pipe-sink: new option "use_system_clock_for_timing"

Using this option, even the simplest tools like "cat" can properly
dump raw audio from the pipe.

src/modules/module-pipe-sink.c

@@ -34,6 +34,9 @@
 #endif
 
 #include <pulse/xmalloc.h>
+#include <pulse/timeval.h>
+#include <pulse/util.h>
+#include <pulse/rtclock.h>
 
 #include <pulsecore/core-error.h>
 #include <pulsecore/sink.h>
@@ -57,7 +60,9 @@ PA_MODULE_USAGE(
         "format=<sample format> "
         "rate=<sample rate> "
         "channels=<number of channels> "
-        "channel_map=<channel map>");
+        "channel_map=<channel map> "
+        "use_system_clock_for_timing=<yes or no> "
+);
 
 #define DEFAULT_FILE_NAME "fifo_output"
 #define DEFAULT_SINK_NAME "fifo_output"
@@ -74,12 +79,18 @@ struct userdata {
     char *filename;
     int fd;
     size_t buffer_size;
+    size_t bytes_dropped;
+    bool fifo_error;
 
     pa_memchunk memchunk;
 
     pa_rtpoll_item *rtpoll_item;
 
     int write_type;
+    pa_usec_t block_usec;
+    pa_usec_t timestamp;
+
+    bool use_system_clock_for_timing;
 };
 
 static const char* const valid_modargs[] = {
@@ -90,6 +101,7 @@ static const char* const valid_modargs[] = {
     "rate",
     "channels",
     "channel_map",
+    "use_system_clock_for_timing",
     NULL
 };
 
@@ -97,27 +109,156 @@ static int sink_process_msg(pa_msgobject *o, int code, void *data, int64_t offse
     struct userdata *u = PA_SINK(o)->userdata;
 
     switch (code) {
+        case PA_SINK_MESSAGE_SET_STATE:
+            if (pa_sink_get_state(u->sink) == PA_SINK_SUSPENDED || pa_sink_get_state(u->sink) == PA_SINK_INIT) {
+                if (PA_PTR_TO_UINT(data) == PA_SINK_RUNNING || PA_PTR_TO_UINT(data) == PA_SINK_IDLE)
+                    u->timestamp = pa_rtclock_now();
+            } else if (pa_sink_get_state(u->sink) == PA_SINK_RUNNING || pa_sink_get_state(u->sink) == PA_SINK_IDLE) {
+                if (PA_PTR_TO_UINT(data) == PA_SINK_SUSPENDED) {
+                    /* Clear potential FIFO error flag */
+                    u->fifo_error = false;
 
-        case PA_SINK_MESSAGE_GET_LATENCY: {
+                    /* Continuously dropping data (clear counter on entering suspended state. */
-            size_t n = 0;
+                    if (u->bytes_dropped != 0) {
+                        pa_log_debug("Pipe-sink continuously dropping data - clear statistics (%zu -> 0 bytes dropped)", u->bytes_dropped);
+                        u->bytes_dropped = 0;
+                    }
+                }
+            }
+            break;
+
+        case PA_SINK_MESSAGE_GET_LATENCY:
+            if (u->use_system_clock_for_timing) {
+                pa_usec_t now;
+                now = pa_rtclock_now();
+                *((int64_t*) data) = (int64_t)u->timestamp - (int64_t)now;
+            } else {
+                size_t n = 0;
 
 #ifdef FIONREAD
-            int l;
+                int l;
 
-            if (ioctl(u->fd, FIONREAD, &l) >= 0 && l > 0)
+                if (ioctl(u->fd, FIONREAD, &l) >= 0 && l > 0)
-                n = (size_t) l;
+                    n = (size_t) l;
 #endif
 
-            n += u->memchunk.length;
+                n += u->memchunk.length;
 
-            *((int64_t*) data) = pa_bytes_to_usec(n, &u->sink->sample_spec);
+                *((int64_t*) data) = pa_bytes_to_usec(n, &u->sink->sample_spec);
+            }
             return 0;
-        }
     }
 
     return pa_sink_process_msg(o, code, data, offset, chunk);
 }
 
+static void sink_update_requested_latency_cb(pa_sink *s) {
+    struct userdata *u;
+    size_t nbytes;
+
+    pa_sink_assert_ref(s);
+    pa_assert_se(u = s->userdata);
+
+    u->block_usec = pa_sink_get_requested_latency_within_thread(s);
+
+    if (u->block_usec == (pa_usec_t) -1)
+        u->block_usec = s->thread_info.max_latency;
+
+    nbytes = pa_usec_to_bytes(u->block_usec, &s->sample_spec);
+    pa_sink_set_max_request_within_thread(s, nbytes);
+}
+
+static ssize_t pipe_sink_write(struct userdata *u, pa_memchunk *pchunk) {
+    size_t index, length;
+    ssize_t count = 0;
+    void *p;
+
+    pa_assert(u);
+    pa_assert(pchunk);
+
+    index = pchunk->index;
+    length = pchunk->length;
+    p = pa_memblock_acquire(pchunk->memblock);
+
+    for (;;) {
+        ssize_t l;
+
+        l = pa_write(u->fd, (uint8_t*) p + index, length, &u->write_type);
+
+        pa_assert(l != 0);
+
+        if (l < 0) {
+            if (errno == EAGAIN)
+                break;
+            else if (errno != EINTR) {
+                if (!u->fifo_error) {
+                    pa_log("Failed to write data to FIFO: %s", pa_cstrerror(errno));
+                    u->fifo_error = true;
+                }
+                count = -1 - count;
+                break;
+            }
+        } else {
+            if (u->fifo_error) {
+                pa_log_debug("Recovered from FIFO error");
+                u->fifo_error = false;
+            }
+            count += l;
+            index += l;
+            length -= l;
+
+            if (length <= 0) {
+                break;
+            }
+        }
+    }
+
+    pa_memblock_release(pchunk->memblock);
+
+    return count;
+}
+
+static void process_render_use_timing(struct userdata *u, pa_usec_t now) {
+    size_t dropped = 0;
+    size_t consumed = 0;
+
+    pa_assert(u);
+
+    /* Fill the buffer up the latency size */
+    while (u->timestamp < now + u->block_usec) {
+        ssize_t written = 0;
+        pa_memchunk chunk;
+
+        pa_sink_render(u->sink, u->sink->thread_info.max_request, &chunk);
+
+        pa_assert(chunk.length > 0);
+
+        if ((written = pipe_sink_write(u, &chunk)) < 0)
+            written = -1 - written;
+
+        pa_memblock_unref(chunk.memblock);
+
+        u->timestamp += pa_bytes_to_usec(chunk.length, &u->sink->sample_spec);
+
+        dropped = chunk.length - written;
+
+        if (u->bytes_dropped != 0 && dropped != chunk.length) {
+            pa_log_debug("Pipe-sink continuously dropped %zu bytes", u->bytes_dropped);
+            u->bytes_dropped = 0;
+        }
+
+        if (u->bytes_dropped == 0 && dropped != 0)
+            pa_log_debug("Pipe-sink just dropped %zu bytes", dropped);
+
+        u->bytes_dropped += dropped;
+
+        consumed += chunk.length;
+
+        if (consumed >= u->sink->thread_info.max_request)
+            break;
+    }
+}
+
 static int process_render(struct userdata *u) {
     pa_assert(u);
 
@@ -162,6 +303,54 @@ static int process_render(struct userdata *u) {
     }
 }
 
+static void thread_func_use_timing(void *userdata) {
+    struct userdata *u = userdata;
+
+    pa_assert(u);
+
+    pa_log_debug("Thread (use timing) starting up");
+
+    pa_thread_mq_install(&u->thread_mq);
+
+    u->timestamp = pa_rtclock_now();
+
+    for (;;) {
+        pa_usec_t now = 0;
+        int ret;
+
+        if (PA_SINK_IS_OPENED(u->sink->thread_info.state))
+            now = pa_rtclock_now();
+
+        if (PA_UNLIKELY(u->sink->thread_info.rewind_requested))
+            pa_sink_process_rewind(u->sink, 0);
+
+        /* Render some data and write it to the fifo */
+        if (PA_SINK_IS_OPENED(u->sink->thread_info.state)) {
+            if (u->timestamp <= now)
+                process_render_use_timing(u, now);
+
+            pa_rtpoll_set_timer_absolute(u->rtpoll, u->timestamp);
+        } else
+            pa_rtpoll_set_timer_disabled(u->rtpoll);
+
+        /* Hmm, nothing to do. Let's sleep */
+        if ((ret = pa_rtpoll_run(u->rtpoll)) < 0)
+            goto fail;
+
+        if (ret == 0)
+            goto finish;
+    }
+
+fail:
+    /* If this was no regular exit from the loop we have to continue
+     * processing messages until we received PA_MESSAGE_SHUTDOWN */
+    pa_asyncmsgq_post(u->thread_mq.outq, PA_MSGOBJECT(u->core), PA_CORE_MESSAGE_UNLOAD_MODULE, u->module, 0, NULL, NULL);
+    pa_asyncmsgq_wait_for(u->thread_mq.inq, PA_MESSAGE_SHUTDOWN);
+
+finish:
+    pa_log_debug("Thread (use timing) shutting down");
+}
+
 static void thread_func(void *userdata) {
     struct userdata *u = userdata;
 
@@ -225,6 +414,7 @@ int pa__init(pa_module *m) {
     pa_modargs *ma;
     struct pollfd *pollfd;
     pa_sink_new_data data;
+    pa_thread_func_t thread_routine;
 
     pa_assert(m);
 
@@ -247,6 +437,11 @@ int pa__init(pa_module *m) {
     pa_memchunk_reset(&u->memchunk);
     u->rtpoll = pa_rtpoll_new();
 
+    if (pa_modargs_get_value_boolean(ma, "use_system_clock_for_timing", &u->use_system_clock_for_timing) < 0) {
+        pa_log("Failed to parse use_system_clock_for_timing argument.");
+        goto fail;
+    }
+
     if (pa_thread_mq_init(&u->thread_mq, m->core->mainloop, u->rtpoll) < 0) {
         pa_log("pa_thread_mq_init() failed.");
         goto fail;
@@ -292,7 +487,10 @@ int pa__init(pa_module *m) {
         goto fail;
     }
 
-    u->sink = pa_sink_new(m->core, &data, PA_SINK_LATENCY);
+    if (u->use_system_clock_for_timing)
+        u->sink = pa_sink_new(m->core, &data, PA_SINK_LATENCY|PA_SINK_DYNAMIC_LATENCY);
+    else
+        u->sink = pa_sink_new(m->core, &data, PA_SINK_LATENCY);
     pa_sink_new_data_done(&data);
 
     if (!u->sink) {
@@ -301,21 +499,32 @@ int pa__init(pa_module *m) {
     }
 
     u->sink->parent.process_msg = sink_process_msg;
+    if (u->use_system_clock_for_timing)
+        u->sink->update_requested_latency = sink_update_requested_latency_cb;
     u->sink->userdata = u;
 
     pa_sink_set_asyncmsgq(u->sink, u->thread_mq.inq);
     pa_sink_set_rtpoll(u->sink, u->rtpoll);
 
+    u->bytes_dropped = 0;
+    u->fifo_error = false;
     u->buffer_size = pa_frame_align(pa_pipe_buf(u->fd), &u->sink->sample_spec);
+    if (u->use_system_clock_for_timing) {
+        u->block_usec = pa_bytes_to_usec(u->buffer_size, &u->sink->sample_spec);
+        pa_sink_set_latency_range(u->sink, 0, u->block_usec);
+        thread_routine = thread_func_use_timing;
+    } else {
+        pa_sink_set_fixed_latency(u->sink, pa_bytes_to_usec(u->buffer_size, &u->sink->sample_spec));
+        thread_routine = thread_func;
+    }
     pa_sink_set_max_request(u->sink, u->buffer_size);
-    pa_sink_set_fixed_latency(u->sink, pa_bytes_to_usec(u->buffer_size, &u->sink->sample_spec));
 
     u->rtpoll_item = pa_rtpoll_item_new(u->rtpoll, PA_RTPOLL_NEVER, 1);
     pollfd = pa_rtpoll_item_get_pollfd(u->rtpoll_item, NULL);
     pollfd->fd = u->fd;
     pollfd->events = pollfd->revents = 0;
 
-    if (!(u->thread = pa_thread_new("pipe-sink", thread_func, u))) {
+    if (!(u->thread = pa_thread_new("pipe-sink", thread_routine, u))) {
         pa_log("Failed to create thread.");
         goto fail;
     }