tbb::spin_rw_mutex_v3::scoped_lock Class Reference

The scoped locking pattern. More...

#include <spin_rw_mutex.h>

Inheritance diagram for tbb::spin_rw_mutex_v3::scoped_lock:

Collaboration diagram for tbb::spin_rw_mutex_v3::scoped_lock:

Public Member Functions
	scoped_lock ()
	Construct lock that has not acquired a mutex. More...
	scoped_lock (spin_rw_mutex &m, bool write=true)
	Acquire lock on given mutex. More...
	~scoped_lock ()
	Release lock (if lock is held). More...
void	acquire (spin_rw_mutex &m, bool write=true)
	Acquire lock on given mutex. More...
bool	upgrade_to_writer ()
	Upgrade reader to become a writer. More...
void	release ()
	Release lock. More...
bool	downgrade_to_reader ()
	Downgrade writer to become a reader. More...
bool	try_acquire (spin_rw_mutex &m, bool write=true)
	Try acquire lock on given mutex. More...

Protected Attributes
spin_rw_mutex *	mutex
	The pointer to the current mutex that is held, or NULL if no mutex is held. More...
bool	is_writer
	If mutex!=NULL, then is_writer is true if holding a writer lock, false if holding a reader lock. More...

Additional Inherited Members
Private Member Functions inherited from tbb::internal::no_copy
	no_copy (const no_copy &)=delete
	no_copy ()=default

Detailed Description

The scoped locking pattern.

It helps to avoid the common problem of forgetting to release lock. It also nicely provides the "node" for queuing locks.

Definition at line 86 of file spin_rw_mutex.h.

Constructor & Destructor Documentation

scoped_lock() [1/2]

tbb::spin_rw_mutex_v3::scoped_lock::scoped_lock ( )

inline

Construct lock that has not acquired a mutex.

Equivalent to zero-initialization of *this.

Definition at line 93 of file spin_rw_mutex.h.

: mutex(NULL), is_writer(false) {}

scoped_lock() [2/2]

tbb::spin_rw_mutex_v3::scoped_lock::scoped_lock ( spin_rw_mutex &  m, bool  write = true  )

inline

Acquire lock on given mutex.

Definition at line 96 of file spin_rw_mutex.h.

                                                           : mutex(NULL) {
            acquire(m, write);
        }

References acquire().

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~scoped_lock()

tbb::spin_rw_mutex_v3::scoped_lock::~scoped_lock ( )

inline

Release lock (if lock is held).

Definition at line 101 of file spin_rw_mutex.h.

                       {
            if( mutex ) release();
        }

References mutex, and release().

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Member Function Documentation

acquire()

void tbb::spin_rw_mutex_v3::scoped_lock::acquire ( spin_rw_mutex &  m, bool  write = true  )

inline

Acquire lock on given mutex.

Definition at line 106 of file spin_rw_mutex.h.

                                                            {
            __TBB_ASSERT( !mutex, "holding mutex already" );
            is_writer = write;
            mutex = &m;
            if( write ) mutex->internal_acquire_writer();
            else        mutex->internal_acquire_reader();
        }

References __TBB_ASSERT, tbb::spin_rw_mutex_v3::internal_acquire_reader(), tbb::spin_rw_mutex_v3::internal_acquire_writer(), is_writer, and mutex.

Referenced by scoped_lock().

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downgrade_to_reader()

bool tbb::spin_rw_mutex_v3::scoped_lock::downgrade_to_reader ( )

inline

Downgrade writer to become a reader.

Definition at line 138 of file spin_rw_mutex.h.

                                   {
            __TBB_ASSERT( mutex, "mutex is not acquired" );
            if (!is_writer) return true; // Already a reader
#if TBB_USE_THREADING_TOOLS||TBB_USE_ASSERT
            mutex->internal_downgrade();
#else
            __TBB_FetchAndAddW( &mutex->state, ((intptr_t)ONE_READER-WRITER));
#endif /* TBB_USE_THREADING_TOOLS||TBB_USE_ASSERT */
            is_writer = false;
            return true;
        }

References __TBB_ASSERT, tbb::spin_rw_mutex_v3::internal_downgrade(), is_writer, mutex, tbb::spin_rw_mutex_v3::ONE_READER, tbb::spin_rw_mutex_v3::state, and tbb::spin_rw_mutex_v3::WRITER.

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release()

void tbb::spin_rw_mutex_v3::scoped_lock::release ( )

inline

Release lock.

Definition at line 124 of file spin_rw_mutex.h.

                       {
            __TBB_ASSERT( mutex, "mutex is not acquired" );
            spin_rw_mutex *m = mutex;
            mutex = NULL;
#if TBB_USE_THREADING_TOOLS||TBB_USE_ASSERT
            if( is_writer ) m->internal_release_writer();
            else            m->internal_release_reader();
#else
            if( is_writer ) __TBB_AtomicAND( &m->state, READERS );
            else            __TBB_FetchAndAddWrelease( &m->state, -(intptr_t)ONE_READER);
#endif /* TBB_USE_THREADING_TOOLS||TBB_USE_ASSERT */
        }

References __TBB_ASSERT, __TBB_AtomicAND(), __TBB_FetchAndAddWrelease, tbb::spin_rw_mutex_v3::internal_release_reader(), tbb::spin_rw_mutex_v3::internal_release_writer(), is_writer, mutex, tbb::spin_rw_mutex_v3::ONE_READER, tbb::spin_rw_mutex_v3::READERS, and tbb::spin_rw_mutex_v3::state.

Referenced by ~scoped_lock().

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try_acquire()

bool tbb::spin_rw_mutex_v3::scoped_lock::try_acquire ( spin_rw_mutex &  m, bool  write = true  )

inline

Try acquire lock on given mutex.

Definition at line 151 of file spin_rw_mutex.h.

                                                                {
            __TBB_ASSERT( !mutex, "holding mutex already" );
            bool result;
            is_writer = write;
            result = write? m.internal_try_acquire_writer()
                          : m.internal_try_acquire_reader();
            if( result )
                mutex = &m;
            return result;
        }

References __TBB_ASSERT, tbb::spin_rw_mutex_v3::internal_try_acquire_reader(), tbb::spin_rw_mutex_v3::internal_try_acquire_writer(), is_writer, and mutex.

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upgrade_to_writer()

bool tbb::spin_rw_mutex_v3::scoped_lock::upgrade_to_writer ( )

inline

Upgrade reader to become a writer.

Returns whether the upgrade happened without releasing and re-acquiring the lock

Definition at line 116 of file spin_rw_mutex.h.

                                 {
            __TBB_ASSERT( mutex, "mutex is not acquired" );
            if (is_writer) return true; // Already a writer
            is_writer = true;
            return mutex->internal_upgrade();
        }

References __TBB_ASSERT, tbb::spin_rw_mutex_v3::internal_upgrade(), is_writer, and mutex.

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Member Data Documentation

is_writer

bool tbb::spin_rw_mutex_v3::scoped_lock::is_writer

protected

If mutex!=NULL, then is_writer is true if holding a writer lock, false if holding a reader lock.

Not defined if not holding a lock.

Definition at line 169 of file spin_rw_mutex.h.

Referenced by acquire(), downgrade_to_reader(), release(), try_acquire(), and upgrade_to_writer().

mutex

spin_rw_mutex* tbb::spin_rw_mutex_v3::scoped_lock::mutex

protected

The pointer to the current mutex that is held, or NULL if no mutex is held.

Definition at line 165 of file spin_rw_mutex.h.

Referenced by acquire(), downgrade_to_reader(), release(), try_acquire(), upgrade_to_writer(), and ~scoped_lock().

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The documentation for this class was generated from the following file:

• spin_rw_mutex.h