[WIP] WebFonts cache-aware timeout adaption

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 21 matching lines @@
 #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
 static const double fontLoadWaitShortLimitSec = 0.1;

[Kunihiko Sakamoto, 2016/10/12 08:56:30]

With cache-aware loading, disk cache RTT longer than this threshold won't result
in FOUT anymore.
Can you add a TODO comment saying that we should revisit this once cache-aware
loading launched?

[Shao-Chuan Lee, 2016/10/17 03:45:59]

Done.

 static const double fontLoadWaitLongLimitSec = 3.0;
 
 enum FontPackageFormat {
   PackageFormatUnknown,
   PackageFormatSFNT,
   PackageFormatWOFF,
   PackageFormatWOFF2,
   PackageFormatSVG,
   PackageFormatEnumMax
 };
@@ skipping 84 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() {
+  ProhibitAddRemoveClientInScope prohibitAddRemoveClient(this);
+
+  ResourceClientWalker<FontResourceClient> walker(clients());
+  while (FontResourceClient* client = walker.next())
+    client->willReloadAfterDiskCacheMiss(this);
+
+  DCHECK(!resourceRequest().isCacheAwareLoadingActivated());
+  if (!m_fontLoadShortLimitTimer.isActive())
+    fontLoadShortLimitCallback(nullptr);

[yhirano, 2016/10/12 06:30:38]

This code assumes that startLoadLimitTimersIfNeeded has been called. Is the
assumption always hold? It's a public method and we cannot assume when / if it's
called in general. Even if it holds I want some documentation.

[Shao-Chuan Lee, 2016/10/13 05:20:45]

Load limit timers are always started after FontResource loading is triggered in
RemoteFontFaceSource::beginLoadIfNeeded().
However load limit timers may be restarted during loading, this will be fixed in
https://crrev.com/2419753002. Thanks for noting this.

[Shao-Chuan Lee, 2016/10/17 03:45:59]

Added comments.

+  if (!m_fontLoadLongLimitTimer.isActive())
+    fontLoadLongLimitCallback(nullptr);
+}
+
 void FontResource::fontLoadShortLimitCallback(TimerBase*) {
   if (!isLoading())
     return;
+  if (resourceRequest().isCacheAwareLoadingActivated())
+    return;
   DCHECK_EQ(m_loadLimitState, UnderLimit);
   m_loadLimitState = ShortLimitExceeded;
   ResourceClientWalker<FontResourceClient> walker(clients());
   while (FontResourceClient* client = walker.next())
     client->fontLoadShortLimitExceeded(this);
 }
 
 void FontResource::fontLoadLongLimitCallback(TimerBase*) {
   if (!isLoading())
     return;
+  if (resourceRequest().isCacheAwareLoadingActivated())
+    return;
   DCHECK_EQ(m_loadLimitState, ShortLimitExceeded);
   m_loadLimitState = LongLimitExceeded;
   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