public IAsyncResult BeginWrite(ReaderWriterGateCallback callback, Object state,
AsyncCallback asyncCallback, Object asyncState) {
AsyncResult<Object> ar = new AsyncResult<Object>(asyncCallback, asyncState);
ReaderWriterGateReleaser releaser = new ReaderWriterGateReleaser(callback, this, false, state, ar);
m_syncLock.Enter(true);
switch (m_state) {
case ReaderWriterGateStates.Free: // If Free "RFW -> OBW, invoke, return
case ReaderWriterGateStates.ReservedForWriter:
m_state = ReaderWriterGateStates.OwnedByWriter;
ThreadPool.QueueUserWorkItem(releaser.Invoke);
break;
case ReaderWriterGateStates.OwnedByReaders: // If OBR | OBRAWP -> OBRAWP, queue, return
case ReaderWriterGateStates.OwnedByReadersAndWriterPending:
m_state = ReaderWriterGateStates.OwnedByReadersAndWriterPending;
m_qWriteRequests.Enqueue(releaser);
break;
case ReaderWriterGateStates.OwnedByWriter: // If OBW, queue, return
m_qWriteRequests.Enqueue(releaser);
break;
}
m_syncLock.Leave();
return ar;
}
public IAsyncResult BeginWrite(ReaderWriterGateCallback callback, Object state,
AsyncCallback asyncCallback, Object asyncState)
{
AsyncResult <Object> ar = new AsyncResult <Object>(asyncCallback, asyncState);
ReaderWriterGateReleaser releaser = new ReaderWriterGateReleaser(callback, this, false, state, ar);
m_syncLock.Enter(true);
switch (m_state)
{
case ReaderWriterGateStates.Free: // If Free "RFW -> OBW, invoke, return
case ReaderWriterGateStates.ReservedForWriter:
m_state = ReaderWriterGateStates.OwnedByWriter;
ThreadPool.QueueUserWorkItem(releaser.Invoke);
break;
case ReaderWriterGateStates.OwnedByReaders: // If OBR | OBRAWP -> OBRAWP, queue, return
case ReaderWriterGateStates.OwnedByReadersAndWriterPending:
m_state = ReaderWriterGateStates.OwnedByReadersAndWriterPending;
m_qWriteRequests.Enqueue(releaser);
break;
case ReaderWriterGateStates.OwnedByWriter: // If OBW, queue, return
m_qWriteRequests.Enqueue(releaser);
break;
}
m_syncLock.Leave();
return(ar);
}
// The code in this method has exclusive access to the catalog.
private Object UpdateCatalog(ReaderWriterGateReleaser r)
{
CatalogEntry[] catalogEntries = (CatalogEntry[])r.State;
// Update the catalog with the new entries...
// When this method returns, exclusive access is relinquished.
return null;
}
// The code in this method has shared read access to the catalog.
private Object BuyCatalogProducts(ReaderWriterGateReleaser r)
{
using (r) {
CatIDAndQuantity[] items = (CatIDAndQuantity[])r.State;
foreach (CatIDAndQuantity item in items) {
// Process each catalog item to build customer's order...
}
} // When r is Disposed, read access is relinquished.
// Save customer's order to database
// Send customer e-mail confirming order
return null;
}
private void UpdateFile(ReaderWriterGateReleaser r)
{
// Update the file (NOTE: should be async I/O if file is on remote server)
File.WriteAllText(m_filename, (String)r.State);
// Update the time of the last update
m_lastUpdate = DateTime.Now;
}
