Bug 1967381 - Optimize Document::RecomputeLanguageFromCharset. a=dmeehan DONTBUILD

Original Revision: https://phabricator.services.mozilla.com/D251598

Differential Revision: https://phabricator.services.mozilla.com/D264905

dom/base/Document.cpp

@@ -276,6 +276,7 @@
 #include "mozilla/gfx/ScaleFactor.h"
 #include "mozilla/glean/DomMetrics.h"
 #include "mozilla/glean/DomUseCounterMetrics.h"
+#include "mozilla/intl/EncodingToLang.h"
 #include "mozilla/intl/LocaleService.h"
 #include "mozilla/ipc/IdleSchedulerChild.h"
 #include "mozilla/ipc/MessageChannel.h"
@@ -417,7 +418,6 @@
 #include "nsIXULRuntime.h"
 #include "nsImageLoadingContent.h"
 #include "nsImportModule.h"
-#include "nsLanguageAtomService.h"
 #include "nsLayoutUtils.h"
 #include "nsMimeTypes.h"
 #include "nsNetCID.h"
@@ -1500,6 +1500,7 @@ Document::Document(const char* aContentType)
       mInteractiveWidgetMode(
           InteractiveWidgetUtils::DefaultInteractiveWidgetMode()),
       mHeaderData(nullptr),
+      mLanguageFromCharset(nullptr),
       mServoRestyleRootDirtyBits(0),
       mThrowOnDynamicMarkupInsertionCounter(0),
       mIgnoreOpensDuringUnloadCounter(0),
@@ -19746,7 +19747,7 @@ nsAtom* Document::GetLanguageForStyle() const {
   if (nsAtom* lang = GetContentLanguageAsAtomForStyle()) {
     return lang;
   }
-  return mLanguageFromCharset.get();
+  return mLanguageFromCharset;
 }
 
 void Document::GetContentLanguageForBindings(DOMString& aString) const {
@@ -19755,7 +19756,7 @@ void Document::GetContentLanguageForBindings(DOMString& aString) const {
 
 const LangGroupFontPrefs* Document::GetFontPrefsForLang(
     nsAtom* aLanguage, bool* aNeedsToCache) const {
-  nsAtom* lang = aLanguage ? aLanguage : mLanguageFromCharset.get();
+  nsAtom* lang = aLanguage ? aLanguage : mLanguageFromCharset;
   return StaticPresData::Get()->GetFontPrefsForLang(lang, aNeedsToCache);
 }
 
@@ -19763,7 +19764,7 @@ void Document::DoCacheAllKnownLangPrefs() {
   MOZ_ASSERT(mMayNeedFontPrefsUpdate);
   RefPtr<nsAtom> lang = GetLanguageForStyle();
   StaticPresData* data = StaticPresData::Get();
-  data->GetFontPrefsForLang(lang ? lang.get() : mLanguageFromCharset.get());
+  data->GetFontPrefsForLang(lang ? lang.get() : mLanguageFromCharset);
   data->GetFontPrefsForLang(nsGkAtoms::x_math);
   // https://bugzilla.mozilla.org/show_bug.cgi?id=1362599#c12
   data->GetFontPrefsForLang(nsGkAtoms::Unicode);
@@ -19774,29 +19775,14 @@ void Document::DoCacheAllKnownLangPrefs() {
 }
 
 void Document::RecomputeLanguageFromCharset() {
-  RefPtr<nsAtom> language;
+  nsAtom* language = mozilla::intl::EncodingToLang::Lookup(mCharacterSet);
-  // Optimize the default character sets.
-  if (mCharacterSet == WINDOWS_1252_ENCODING) {
-    language = nsGkAtoms::x_western;
-  } else {
-    nsLanguageAtomService* service = nsLanguageAtomService::GetService();
-    if (mCharacterSet == UTF_8_ENCODING) {
-      language = nsGkAtoms::Unicode;
-    } else {
-      language = service->LookupCharSet(mCharacterSet);
-    }
-
-    if (language == nsGkAtoms::Unicode) {
-      language = service->GetLocaleLanguage();
-    }
-  }
 
   if (language == mLanguageFromCharset) {
     return;
   }
 
   mMayNeedFontPrefsUpdate = true;
-  mLanguageFromCharset = std::move(language);
+  mLanguageFromCharset = language;
 }
 
 nsICookieJarSettings* Document::CookieJarSettings() {

dom/base/Document.h

@@ -5489,7 +5489,9 @@ class Document : public nsINode,
   nsTHashSet<RefPtr<nsAtom>> mLanguagesUsed;
 
   // TODO(emilio): Is this hot enough to warrant to be cached?
-  RefPtr<nsAtom> mLanguageFromCharset;
+  // EncodingToLang.cpp keeps the atom alive until shutdown, so
+  // no need for a RefPtr.
+  nsAtom* mLanguageFromCharset;
 
   // Restyle root for servo's style system.
   //

intl/locale/EncodingToLang.cpp

@@ -0,0 +1,66 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/intl/EncodingToLang.h"
+#include "nsGkAtoms.h"
+#include "nsLanguageAtomService.h"
+
+using namespace mozilla;
+using namespace mozilla::intl;
+
+// Parallel arrays of Encoding and corresponding Lang atoms,
+// in rough order of frequency.
+
+// Unfortunately, the `mozilla::NotNull` hack that was used to
+// declare the encoding pointers in C++ does not allow putting
+// the pointers in a static array without a run-time initializer,
+// so our options are:
+// 1. Putting the pointers in a static array in Rust, at a distance.
+// 2. Run-time initializer.
+// 3. Using pointer pointers, as seen here.
+const mozilla::NotNull<const mozilla::Encoding *> *
+    EncodingToLang::kEncodingsByRoughFrequency[] = {
+#define _(encoding, lang) &encoding,
+#include "EncodingsByFrequency.inc"
+#undef _
+};
+
+// This one isn't constant, as it gets adjusted during Initialize().
+// static
+nsAtom* EncodingToLang::sLangs[] = {
+#define _(encoding, lang) lang,
+#include "EncodingsByFrequency.inc"
+#undef _
+};
+
+// static
+nsAtom* EncodingToLang::Lookup(NotNull<const mozilla::Encoding*> aEncoding) {
+  // Linear search should be fine, since in the vast, vast majority of cases,
+  // the search stops at the first or second item.
+  unsigned int i = 0;
+  for (; i < std::size(kEncodingsByRoughFrequency); i++) {
+    if (*kEncodingsByRoughFrequency[i] == aEncoding) {
+      return sLangs[i];
+    }
+  }
+  MOZ_ASSERT(false, "The encoding is always supposed to be found in the array");
+  return sLangs[0];
+}
+
+// static
+void EncodingToLang::Initialize() {
+  sLangs[0] = nsLanguageAtomService::GetService()->GetLocaleLanguage();
+  // We logically hold a strong ref to the first occurrence
+  // and a non-owning pointer to the rest.
+  NS_ADDREF(sLangs[0]);
+  for (size_t i = 1; i < std::size(sLangs); ++i) {
+    if (!sLangs[i]) {
+      sLangs[i] = sLangs[0];
+    }
+  }
+}
+
+// static
+void EncodingToLang::Shutdown() { NS_RELEASE(sLangs[0]); }

intl/locale/EncodingToLang.h

@@ -0,0 +1,34 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_intl_EncodingToLang_h
+#define mozilla_intl_EncodingToLang_h
+
+#include "nsAtom.h"
+#include "mozilla/Encoding.h"
+
+namespace mozilla::intl {
+
+class EncodingToLang {
+ public:
+  // Call once from nsLayoutStatics::Initialize()
+  static void Initialize();
+  // Call once from nsLayoutStatics::Shutdown()
+  static void Shutdown();
+
+  // Looks up a font matching language atom by encoding.
+  // The atom will be kept alive until nsLayoutStatics::Shutdown(),
+  // which is why it's a raw pointer.
+  static nsAtom* Lookup(mozilla::NotNull<const mozilla::Encoding*> aEncoding);
+
+ private:
+  static nsAtom* sLangs[];
+  static const mozilla::NotNull<const mozilla::Encoding *> *
+      kEncodingsByRoughFrequency[];
+};
+
+};  // namespace mozilla::intl
+
+#endif  // mozilla_intl_EncodingToLang_h

intl/locale/EncodingsByFrequency.inc

@@ -0,0 +1,50 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// List of encodings and their corresponding Lang atoms for font selection.
+// nullptr indicates that the browser UI locale language will be used.
+
+// These are in roughly-estimated frequency order sometimes by group.
+// The main thing is that UTF-8 is first and windows-1252 is second,
+// followed by other encodings that were a legacy default somewhere.
+    _(UTF_8_ENCODING,          nullptr)
+    _(WINDOWS_1252_ENCODING,   nsGkAtoms::x_western)
+    _(GBK_ENCODING,            nsGkAtoms::zh_cn)
+    _(SHIFT_JIS_ENCODING,      nsGkAtoms::Japanese)
+    _(BIG5_ENCODING,           nsGkAtoms::zh_tw)
+    _(EUC_KR_ENCODING,         nsGkAtoms::ko)
+    _(WINDOWS_1250_ENCODING,   nsGkAtoms::x_western)
+    _(WINDOWS_1251_ENCODING,   nsGkAtoms::x_cyrillic)
+    _(WINDOWS_1253_ENCODING,   nsGkAtoms::el)
+    _(WINDOWS_1254_ENCODING,   nsGkAtoms::x_western)
+    _(WINDOWS_1255_ENCODING,   nsGkAtoms::he)
+    _(WINDOWS_1256_ENCODING,   nsGkAtoms::ar)
+    _(WINDOWS_1257_ENCODING,   nsGkAtoms::x_western)
+    _(WINDOWS_1258_ENCODING,   nsGkAtoms::x_western)
+    _(WINDOWS_874_ENCODING,    nsGkAtoms::th)
+    _(ISO_8859_2_ENCODING,     nsGkAtoms::x_western)
+    _(EUC_JP_ENCODING,         nsGkAtoms::Japanese)
+    _(GB18030_ENCODING,        nsGkAtoms::zh_cn)
+    _(UTF_16BE_ENCODING,       nullptr)
+    _(UTF_16LE_ENCODING,       nullptr)
+    _(ISO_2022_JP_ENCODING,    nsGkAtoms::Japanese)
+    _(ISO_8859_3_ENCODING,     nsGkAtoms::x_western)
+    _(ISO_8859_4_ENCODING,     nsGkAtoms::x_western)
+    _(ISO_8859_5_ENCODING,     nsGkAtoms::x_cyrillic)
+    _(ISO_8859_6_ENCODING,     nsGkAtoms::ar)
+    _(ISO_8859_7_ENCODING,     nsGkAtoms::el)
+    _(ISO_8859_8_ENCODING,     nsGkAtoms::he)
+    _(ISO_8859_8_I_ENCODING,   nsGkAtoms::he)
+    _(ISO_8859_10_ENCODING,    nsGkAtoms::x_western)
+    _(ISO_8859_13_ENCODING,    nsGkAtoms::x_western)
+    _(ISO_8859_14_ENCODING,    nsGkAtoms::x_western)
+    _(ISO_8859_15_ENCODING,    nsGkAtoms::x_western)
+    _(ISO_8859_16_ENCODING,    nsGkAtoms::x_western)
+    _(KOI8_R_ENCODING,         nsGkAtoms::x_cyrillic)
+    _(KOI8_U_ENCODING,         nsGkAtoms::x_cyrillic)
+    _(MACINTOSH_ENCODING,      nsGkAtoms::x_western)
+    _(REPLACEMENT_ENCODING,    nullptr)
+    _(IBM866_ENCODING,         nsGkAtoms::x_cyrillic)
+    _(X_MAC_CYRILLIC_ENCODING, nsGkAtoms::x_cyrillic)
+    _(X_USER_DEFINED_ENCODING, nullptr)

intl/locale/encodingsgroups.properties

@@ -1,40 +0,0 @@
-# This Source Code Form is subject to the terms of the Mozilla Public
-# License, v. 2.0. If a copy of the MPL was not distributed with this
-# file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
-# x-unicode is assumed for encodings not listed here
-
-Big5=zh-TW
-EUC-JP=ja
-EUC-KR=ko
-gb18030=zh-CN
-GBK=zh-CN
-IBM866=x-cyrillic
-ISO-2022-JP=ja
-ISO-8859-3=x-western
-ISO-8859-4=x-western
-ISO-8859-5=x-cyrillic
-ISO-8859-6=ar
-ISO-8859-7=el
-ISO-8859-8=he
-ISO-8859-8-I=he
-ISO-8859-10=x-western
-ISO-8859-13=x-western
-ISO-8859-14=x-western
-ISO-8859-15=x-western
-ISO-8859-16=x-western
-ISO-8859-2=x-western
-KOI8-R=x-cyrillic
-KOI8-U=x-cyrillic
-Shift_JIS=ja
-windows-1250=x-western
-windows-1251=x-cyrillic
-windows-1252=x-western
-windows-1253=el
-windows-1254=x-western
-windows-1255=he
-windows-1256=ar
-windows-1257=x-western
-windows-1258=x-western
-windows-874=th
-x-mac-cyrillic=x-cyrillic

intl/locale/moz.build

@@ -35,6 +35,7 @@ EXPORTS += [
 
 EXPORTS.mozilla.intl += [
     "AppDateTimeFormat.h",
+    "EncodingToLang.h",
     "LocaleService.h",
     "MozLocaleBindings.h",
     "OSPreferences.h",
@@ -43,6 +44,7 @@ EXPORTS.mozilla.intl += [
 
 UNIFIED_SOURCES += [
     "AppDateTimeFormat.cpp",
+    "EncodingToLang.cpp",
     "LocaleService.cpp",
     "nsLanguageAtomService.cpp",
     "nsUConvPropertySearch.cpp",
@@ -68,13 +70,6 @@ RESOURCE_FILES += [
     "language.properties",
 ]
 
-prefixes = ("encodingsgroups",)
-
-for prefix in prefixes:
-    input_file = prefix + ".properties"
-    header = prefix + ".properties.h"
-    GeneratedFile(header, script="props2arrays.py", inputs=[input_file])
-
 if CONFIG["ENABLE_TESTS"]:
     DIRS += ["tests/gtest"]
 

intl/locale/nsLanguageAtomService.cpp

@@ -20,10 +20,6 @@
 using namespace mozilla;
 using mozilla::intl::OSPreferences;
 
-static constexpr nsUConvProp encodingsGroups[] = {
-#include "encodingsgroups.properties.h"
-};
-
 // List of mozilla internal x-* tags that map to themselves (see bug 256257)
 static constexpr nsStaticAtom* kLangGroups[] = {
     // This list must be sorted!
@@ -110,18 +106,6 @@ nsStaticAtom* nsLanguageAtomService::LookupLanguage(
   return GetLanguageGroup(lang);
 }
 
-already_AddRefed<nsAtom> nsLanguageAtomService::LookupCharSet(
-    NotNull<const Encoding*> aEncoding) {
-  nsAutoCString charset;
-  aEncoding->Name(charset);
-  nsAutoCString group;
-  if (NS_FAILED(nsUConvPropertySearch::SearchPropertyValue(
-          encodingsGroups, std::size(encodingsGroups), charset, group))) {
-    return RefPtr<nsAtom>(nsGkAtoms::Unicode).forget();
-  }
-  return NS_Atomize(group);
-}
-
 nsAtom* nsLanguageAtomService::GetLocaleLanguage() {
   {
     AutoReadLock lock(mLock);

intl/locale/nsLanguageAtomService.h

@@ -33,7 +33,6 @@ class nsLanguageAtomService final {
   static void Shutdown();
 
   nsStaticAtom* LookupLanguage(const nsACString& aLanguage);
-  already_AddRefed<nsAtom> LookupCharSet(NotNull<const Encoding*> aCharSet);
   nsAtom* GetLocaleLanguage();
 
   // Returns the language group that the specified language is a part of,

intl/locale/props2arrays.py

@@ -1,26 +0,0 @@
-# This Source Code Form is subject to the terms of the Mozilla Public
-# License, v. 2.0. If a copy of the MPL was not distributed with this
-# file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
-
-def main(header, propFile):
-    mappings = {}
-
-    with open(propFile) as f:
-        for line in f:
-            line = line.strip()
-            if not line.startswith("#"):
-                parts = line.split("=", 1)
-                if len(parts) == 2 and len(parts[0]) > 0:
-                    mappings[parts[0].strip()] = parts[1].strip()
-
-    keys = mappings.keys()
-
-    header.write("// This is a generated file. Please do not edit.\n")
-    header.write("// Please edit the corresponding .properties file instead.\n")
-
-    entries = [
-        '{ "%s", "%s", %d }' % (key, mappings[key], len(mappings[key]))
-        for key in sorted(keys)
-    ]
-    header.write(",\n".join(entries) + "\n")

layout/build/nsLayoutStatics.cpp

@@ -10,6 +10,7 @@
 #include "nscore.h"
 
 #include "mozilla/intl/AppDateTimeFormat.h"
+#include "mozilla/intl/EncodingToLang.h"
 #include "mozilla/dom/ServiceWorkerRegistrar.h"
 #include "nsAttrValue.h"
 #include "nsComputedDOMStyle.h"
@@ -299,6 +300,8 @@ nsresult nsLayoutStatics::Initialize() {
   }
 #endif
 
+  mozilla::intl::EncodingToLang::Initialize();
+
   return NS_OK;
 }
 
@@ -401,4 +404,6 @@ void nsLayoutStatics::Shutdown() {
   RestoreTabContentObserver::Shutdown();
 
   mozilla::intl::LineBreakCache::Shutdown();
+
+  mozilla::intl::EncodingToLang::Shutdown();
 }