libvpx: Pull from upstream

source/libvpx/vp9/common/vp9_thread.h

 // Copyright 2013 Google Inc. All Rights Reserved.
 //
 // Use of this source code is governed by a BSD-style license
 // that can be found in the COPYING file in the root of the source
 // tree. An additional intellectual property rights grant can be found
 // in the file PATENTS. All contributing project authors may
 // be found in the AUTHORS file in the root of the source tree.
 // -----------------------------------------------------------------------------
 //
 // Multi-threaded worker
 //
 // Original source:
 //  http://git.chromium.org/webm/libwebp.git
 //  100644 blob 7bd451b124ae3b81596abfbcc823e3cb129d3a38  src/utils/thread.h
 
 #ifndef VP9_DECODER_VP9_THREAD_H_
 #define VP9_DECODER_VP9_THREAD_H_
 
 #include "./vpx_config.h"
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
+// Set maximum decode threads to be 8 due to the limit of frame buffers
+// and not enough semaphores in the emulation layer on windows.
+#define MAX_DECODE_THREADS 8
+
 #if CONFIG_MULTITHREAD
 
-#if defined(_WIN32)
+#if defined(_WIN32) && !HAVE_PTHREAD_H
 #include <errno.h>  // NOLINT
 #include <process.h>  // NOLINT
 #include <windows.h>  // NOLINT
 typedef HANDLE pthread_t;
 typedef CRITICAL_SECTION pthread_mutex_t;
 typedef struct {
   HANDLE waiting_sem_;
   HANDLE received_sem_;
   HANDLE signal_event_;
 } pthread_cond_t;
@@ skipping 58 matching lines @@
   int ok = 1;
   ok &= (CloseHandle(condition->waiting_sem_) != 0);
   ok &= (CloseHandle(condition->received_sem_) != 0);
   ok &= (CloseHandle(condition->signal_event_) != 0);
   return !ok;
 }
 
 static INLINE int pthread_cond_init(pthread_cond_t *const condition,
                                     void* cond_attr) {
   (void)cond_attr;
-  condition->waiting_sem_ = CreateSemaphore(NULL, 0, 1, NULL);
-  condition->received_sem_ = CreateSemaphore(NULL, 0, 1, NULL);
+  condition->waiting_sem_ = CreateSemaphore(NULL, 0, MAX_DECODE_THREADS, NULL);
+  condition->received_sem_ = CreateSemaphore(NULL, 0, MAX_DECODE_THREADS, NULL);
   condition->signal_event_ = CreateEvent(NULL, FALSE, FALSE, NULL);
   if (condition->waiting_sem_ == NULL ||
       condition->received_sem_ == NULL ||
       condition->signal_event_ == NULL) {
     pthread_cond_destroy(condition);
     return 1;
   }
   return 0;
 }
 
@@ skipping 92 matching lines @@
 // Retrieve the currently set thread worker interface.
 const VP9WorkerInterface *vp9_get_worker_interface(void);
 
 //------------------------------------------------------------------------------
 
 #ifdef __cplusplus
 }    // extern "C"
 #endif
 
 #endif  // VP9_DECODER_VP9_THREAD_H_