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2008-03-26notify: cleanupsEric Wong1-32/+9
* move set_nonblock{,ing}() into utils.c since we use it elsewhere, too * add proper error checking to set_nonblocking() * use os_compat.h instead of individually #includ-ing system headers git-svn-id: https://svn.musicpd.org/mpd/trunk@7217 09075e82-0dd4-0310-85a5-a0d7c8717e4f
2008-03-26notify the decoder instead of polling 100hzMax Kellermann1-26/+38
When the decoder process is faster than the player process, all decodedd buffers are full at some point in time. The decoder has to wait for buffers to become free (finished playing). It used to do this by polling the buffer status 100 times a second. This generates a lot of unnecessary CPU wakeups. This patch adds a way for the player process to notify the decoder process that it may continue its work. We could use pthread_cond for that, unfortunately inter-process mutexes/conds are not supported by some kernels (Linux), so we cannot use this light-weight method until mpd moves to using threads instead of processes. The other method would be semaphores, which historically are global resources with a unique name; this historic API is cumbersome, and I wanted to avoid it. I came up with a quite naive solution for now: I create an anonymous pipe with pipe(), and the decoder process reads on that pipe. Until the player process sends data on it as a signal, the decoder process blocks. This can be optimized in a number of ways: - if the decoder process is still working (instead of waiting for buffers), we could save the write() system call, since there is nobody waiting for the notification. [ew: I tried this using a counter in shared memory, didn't help] - the pipe buffer will be full at some point, when the decoder thread is too slow. For this reason, the writer side of the pipe is non-blocking, and mpd can ignore the resulting EWOULDBLOCK. - since we have shared memory, we could check whether somebody is actually waiting without a context switch, and we could just not write the notification byte. [ew: tried same method/result as first point above] - if there is already a notification in the pipe, we could also not write another one. [ew: tried same method/result as first/third points above] - the decoder will only consume 64 bytes at a time. If the pipe buffer is full, this will result in a lot of read() invocations. This does not hurt badly, but on a heavily loaded system, this might add a little bit more load. The preceding optimizations however are able eliminate the this. - finally, we should use another method for inter process notifications - maybe kill() or just make mpd use threads, finally. In spite of all these possibilities to optimize this code further, this pipe notification trick is faster than the 100 Hz poll. On my machine, it reduced the number of wakeups to less than 30%. git-svn-id: https://svn.musicpd.org/mpd/trunk@7215 09075e82-0dd4-0310-85a5-a0d7c8717e4f
2008-01-03Cleanup #includes of standard system headers and put them in one placeEric Wong1-3/+1
This will make refactoring features easier, especially now that pthreads support and larger refactorings are on the horizon. Hopefully, this will make porting to other platforms (even non-UNIX-like ones for masochists) easier, too. os_compat.h will house all the #includes for system headers considered to be the "core" of MPD. Headers for optional features will be left to individual source files. git-svn-id: https://svn.musicpd.org/mpd/trunk@7130 09075e82-0dd4-0310-85a5-a0d7c8717e4f
2007-04-05The massive copyright updateAvuton Olrich1-1/+1
git-svn-id: https://svn.musicpd.org/mpd/trunk@5834 09075e82-0dd4-0310-85a5-a0d7c8717e4f
2007-02-18Closing some parenthesis around shank's email address in copyright headers.J. Alexander Treuman1-1/+1
git-svn-id: https://svn.musicpd.org/mpd/trunk@5376 09075e82-0dd4-0310-85a5-a0d7c8717e4f
2006-09-15signal_check: [trivial] make __caught_signals array staticEric Wong1-1/+1
git-svn-id: https://svn.musicpd.org/mpd/trunk@4780 09075e82-0dd4-0310-85a5-a0d7c8717e4f
2006-07-20Add mpd-indent.shAvuton Olrich1-12/+12
Indent the entire tree, hopefully we can keep it indented. git-svn-id: https://svn.musicpd.org/mpd/trunk@4410 09075e82-0dd4-0310-85a5-a0d7c8717e4f
2006-07-18Initialize sigaction.sa_mask to an empty set in a few places we forgot toJ. Alexander Treuman1-0/+1
git-svn-id: https://svn.musicpd.org/mpd/trunk@4400 09075e82-0dd4-0310-85a5-a0d7c8717e4f
2006-07-17sparse: replace 0 (integer) usage with NULL where appropriateEric Wong1-1/+2
Probably pedantic, but yes, might as well in case we run into strange platforms where NULL is something strange. git-svn-id: https://svn.musicpd.org/mpd/trunk@4380 09075e82-0dd4-0310-85a5-a0d7c8717e4f
2006-07-14Change shank's email addressJ. Alexander Treuman1-1/+1
git-svn-id: https://svn.musicpd.org/mpd/trunk@4333 09075e82-0dd4-0310-85a5-a0d7c8717e4f
2006-07-13Huge header update, update the copyright and addAvuton Olrich1-1/+1
the GPL header where necessary git-svn-id: https://svn.musicpd.org/mpd/trunk@4317 09075e82-0dd4-0310-85a5-a0d7c8717e4f
2004-11-02a few extra strerror()'s sprinkled in the codeWarren Dukes1-2/+0
git-svn-id: https://svn.musicpd.org/mpd/trunk@2467 09075e82-0dd4-0310-85a5-a0d7c8717e4f
2004-04-14add vim shiznit to end of all source filesWarren Dukes1-0/+1
git-svn-id: https://svn.musicpd.org/mpd/trunk@750 09075e82-0dd4-0310-85a5-a0d7c8717e4f
2004-04-13add copyright notices to new filesWarren Dukes1-0/+19
git-svn-id: https://svn.musicpd.org/mpd/trunk@739 09075e82-0dd4-0310-85a5-a0d7c8717e4f
2004-04-13when doing signal functions (like sigaction) make sure it wasn't interrupted ↵Warren Dukes1-1/+3
by a signal (errno==EINTR) git-svn-id: https://svn.musicpd.org/mpd/trunk@729 09075e82-0dd4-0310-85a5-a0d7c8717e4f
2004-04-11clean up signal handling using a polling method, from the genius that is ↵Warren Dukes1-0/+38
mackstann git-svn-id: https://svn.musicpd.org/mpd/trunk@697 09075e82-0dd4-0310-85a5-a0d7c8717e4f
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