How do I setup CFReadStreamRead to timeout in iOS? - iphone

Question

I have legacy code using CFReadStreamRead on the iOS, but if there is no/loss of a connection CFReadStreamRead will block forever. How do I setup CFReadStreamRead to timeout?
Thanks in advance

Answer 1

#Michael Wildermuth Yes, there was an error on opening the stream and got it fixed. Someone who face the same issue, the below code would help.
NSURL *url = [NSURL URLWithString:#"http://www.google.com"];
CFStreamClientContext dataStreamContext = {0, (__bridge void *)(self), NULL, NULL, NULL};
CFHTTPMessageRef message = CFHTTPMessageCreateRequest(kCFAllocatorDefault, CFSTR("GET"), (__bridge CFURLRef)url, kCFHTTPVersion1_1);
NSString *header;
NSDictionary *requestHeaders = [NSDictionary dictionaryWithObject:#"application/html;charset=UTF-8" forKey:#"Content-Type"];
for (header in requestHeaders) {
CFHTTPMessageSetHeaderFieldValue(message, (__bridge CFStringRef)header, (__bridge CFStringRef)[requestHeaders objectForKey:header]);
}
CFHTTPMessageSetBody(message, (CFDataRef)(CFSTR("")));
CFReadStreamRef readStream = CFReadStreamCreateForHTTPRequest(kCFAllocatorDefault, message);
CFOptionFlags events = kCFStreamEventHasBytesAvailable | kCFStreamEventErrorOccurred | kCFStreamEventEndEncountered;
if(CFReadStreamSetClient(readStream, events, EvenCallBack, &dataStreamContext)){
CFReadStreamScheduleWithRunLoop(readStream, CFRunLoopGetCurrent(), kCFRunLoopCommonModes);
}
CFReadStreamOpen(readStream);
And for the callback function,
void EvenCallBack(CFReadStreamRef readStream, CFStreamEventType type, void *clientCallBackInfo){
if(CFReadStreamHasBytesAvailable(readStream))
{
uint8_t buf[1024];
unsigned int len = 1024;
CFIndex numBytesRead = CFReadStreamRead(readStream, buf, len);
NSMutableData* data = [[NSMutableData alloc] init];
[data appendBytes:&buf length:numBytesRead];
NSString *str = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
NSLog(#"Network read (%d): %#", len, str);
}else {
return;
}
CFHTTPMessageRef message = (CFHTTPMessageRef)CFReadStreamCopyProperty((CFReadStreamRef)readStream, kCFStreamPropertyHTTPResponseHeader);
if (!message) {
NSLog(#"No message");
}
}
Thanks!

Answer 2

I ended up using a home grown timeout. The code was something like this:
uint64_t start = get_current_time();
while(TRUE) {
if(CFReadStreamHasBytesAvailable(stream) == TRUE) {
while ((bytes_read = CFReadStreamRead(stream, buffer, read_size)) > 0) {
// do work!
}
start = get_current_time();
}
uint64_t elapsed = get_current_time() - start;
if(elapsed > timeout) {
break;
}
sleep(10);
}

Answer 3

while ((bytes_read = CFReadStreamRead(stream, buffer, read_size)) > 0) {
// do work!
}
I don't think this code achieves anything special. CFReadStreamRead is internally implemented in a similar manner. Quoting Apple's documentation on this: "This function blocks until at least one byte is available; it does not block until buffer is filled."

Answer 4

I set a custom timeout method:
var hasRecievedUpdate = false
var httpStream: CFReadStream?
var handler: ((Data?, URLResponse?, Error?) -> Void)?
func send() {
let stream = httpStream as Stream
stream.delegate = self
stream.schedule(in: RunLoop.current, forMode: RunLoop.Mode.default)
stream.open()
hasRecievedUpdate = false
DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + self.timeout) {
if !self.hasRecievedUpdate
{
stream.close()
self.handler?(nil, nil, nil)
}
}
}
func stream(_ aStream: Stream, handle eventCode: Stream.Event) {
self.hasRecievedUpdate = true
...
}