Revert of SkTime::GetNSecs()

tools/timer/GpuTimer.cpp

+
+/*
+ * Copyright 2011 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+#include "GpuTimer.h"
+#include "gl/SkGLContext.h"
+#include "gl/GrGLUtil.h"
+
+GpuTimer::GpuTimer(const SkGLContext* glctx) : fContext(glctx) {
+    if (fContext) {
+        fContext->ref();
+        fContext->makeCurrent();
+        fStarted = false;
+        fSupported = GrGLGetVersion(fContext->gl()) > GR_GL_VER(3,3) ||
+                fContext->gl()->hasExtension("GL_ARB_timer_query") ||
+                fContext->gl()->hasExtension("GL_EXT_timer_query");
+
+        if (fSupported) {
+            SK_GL(*fContext, GenQueries(1, &fQuery));
+        }
+    }
+}
+
+GpuTimer::~GpuTimer() {
+    if (fContext) {
+        if (fSupported) {
+            fContext->makeCurrent();
+            SK_GL(*fContext, DeleteQueries(1, &fQuery));
+        }
+        fContext->unref();
+    }
+}
+
+void GpuTimer::start() {
+    if (fContext && fSupported) {
+        fContext->makeCurrent();
+        fStarted = true;
+        SK_GL(*fContext, BeginQuery(GR_GL_TIME_ELAPSED, fQuery));
+    }
+}
+
+/**
+ * It is important to stop the cpu clocks first,
+ * as this will cpu wait for the gpu to finish.
+ */
+double GpuTimer::end() {
+    if (fContext && fSupported) {
+        fStarted = false;
+        fContext->makeCurrent();
+        SK_GL(*fContext, EndQuery(GR_GL_TIME_ELAPSED));
+
+        GrGLint available = 0;
+        while (!available) {
+            SK_GL_NOERRCHECK(*fContext, GetQueryObjectiv(fQuery,
+                                                         GR_GL_QUERY_RESULT_AVAILABLE,
+                                                         &available));
+            // If GetQueryObjectiv is erroring out we need some alternative
+            // means of breaking out of this loop
+            GrGLenum error;
+            SK_GL_RET_NOERRCHECK(*fContext, error, GetError());
+            if (GR_GL_NO_ERROR != error) {
+                break;
+            }
+        }
+        GrGLuint64 totalGPUTimeElapsed = 0;
+        SK_GL(*fContext, GetQueryObjectui64v(fQuery,
+                                             GR_GL_QUERY_RESULT,
+                                             &totalGPUTimeElapsed));
+
+        return totalGPUTimeElapsed / 1000000.0;
+    } else {
+        return 0;
+    }
+}