forked-daapd v0.17 is out; the main purpose of this release is to add support for libav 0.7. There are also a few bugfixes that made it into this release, but nothing earth-shattering. One More Thing You ll notice an extra tarball and tag in this release, both marked 0.17gcd. With this release, the GCD (Grand Central Dispatch / libdispatch) codebase is making its debut. libdispatch replaces libevent and allows for greater concurrency inside forked-daapd. This makes forked-daapd snappier, which shows when using Remote or a SoundBridge. The filescanner also benefits from this; it now scans several directories concurrently, reducing the time needed for a rescan by making better use of the machine resources. Thanks to Mark Heily s efforts on libdispatch/libkqueue/libpthread_workqueue over the past year, we now have a Linux version of libdispatch that works well enough to support forked-daapd. This codebase will become the primary codebase for forked-daapd once the database performance issue will be fixed. After this point, the current libevent 1.4 codebase will be legacy and won t see any further development (we ll discuss bugfixes in due time). This new codebase comes with new requirements:

• the Clang compiler from the LLVM project is required, due to the use of the C Blocks extension that isn t supported by GCC;
• libdispatch, of course, is required;
• libtre is a new dependency for concurrent regexps;
• glibc 2.13+ is required, or any glibc version containing a fix for glibc BZ#10563.

libdispatch and its dependencies are available in Debian unstable; it s best and easier to use whatever is in unstable, instead of mixing and matching the libdispatch/libkqueue/libpthread_workqueue versions until they all work together. Due to platform support in Clang, the GCD codebase can only be built for and will only run on i386 and amd64, as far as Linux is concerned. Other architectures will have to wait until support for them is added to Clang. FreeBSD is untested and will probably require some modifications to work; recent enough versions of FreeBSD have a native pthread_workqueue implementation and do not need libpthread_workqueue. Packages are available in experimental for Debian users; they ll end up in unstable in a few weeks, before the libevent2 migration happens there. Tarballs available at http://alioth.debian.org/~jblache/forked-daapd/ ; GPG signatures made with my Debian key F5D65169.

Thanks to the work of Mark Heily, both upstream and in Debian, this week saw the arrival of libdispatch in Debian. libdispatch is the userspace component of Apple s Grand Central Dispatch technology, designed to help write applications that really take advantage of multicore processors without having to fiddle directly with threads and locking (and getting it terribly wrong). To get that working on Linux, Mark wrote a userspace implementation of the pthread workqueues and a kqueue compatibility library (libkqueue). He also packaged the Blocks runtime (libblocksruntime) for Debian so as to build libdispatch with Blocks support. That means code using libdispatch must be built with CLang (or llvm-gcc-4.2) rather than gcc, as getting Blocks support in gcc in the near future looks highly improbable. On Mac OS X and FreeBSD, a kernel-based implementation of the pthread workqueues is used; we don t have that for Linux yet. The all-userspace implementation we have at the moment works really well; there are some caveats, though, but that s no reason for not starting to play with libdispatch right now! Try it out, it s great. Thanks again, Mark!