Merge branch 't/afh_receiver'

[paraslash.git] / osx_write.c

diff --git a/osx_write.c b/osx_write.c
index f8476bfde425cb7f41c16c33e13f70d7d6d1c398..b057b9c057991864b582ad8519cbac1b9083a90d 100644 (file)
--- a/osx_write.c
+++ b/osx_write.c
@@ -43,9 +43,28 @@ struct private_osx_write_data {
        unsigned sample_format;
        /** Number of channels of the current audio stream. */
        unsigned channels;
-       /** Serializes access to buffer tree nodes. */
+       /**
+        * Serializes access to buffer tree nodes between the writer and
+        * the callback which runs in a different thread.
+        */
        int mutex;
-       /** The btr node of the callback. */
+       /**
+        * The btr node of the callback.
+        *
+        * Although access to the btr node is serialized between the writer and
+        * the callback via the above mutex, this does not stop other buffer
+        * tree nodes, for example the decoder, to race against the osx
+        * callback.
+        *
+        * However, since all operations on buffer tree nodes are local in the
+        * sense that they only affect one level in the buffer tree (i.e.
+        * parent or child nodes, but not the grandparent or the
+        * grandchildren), we may work around this problem by using another
+        * buffer tree node for the callback.
+        *
+        * The writer grabs the mutex in its post_select method and pushes down
+        * the buffers to the callback node.
+        */
        struct btr_node *callback_btrn;
 };
 
@@ -59,10 +78,14 @@ static OSStatus osx_callback(void *cb_arg, __a_unused AudioUnitRenderActionFlags
 {
        int i;
        struct writer_node *wn = cb_arg;
-       struct private_osx_write_data *powd = wn->private_data;
+       struct private_osx_write_data *powd;
        size_t samples_have, samples_want = 0;
 
+       powd = wn->private_data;
        mutex_lock(powd->mutex);
+       powd = wn->private_data;
+       if (!powd || !wn->btrn)
+               goto out;
        /*
         * We fill with zeros if no data was yet written and we do not have
         * enough to fill all buffers.
@@ -266,7 +289,7 @@ static void osx_write_pre_select(struct sched *s, struct task *t)
        }
 
        mutex_lock(powd->mutex);
-       ret = btr_node_status(wn->btrn, wn->min_iqs, BTR_NT_LEAF);
+       ret = btr_node_status(wn->btrn, wn->min_iqs, BTR_NT_INTERNAL);
        if (ret < 0)
                drain_delay_nec = need_drain_delay(powd);
        mutex_unlock(powd->mutex);
@@ -298,11 +321,18 @@ static void osx_write_post_select(__a_unused struct sched *s, struct task *t)
                if (ret < 0)
                        goto fail;
                powd = wn->private_data;
-               AudioOutputUnitStart(powd->audio_unit);
+               ret = -E_UNIT_START;
+               if (AudioOutputUnitStart(powd->audio_unit) != noErr) {
+                       AudioUnitUninitialize(powd->audio_unit);
+                       CloseComponent(powd->audio_unit);
+                       btr_remove_node(&powd->callback_btrn);
+                       goto remove_btrn;
+               }
        }
        mutex_lock(powd->mutex);
-       btr_pushdown(btrn);
-       ret = btr_node_status(btrn, wn->min_iqs, BTR_NT_LEAF);
+       ret = btr_node_status(btrn, wn->min_iqs, BTR_NT_INTERNAL);
+       if (ret > 0)
+               btr_pushdown(btrn);
        if (ret < 0 && need_drain_delay(powd))
                ret = 0;
        mutex_unlock(powd->mutex);