149 lines
4.4 KiB
C++
149 lines
4.4 KiB
C++
/*
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Copyright (c) 2005-2017 Intel Corporation
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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#ifndef __TBB__x86_eliding_mutex_impl_H
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#define __TBB__x86_eliding_mutex_impl_H
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#ifndef __TBB_spin_mutex_H
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#error Do not #include this internal file directly; use public TBB headers instead.
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#endif
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#if ( __TBB_x86_32 || __TBB_x86_64 )
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namespace tbb {
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namespace interface7 {
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namespace internal {
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template<typename Mutex, bool is_rw>
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class padded_mutex;
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//! An eliding lock that occupies a single byte.
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/** A x86_eliding_mutex is an HLE-enabled spin mutex. It is recommended to
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put the mutex on a cache line that is not shared by the data it protects.
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It should be used for locking short critical sections where the lock is
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contended but the data it protects are not. If zero-initialized, the
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mutex is considered unheld.
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@ingroup synchronization */
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class x86_eliding_mutex : tbb::internal::mutex_copy_deprecated_and_disabled {
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//! 0 if lock is released, 1 if lock is acquired.
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__TBB_atomic_flag flag;
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friend class padded_mutex<x86_eliding_mutex, false>;
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public:
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//! Construct unacquired lock.
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/** Equivalent to zero-initialization of *this. */
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x86_eliding_mutex() : flag(0) {}
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// bug in gcc 3.x.x causes syntax error in spite of the friend declaration above.
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// Make the scoped_lock public in that case.
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#if __TBB_USE_X86_ELIDING_MUTEX || __TBB_GCC_VERSION < 40000
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#else
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// by default we will not provide the scoped_lock interface. The user
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// should use the padded version of the mutex. scoped_lock is used in
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// padded_mutex template.
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private:
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#endif
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// scoped_lock in padded_mutex<> is the interface to use.
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//! Represents acquisition of a mutex.
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class scoped_lock : tbb::internal::no_copy {
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private:
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//! Points to currently held mutex, or NULL if no lock is held.
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x86_eliding_mutex* my_mutex;
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public:
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//! Construct without acquiring a mutex.
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scoped_lock() : my_mutex(NULL) {}
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//! Construct and acquire lock on a mutex.
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scoped_lock( x86_eliding_mutex& m ) : my_mutex(NULL) { acquire(m); }
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//! Acquire lock.
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void acquire( x86_eliding_mutex& m ) {
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__TBB_ASSERT( !my_mutex, "already holding a lock" );
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my_mutex=&m;
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my_mutex->lock();
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}
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//! Try acquiring lock (non-blocking)
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/** Return true if lock acquired; false otherwise. */
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bool try_acquire( x86_eliding_mutex& m ) {
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__TBB_ASSERT( !my_mutex, "already holding a lock" );
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bool result = m.try_lock();
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if( result ) {
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my_mutex = &m;
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}
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return result;
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}
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//! Release lock
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void release() {
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__TBB_ASSERT( my_mutex, "release on scoped_lock that is not holding a lock" );
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my_mutex->unlock();
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my_mutex = NULL;
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}
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//! Destroy lock. If holding a lock, releases the lock first.
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~scoped_lock() {
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if( my_mutex ) {
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release();
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}
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}
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};
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#if __TBB_USE_X86_ELIDING_MUTEX || __TBB_GCC_VERSION < 40000
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#else
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public:
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#endif /* __TBB_USE_X86_ELIDING_MUTEX */
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// Mutex traits
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static const bool is_rw_mutex = false;
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static const bool is_recursive_mutex = false;
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static const bool is_fair_mutex = false;
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// ISO C++0x compatibility methods
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//! Acquire lock
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void lock() {
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__TBB_LockByteElided(flag);
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}
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//! Try acquiring lock (non-blocking)
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/** Return true if lock acquired; false otherwise. */
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bool try_lock() {
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return __TBB_TryLockByteElided(flag);
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}
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//! Release lock
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void unlock() {
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__TBB_UnlockByteElided( flag );
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}
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}; // end of x86_eliding_mutex
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} // namespace internal
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} // namespace interface7
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} // namespace tbb
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#endif /* ( __TBB_x86_32 || __TBB_x86_64 ) */
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#endif /* __TBB__x86_eliding_mutex_impl_H */
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