Question

On one hand, I’m told that exceptions in C# are ‘expensive’, but on the other, I’m stuck on how to implement this.

My problem is this: I’m making a Stream derivitive, that wraps a NetworkStream. Now, the problem I’m facing is this: Read(byte[] buffer, int offset, int count). From the Stream docs for the function:

Returns:

… or zero (0) if the end of the stream has been reached.

The problem is, in the protocol I’m implementing the remote side can send an “end of record” token, or a “please respond” token. Obviously, if this happens at the start of the Read() this causes problems, since I need to return from the function, and I havn’t read anything, so I need to return 0, which means the stream is finished, but it isn’t… is a EndOfRecordException or similar justified in this case? And in this case, should it aways be thrown when this token is encountered (at the start of the Read() call and make sure these tokens are always at the start by returning early) so that there is some sort of pattern to how these tokens should be handled.

Edit: For what it’s worth, these tokens generally come through 3-10 times a second. At the most, I wouldn’t expect more than 25 a second.

Answer 1

Exceptions aren’t really all that expensive – but they also aren’t necessarily the best way to manage expected/normal flow.

To me, it sounds like you aren’t actually implementing a Stream – you are encapsulating a stream into a “reader”. I might be inclined to write a protocol-specific reader class with suitable methods to detect the end of a record, or Try... methods to get data or return false.