From 1fe0c673bc3ead4e99e47e61e7aa3f0ed590bbba Mon Sep 17 00:00:00 2001
From: Max Kellermann <max@musicpd.org>
Date: Wed, 10 Mar 2021 20:25:20 +0100
Subject: [PATCH] output/wasapi: implement Cancel() properly
Calling consume_all() is illegal in the producer thread.
---
.../plugins/wasapi/WasapiOutputPlugin.cxx | 29 ++++++++++++++++++-
1 file changed, 28 insertions(+), 1 deletion(-)
diff --git a/src/output/plugins/wasapi/WasapiOutputPlugin.cxx b/src/output/plugins/wasapi/WasapiOutputPlugin.cxx
index ba6b61a80..e7075c0b5 100644
--- a/src/output/plugins/wasapi/WasapiOutputPlugin.cxx
+++ b/src/output/plugins/wasapi/WasapiOutputPlugin.cxx
@@ -170,7 +170,10 @@ class WasapiOutputThread {
bool started = false;
+ std::atomic_bool cancel = false;
+
enum class Status : uint32_t { FINISH, PLAY, PAUSE };
+
alignas(BOOST_LOCKFREE_CACHELINE_BYTES) std::atomic<Status> status =
Status::PAUSE;
alignas(BOOST_LOCKFREE_CACHELINE_BYTES) struct {
@@ -201,6 +204,24 @@ public:
void Play() noexcept { return SetStatus(Status::PLAY); }
void Pause() noexcept { return SetStatus(Status::PAUSE); }
+ /**
+ * Instruct the thread to discard the buffer (and wait for
+ * completion). This needs to be done inside this thread,
+ * because only the consumer thread is allowed to do that.
+ */
+ void Cancel() noexcept {
+ cancel.store(true);
+ event.Set();
+
+ while (cancel.load() && !error.occur.load())
+ Wait();
+
+ /* not rethrowing the exception here via
+ CheckException() because this method must be
+ "noexcept"; the next WasapiOutput::Play() call will
+ throw */
+ }
+
/**
* Wait for the thread to finish some work (e.g. until some
* buffer space becomes available).
@@ -366,6 +387,12 @@ try {
while (true) {
event.Wait();
+ if (cancel.load()) {
+ spsc_buffer.consume_all([](auto &&) {});
+ cancel.store(false);
+ InterruptWaiter();
+ }
+
Status current_state = status.load();
switch (current_state) {
case Status::FINISH:
@@ -707,7 +734,7 @@ WasapiOutput::Cancel() noexcept
{
assert(thread);
- thread->spsc_buffer.consume_all([](auto &&) {});
+ thread->Cancel();
}
/// run inside COMWorkerThread