[PATCH] winealsa: Wait for the notify buffer to empty, rather than dropping an event.

[Huw Davies]

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=52828
Signed-off-by: Huw Davies 
---
 dlls/winealsa.drv/alsamidi.c | 42 ++++++++++++++++++++++++------------
 1 file changed, 28 insertions(+), 14 deletions(-)

diff --git a/dlls/winealsa.drv/alsamidi.c b/dlls/winealsa.drv/alsamidi.c
index 4f3f5538891..b226dac310f 100644
--- a/dlls/winealsa.drv/alsamidi.c
+++ b/dlls/winealsa.drv/alsamidi.c
@@ -90,7 +90,8 @@ static int rec_cancel_pipe[2];
 static pthread_t rec_thread_id;

static pthread_mutex_t notify_mutex = PTHREAD_MUTEX_INITIALIZER;
-static pthread_cond_t notify_cond = PTHREAD_COND_INITIALIZER;
+static pthread_cond_t notify_read_cond = PTHREAD_COND_INITIALIZER;
+static pthread_cond_t notify_write_cond = PTHREAD_COND_INITIALIZER;
 static BOOL notify_quit;
 #define NOTIFY_BUFFER_SIZE 64 + 1 /* + 1 for the sentinel */
 static struct notify_context notify_buffer[NOTIFY_BUFFER_SIZE];
@@ -156,19 +157,23 @@ static struct notify_context *notify_buffer_next(struct notify_context *notify)
     return notify;
 }

-static void notify_buffer_add(struct notify_context *notify)
+static BOOL notify_buffer_empty(void)
 {
-    struct notify_context *next = notify_buffer_next(notify_write);
+    return notify_read == notify_write;
+}

-    if (next == notify_read) /* buffer is full - we can't issue a WARN() in a non-Win32 thread */
-        notify_read = notify_buffer_next(notify_read); /* drop the oldest notification */
-    *notify_write = *notify;
-    notify_write = next;
+static BOOL notify_buffer_full(void)
+{
+    return notify_buffer_next(notify_write) == notify_read;
 }

-static BOOL notify_buffer_empty(void)
+static BOOL notify_buffer_add(struct notify_context *notify)
 {
-    return notify_read == notify_write;
+    if (notify_buffer_full()) return FALSE;
+
+    *notify_write = *notify;
+    notify_write = notify_buffer_next(notify_write);
+    return TRUE;
 }

static BOOL notify_buffer_remove(struct notify_context *notify)
@@ -184,9 +189,15 @@ static void notify_post(struct notify_context *notify)
 {
     pthread_mutex_lock(&notify_mutex);

-    if (notify) notify_buffer_add(notify);
+    if (notify)
+    {
+        while (notify_buffer_full())
+            pthread_cond_wait(&notify_write_cond, &notify_mutex);
+
+        notify_buffer_add(notify);
+    }
     else notify_quit = TRUE;
-    pthread_cond_signal(&notify_cond);
+    pthread_cond_signal(&notify_read_cond);

pthread_mutex_unlock(&notify_mutex);
 }
@@ -1476,11 +1487,14 @@ NTSTATUS midi_notify_wait(void *args)
     pthread_mutex_lock(&notify_mutex);

while (!notify_quit && notify_buffer_empty())
-        pthread_cond_wait(&notify_cond, &notify_mutex);
+        pthread_cond_wait(&notify_read_cond, &notify_mutex);

*params->quit = notify_quit;
-    if (!notify_quit) notify_buffer_remove(params->notify);
-
+    if (!notify_quit)
+    {
+        notify_buffer_remove(params->notify);
+        pthread_cond_signal(&notify_write_cond);
+    }
     pthread_mutex_unlock(&notify_mutex);

return STATUS_SUCCESS;