protocol-native: Allow clients to know at what index underrun occurred

This patch introduces some extra protocol information, so protocol
version is bumped. This functionality is primarily needed to solve
a long standing issue in alsa-plugins, which should ignore underruns
if and only if it is obsolete, i e, if more data has been written to
the pipe in the meantime (which will automatically end the underrun).

BugLink: http://bugs.launchpad.net/bugs/805940
Signed-off-by: David Henningsson <david.henningsson@canonical.com>

6 files changed, 36 insertions, 4 deletions

diff --git a/configure.ac b/configure.ac
index 077ab43d..5fdcc605 100644
--- a/configure.ac
+++ b/configure.ac
@@ -36,7 +36,7 @@ AC_SUBST(PA_MINOR, pa_minor)
 AC_SUBST(PA_MAJORMINOR, pa_major.pa_minor)
 
 AC_SUBST(PA_API_VERSION, 12)
-AC_SUBST(PA_PROTOCOL_VERSION, 22)
+AC_SUBST(PA_PROTOCOL_VERSION, 23)
 
 # The stable ABI for client applications, for the version info x:y:z
 # always will hold y=z
diff --git a/src/map-file b/src/map-file
index d9c3e9f6..aacd5241 100644
--- a/src/map-file
+++ b/src/map-file
@@ -277,6 +277,7 @@ pa_stream_get_sample_spec;
 pa_stream_get_state;
 pa_stream_get_time;
 pa_stream_get_timing_info;
+pa_stream_get_underflow_index;
 pa_stream_is_corked;
 pa_stream_is_suspended;
 pa_stream_new;
diff --git a/src/pulse/internal.h b/src/pulse/internal.h
index 92379094..60b37999 100644
--- a/src/pulse/internal.h
+++ b/src/pulse/internal.h
@@ -169,6 +169,7 @@ struct pa_stream {
     /* playback */
     pa_memblock *write_memblock;
     void *write_data;
+    int64_t latest_underrun_at_index;
 
     /* recording */
     pa_memchunk peek_memchunk;
diff --git a/src/pulse/stream.c b/src/pulse/stream.c
index 3658064f..416efb7f 100644
--- a/src/pulse/stream.c
+++ b/src/pulse/stream.c
@@ -180,6 +180,7 @@ static pa_stream *pa_stream_new_with_proplist_internal(
     s->timing_info_valid = FALSE;
 
     s->previous_time = 0;
+    s->latest_underrun_at_index = -1;
 
     s->read_index_not_before = 0;
     s->write_index_not_before = 0;
@@ -843,10 +844,17 @@ finish:
     pa_context_unref(c);
 }
 
+int64_t pa_stream_get_underflow_index(pa_stream *p)
+{
+    pa_assert(p);
+    return p->latest_underrun_at_index;
+}
+
 void pa_command_overflow_or_underflow(pa_pdispatch *pd, uint32_t command, uint32_t tag, pa_tagstruct *t, void *userdata) {
     pa_stream *s;
     pa_context *c = userdata;
     uint32_t channel;
+    int64_t offset = -1;
 
     pa_assert(pd);
     pa_assert(command == PA_COMMAND_OVERFLOW || command == PA_COMMAND_UNDERFLOW);
@@ -856,8 +864,19 @@ void pa_command_overflow_or_underflow(pa_pdispatch *pd, uint32_t command, uint32
 
     pa_context_ref(c);
 
-    if (pa_tagstruct_getu32(t, &channel) < 0 ||
-        !pa_tagstruct_eof(t)) {
+    if (pa_tagstruct_getu32(t, &channel) < 0) {
+        pa_context_fail(c, PA_ERR_PROTOCOL);
+        goto finish;
+    }
+
+    if (c->version >= 23 && command == PA_COMMAND_UNDERFLOW) {
+        if (pa_tagstruct_gets64(t, &offset) < 0) {
+            pa_context_fail(c, PA_ERR_PROTOCOL);
+            goto finish;
+        }
+    }
+
+    if (!pa_tagstruct_eof(t)) {
         pa_context_fail(c, PA_ERR_PROTOCOL);
         goto finish;
     }
@@ -868,6 +887,9 @@ void pa_command_overflow_or_underflow(pa_pdispatch *pd, uint32_t command, uint32
     if (s->state != PA_STREAM_READY)
         goto finish;
 
+    if (offset != -1)
+        s->latest_underrun_at_index = offset;
+
     if (s->buffer_attr.prebuf > 0)
         check_smoother_status(s, TRUE, FALSE, TRUE);
 
diff --git a/src/pulse/stream.h b/src/pulse/stream.h
index 010f968f..e50ff0b1 100644
--- a/src/pulse/stream.h
+++ b/src/pulse/stream.h
@@ -570,6 +570,12 @@ void pa_stream_set_read_callback(pa_stream *p, pa_stream_request_cb_t cb, void *
 /** Set the callback function that is called when a buffer overflow happens. (Only for playback streams) */
 void pa_stream_set_overflow_callback(pa_stream *p, pa_stream_notify_cb_t cb, void *userdata);
 
+/** Return at what position the latest underflow occurred, or -1 if this information is not
+ * known (e g if no underflow has occurred, or server is older than 1.0).
+ * Can be used inside the underflow callback to get information about the current underflow.
+ * (Only for playback streams) \since 1.0 */
+int64_t pa_stream_get_underflow_index(pa_stream *p);
+
 /** Set the callback function that is called when a buffer underflow happens. (Only for playback streams) */
 void pa_stream_set_underflow_callback(pa_stream *p, pa_stream_notify_cb_t cb, void *userdata);
 
diff --git a/src/pulsecore/protocol-native.c b/src/pulsecore/protocol-native.c
index f069e836..3ed9f1a9 100644
--- a/src/pulsecore/protocol-native.c
+++ b/src/pulsecore/protocol-native.c
@@ -822,6 +822,8 @@ static int playback_stream_process_msg(pa_msgobject *o, int code, void*userdata,
             pa_tagstruct_putu32(t, PA_COMMAND_UNDERFLOW);
             pa_tagstruct_putu32(t, (uint32_t) -1); /* tag */
             pa_tagstruct_putu32(t, s->index);
+            if (s->connection->version >= 23)
+                pa_tagstruct_puts64(t, offset);
             pa_pstream_send_tagstruct(s->connection->pstream, t);
             break;
         }
@@ -1562,7 +1564,7 @@ static int sink_input_pop_cb(pa_sink_input *i, size_t nbytes, pa_memchunk *chunk
             s->drain_request = FALSE;
             pa_asyncmsgq_post(pa_thread_mq_get()->outq, PA_MSGOBJECT(s), PLAYBACK_STREAM_MESSAGE_DRAIN_ACK, PA_UINT_TO_PTR(s->drain_tag), 0, NULL, NULL);
         } else if (!s->is_underrun)
-            pa_asyncmsgq_post(pa_thread_mq_get()->outq, PA_MSGOBJECT(s), PLAYBACK_STREAM_MESSAGE_UNDERFLOW, NULL, 0, NULL, NULL);
+            pa_asyncmsgq_post(pa_thread_mq_get()->outq, PA_MSGOBJECT(s), PLAYBACK_STREAM_MESSAGE_UNDERFLOW, NULL, pa_memblockq_get_read_index(s->memblockq), NULL, NULL);
 
         s->is_underrun = TRUE;