124 lines
3.4 KiB
C++
124 lines
3.4 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_queuing_mutex_H
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#define __TBB_queuing_mutex_H
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#include "tbb_config.h"
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#if !TBB_USE_EXCEPTIONS && _MSC_VER
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// Suppress "C++ exception handler used, but unwind semantics are not enabled" warning in STL headers
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#pragma warning (push)
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#pragma warning (disable: 4530)
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#endif
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#include <cstring>
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#if !TBB_USE_EXCEPTIONS && _MSC_VER
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#pragma warning (pop)
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#endif
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#include "atomic.h"
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#include "tbb_profiling.h"
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namespace tbb {
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//! Queuing mutex with local-only spinning.
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/** @ingroup synchronization */
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class queuing_mutex : internal::mutex_copy_deprecated_and_disabled {
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public:
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//! Construct unacquired mutex.
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queuing_mutex() {
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q_tail = NULL;
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#if TBB_USE_THREADING_TOOLS
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internal_construct();
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#endif
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}
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//! The scoped locking pattern
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/** It helps to avoid the common problem of forgetting to release lock.
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It also nicely provides the "node" for queuing locks. */
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class scoped_lock: internal::no_copy {
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//! Initialize fields to mean "no lock held".
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void initialize() {
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mutex = NULL;
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#if TBB_USE_ASSERT
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internal::poison_pointer(next);
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#endif /* TBB_USE_ASSERT */
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}
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public:
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//! Construct lock that has not acquired a mutex.
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/** Equivalent to zero-initialization of *this. */
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scoped_lock() {initialize();}
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//! Acquire lock on given mutex.
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scoped_lock( queuing_mutex& m ) {
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initialize();
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acquire(m);
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}
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//! Release lock (if lock is held).
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~scoped_lock() {
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if( mutex ) release();
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}
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//! Acquire lock on given mutex.
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void __TBB_EXPORTED_METHOD acquire( queuing_mutex& m );
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//! Acquire lock on given mutex if free (i.e. non-blocking)
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bool __TBB_EXPORTED_METHOD try_acquire( queuing_mutex& m );
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//! Release lock.
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void __TBB_EXPORTED_METHOD release();
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private:
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//! The pointer to the mutex owned, or NULL if not holding a mutex.
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queuing_mutex* mutex;
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//! The pointer to the next competitor for a mutex
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scoped_lock *next;
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//! The local spin-wait variable
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/** Inverted (0 - blocked, 1 - acquired the mutex) for the sake of
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zero-initialization. Defining it as an entire word instead of
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a byte seems to help performance slightly. */
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uintptr_t going;
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};
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void __TBB_EXPORTED_METHOD internal_construct();
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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 = true;
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private:
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//! The last competitor requesting the lock
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atomic<scoped_lock*> q_tail;
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};
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__TBB_DEFINE_PROFILING_SET_NAME(queuing_mutex)
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} // namespace tbb
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#endif /* __TBB_queuing_mutex_H */
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