WebFonts cache-aware timeout adaptation

third_party/WebKit/Source/core/fetch/FontResource.cpp

 /*
  * Copyright (C) 2006, 2007, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile, Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 11 matching lines @@
  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "core/fetch/FontResource.h"
 
 #include "core/fetch/FetchRequest.h"
 #include "core/fetch/ResourceClientWalker.h"
 #include "core/fetch/ResourceFetcher.h"
+#include "core/fetch/ResourceLoader.h"
 #include "platform/Histogram.h"
 #include "platform/SharedBuffer.h"
 #include "platform/fonts/FontCustomPlatformData.h"
 #include "platform/fonts/FontPlatformData.h"
 #include "wtf/CurrentTime.h"
 
 namespace blink {
 
 // Durations of font-display periods.
 // https://tabatkins.github.io/specs/css-font-display/#font-display-desc
+// TODO(shaochuan): Revisit short limit value once cache-aware font display is
+// launched. crbug.com/570205
 static const double fontLoadWaitShortLimitSec = 0.1;
 static const double fontLoadWaitLongLimitSec = 3.0;
 
 enum FontPackageFormat {
   PackageFormatUnknown,
   PackageFormatSFNT,
   PackageFormatWOFF,
   PackageFormatWOFF2,
   PackageFormatSVG,
   PackageFormatEnumMax
@@ skipping 36 matching lines @@
       m_fontLoadShortLimitTimer(this,
                                 &FontResource::fontLoadShortLimitCallback),
       m_fontLoadLongLimitTimer(this, &FontResource::fontLoadLongLimitCallback) {
 }
 
 FontResource::~FontResource() {}
 
 void FontResource::didAddClient(ResourceClient* c) {
   DCHECK(FontResourceClient::isExpectedType(c));
   Resource::didAddClient(c);
+
+  // Block client callbacks if currently loading from cache.
+  if (isLoading() && loader()->isCacheAwareLoadingActivated())
+    return;
+
   if (m_loadLimitState == ShortLimitExceeded ||
       m_loadLimitState == LongLimitExceeded)
     static_cast<FontResourceClient*>(c)->fontLoadShortLimitExceeded(this);
   if (m_loadLimitState == LongLimitExceeded)
     static_cast<FontResourceClient*>(c)->fontLoadLongLimitExceeded(this);
 }
 
 void FontResource::setRevalidatingRequest(const ResourceRequest& request) {
   // Reload will use the same object, and needs to reset |m_loadLimitState|
   // before any didAddClient() is called again.
@@ skipping 28 matching lines @@
 
 FontPlatformData FontResource::platformDataFromCustomData(
     float size,
     bool bold,
     bool italic,
     FontOrientation orientation) {
   DCHECK(m_fontData);
   return m_fontData->fontPlatformData(size, bold, italic, orientation);
 }
 
+void FontResource::willReloadAfterDiskCacheMiss() {
+  DCHECK(isLoading());
+  DCHECK(loader()->isCacheAwareLoadingActivated());
+
+  ProhibitAddRemoveClientInScope prohibitAddRemoveClient(this);

[Shao-Chuan Lee, 2016/11/07 06:52:47]

I feel like having this whenever client callbacks are called?
Though this is currently not major problem but more about code health,
preventing problems if state become complicated in the future.

+
+  if (m_loadLimitState == ShortLimitExceeded ||
+      m_loadLimitState == LongLimitExceeded)
+    notifyClientsShortLimitExceeded();
+  if (m_loadLimitState == LongLimitExceeded)
+    notifyClientsLongLimitExceeded();
+
+  DEFINE_STATIC_LOCAL(
+      EnumerationHistogram, loadLimitHistogram,
+      ("WebFont.LoadLimitOnDiskCacheMiss", LoadLimitStateEnumMax));
+  loadLimitHistogram.count(m_loadLimitState);

[Shao-Chuan Lee, 2016/11/07 06:52:47]

ksakamoto@: PTAL

[Kunihiko Sakamoto, 2016/11/07 07:56:24]

Looks good. Please add a histogram.xml entry.

[Shao-Chuan Lee, 2016/11/07 08:43:44]

Done.

+}
+
 void FontResource::fontLoadShortLimitCallback(TimerBase*) {
-  if (!isLoading())
-    return;
+  DCHECK(isLoading());
   DCHECK_EQ(m_loadLimitState, UnderLimit);
   m_loadLimitState = ShortLimitExceeded;
+
+  // Block client callbacks if currently loading from cache.
+  if (loader()->isCacheAwareLoadingActivated())
+    return;
+  notifyClientsShortLimitExceeded();
+}
+
+void FontResource::fontLoadLongLimitCallback(TimerBase*) {
+  DCHECK(isLoading());
+  DCHECK_EQ(m_loadLimitState, ShortLimitExceeded);
+  m_loadLimitState = LongLimitExceeded;
+
+  // Block client callbacks if currently loading from cache.
+  if (loader()->isCacheAwareLoadingActivated())
+    return;
+  notifyClientsLongLimitExceeded();
+}
+
+void FontResource::notifyClientsShortLimitExceeded() {
   ResourceClientWalker<FontResourceClient> walker(clients());
   while (FontResourceClient* client = walker.next())
     client->fontLoadShortLimitExceeded(this);
 }
 
-void FontResource::fontLoadLongLimitCallback(TimerBase*) {
-  if (!isLoading())
-    return;
-  DCHECK_EQ(m_loadLimitState, ShortLimitExceeded);
-  m_loadLimitState = LongLimitExceeded;
+void FontResource::notifyClientsLongLimitExceeded() {
   ResourceClientWalker<FontResourceClient> walker(clients());
   while (FontResourceClient* client = walker.next())
     client->fontLoadLongLimitExceeded(this);
 }
 
 void FontResource::allClientsAndObserversRemoved() {
   m_fontData.reset();
   Resource::allClientsAndObserversRemoved();
 }
 
 void FontResource::checkNotify() {
   m_fontLoadShortLimitTimer.stop();
   m_fontLoadLongLimitTimer.stop();
 
   Resource::checkNotify();
 }
 
 }  // namespace blink