From 8df79e9d427fe2e334f110a8abfe3e43449d87c4 Mon Sep 17 00:00:00 2001
From: John Koleszar <jkoleszar@google.com>
Date: Fri, 15 Jun 2012 15:40:13 -0700
Subject: Remove threading dependencies with --disable-multithread

Avoid a pthreads dependency via pthread_once() when compiled with
--disable-multithread.

In addition, this synchronization is disabled for Win32 as well, even
though we can be sure that the required primatives exist, so that the
requirements on the application when built with --disable-multithread
are consistent across platforms.

Users using libvpx built with --disable-multithread in a multithreaded
context should provide their own synchronization. Updated the
documentation to vpx_codec_enc_init_ver() and vpx_codec_dec_init_ver()
to note this requirement. Moved the RTCD initialization call to match
this description, as previously it didn't happen until the first
frame.

Change-Id: Id576f6bce2758362188278d3085051c218a56d4a
---
 vp8/common/generic/systemdependent.c | 53 ---------------------------------
 vp8/common/rtcd.c                    | 57 ++++++++++++++++++++++++++++++++++++
 vp8/vp8_cx_iface.c                   |  3 ++
 vp8/vp8_dx_iface.c                   |  3 ++
 4 files changed, 63 insertions(+), 53 deletions(-)

(limited to 'vp8')

diff --git a/vp8/common/generic/systemdependent.c b/vp8/common/generic/systemdependent.c
index 2a3016618..5a6ac7b0e 100644
--- a/vp8/common/generic/systemdependent.c
+++ b/vp8/common/generic/systemdependent.c
@@ -83,57 +83,6 @@ static int get_cpu_count()
 #endif
 
 
-#if HAVE_PTHREAD_H
-#include <pthread.h>
-static void once(void (*func)(void))
-{
-    static pthread_once_t lock = PTHREAD_ONCE_INIT;
-    pthread_once(&lock, func);
-}
-
-
-#elif defined(_WIN32)
-static void once(void (*func)(void))
-{
-    /* Using a static initializer here rather than InitializeCriticalSection()
-     * since there's no race-free context in which to execute it. Protecting
-     * it with an atomic op like InterlockedCompareExchangePointer introduces
-     * an x86 dependency, and InitOnceExecuteOnce requires Vista.
-     */
-    static CRITICAL_SECTION lock = {(void *)-1, -1, 0, 0, 0, 0};
-    static int done;
-
-    EnterCriticalSection(&lock);
-
-    if (!done)
-    {
-        func();
-        done = 1;
-    }
-
-    LeaveCriticalSection(&lock);
-}
-
-
-#else
-/* No-op version that performs no synchronization. vpx_rtcd() is idempotent,
- * so as long as your platform provides atomic loads/stores of pointers
- * no synchronization is strictly necessary.
- */
-
-static void once(void (*func)(void))
-{
-    static int done;
-
-    if(!done)
-    {
-        func();
-        done = 1;
-    }
-}
-#endif
-
-
 void vp8_machine_specific_config(VP8_COMMON *ctx)
 {
 #if CONFIG_MULTITHREAD
@@ -145,6 +94,4 @@ void vp8_machine_specific_config(VP8_COMMON *ctx)
 #elif ARCH_X86 || ARCH_X86_64
     ctx->cpu_caps = x86_simd_caps();
 #endif
-
-    once(vpx_rtcd);
 }
diff --git a/vp8/common/rtcd.c b/vp8/common/rtcd.c
index 232640dc8..4980f48ad 100644
--- a/vp8/common/rtcd.c
+++ b/vp8/common/rtcd.c
@@ -10,3 +10,60 @@
 #include "vpx_config.h"
 #define RTCD_C
 #include "vpx_rtcd.h"
+
+#if CONFIG_MULTITHREAD && HAVE_PTHREAD_H
+#include <pthread.h>
+static void once(void (*func)(void))
+{
+    static pthread_once_t lock = PTHREAD_ONCE_INIT;
+    pthread_once(&lock, func);
+}
+
+
+#elif CONFIG_MULTITHREAD && defined(_WIN32)
+#include <windows.h>
+static void once(void (*func)(void))
+{
+    /* Using a static initializer here rather than InitializeCriticalSection()
+     * since there's no race-free context in which to execute it. Protecting
+     * it with an atomic op like InterlockedCompareExchangePointer introduces
+     * an x86 dependency, and InitOnceExecuteOnce requires Vista.
+     */
+    static CRITICAL_SECTION lock = {(void *)-1, -1, 0, 0, 0, 0};
+    static int done;
+
+    EnterCriticalSection(&lock);
+
+    if (!done)
+    {
+        func();
+        done = 1;
+    }
+
+    LeaveCriticalSection(&lock);
+}
+
+
+#else
+/* No-op version that performs no synchronization. vpx_rtcd() is idempotent,
+ * so as long as your platform provides atomic loads/stores of pointers
+ * no synchronization is strictly necessary.
+ */
+
+static void once(void (*func)(void))
+{
+    static int done;
+
+    if(!done)
+    {
+        func();
+        done = 1;
+    }
+}
+#endif
+
+
+void vpx_rtcd()
+{
+    once(setup_rtcd_internal);
+}
diff --git a/vp8/vp8_cx_iface.c b/vp8/vp8_cx_iface.c
index 967110768..a499825fd 100644
--- a/vp8/vp8_cx_iface.c
+++ b/vp8/vp8_cx_iface.c
@@ -9,6 +9,7 @@
  */
 
 
+#include "vpx_rtcd.h"
 #include "vpx/vpx_codec.h"
 #include "vpx/internal/vpx_codec_internal.h"
 #include "vpx_version.h"
@@ -572,6 +573,8 @@ static vpx_codec_err_t vp8e_init(vpx_codec_ctx_t *ctx,
 
     struct VP8_COMP *optr;
 
+    vpx_rtcd();
+
     if (!ctx->priv)
     {
         priv = calloc(1, sizeof(struct vpx_codec_alg_priv));
diff --git a/vp8/vp8_dx_iface.c b/vp8/vp8_dx_iface.c
index 37773dba5..fe8c9a0c0 100644
--- a/vp8/vp8_dx_iface.c
+++ b/vp8/vp8_dx_iface.c
@@ -11,6 +11,7 @@
 
 #include <stdlib.h>
 #include <string.h>
+#include "vpx_rtcd.h"
 #include "vpx/vpx_decoder.h"
 #include "vpx/vp8dx.h"
 #include "vpx/internal/vpx_codec_internal.h"
@@ -187,6 +188,8 @@ static vpx_codec_err_t vp8_init(vpx_codec_ctx_t *ctx,
     vpx_codec_err_t        res = VPX_CODEC_OK;
     (void) data;
 
+    vpx_rtcd();
+
     /* This function only allocates space for the vpx_codec_alg_priv_t
      * structure. More memory may be required at the time the stream
      * information becomes known.
-- 
cgit v1.2.3