public Subscription Subscribe(
CancellationToken ct,
long start,
int bufferSize,
int cacheSize
) {
var sub = new Subscription();
sub.Task = Task.Factory.StartNew(() => RunSubscription(sub, start, ct, bufferSize, cacheSize),
TaskCreationOptions.LongRunning);
return sub;
}
void RunSubscription(
Subscription sub,
long position,
CancellationToken ct,
int bufferSize,
int cacheSize
) {
sub.DebugStartPosition = position;
var buffer = new byte[bufferSize];
// forever try
while (!ct.IsCancellationRequested) {
try {
// read current max length
var length = _position.Read();
sub.DebugKnownMaxOffset = length;
using (var prs = new PageReadStream(_messages, position, length, buffer)) {
using (var bin = new BinaryReader(prs)) {
while (prs.Position < prs.Length) {
var message = StorageFormat.Read(bin);
sub.Buffer.Enqueue(message);
sub.DebugEnqueuedOffset = prs.Position;
position = prs.Position;
while (sub.Buffer.Count >= cacheSize) {
ct.WaitHandle.WaitOne(500);
}
}
}
}
// wait till we get chance to advance
while (_position.Read() == position)
{
if (ct.WaitHandle.WaitOne(1000)) {
return;
}
}
}
catch (Exception ex) {
Debug.Print("Exception {0}", ex);
ct.WaitHandle.WaitOne(1000*5);
}
}
}