Attachment 137477 Details for Bug 58746 – patch: rewrite of thread function

patch: rewrite of thread function

patch.txt (text/plain), 18.69 KB, created by Georg Chini on 2018-02-20 20:51:25 UTC

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Creator: Georg Chini

Created: 2018-02-20 20:51:25 UTC

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patch

obsolete

>From 6084127b2918bbb5b6a0986692e7f0f0349eed13 Mon Sep 17 00:00:00 2001
>From: Georg Chini <georg@chini.tk>
>Date: Tue, 20 Feb 2018 21:45:01 +0100
>Subject: [PATCH] bluez5-device: Rewrite of thread function, reduce send buffer
> size for a2dp sink
>
>The rewrite of the thread function does not change functionality much,
>most of it is only cleanup, minor bug fixing and documentation work.
>
>This patch also changes the send buffer size for a2dp sink to avoid lags
>after temporary connection drops, following the proof-of-concept patch
>posted by Dmitry Kalyanov.
>
>Bug-Link: https://bugs.freedesktop.org/show_bug.cgi?id=58746
>---
> src/modules/bluetooth/module-bluez5-device.c | 290 +++++++++++++++++----------
> 1 file changed, 188 insertions(+), 102 deletions(-)
>
>diff --git a/src/modules/bluetooth/module-bluez5-device.c b/src/modules/bluetooth/module-bluez5-device.c
>index 7970dda7..1c23335f 100644
>--- a/src/modules/bluetooth/module-bluez5-device.c
>+++ b/src/modules/bluetooth/module-bluez5-device.c
>@@ -56,7 +56,6 @@ PA_MODULE_LOAD_ONCE(false);
> PA_MODULE_USAGE("path=<device object path>"
>                 "autodetect_mtu=<boolean>");
> 
>-#define MAX_PLAYBACK_CATCH_UP_USEC (100 * PA_USEC_PER_MSEC)
> #define FIXED_LATENCY_PLAYBACK_A2DP (25 * PA_USEC_PER_MSEC)
> #define FIXED_LATENCY_PLAYBACK_SCO (125 * PA_USEC_PER_MSEC)
> #define FIXED_LATENCY_RECORD_A2DP   (25 * PA_USEC_PER_MSEC)
>@@ -660,6 +659,35 @@ static int a2dp_process_push(struct userdata *u) {
>     return ret;
> }
> 
>+static void update_buffer_size(struct userdata *u) {
>+    int old_bufsize;
>+    socklen_t len = sizeof(int);
>+    int ret;
>+
>+    ret = getsockopt(u->stream_fd, SOL_SOCKET, SO_SNDBUF, &old_bufsize, &len);
>+    if (ret == -1) {
>+        pa_log_warn("Changing bluetooth buffer size: Failed to getsockopt(SO_SNDBUF): %s", pa_cstrerror(errno));
>+    } else {
>+        unsigned n;
>+        int new_bufsize;
>+
>+        /* Set send buffer size as small as possible. The minimum value is 1024 according to
>+         * the socket man page, so let's use the next multiple of write_link_mtu which is
>+         * larger than 1024. If write_link_mtu is larger than 1024, use 2 * write_link_mtu */
>+        n = 1024 / u->write_link_mtu + 1;
>+        if (n == 1)
>+            n = 2;
>+
>+         new_bufsize = n * u->write_link_mtu;
>+
>+         ret = setsockopt(u->stream_fd, SOL_SOCKET, SO_SNDBUF, &new_bufsize, len);
>+         if (ret == -1)
>+             pa_log_warn("Changing bluetooth buffer size: Failed to change from %d to %d: %s", old_bufsize, new_bufsize, pa_cstrerror(errno));
>+         else
>+             pa_log_info("Changing bluetooth buffer size: Changed from %d to %d", old_bufsize, new_bufsize);
>+    }
>+}
>+
> /* Run from I/O thread */
> static void a2dp_set_bitpool(struct userdata *u, uint8_t bitpool) {
>     struct sbc_info *sbc_info;
>@@ -694,6 +722,8 @@ static void a2dp_set_bitpool(struct userdata *u, uint8_t bitpool) {
>     pa_sink_set_max_request_within_thread(u->sink, u->write_block_size);
>     pa_sink_set_fixed_latency_within_thread(u->sink,
>             FIXED_LATENCY_PLAYBACK_A2DP + pa_bytes_to_usec(u->write_block_size, &u->sample_spec));
>+
>+    update_buffer_size(u);
> }
> 
> /* Run from I/O thread */
>@@ -852,8 +882,10 @@ static void setup_stream(struct userdata *u) {
> 
>     pa_log_debug("Stream properly set up, we're ready to roll!");
> 
>-    if (u->profile == PA_BLUETOOTH_PROFILE_A2DP_SINK)
>+    if (u->profile == PA_BLUETOOTH_PROFILE_A2DP_SINK) {
>         a2dp_set_bitpool(u, u->sbc_info.max_bitpool);
>+        update_buffer_size(u);
>+    }
> 
>     u->rtpoll_item = pa_rtpoll_item_new(u->rtpoll, PA_RTPOLL_NEVER, 1);
>     pollfd = pa_rtpoll_item_get_pollfd(u->rtpoll_item, NULL);
>@@ -861,7 +893,7 @@ static void setup_stream(struct userdata *u) {
>     pollfd->events = pollfd->revents = 0;
> 
>     u->read_index = u->write_index = 0;
>-    u->started_at = 0;
>+    u->started_at = pa_rtclock_now();
>     u->stream_setup_done = true;
> 
>     if (u->source)
>@@ -1407,12 +1439,32 @@ static int init_profile(struct userdata *u) {
>     return r;
> }
> 
>+static int write_block(struct userdata *u) {
>+    int n_written;
>+
>+    if (u->write_index <= 0)
>+        u->started_at = pa_rtclock_now();
>+
>+    if (u->profile == PA_BLUETOOTH_PROFILE_A2DP_SINK) {
>+        if ((n_written = a2dp_process_render(u)) < 0)
>+            return -1;
>+    } else {
>+        if ((n_written = sco_process_render(u)) < 0)
>+            return -1;
>+    }
>+
>+    if (n_written == 0)
>+        pa_log("Broken kernel: we got EAGAIN on write() after POLLOUT!");
>+
>+    return n_written;
>+}
>+
>+
> /* I/O thread function */
> static void thread_func(void *userdata) {
>     struct userdata *u = userdata;
>-    unsigned do_write = 0;
>-    unsigned pending_read_bytes = 0;
>-    bool writable = false;
>+    unsigned blocks_to_write = 0;
>+    unsigned bytes_to_write = 0;
> 
>     pa_assert(u);
>     pa_assert(u->transport);
>@@ -1432,9 +1484,13 @@ static void thread_func(void *userdata) {
>         struct pollfd *pollfd;
>         int ret;
>         bool disable_timer = true;
>+        bool writable = false;
>+        bool have_source = u->source ? PA_SOURCE_IS_LINKED(u->source->thread_info.state) : false;
>+        bool have_sink = u->sink ? PA_SINK_IS_LINKED(u->sink->thread_info.state) : false;
> 
>         pollfd = u->rtpoll_item ? pa_rtpoll_item_get_pollfd(u->rtpoll_item, NULL) : NULL;
> 
>+        /* Check for stream error or close */
>         if (pollfd && (pollfd->revents & ~(POLLOUT|POLLIN))) {
>             pa_log_info("FD error: %s%s%s%s",
>                         pollfd->revents & POLLERR ? "POLLERR " :"",
>@@ -1445,147 +1501,177 @@ static void thread_func(void *userdata) {
>             if (pollfd->revents & POLLHUP) {
>                 pollfd = NULL;
>                 teardown_stream(u);
>-                do_write = 0;
>-                pending_read_bytes = 0;
>+                blocks_to_write = 0;
>+                bytes_to_write = 0;
>                 writable = false;
>                 pa_asyncmsgq_post(pa_thread_mq_get()->outq, PA_MSGOBJECT(u->msg), BLUETOOTH_MESSAGE_STREAM_FD_HUP, NULL, 0, NULL, NULL);
>             } else
>                 goto fail;
>         }
> 
>-        if (u->source && PA_SOURCE_IS_LINKED(u->source->thread_info.state)) {
>+        /* If there is a pollfd, the stream is set up and we need to do something */
>+        if (pollfd) {
> 
>-            /* We should send two blocks to the device before we expect
>-             * a response. */
>+            /* Handle source if present */
>+            if (have_source) {
> 
>-            if (u->write_index == 0 && u->read_index <= 0)
>-                do_write = 2;
>+                /* We should send two blocks to the device before we expect a response. */
>+                if (u->write_index == 0 && u->read_index <= 0)
>+                    blocks_to_write = 2;
> 
>-            if (pollfd && (pollfd->revents & POLLIN)) {
>-                int n_read;
>+                /* If we got woken up by POLLIN let's do some reading */
>+                if (pollfd->revents & POLLIN) {
>+                    int n_read;
> 
>-                if (u->profile == PA_BLUETOOTH_PROFILE_A2DP_SOURCE)
>-                    n_read = a2dp_process_push(u);
>-                else
>-                    n_read = sco_process_push(u);
>+                    if (u->profile == PA_BLUETOOTH_PROFILE_A2DP_SOURCE)
>+                        n_read = a2dp_process_push(u);
>+                    else
>+                        n_read = sco_process_push(u);
> 
>-                if (n_read < 0)
>-                    goto fail;
>+                    if (n_read < 0)
>+                        goto fail;
> 
>-                if (n_read > 0) {
>-                    /* We just read something, so we are supposed to write something, too */
>-                    pending_read_bytes += n_read;
>-                    do_write += pending_read_bytes / u->write_block_size;
>-                    pending_read_bytes = pending_read_bytes % u->write_block_size;
>+                    if (n_read > 0) {
>+                        /* We just read something, so we are supposed to write something, too */
>+                        bytes_to_write += n_read;
>+                        blocks_to_write += bytes_to_write / u->write_block_size;
>+                        bytes_to_write = bytes_to_write % u->write_block_size;
>+                    }
>                 }
>             }
>-        }
> 
>-        if (u->sink && PA_SINK_IS_LINKED(u->sink->thread_info.state)) {
>+            /* Handle sink if present */
>+            if (have_sink) {
> 
>-            if (PA_UNLIKELY(u->sink->thread_info.rewind_requested))
>-                pa_sink_process_rewind(u->sink, 0);
>+                /* Process rewinds */
>+                if (PA_UNLIKELY(u->sink->thread_info.rewind_requested))
>+                    pa_sink_process_rewind(u->sink, 0);
> 
>-            if (pollfd) {
>+                /* Test if the stream is writable */
>                 if (pollfd->revents & POLLOUT)
>                     writable = true;
> 
>-                if ((!u->source || !PA_SOURCE_IS_LINKED(u->source->thread_info.state)) && do_write <= 0 && writable) {
>-                    pa_usec_t time_passed;
>-                    pa_usec_t audio_sent;
>-
>-                    /* Hmm, there is no input stream we could synchronize
>-                     * to. So let's do things by time */
>+                /* If we have a source, we let the source determine the timing
>+                 * for the sink */
>+                if (have_source) {
> 
>-                    time_passed = pa_rtclock_now() - u->started_at;
>-                    audio_sent = pa_bytes_to_usec(u->write_index, &u->sample_spec);
>+                    if (writable && blocks_to_write > 0) {
>+                        int result;
> 
>-                    if (audio_sent <= time_passed) {
>-                        pa_usec_t audio_to_send = time_passed - audio_sent;
>-
>-                        /* Never try to catch up for more than 100ms */
>-                        if (u->write_index > 0 && audio_to_send > MAX_PLAYBACK_CATCH_UP_USEC) {
>-                            pa_usec_t skip_usec;
>-                            uint64_t skip_bytes;
>-
>-                            skip_usec = audio_to_send - MAX_PLAYBACK_CATCH_UP_USEC;
>-                            skip_bytes = pa_usec_to_bytes(skip_usec, &u->sample_spec);
>+                        if ((result = write_block(u)) < 0)
>+                            goto fail;
> 
>-                            if (skip_bytes > 0) {
>-                                pa_memchunk tmp;
>+                        blocks_to_write -= result;
>+                        writable = false;
>+                    }
> 
>-                                pa_log_warn("Skipping %llu us (= %llu bytes) in audio stream",
>-                                            (unsigned long long) skip_usec,
>-                                            (unsigned long long) skip_bytes);
>+                /* There is no source, we have to use the system clock for timing */
>+                } else {
>+                    bool have_written = false;
> 
>-                                pa_sink_render_full(u->sink, skip_bytes, &tmp);
>-                                pa_memblock_unref(tmp.memblock);
>-                                u->write_index += skip_bytes;
>+                    /* If the stream is writable, send some data if necessary */
>+                    if (writable) {
>+                        pa_usec_t time_passed;
>+                        pa_usec_t audio_sent;
> 
>-                                if (u->profile == PA_BLUETOOTH_PROFILE_A2DP_SINK)
>-                                    a2dp_reduce_bitpool(u);
>+                        time_passed = pa_rtclock_now() - u->started_at;
>+                        audio_sent = pa_bytes_to_usec(u->write_index, &u->sample_spec);
>+
>+                        /* A new block needs to be sent. */
>+                        if (audio_sent <= time_passed) {
>+                            size_t bytes_to_send = pa_usec_to_bytes(time_passed - audio_sent, &u->sample_spec);
>+
>+                            /* There is more than one block that needs to be written.
>+                             * We cannot catch up, therefore discard everything older
>+                             * than two block sizes */
>+                            if (bytes_to_send > 2 * u->write_block_size) {
>+                                uint64_t skip_bytes;
>+
>+                                skip_bytes = bytes_to_send - 2 * u->write_block_size;
>+
>+                                if (skip_bytes > 0) {
>+                                    pa_memchunk tmp;
>+                                    size_t mempool_max_block_size = pa_mempool_block_size_max(u->core->mempool);
>+                                    pa_usec_t skip_usec = pa_bytes_to_usec(skip_bytes, &u->sample_spec);
>+
>+                                    pa_log_warn("Skipping %llu us (= %llu bytes) in audio stream",
>+                                                (unsigned long long) skip_usec,
>+                                                (unsigned long long) skip_bytes);
>+
>+                                    while (skip_bytes > 0) {
>+                                        size_t bytes_to_render;
>+
>+                                        if (skip_bytes > mempool_max_block_size)
>+                                            bytes_to_render = mempool_max_block_size;
>+                                        else
>+                                            bytes_to_render = skip_bytes;
>+
>+                                        pa_sink_render_full(u->sink, bytes_to_render, &tmp);
>+                                        pa_memblock_unref(tmp.memblock);
>+                                        u->write_index += bytes_to_render;
>+                                        skip_bytes -= bytes_to_render;
>+                                    }
>+
>+                                    if (u->profile == PA_BLUETOOTH_PROFILE_A2DP_SINK)
>+                                        a2dp_reduce_bitpool(u);
>+                                }
>                             }
>-                        }
> 
>-                        do_write = 1;
>-                        pending_read_bytes = 0;
>-                    }
>-                }
>+                            blocks_to_write = 1;
>+                        }
> 
>-                if (writable && do_write > 0) {
>-                    int n_written;
>+                        /* Send block */
>+                        if (blocks_to_write > 0) {
>+                            int result;
> 
>-                    if (u->write_index <= 0)
>-                        u->started_at = pa_rtclock_now();
>+                            if ((result = write_block(u)) < 0)
>+                                goto fail;
> 
>-                    if (u->profile == PA_BLUETOOTH_PROFILE_A2DP_SINK) {
>-                        if ((n_written = a2dp_process_render(u)) < 0)
>-                            goto fail;
>-                    } else {
>-                        if ((n_written = sco_process_render(u)) < 0)
>-                            goto fail;
>+                            blocks_to_write -= result;
>+                            writable = false;
>+                            have_written = true;
>+                        }
>                     }
> 
>-                    if (n_written == 0)
>-                        pa_log("Broken kernel: we got EAGAIN on write() after POLLOUT!");
>-
>-                    do_write -= n_written;
>-                    writable = false;
>+                    /* If nothing was written during this iteration, either the stream
>+                     * is not writable or there was no write pending. Set up a timer that
>+                     * will wake up the thread when the next data needs to be written. */
>+                    if (!have_written) {
>+                        pa_usec_t sleep_for;
>+                        pa_usec_t time_passed, next_write_at;
>+
>+                        if (writable) {
>+                            /* There was no write pending on this iteration of the loop.
>+                             * Let's estimate when we need to wake up next */
>+                            time_passed = pa_rtclock_now() - u->started_at;
>+                            next_write_at = pa_bytes_to_usec(u->write_index, &u->sample_spec);
>+                            sleep_for = time_passed < next_write_at ? next_write_at - time_passed : 0;
>+                            /* pa_log("Sleeping for %lu; time passed %lu, next write at %lu", (unsigned long) sleep_for, (unsigned long) time_passed, (unsigned long)next_write_at); */
>+                        } else
>+                            /* We could not write because the stream was not ready. Let's try
>+                             * again in 500 ms and drop audio if we still can't write. The
>+                             * thread will also be woken up when we can write again. */
>+                            sleep_for = PA_USEC_PER_MSEC * 500;
>+
>+                        pa_rtpoll_set_timer_relative(u->rtpoll, sleep_for);
>+                        disable_timer = false;
>+                    }
>                 }
>+            }
> 
>-                if ((!u->source || !PA_SOURCE_IS_LINKED(u->source->thread_info.state)) && do_write <= 0) {
>-                    pa_usec_t sleep_for;
>-                    pa_usec_t time_passed, next_write_at;
>+            /* Set events to wake up the thread */
>+            pollfd->events = (short) (((have_sink && !writable) ? POLLOUT : 0) | (have_source ? POLLIN : 0));
> 
>-                    if (writable) {
>-                        /* Hmm, there is no input stream we could synchronize
>-                         * to. So let's estimate when we need to wake up the latest */
>-                        time_passed = pa_rtclock_now() - u->started_at;
>-                        next_write_at = pa_bytes_to_usec(u->write_index, &u->sample_spec);
>-                        sleep_for = time_passed < next_write_at ? next_write_at - time_passed : 0;
>-                        /* pa_log("Sleeping for %lu; time passed %lu, next write at %lu", (unsigned long) sleep_for, (unsigned long) time_passed, (unsigned long)next_write_at); */
>-                    } else
>-                        /* drop stream every 500 ms */
>-                        sleep_for = PA_USEC_PER_MSEC * 500;
>-
>-                    pa_rtpoll_set_timer_relative(u->rtpoll, sleep_for);
>-                    disable_timer = false;
>-                }
>-            }
>         }
> 
>         if (disable_timer)
>             pa_rtpoll_set_timer_disabled(u->rtpoll);
> 
>-        /* Hmm, nothing to do. Let's sleep */
>-        if (pollfd)
>-            pollfd->events = (short) (((u->sink && PA_SINK_IS_LINKED(u->sink->thread_info.state) && !writable) ? POLLOUT : 0) |
>-                                      (u->source && PA_SOURCE_IS_LINKED(u->source->thread_info.state) ? POLLIN : 0));
>-
>         if ((ret = pa_rtpoll_run(u->rtpoll)) < 0) {
>             pa_log_debug("pa_rtpoll_run failed with: %d", ret);
>             goto fail;
>         }
>+
>         if (ret == 0) {
>             pa_log_debug("IO thread shutdown requested, stopping cleanly");
>             transport_release(u);
>-- 
>2.14.1
>

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Attachments on bug 58746: 125291 | 137440 | 137477 | 137779 | 138573

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