Bug 1404666 - patch 1 - Accelerate OSPreferences::GetDateTimePattern …

…by caching patterns found for particular style/locale combinations. r=gandalf
dothq · Dec 18, 2018 · 572203b · 572203b
1 parent 0e5b436
commit 572203b
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Showing 2 changed files with 29 additions and 2 deletions.
diff --git a/intl/locale/OSPreferences.cpp b/intl/locale/OSPreferences.cpp
@@ -333,11 +333,34 @@ OSPreferences::GetDateTimePattern(int32_t aDateFormatStyle,
     return NS_OK;
   }
 
-  if (!ReadDateTimePattern(dateStyle, timeStyle, aLocale, aRetVal)) {
-    if (!GetDateTimePatternForStyle(dateStyle, timeStyle, aLocale, aRetVal)) {
+  // Create a cache key from the locale + style options
+  nsAutoCString key(aLocale);
+  key.Append(':');
+  key.AppendInt(aDateFormatStyle);
+  key.Append(':');
+  key.AppendInt(aTimeFormatStyle);
+
+  nsString pattern;
+  if (mPatternCache.Get(key, &pattern)) {
+    aRetVal = pattern;
+    return NS_OK;
+  }
+
+  if (!ReadDateTimePattern(dateStyle, timeStyle, aLocale, pattern)) {
+    if (!GetDateTimePatternForStyle(dateStyle, timeStyle, aLocale, pattern)) {
       return NS_ERROR_FAILURE;
     }
   }
 
+  if (mPatternCache.Count() == kMaxCachedPatterns) {
+    // Don't allow unlimited cache growth; just throw it away in the case of
+    // pathological behavior where a page keeps requesting different formats
+    // and locales.
+    NS_WARNING("flushing DateTimePattern cache");
+    mPatternCache.Clear();
+  }
+  mPatternCache.Put(key, pattern);
+
+  aRetVal = pattern;
   return NS_OK;
 }
diff --git a/intl/locale/OSPreferences.h b/intl/locale/OSPreferences.h
@@ -7,6 +7,7 @@
 #define mozilla_intl_IntlOSPreferences_h__
 
 #include "mozilla/StaticPtr.h"
+#include "nsDataHashtable.h"
 #include "nsString.h"
 #include "nsTArray.h"
 #include "unicode/uloc.h"
@@ -97,6 +98,9 @@ class OSPreferences : public mozIOSPreferences {
   nsTArray<nsCString> mSystemLocales;
   nsTArray<nsCString> mRegionalPrefsLocales;
 
+  const size_t kMaxCachedPatterns = 15;
+  nsDataHashtable<nsCStringHashKey, nsString> mPatternCache;
+
  private:
   virtual ~OSPreferences();