl()) Mutex(); }
+    ~padded_mutex() { impl()->~Mutex(); }
+
+    //! Represents acquisition of a mutex.
+    class scoped_lock :  tbb::internal::no_copy {
+        typename Mutex::scoped_lock my_scoped_lock;
+    public:
+        scoped_lock() : my_scoped_lock() {}
+        scoped_lock( padded_mutex& m ) : my_scoped_lock(*m.impl()) { }
+        ~scoped_lock() {  }
+
+        void acquire( padded_mutex& m ) { my_scoped_lock.acquire(*m.impl()); }
+        bool try_acquire( padded_mutex& m ) { return my_scoped_lock.try_acquire(*m.impl()); }
+        void release() { my_scoped_lock.release(); }
+    };
+};
+
+template<typename Mutex>
+class padded_mutex<Mutex,true> : tbb::internal::mutex_copy_deprecated_and_disabled {
+    typedef long pad_type;
+    pad_type my_pad[((sizeof(Mutex)+cache_line_size-1)/cache_line_size+1)*cache_line_size/sizeof(pad_type)];
+
+    Mutex *impl() { return (Mutex *)((uintptr_t(this)|(cache_line_size-1))+1);}
+
+public:
+    static const bool is_rw_mutex = Mutex::is_rw_mutex;
+    static const bool is_recursive_mutex = Mutex::is_recursive_mutex;
+    static const bool is_fair_mutex = Mutex::is_fair_mutex;
+
+    padded_mutex() { new(impl()) Mutex(); }
+    ~padded_mutex() { impl()->~Mutex(); }
+
+    //! Represents acquisition of a mutex.
+    class scoped_lock :  tbb::internal::no_copy {
+        typename Mutex::scoped_lock my_scoped_lock;
+    public:
+        scoped_lock() : my_scoped_lock() {}
+        scoped_lock( padded_mutex& m, bool write = true ) : my_scoped_lock(*m.impl(),write) { }
+        ~scoped_lock() {  }
+
+        void acquire( padded_mutex& m, bool write = true ) { my_scoped_lock.acquire(*m.impl(),write); }
+        bool try_acquire( padded_mutex& m, bool write = true ) { return my_scoped_lock.try_acquire(*m.impl(),write); }
+        bool upgrade_to_writer() { return my_scoped_lock.upgrade_to_writer(); }
+        bool downgrade_to_reader() { return my_scoped_lock.downgrade_to_reader(); }
+        void release() { my_scoped_lock.release(); }
+    };
+};
+
+} // namespace internal
+} // namespace interface7
+} // namespace tbb
+
+#endif /* __TBB_mutex_padding_H */