WebFonts cache-aware timeout adaptation

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

Index: third_party/WebKit/Source/core/fetch/FontResource.cpp
diff --git a/third_party/WebKit/Source/core/fetch/FontResource.cpp b/third_party/WebKit/Source/core/fetch/FontResource.cpp
index 2de0a247cda364998c55aca696d0456f8f37c313..f8daa718b4f277e59afbbe23de5909a137276841 100644
--- a/third_party/WebKit/Source/core/fetch/FontResource.cpp
+++ b/third_party/WebKit/Source/core/fetch/FontResource.cpp
@@ -29,6 +29,7 @@
 #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"
@@ -39,6 +40,8 @@ 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;
 
@@ -95,6 +98,11 @@ 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);
@@ -143,21 +151,53 @@ FontPlatformData FontResource::platformDataFromCustomData(
   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;
-  ResourceClientWalker<FontResourceClient> walker(clients());
-  while (FontResourceClient* client = walker.next())
-    client->fontLoadShortLimitExceeded(this);
+
+  // Block client callbacks if currently loading from cache.
+  if (loader()->isCacheAwareLoadingActivated())
+    return;
+  notifyClientsShortLimitExceeded();
 }
 
 void FontResource::fontLoadLongLimitCallback(TimerBase*) {
-  if (!isLoading())
-    return;
+  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::notifyClientsLongLimitExceeded() {
   ResourceClientWalker<FontResourceClient> walker(clients());
   while (FontResourceClient* client = walker.next())
     client->fontLoadLongLimitExceeded(this);