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* notify the decoder instead of polling 100hzMax Kellermann2008-03-261-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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
* moved code to initOutputBuffer()Max Kellermann2008-03-261-0/+2
| | | | | | | This patch moves code which initializes the OutputBuffer struct to outputBuffer.c. Although this is generally a good idea, it prepares the following patch. git-svn-id: https://svn.musicpd.org/mpd/trunk@7206 09075e82-0dd4-0310-85a5-a0d7c8717e4f
* use size_tMax Kellermann2008-03-261-1/+1
| | | | | | | | When dealing with in-memory lengths, the standard type "size_t" should be used. Missing one can be quite dangerous, because an attacker could provoke an integer under-/overflow, which may provide an attack vector. git-svn-id: https://svn.musicpd.org/mpd/trunk@7205 09075e82-0dd4-0310-85a5-a0d7c8717e4f
* Reverting to the full lsr API. Turns out the simple API needs all of theJ. Alexander Treuman2007-05-241-0/+2
| | | | | | | | audio at once, so it won't work for us. The old full API code was still heavily broken, as each call to pcm_convertSampleRate() used the same state, even if it was processing two streams of audio. The new code keeps a separate state for each audio stream that's being converted. git-svn-id: https://svn.musicpd.org/mpd/trunk@6255 09075e82-0dd4-0310-85a5-a0d7c8717e4f
* The massive copyright updateAvuton Olrich2007-04-051-1/+1
| | | git-svn-id: https://svn.musicpd.org/mpd/trunk@5834 09075e82-0dd4-0310-85a5-a0d7c8717e4f
* Add mpd-indent.shAvuton Olrich2006-07-201-16/+14
| | | | | | 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
* Remove useless buffer signedness warnings, useAvuton Olrich2006-07-191-1/+1
| | | | | void * rather than "x char *" git-svn-id: https://svn.musicpd.org/mpd/trunk@4408 09075e82-0dd4-0310-85a5-a0d7c8717e4f
* Change shank's email addressJ. Alexander Treuman2006-07-141-1/+1
| | | git-svn-id: https://svn.musicpd.org/mpd/trunk@4333 09075e82-0dd4-0310-85a5-a0d7c8717e4f
* Huge header update, update the copyright and addAvuton Olrich2006-07-131-1/+1
| | | | | the GPL header where necessary git-svn-id: https://svn.musicpd.org/mpd/trunk@4317 09075e82-0dd4-0310-85a5-a0d7c8717e4f
* rewrite replaygain code, needs testingWarren Dukes2004-11-021-3/+11
| | | git-svn-id: https://svn.musicpd.org/mpd/trunk@2482 09075e82-0dd4-0310-85a5-a0d7c8717e4f
* minor little cleanupsWarren Dukes2004-06-101-1/+0
| | | git-svn-id: https://svn.musicpd.org/mpd/trunk@1439 09075e82-0dd4-0310-85a5-a0d7c8717e4f
* remove "wrap" from buffering control, its not needed, and could potentiallyWarren Dukes2004-06-081-1/+0
| | | | | | create a race condition (but hasn't happened in the last 10 months since this code was written) git-svn-id: https://svn.musicpd.org/mpd/trunk@1397 09075e82-0dd4-0310-85a5-a0d7c8717e4f
* harden metadatabufferWarren Dukes2004-06-061-3/+3
| | | git-svn-id: https://svn.musicpd.org/mpd/trunk@1362 09075e82-0dd4-0310-85a5-a0d7c8717e4f
* spelling fix for avutonWarren Dukes2004-06-061-0/+3
| | | git-svn-id: https://svn.musicpd.org/mpd/trunk@1361 09075e82-0dd4-0310-85a5-a0d7c8717e4f
* mechanism for updating metadata while decodingWarren Dukes2004-06-061-7/+5
| | | | | | | vorbis comments are updated on the fly for streams need to decode icy metadata buffering of metadata needs to be hardened, to ensure that player has already read a particular metachunk or passed over it git-svn-id: https://svn.musicpd.org/mpd/trunk@1358 09075e82-0dd4-0310-85a5-a0d7c8717e4f
* todo updateWarren Dukes2004-06-061-1/+10
| | | git-svn-id: https://svn.musicpd.org/mpd/trunk@1352 09075e82-0dd4-0310-85a5-a0d7c8717e4f
* clean up some grammarWarren Dukes2004-05-301-1/+1
| | | git-svn-id: https://svn.musicpd.org/mpd/trunk@1239 09075e82-0dd4-0310-85a5-a0d7c8717e4f
* fix TIcho's seeking while paused bugWarren Dukes2004-05-291-2/+2
| | | git-svn-id: https://svn.musicpd.org/mpd/trunk@1225 09075e82-0dd4-0310-85a5-a0d7c8717e4f
* do input buffering in while sleeping loop of sending stuff to output bufferWarren Dukes2004-05-211-2/+6
| | | git-svn-id: https://svn.musicpd.org/mpd/trunk@1125 09075e82-0dd4-0310-85a5-a0d7c8717e4f
* yes! rudimentary stream playing for mp3's!Warren Dukes2004-05-181-0/+2
| | | | | be gentle git-svn-id: https://svn.musicpd.org/mpd/trunk@1051 09075e82-0dd4-0310-85a5-a0d7c8717e4f
* some more work on organizing code for resampling/audioFormat conversionWarren Dukes2004-05-101-1/+2
| | | git-svn-id: https://svn.musicpd.org/mpd/trunk@968 09075e82-0dd4-0310-85a5-a0d7c8717e4f
* rewrite outputBuffer'ing abstraction a bit to be more effecient and easierWarren Dukes2004-05-071-3/+4
| | | | | to interface. Also, use outputBuffer abstraction for ogg git-svn-id: https://svn.musicpd.org/mpd/trunk@941 09075e82-0dd4-0310-85a5-a0d7c8717e4f
* new OutputBuffer abstraction stuff, implemented for mp3, now need toWarren Dukes2004-05-071-0/+45
implement in other decoders git-svn-id: https://svn.musicpd.org/mpd/trunk@940 09075e82-0dd4-0310-85a5-a0d7c8717e4f
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