From 82dbc7429f5f9f2b303b31dc5b9f2bfd1bbe6add Mon Sep 17 00:00:00 2001
From: Jamie Gennis <jgennis@google.com>
Date: Thu, 8 Nov 2012 19:23:28 -0800
Subject: SurfaceFlinger: refactor frame time tracking

This change moves the frame time history tracking code out of Layer and into a
new class called FrameTracker.  It also changes the tracking to use signal
timestamps from fences when available for more accurate results.

Change-Id: I323c5f075c58bf86ce363b52af885ad0f6365f2b
---
 libs/ui/Fence.cpp | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

(limited to 'libs/ui/Fence.cpp')

diff --git a/libs/ui/Fence.cpp b/libs/ui/Fence.cpp
index d214b97..84f5a47 100644
--- a/libs/ui/Fence.cpp
+++ b/libs/ui/Fence.cpp
@@ -18,6 +18,9 @@
 #define ATRACE_TAG ATRACE_TAG_GRAPHICS
 //#define LOG_NDEBUG 0
 
+ // This is needed for stdint.h to define INT64_MAX in C++
+ #define __STDC_LIMIT_MACROS
+
 #include <sync/sync.h>
 #include <ui/Fence.h>
 #include <unistd.h>
@@ -86,6 +89,32 @@ int Fence::dup() const {
     return ::dup(mFenceFd);
 }
 
+nsecs_t Fence::getSignalTime() const {
+    if (mFenceFd == -1) {
+        return -1;
+    }
+
+    struct sync_fence_info_data* finfo = sync_fence_info(mFenceFd);
+    if (finfo == NULL) {
+        ALOGE("sync_fence_info returned NULL for fd %d", mFenceFd);
+        return -1;
+    }
+    if (finfo->status != 1) {
+        return INT64_MAX;
+    }
+
+    struct sync_pt_info* pinfo = NULL;
+    uint64_t timestamp = 0;
+    while ((pinfo = sync_pt_info(finfo, pinfo)) != NULL) {
+        if (pinfo->timestamp_ns > timestamp) {
+            timestamp = pinfo->timestamp_ns;
+        }
+    }
+    sync_fence_info_free(finfo);
+
+    return nsecs_t(timestamp);
+}
+
 size_t Fence::getFlattenedSize() const {
     return 0;
 }
-- 
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