Adaptively throttle texture uploads

cc/ThrottledTextureUploader.cpp

Index: cc/ThrottledTextureUploader.cpp
diff --git a/cc/ThrottledTextureUploader.cpp b/cc/ThrottledTextureUploader.cpp
index 594342e54ec96873a141c2aad5535ea7a3e62894..410b0ca3a7bcefccc6bb1d93004f9691a00bd27a 100644
--- a/cc/ThrottledTextureUploader.cpp
+++ b/cc/ThrottledTextureUploader.cpp
@@ -3,10 +3,10 @@
 // found in the LICENSE file.
 
 #include "config.h"
-
 #include "ThrottledTextureUploader.h"
 
 #include "Extensions3DChromium.h"
+#include <algorithm>
 #include <public/WebGraphicsContext3D.h>
 
 namespace {
@@ -14,6 +14,12 @@ namespace {
 // Number of pending texture update queries to allow.
 static const size_t maxPendingQueries = 2;
 
+// How many previous uploads to use when predicting future throughput.
+static const size_t uploadHistorySize = 10;
+
+// Default number of pixels per second.
+static double estimatedPixelsPerSecondDefault = 256 * 256 * 48;
+
 } // anonymous namespace
 
 namespace WebCore {
@@ -21,6 +27,7 @@ namespace WebCore {
 ThrottledTextureUploader::Query::Query(WebKit::WebGraphicsContext3D* context)
     : m_context(context)
     , m_queryId(0)
+    , m_pixelsUploaded(0)
 {
     m_queryId = m_context->createQueryEXT();
 }
@@ -35,9 +42,10 @@ void ThrottledTextureUploader::Query::begin()
     m_context->beginQueryEXT(Extensions3DChromium::COMMANDS_ISSUED_CHROMIUM, m_queryId);
 }
 
-void ThrottledTextureUploader::Query::end()
+void ThrottledTextureUploader::Query::end(double pixelsUploaded)
 {
     m_context->endQueryEXT(Extensions3DChromium::COMMANDS_ISSUED_CHROMIUM);
+    m_pixelsUploaded = pixelsUploaded;
 }
 
 bool ThrottledTextureUploader::Query::isPending()
@@ -49,19 +57,33 @@ bool ThrottledTextureUploader::Query::isPending()
 
 void ThrottledTextureUploader::Query::wait()
 {
+    value();
+    return;
+}
+
+unsigned ThrottledTextureUploader::Query::value()
+{
     unsigned result;
     m_context->getQueryObjectuivEXT(m_queryId, Extensions3DChromium::QUERY_RESULT_EXT, &result);
+    return result;
+}
+
+double ThrottledTextureUploader::Query::pixelsUploaded()
+{
+    return m_pixelsUploaded;
 }
 
 ThrottledTextureUploader::ThrottledTextureUploader(WebKit::WebGraphicsContext3D* context)
     : m_context(context)
     , m_maxPendingQueries(maxPendingQueries)
+    , m_pixelsUploaded(0)
 {
 }
 
 ThrottledTextureUploader::ThrottledTextureUploader(WebKit::WebGraphicsContext3D* context, size_t pendingUploadLimit)
     : m_context(context)
     , m_maxPendingQueries(pendingUploadLimit)
+    , m_pixelsUploaded(0)
 {
     ASSERT(m_context);
 }
@@ -69,7 +91,6 @@ ThrottledTextureUploader::ThrottledTextureUploader(WebKit::WebGraphicsContext3D*
 ThrottledTextureUploader::~ThrottledTextureUploader()
 {
 }
-
 bool ThrottledTextureUploader::isBusy()
 {
     processQueries();
@@ -84,8 +105,23 @@ bool ThrottledTextureUploader::isBusy()
     return false;
 }
 
+double ThrottledTextureUploader::estimatedPixelsPerSecond()
+{
+    processQueries();
+
+    if (m_pixelsPerSecondHistory.empty())
+        return estimatedPixelsPerSecondDefault;
+
+    // Sort the history and use the median as our estimate.
+    std::deque<double> sortedHistory(m_pixelsPerSecondHistory);
+    std::sort(sortedHistory.begin(), sortedHistory.end());
+    return sortedHistory[sortedHistory.size() / 2];
+}
+
 void ThrottledTextureUploader::beginUploads()
 {
+    m_pixelsUploaded = 0;
+
     // Wait for query to become available.
     while (isBusy())
         m_pendingQueries.first()->wait();
@@ -96,12 +132,13 @@ void ThrottledTextureUploader::beginUploads()
 
 void ThrottledTextureUploader::endUploads()
 {
-    m_availableQueries.first()->end();
+    m_availableQueries.first()->end(m_pixelsUploaded);
     m_pendingQueries.append(m_availableQueries.takeFirst());
 }
 
 void ThrottledTextureUploader::uploadTexture(CCResourceProvider* resourceProvider, Parameters upload)
 {
+    m_pixelsUploaded += upload.sourceRect.width() * upload.sourceRect.width();
     upload.texture->updateRect(resourceProvider, upload.sourceRect, upload.destOffset);
 }
 
@@ -111,6 +148,14 @@ void ThrottledTextureUploader::processQueries()
         if (m_pendingQueries.first()->isPending())
             break;
 
+        unsigned usElapsed = m_pendingQueries.first()->value();
+        double pixelsPerSecond = m_pendingQueries.first()->pixelsUploaded() / (usElapsed * 1e-6);
+
+        // Remove the oldest values from our history and insert the new one
+        if (m_pixelsPerSecondHistory.size() >= uploadHistorySize)
+            m_pixelsPerSecondHistory.pop_back();
+        m_pixelsPerSecondHistory.push_front(pixelsPerSecond);
+
         m_availableQueries.append(m_pendingQueries.takeFirst());
     }
 }