ReaderWriterLock::ReleaseLock Method ()
.NET Framework (current version)
Releases the lock, regardless of the number of times the thread acquired the lock.
Assembly: mscorlib (in mscorlib.dll)
ReleaseLock releases the reader lock or writer lock, regardless of the recursive lock count. To restore the state of the lock, including the lock count, pass the LockCookie to RestoreLock.
The following code example shows how to use the ReleaseLock method to release the lock, regardless of how many times it has been acquired by the thread, and how to restore the state of the lock later.
This code is part of a larger example provided for the ReaderWriterLock class.
// The complete code is located in the ReaderWriterLock // class topic. using namespace System; using namespace System::Threading; public ref class Test { public: // Declaring the ReaderWriterLock at the class level // makes it visible to all threads. static ReaderWriterLock^ rwl = gcnew ReaderWriterLock; // For this example, the shared resource protected by the // ReaderWriterLock is just an integer. static int resource = 0;
// Shows how to release all locks and later restore // the lock state. Shows how to use sequence numbers // to determine whether another thread has obtained // a writer lock since this thread last accessed the // resource. static void ReleaseRestore( int timeOut ) { int lastWriter; try { rwl->AcquireReaderLock( timeOut ); try { // It is safe for this thread to read from // the shared resource. Cache the value. (You // might do this if reading the resource is // an expensive operation.) int resourceValue = resource; Display( String::Format( "reads resource value {0}", resourceValue ) ); Interlocked::Increment( reads ); // Save the current writer sequence number. lastWriter = rwl->WriterSeqNum; // Release the lock, and save a cookie so the // lock can be restored later. LockCookie lc = rwl->ReleaseLock(); // Wait for a random interval (up to a // quarter of a second), and then restore // the previous state of the lock. Note that // there is no timeout on the Restore method. Thread::Sleep( rnd->Next( 250 ) ); rwl->RestoreLock( lc ); // Check whether other threads obtained the // writer lock in the interval. If not, then // the cached value of the resource is still // valid. if ( rwl->AnyWritersSince( lastWriter ) ) { resourceValue = resource; Interlocked::Increment( reads ); Display( String::Format( "resource has changed {0}", resourceValue ) ); } else { Display( String::Format( "resource has not changed {0}", resourceValue ) ); } } finally { // Ensure that the lock is released. rwl->ReleaseReaderLock(); } } catch ( ApplicationException^ ) { // The reader lock request timed out. Interlocked::Increment( readerTimeouts ); } }
.NET Framework
Available since 1.1
Available since 1.1
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