Track performance of toBlob and its complete timeout delay

third_party/WebKit/Source/core/html/canvas/CanvasAsyncBlobCreator.cpp

Index: third_party/WebKit/Source/core/html/canvas/CanvasAsyncBlobCreator.cpp
diff --git a/third_party/WebKit/Source/core/html/canvas/CanvasAsyncBlobCreator.cpp b/third_party/WebKit/Source/core/html/canvas/CanvasAsyncBlobCreator.cpp
index 01136649524082b8b79b83dda662a2a4852c957e..32aa475cf162aa0828a5c3652916d23f8d0f32f8 100644
--- a/third_party/WebKit/Source/core/html/canvas/CanvasAsyncBlobCreator.cpp
+++ b/third_party/WebKit/Source/core/html/canvas/CanvasAsyncBlobCreator.cpp
@@ -5,6 +5,7 @@
 #include "core/html/canvas/CanvasAsyncBlobCreator.h"
 
 #include "core/fileapi/Blob.h"
+#include "platform/Histogram.h"
 #include "platform/ThreadSafeFunctional.h"
 #include "platform/graphics/ImageBuffer.h"
 #include "platform/image-encoders/JPEGImageEncoder.h"
@@ -94,6 +95,7 @@ CanvasAsyncBlobCreator::CanvasAsyncBlobCreator(DOMUint8ClampedArray* data, MimeT
     m_pixelRowStride = size.width() * NumChannelsPng;
     m_idleTaskStatus = IdleTaskNotSupported;
     m_numRowsCompleted = 0;
+    m_startTime = WTF::monotonicallyIncreasingTime();
 }
 
 CanvasAsyncBlobCreator::~CanvasAsyncBlobCreator()
@@ -251,6 +253,24 @@ void CanvasAsyncBlobCreator::encodeRowsJpegOnMainThread()
     this->signalAlternativeCodePathFinishedForTesting();
 }
 
+void CanvasAsyncBlobCreator::recordElapsedTime()
+{
+    double elapsedTime = WTF::monotonicallyIncreasingTime()  - m_startTime;
+    if (m_mimeType == MimeTypePng) {
+        DEFINE_THREAD_SAFE_STATIC_LOCAL(CustomCountHistogram, toBlobPNGCounter, new CustomCountHistogram("Blink.Canvas.ToBlob.PNG", 0, 10000000, 50));
+        toBlobPNGCounter.count(elapsedTime * 1000000.0);
+    } else if (m_mimeType == MimeTypeJpeg) {
+        DEFINE_THREAD_SAFE_STATIC_LOCAL(CustomCountHistogram, toBlobJPEGCounter, new CustomCountHistogram("Blink.Canvas.ToBlob.JPEG", 0, 10000000, 50));
+        toBlobJPEGCounter.count(elapsedTime * 1000000.0);
+    } else if (m_mimeType == MimeTypeWebp) {
+        DEFINE_THREAD_SAFE_STATIC_LOCAL(CustomCountHistogram, toBlobWEBPCounter, new CustomCountHistogram("Blink.Canvas.ToBlob.WEBP", 0, 10000000, 50));
+        toBlobWEBPCounter.count(elapsedTime * 1000000.0);
+    } else {
+        DEFINE_THREAD_SAFE_STATIC_LOCAL(CustomCountHistogram, toBlobUnknownCounter, new CustomCountHistogram("Blink.Canvas.ToBlob.Unknown", 0, 10000000, 50));
+        toBlobUnknownCounter.count(elapsedTime * 1000000.0);
+    }
+}
+
 void CanvasAsyncBlobCreator::createBlobAndInvokeCallback()
 {
     ASSERT(isMainThread());
@@ -260,6 +280,7 @@ void CanvasAsyncBlobCreator::createBlobAndInvokeCallback()
     // non-GC members to allow teardown of CanvasAsyncBlobCreator.
     m_data.clear();
     m_callback.clear();
+    recordElapsedTime();
 }
 
 void CanvasAsyncBlobCreator::createNullAndInvokeCallback()
@@ -270,6 +291,7 @@ void CanvasAsyncBlobCreator::createNullAndInvokeCallback()
     // clear non-GC members to allow teardown of CanvasAsyncBlobCreator.
     m_data.clear();
     m_callback.clear();
+    recordElapsedTime();

[Justin Novosad, 2016/06/06 15:16:03]

The failure case should not be recording to the same timing metrics as the
success case.  We could probably do without capturing time for the failure
cases.  However, it would be relevant to have a fail vs. succeed histogram for
each mime type.

 }
 
 void CanvasAsyncBlobCreator::encodeImageOnEncoderThread(double quality)
@@ -344,6 +366,9 @@ void CanvasAsyncBlobCreator::idleTaskCompleteTimeoutEvent()
 {
     ASSERT(m_idleTaskStatus != IdleTaskNotStarted);
 
+    DEFINE_THREAD_SAFE_STATIC_LOCAL(EnumerationHistogram, idleTaskCompleteTimeoutDelayHistogram, new EnumerationHistogram("Canvas.ToBlob.IdleTaskCompleteTimeoutDelay", NumberOfMimeTypeSupported));

[Justin Novosad, 2016/06/06 15:16:03]

This histogram does not provide very significant info on its own. It would be
better to have a separate histogram per mime type, and for each such histogram,
the bins should be idleTaskTimeout vs. idleTaskCompleted.  That way we get
histograms that tell us the fraction of tasks that timed-out, which is directly
relevant data.  Also, the word "Delay" is not very relevant here.

+    idleTaskCompleteTimeoutDelayHistogram.count(m_mimeType);
+
     if (m_idleTaskStatus == IdleTaskStarted) {
         // It has taken too long to complete for the idle task.
         m_idleTaskStatus = IdleTaskSwitchedToMainThreadTask;