rework memory block management to be thread-safe and mostly lock-free.

pa_memblock is now an opaque structure. Access to its fields is now done
through various accessor functions in a thread-safe manner.

pa_memblock_acquire() and pa_memblock_release() are now used to access the
attached audio data. Why? To allow safe manipulation of the memory pointer
maintained by the memory block. Internally _acquire() and _release() maintain a
reference counter. Please do not confuse this reference counter whith the one
maintained by pa_memblock_ref()/_unref()!

As a side effect this patch removes all direct usages of AO_t and replaces it
with pa_atomic_xxx based code.

This stuff needs some serious testing love. Especially if threads are actively
used.



git-svn-id: file:///home/lennart/svn/public/pulseaudio/trunk@1404 fefdeb5f-60dc-0310-8127-8f9354f1896f

1 files changed, 7 insertions, 2 deletions

diff --git a/src/pulsecore/sound-file-stream.c b/src/pulsecore/sound-file-stream.c
index e6f24a79..d2ffeeed 100644
--- a/src/pulsecore/sound-file-stream.c
+++ b/src/pulsecore/sound-file-stream.c
@@ -74,21 +74,26 @@ static int sink_input_peek(pa_sink_input *i, pa_memchunk *chunk) {
     if (!u->memchunk.memblock) {
         uint32_t fs = pa_frame_size(&i->sample_spec);
         sf_count_t n;
+        void *p;
 
         u->memchunk.memblock = pa_memblock_new(i->sink->core->mempool, BUF_SIZE);
         u->memchunk.index = 0;
 
+        p = pa_memblock_acquire(u->memchunk.memblock);
+        
         if (u->readf_function) {
-            if ((n = u->readf_function(u->sndfile, u->memchunk.memblock->data, BUF_SIZE/fs)) <= 0)
+            if ((n = u->readf_function(u->sndfile, p, BUF_SIZE/fs)) <= 0)
                 n = 0;
 
             u->memchunk.length = n * fs;
         } else {
-            if ((n = sf_read_raw(u->sndfile, u->memchunk.memblock->data, BUF_SIZE)) <= 0)
+            if ((n = sf_read_raw(u->sndfile, p, BUF_SIZE)) <= 0)
                 n = 0;
             
             u->memchunk.length = n;
         }
+
+        pa_memblock_release(u->memchunk.memblock);
         
         if (!u->memchunk.length) {
             free_userdata(u);