Hello Devs,
I'd like some feedback on my design here as I'm building an API that I hope
will be of use to the community, and some of the finer nuances of Cocoa still
escape me.
I'm building a class called TDSConnection which is part of a object graph
providing connectivity to the Tabular Data Stream format in objective-c. (TDS
is the Microsoft SQL protocol). What I've got is some interesting threading
and synchronization issues. The one that I'm trying to check for correctness
currently is thus:
I have a method -[TDSConnection open] which should open two NSStreams (input
and output), block until both are open or erred then perform the TDS packets
for login. The method of doing this for me looks like this:
- (void)open
{
[self close];
[NSStream getStreamsToHost:host
port:port
inputStream:&inputStream
outputStream:&outputStream];
[inputStream setDelegate:self];
[outputStream setDelegate:self];
[inputStream scheduleInRunLoop:[NSRunLoop currentRunLoop]
forMode:NSDefaultRunLoopMode];
[outputStream scheduleInRunLoop:[NSRunLoop currentRunLoop]
forMode:NSDefaultRunLoopMode];
[inputStreamCondition lock];
[outputStreamCondition lock];
[inputStream open];
[outputStream open];
[inputStreamCondition wait];
[outputStreamCondition wait];
}
- (void)stream:(NSStream *)stream handleEvent:(NSStreamEvent)eventCode
{
if (stream == inputStream) {
[self handleInputStreamEvent:eventCode];
} else if (stream == outputStream) {
[self handleOutputStreamEvent:eventCode];
} else {
NSLog(@"Recieved a stream event for instance %@ which was not
the input or output stream", stream);
}
}
- (void)handleInputStreamEvent:(NSStreamEvent)eventCode {
switch (eventCode) {
case NSStreamEventOpenCompleted:
[inputStreamCondition signal];
break;
default:
break;
}
}
- (void)handleOutputStreamEvent:(NSStreamEvent)eventCode {
switch (eventCode) {
case NSStreamEventOpenCompleted:
[outputStreamCondition signal];
break;
default:
break;
}
}
As can be seen, I am using a NSCondition to block the main thread until I
receive both NSStreamEventOpenCompleted events.
I have a feeling that this code smells a bit, and was wondering if someone
who's done some networking programming has recommendations.
Grateful as always,
Richard
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