Intel Threading Building Blocks

ReaderWriterMutex Concept

The ReaderWriterMutex Concept extends the Mutex Concept to include the notion of reader-writer locks. It introduces a Boolean parameter, write, that specifies whether a writer lock (write = true) or reader lock (write = false) is being requested. Multiple reader locks can be held simultaneously on a ReaderWriterMutex if it does not have a writer lock on it. A writer lock on a ReaderWriterMutex excludes all other tasks from holding a lock on the mutex at the same time.

Table 7-3 shows the requirements for ReaderWriterMutexRW.

Table 7-3. ReaderWriterMutex Concept

Pseudosignature	Semantics
RW ()	Construct an unlocked mutex.
~RW ()	Destroy an unlocked mutex.
RW ::scoped_lock::acquire(RW&, bool write=true)	Acquire lock on mutex.
RW ::scoped_lock::release( )	Release lock.
bool RW::scoped_lock::upgrade_to_writer( )	Change reader lock to writer lock.
bool RW::scoped_lock::downgrade_to_reader( )	Change writer lock to reader lock.