Friday, October 3, 2014

Rudiments - 0.48 is out

Rudiments 0.48 is now available!

This release has a few fairly important features.

Random Number Generation

The randomnumber class has been updated to support CryptGenRandom (on Windows), arc4random, random_r, rand_r, lrand48_r, random, rand and lrand48. It will use whichever of those it can find, in that order. The class has static and non-static members now. When the non-static members are used, the class can be seeded once and numbers (or scaled numbers) can be generated over and over without explicitly re-seeding.

Inet Socket Clients

Several improvements have been made to the inetsocketclient class.

Internally, inetsocketclient uses either getaddrinfo() or some variant of gethostbyname(), depending on what's available.

First, a bug was fixed that caused timeouts not to work on systems that don't have getaddrinfo().

Second, it seems that the behavior of getaddrinfo() has changed over the years and a workaround has been introduced to deal with some issues that the new behavior causes...

When round-robin DNS is used, gethostbyname() and getaddrinfo() fetch the entire list of IP addresses that the host name resolves to. The inetsocketclient's connect() method gets this list and tries to connect to each of these IP's, in the order that they were returned by gethostbyname()/getaddrinfo(). When round-robin DNS is used, the order of the IP's in the list is rotated with each DNS request. This can be used to implement a simple load-balancing scheme.

"Recent" (I'm not sure how recent) implementations of getaddrinfo() have begun sorting the IP's, defeating round-robin DNS entirely. Some implementations have a /etc/gai.conf file that allow a sortv4=no directive, but many do not. Some implementations randomize the list of IP's. Some implementations return them in the order that the DNS server returned them in.

Rudiments has no way of knowing what the behavior of getaddrinfo() is, so now, by default, the list of IP addresses is randomized. For the sake of consistency, it's randomized whether it uses getaddrinfo() internally or some variant of gethostbyname(). Methods have been added to the class to enable or disable this behavior too.

Randomization provides a benefit over round-robin DNS as well. With round-robin DNS, when a host goes down, the next host in the list will receive all of the downed host's traffic. With randomization, traffic is distributed evenly over the hosts that are still up.

listner class

The listener class has been refactored entirely to match the paradigms established by kqueue, epoll, /dev/poll, etc. It now supports kqueue, epoll, port_create, /dev/poll, poll and select internally as well, and will use whichever is available, in that order.

In the previous release, support was added for kqueue, epoll and poll but the implementation still did some inefficient things like rebuilding the list of file descriptors to listen on before each iteration. The list is only rebuilt if a file descriptor is added or removed now.

Minix 3.3.0

Minix 3.3.0 came out since the last release and it's now supported.

General Bug Fixes and Improvements

Some general bug fixes and improvements were implemented as well. Cygwin builds ought to work correctly now. Setting file permissions ought to work natively on Windows now too.