Fix semaphore emulation on Windows

The existing emulation of posix semaphores on Windows uses SetEvent()
and WaitForSingleObject(), which implements a binary semaphore, not a
counting semaphore as implemented by posix. This causes deadlock when
used with the expected posix semantics. Instead, this patch uses the
CreateSemaphore() and ReleaseSemaphore() calls (introduced in Windows
2000) which have the expected behavior.

This patch also reverts commit eb16f00, which split a semaphore that
was being used with counting semantics into two binary semaphores.
That commit is unnecessary with corrected emulation.

Change-Id: If400771536a27af4b0c3a31aa4c4e9ced89ce6a0

diff --git a/vp8/common/threading.h b/vp8/common/threading.h
index b7542b3..5927cb1 100644 (file)
--- a/vp8/common/threading.h
+++ b/vp8/common/threading.h
@@ -59,9 +59,9 @@
 #ifdef _WIN32
 #define sem_t HANDLE
 #define pause(voidpara) __asm PAUSE
-#define sem_init(sem, sem_attr1, sem_init_value) (int)((*sem = CreateEvent(NULL,FALSE,FALSE,NULL))==NULL)
+#define sem_init(sem, sem_attr1, sem_init_value) (int)((*sem = CreateSemaphore(NULL,0,32768,NULL))==NULL)
 #define sem_wait(sem) (int)(WAIT_OBJECT_0 != WaitForSingleObject(*sem,INFINITE))
-#define sem_post(sem) SetEvent(*sem)
+#define sem_post(sem) ReleaseSemaphore(*sem,1,NULL)
 #define sem_destroy(sem) if(*sem)((int)(CloseHandle(*sem))==TRUE)
 #define thread_sleep(nms) Sleep(nms)
 

diff --git a/vp8/encoder/ethreading.c b/vp8/encoder/ethreading.c
index c92a366..c00494d 100644 (file)
--- a/vp8/encoder/ethreading.c
+++ b/vp8/encoder/ethreading.c
@@ -514,7 +514,6 @@ void vp8cx_create_encoder_threads(VP8_COMP *cpi)
             LPFTHREAD_DATA * lpfthd = &cpi->lpf_thread_data;
 
             sem_init(&cpi->h_event_start_lpf, 0, 0);
-            sem_init(&cpi->h_event_end_picklpf, 0, 0);
             sem_init(&cpi->h_event_end_lpf, 0, 0);
 
             lpfthd->ptr1 = (void *)cpi;
@@ -548,7 +547,6 @@ void vp8cx_remove_encoder_threads(VP8_COMP *cpi)
 
         sem_destroy(&cpi->h_event_end_encoding);
         sem_destroy(&cpi->h_event_end_lpf);
-        sem_destroy(&cpi->h_event_end_picklpf);
         sem_destroy(&cpi->h_event_start_lpf);
 
         //free thread related resources

diff --git a/vp8/encoder/onyx_if.c b/vp8/encoder/onyx_if.c
index 78f8655..1738e56 100644 (file)
--- a/vp8/encoder/onyx_if.c
+++ b/vp8/encoder/onyx_if.c
@@ -3140,7 +3140,7 @@ void loopfilter_frame(VP8_COMP *cpi, VP8_COMMON *cm)
 
 #if CONFIG_MULTITHREAD
     if (cpi->b_multi_threaded)
-        sem_post(&cpi->h_event_end_picklpf); /* signal that we have set filter_level */
+        sem_post(&cpi->h_event_end_lpf); /* signal that we have set filter_level */
 #endif
 
     if (cm->filter_level > 0)
@@ -4135,7 +4135,7 @@ static void encode_frame_to_data_rate
 #if CONFIG_MULTITHREAD
     /* wait that filter_level is picked so that we can continue with stream packing */
     if (cpi->b_multi_threaded)
-        sem_wait(&cpi->h_event_end_picklpf);
+        sem_wait(&cpi->h_event_end_lpf);
 #endif
 
     // build the bitstream

diff --git a/vp8/encoder/onyx_int.h b/vp8/encoder/onyx_int.h
index c2fcff8..e2e6b36 100644 (file)
--- a/vp8/encoder/onyx_int.h
+++ b/vp8/encoder/onyx_int.h
@@ -590,7 +590,6 @@ typedef struct
     sem_t *h_event_start_encoding;
     sem_t h_event_end_encoding;
     sem_t h_event_start_lpf;
-    sem_t h_event_end_picklpf;
     sem_t h_event_end_lpf;
 #endif