On 3/14/11 4:11 PM, Jonas Drewsen wrote:
On 14/03/11 18.55, Andrei Alexandrescu wrote:
Assume the body of the loop does some time-consuming processing - like
e.g. writing to another HTTP stream. Then your network reads should not
wait for that processing. While the user code does something, you should
already have the next transfer in flight.
Example: a utility that efficiently uses GET from one http source and
uses the data to POST it to an http target should be an efficient
few-liner. (FTP versions and mixed ones too.)
Andrei
I get it. Any existing implementation that does this I can have a look at?
Unfortunately not at the moment. I wanted to define such a thing for
std.stdio called byLineAsync and byChunkAsync but never got to it.
The basic idea is:
1. Define a new range type, e.g. AsyncHttpInputRange
2. Inside that range start a secondary thread that does the actual
transfer and passes read buffers to the main thread by means of messages
3. See std.concurrency and the free chapter
http://www.informit.com/articles/printerfriendly.aspx?p=1609144 for details
4. Control congestion (too many buffers in flight) with setMaxMailboxSize.
5. Make sure you have a little protocol that stops the secondary thread
when the range is destroyed.
Andrei
