/// <summary>
/// Serialize the first object in the queue to the a memory stream which will be copied into shared memory.
/// The write stream which is being written to is not the shared memory itself, it is a memory stream from which
/// bytes will be copied and placed in the shared memory in the write method.
/// </summary>
private void SerializeCallDescriptorToStream(DualQueue <LocalCallDescriptor> objectsToWrite)
{
// Get the object by peeking at the queue rather than dequeueing the object. This is done
// because we only want to dequeue the object when it has completely been put in shared memory.
// This may be done right away if the object is small enough to fit in the shared memory or
// may happen after a the object is sent as a number of smaller chunks.
object objectToWrite = objectsToWrite.Peek();
Debug.Assert(objectToWrite != null, "Expect to get a non-null object from the queue");
if (objectToWrite is LocalCallDescriptorForPostBuildResult)
{
writeStream.WriteByte((byte)ObjectType.PostBuildResult);
((LocalCallDescriptorForPostBuildResult)objectToWrite).WriteToStream(binaryWriter);
}
else if (objectToWrite is LocalCallDescriptorForPostBuildRequests)
{
writeStream.WriteByte((byte)ObjectType.PostBuildRequests);
((LocalCallDescriptorForPostBuildRequests)objectToWrite).WriteToStream(binaryWriter);
}
else if (objectToWrite is LocalCallDescriptorForPostLoggingMessagesToHost)
{
writeStream.WriteByte((byte)ObjectType.PostLoggingMessagesToHost);
((LocalCallDescriptorForPostLoggingMessagesToHost)objectToWrite).WriteToStream(binaryWriter, loggingTypeCache);
}
else if (objectToWrite is LocalCallDescriptorForInitializeNode)
{
writeStream.WriteByte((byte)ObjectType.InitializeNode);
((LocalCallDescriptorForInitializeNode)objectToWrite).WriteToStream(binaryWriter);
}
else if (objectToWrite is LocalCallDescriptorForInitializationComplete)
{
writeStream.WriteByte((byte)ObjectType.InitializationComplete);
((LocalCallDescriptorForInitializationComplete)objectToWrite).WriteToStream(binaryWriter);
}
else if (objectToWrite is LocalCallDescriptorForUpdateNodeSettings)
{
writeStream.WriteByte((byte)ObjectType.UpdateNodeSettings);
((LocalCallDescriptorForUpdateNodeSettings)objectToWrite).WriteToStream(binaryWriter);
}
else if (objectToWrite is LocalCallDescriptorForRequestStatus)
{
writeStream.WriteByte((byte)ObjectType.RequestStatus);
((LocalCallDescriptorForRequestStatus)objectToWrite).WriteToStream(binaryWriter);
}
else if (objectToWrite is LocalCallDescriptorForPostingCacheEntriesToHost)
{
writeStream.WriteByte((byte)ObjectType.PostCacheEntriesToHost);
((LocalCallDescriptorForPostingCacheEntriesToHost)objectToWrite).WriteToStream(binaryWriter);
}
else if (objectToWrite is LocalCallDescriptorForGettingCacheEntriesFromHost)
{
writeStream.WriteByte((byte)ObjectType.GetCacheEntriesFromHost);
((LocalCallDescriptorForGettingCacheEntriesFromHost)objectToWrite).WriteToStream(binaryWriter);
}
else if (objectToWrite is LocalCallDescriptorForShutdownComplete)
{
writeStream.WriteByte((byte)ObjectType.ShutdownComplete);
((LocalCallDescriptorForShutdownComplete)objectToWrite).WriteToStream(binaryWriter);
}
else if (objectToWrite is LocalCallDescriptorForShutdownNode)
{
writeStream.WriteByte((byte)ObjectType.ShutdownNode);
((LocalCallDescriptorForShutdownNode)objectToWrite).WriteToStream(binaryWriter);
}
else if (objectToWrite is LocalCallDescriptorForPostIntrospectorCommand)
{
writeStream.WriteByte((byte)ObjectType.PostIntrospectorCommand);
((LocalCallDescriptorForPostIntrospectorCommand)objectToWrite).WriteToStream(binaryWriter);
}
else if (objectToWrite is LocalReplyCallDescriptor)
{
writeStream.WriteByte((byte)ObjectType.GenericSingleObjectReply);
((LocalReplyCallDescriptor)objectToWrite).WriteToStream(binaryWriter);
}
else if (objectToWrite is LocalCallDescriptorForPostStatus)
{
writeStream.WriteByte((byte)ObjectType.PostStatus);
((LocalCallDescriptorForPostStatus)objectToWrite).WriteToStream(binaryWriter);
}
else
{
// If the object is not one of the well known local descriptors, use .net Serialization to serialize the object
writeStream.WriteByte((byte)ObjectType.NetSerialization);
binaryFormatter.Serialize(writeStream, objectToWrite);
}
}
/// <summary>
/// This function write out a set of objects into the shared buffer.
/// In normal operation all the objects in the queue are serialized into
/// the buffer followed by an end marker class. If the buffer is not big
/// enough to contain a single object the object is broken into
/// multiple buffers as follows - first a frame marker is sent containing
/// the size of the serialized object + size of end marker. The reader makes
/// sure upon receiving the frame marker that its buffer is large enough
/// to contain the object about to be sent. After the frame marker the object
/// is sent as a series of buffers until all of it is written out.
/// </summary>
/// <param name="objectsToWrite"> Queue of objects to be sent (mostly logging messages)</param>
/// <param name="objectsToWriteHiPriority">Queue of high priority objects (these are commands and statuses) </param>
/// <param name="blockUntilDone"> If true the function will block until both queues are empty</param>
internal void Write(DualQueue <LocalCallDescriptor> objectsToWrite, DualQueue <LocalCallDescriptor> objectsToWriteHiPriority, bool blockUntilDone)
{
Debug.Assert(type == SharedMemoryType.WriteOnly, "Should only be calling Write from a writeonly shared memory object");
lock (writeLock)
{
// Loop as long as there are objects availiable and room in the shared memory.
// If blockUntilDone is set continue to loop until all of the objects in both queues are sent.
while ((objectsToWrite.Count > 0 || objectsToWriteHiPriority.Count > 0) &&
((blockUntilDone && notFullFlag.WaitOne()) || !IsFull))
{
bool isFull = false;
long writeStartPosition = writeStream.Position;
bool writeEndMarker = false;
// Put as many LocalCallDescriptor objects as possible into the shared memory
while (!isFull && (objectsToWrite.Count > 0 || objectsToWriteHiPriority.Count > 0))
{
long writeResetPosition = writeStream.Position;
DualQueue <LocalCallDescriptor> currentQueue = objectsToWriteHiPriority.Count > 0 ? objectsToWriteHiPriority : objectsToWrite;
// writeBytesRemaining == 0 is when we are currently not sending a multi part object through
// the shared memory
if (writeBytesRemaining == 0)
{
// Serialize the object to the memory stream
SerializeCallDescriptorToStream(currentQueue);
// If the size of the serialized object plus the end marker fits within the shared memory
// dequeue the object as it is going to be sent.
if ((writeStream.Position + sizeof(byte)) <= size)
{
currentQueue.Dequeue();
writeEndMarker = true;
}
else
{
// The serialized object plus the end marker is larger than the shared memory buffer
// Check if it necessary break down the object into multiple buffers
// If the memoryStream was empty before trying to serialize the object
// create a frame marker with the size of the object and send through the shared memory
if (writeResetPosition == 0)
{
// We don't want to switch from low priority to high priority queue in the middle of sending a large object
// so we make a record of which queue contains the large object
largeObjectsQueue = currentQueue;
// Calculate the total number of bytes that needs to be sent
writeBytesRemaining = (int)(writeStream.Position + sizeof(byte));
// Send a frame marker out to the reader containing the size of the object
writeStream.Position = 0;
// Write the frameMarkerId byte and then the amount of bytes for the large object
writeStream.WriteByte((byte)ObjectType.FrameMarker);
binaryWriter.Write((Int32)writeBytesRemaining);
writeEndMarker = true;
}
else
{
// Some items were placed in the shared Memory buffer, erase the last one which was too large
// and say the buffer is full so it can be sent
writeStream.Position = writeResetPosition;
}
isFull = true;
}
}
else
{
if (writeStream.Position == 0)
{
// Serialize the object which will be split across multiple buffers
SerializeCallDescriptorToStream(largeObjectsQueue);
writeStream.WriteByte((byte)ObjectType.EndMarker);
}
break;
}
}
// If a multi-buffer object is being sent and the large object is still larger or equal to the shard memory buffer - send the next chunk of the object
if (writeBytesRemaining != 0 && writeStream.Position >= size)
{
// Set write Length to an entire buffer length or just the remaining portion
int writeLength = writeBytesRemaining > size ? size : writeBytesRemaining;
//Write the length of the buffer to the memory file
Marshal.WriteInt32((IntPtr)pageFileView, (int)writeLength);
Marshal.Copy
(
writeStream.GetBuffer(), // Source Buffer
(int)(writeStream.Position - writeBytesRemaining), // Start index
(IntPtr)((int)pageFileView + 4), //Destination (+4 because of the int written to the memory file with the write length)
(int)writeLength // Length of bytes to write
);
writeBytesRemaining -= writeLength;
IncrementUnreadBatchCounter();
// Once the object is fully sent - remove it from the queue
if (writeBytesRemaining == 0)
{
largeObjectsQueue.Dequeue();
}
isFull = true;
}
if (writeEndMarker)
{
writeStream.WriteByte((byte)ObjectType.EndMarker);
// Need to verify the WriteInt32 and ReadInt32 are always atomic operations
//writeSizeMutex.WaitOne();
// Write the size of the buffer to send to the memory stream
Marshal.WriteInt32((IntPtr)pageFileView, (int)writeStream.Position);
//writeSizeMutex.ReleaseMutex();
Marshal.Copy
(
writeStream.GetBuffer(), // Buffer
(int)writeStartPosition, // Start Position
(IntPtr)((int)pageFileView + writeStartPosition + 4), // Destination + 4 for the int indicating the size of the data to be copied to the memory file
(int)(writeStream.Position - writeStartPosition) // Length of data to copy to memory file
);
IncrementUnreadBatchCounter();
}
if (isFull)
{
MarkAsFull();
writeStream.SetLength(0);
}
}
}
}
