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Use initialization-on-demand holder instead of double-checked locking #1746

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Use initialization-on-demand holder instead of double-checked locking #1746

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227 changes: 106 additions & 121 deletions ua/org.eclipse.help.webapp/src/org/eclipse/help/internal/webapp/data/UrlUtil.java
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Original file line number Diff line number Diff line change
Expand Up @@ -42,16 +42,103 @@ public class UrlUtil {
static final Pattern safariPattern = Pattern.compile(
"Safari/(\\d+)(?:\\.|\\s|$)", Pattern.CASE_INSENSITIVE); //$NON-NLS-1$

// Default locale to use for serving requests to help
private static String defaultLocale;
// Locales that infocenter can serve in addition to the default locale.
// null indicates that infocenter can serve every possible client locale.
private static Collection<String> locales;

private static final int INFOCENTER_DIRECTION_BY_LOCALE = 1;
private static final int INFOCENTER_DIRECTION_LTR = 2;
private static final int INFOCENTER_DIRECTION_RTL = 3;
private static int infocenterDirection = INFOCENTER_DIRECTION_BY_LOCALE;

private static class Holder {

/** Default locale to use for serving requests to help. */
private static final String DEFAULT_LOCALE;

/**
* The locales that an infocenter can serve in addition to the default locale.
* {@code null} indicates that infocenter can serve every possible client
* locale.
*/
private static final Collection<String> LOCALES;

private static final int INFOCENTER_DIRECTION;

static {
String defaultLocale = Platform.getNL();
Collection<String> locales = null;
int infocenterDirection = INFOCENTER_DIRECTION_BY_LOCALE;

// initialize default locale
if (defaultLocale == null) {
defaultLocale = Locale.getDefault().toString();
}
if (BaseHelpSystem.getMode() == BaseHelpSystem.MODE_INFOCENTER) {

// locale strings as passed in command line or in preferences
final List<String> infocenterLocales = new ArrayList<>();

// first check if locales passed as command line arguments
String[] args = Platform.getCommandLineArgs();
boolean localeOption = false;
for (String arg : args) {
if ("-locales".equalsIgnoreCase(arg)) { //$NON-NLS-1$
localeOption = true;
continue;
} else if (arg.startsWith("-")) { //$NON-NLS-1$
localeOption = false;
continue;
}
if (localeOption) {
infocenterLocales.add(arg);
}
}
// if no locales from command line, get them from preferences
if (infocenterLocales.isEmpty()) {
String preferredLocales = Platform.getPreferencesService().getString(HelpBasePlugin.PLUGIN_ID,
("locales"), "", null); //$NON-NLS-1$ //$NON-NLS-2$
StringTokenizer tokenizer = new StringTokenizer(preferredLocales, " ,\t"); //$NON-NLS-1$
while (tokenizer.hasMoreTokens()) {
infocenterLocales.add(tokenizer.nextToken());
}
}

// format locales and collect in a set for lookup
if (!infocenterLocales.isEmpty()) {
locales = new HashSet<>(10, 0.4f);
for (String locale : infocenterLocales) {
if (locale.length() >= 5) {
locales.add(locale.substring(0, 2).toLowerCase(Locale.ENGLISH) + "_" //$NON-NLS-1$
+ locale.substring(3, 5).toUpperCase(Locale.ENGLISH));

} else if (locale.length() >= 2) {
locales.add(locale.substring(0, 2).toLowerCase(Locale.ENGLISH));
}
}
}

// initialize direction
// from property
String orientation = System.getProperty("eclipse.orientation"); //$NON-NLS-1$
if ("rtl".equals(orientation)) { //$NON-NLS-1$
infocenterDirection = INFOCENTER_DIRECTION_RTL;
} else if ("ltr".equals(orientation)) { //$NON-NLS-1$
infocenterDirection = INFOCENTER_DIRECTION_LTR;
} else {
// from command line
for (int i = 0; i < args.length; i++) {
if ("-dir".equalsIgnoreCase(args[i])) { //$NON-NLS-1$
if ((i + 1) < args.length && "rtl".equalsIgnoreCase(args[i + 1])) { //$NON-NLS-1$
infocenterDirection = INFOCENTER_DIRECTION_RTL;
break;
}
infocenterDirection = INFOCENTER_DIRECTION_LTR;
break;
}
}
}
}
DEFAULT_LOCALE = defaultLocale;
LOCALES = locales;
INFOCENTER_DIRECTION = infocenterDirection;
}
}

/**
* Encodes string for embedding in JavaScript source
Expand Down Expand Up @@ -474,36 +561,33 @@ public static Locale getLocale(String localeStr) {
*/
public static String getLocale(HttpServletRequest request,
HttpServletResponse response) {
if (defaultLocale == null) {
initializeNL();
}
if ((BaseHelpSystem.getMode() != BaseHelpSystem.MODE_INFOCENTER)
|| request == null) {
return defaultLocale;
return Holder.DEFAULT_LOCALE;
}

// use locale passed in a request in current user session
String forcedLocale = getForcedLocale(request, response);
if (forcedLocale != null) {
if (locales == null) {
if (Holder.LOCALES == null) {
// infocenter set up to serve any locale
return forcedLocale;
}
// match forced locale with one of infocenter locales
if (locales.contains(forcedLocale)) {
if (Holder.LOCALES.contains(forcedLocale)) {
return forcedLocale;
}
// match language of forced locale with one of infocenter locales
if (forcedLocale.length() > 2) {
String ll = forcedLocale.substring(0, 2);
if (locales.contains(ll)) {
if (Holder.LOCALES.contains(ll)) {
return ll;
}
}
}

// use one of the browser locales
if (locales == null) {
if (Holder.LOCALES == null) {
// infocenter set up to serve any locale
return request.getLocale().toString();
}
Expand All @@ -512,21 +596,21 @@ public static String getLocale(HttpServletRequest request,
String locale = e.nextElement().toString();
if (locale.length() >= 5) {
String ll_CC = locale.substring(0, 5);
if (locales.contains(ll_CC)) {
if (Holder.LOCALES.contains(ll_CC)) {
// client locale available
return ll_CC;
}
}
if (locale.length() >= 2) {
String ll = locale.substring(0, 2);
if (locales.contains(ll)) {
if (Holder.LOCALES.contains(ll)) {
// client language available
return ll;
}
}
}
// no match
return defaultLocale;
return Holder.DEFAULT_LOCALE;
}

/*
Expand Down Expand Up @@ -594,119 +678,20 @@ private static String getForcedLocale(HttpServletRequest request,
return forcedLocale;
}

/**
* If locales for infocenter specified in prefernces or as command line
* parameters, this methods stores these locales in locales local variable
* for later access.
*/
private static synchronized void initializeNL() {
if (defaultLocale != null) {
// already initialized
return;
}
initializeLocales();
if ((BaseHelpSystem.getMode() == BaseHelpSystem.MODE_INFOCENTER)) {
initializeIcDirection();
}

}
private static void initializeLocales() {
// initialize default locale
defaultLocale = Platform.getNL();
if (defaultLocale == null) {
defaultLocale = Locale.getDefault().toString();
}
if (BaseHelpSystem.getMode() != BaseHelpSystem.MODE_INFOCENTER) {
return;
}

// locale strings as passed in command line or in preferences
final List<String> infocenterLocales= new ArrayList<>();

// first check if locales passed as command line arguments
String[] args = Platform.getCommandLineArgs();
boolean localeOption = false;
for (String arg : args) {
if ("-locales".equalsIgnoreCase(arg)) { //$NON-NLS-1$
localeOption = true;
continue;
} else if (arg.startsWith("-")) { //$NON-NLS-1$
localeOption = false;
continue;
}
if (localeOption) {
infocenterLocales.add(arg);
}
}
// if no locales from command line, get them from preferences
if (infocenterLocales.isEmpty()) {
String preferredLocales = Platform.getPreferencesService().getString
(HelpBasePlugin.PLUGIN_ID, ("locales"), "", null); //$NON-NLS-1$ //$NON-NLS-2$
StringTokenizer tokenizer = new StringTokenizer(preferredLocales,
" ,\t"); //$NON-NLS-1$
while (tokenizer.hasMoreTokens()) {
infocenterLocales.add(tokenizer.nextToken());
}
}

// format locales and collect in a set for lookup
if (!infocenterLocales.isEmpty()) {
locales = new HashSet<>(10, 0.4f);
for (String locale : infocenterLocales) {
if (locale.length() >= 5) {
locales.add(locale.substring(0, 2).toLowerCase(Locale.ENGLISH) + "_" //$NON-NLS-1$
+ locale.substring(3, 5).toUpperCase(Locale.ENGLISH));

} else if (locale.length() >= 2) {
locales.add(locale.substring(0, 2).toLowerCase(Locale.ENGLISH));
}
}
}
}

private static void initializeIcDirection() {
// from property
String orientation = System.getProperty("eclipse.orientation"); //$NON-NLS-1$
if ("rtl".equals(orientation)) { //$NON-NLS-1$
infocenterDirection = INFOCENTER_DIRECTION_RTL;
return;
} else if ("ltr".equals(orientation)) { //$NON-NLS-1$
infocenterDirection = INFOCENTER_DIRECTION_LTR;
return;
}
// from command line
String[] args = Platform.getCommandLineArgs();
for (int i = 0; i < args.length; i++) {
if ("-dir".equalsIgnoreCase(args[i])) { //$NON-NLS-1$
if ((i + 1) < args.length
&& "rtl".equalsIgnoreCase(args[i + 1])) { //$NON-NLS-1$
infocenterDirection = INFOCENTER_DIRECTION_RTL;
return;
}
infocenterDirection = INFOCENTER_DIRECTION_LTR;
return;
}
}
// by client locale
}

public static boolean isRTL(HttpServletRequest request,
HttpServletResponse response) {
if (BaseHelpSystem.getMode() != BaseHelpSystem.MODE_INFOCENTER) {
return ProductPreferences.isRTL();
}
if (infocenterDirection == INFOCENTER_DIRECTION_RTL) {
if (Holder.INFOCENTER_DIRECTION == INFOCENTER_DIRECTION_RTL) {
return true;
} else if (infocenterDirection == INFOCENTER_DIRECTION_LTR) {
} else if (Holder.INFOCENTER_DIRECTION == INFOCENTER_DIRECTION_LTR) {
return false;
}
String locale = getLocale(request, response);
if (locale.startsWith("ar") || locale.startsWith("fa") //$NON-NLS-1$ //$NON-NLS-2$
return (locale.startsWith("ar") || locale.startsWith("fa") //$NON-NLS-1$ //$NON-NLS-2$
|| locale.startsWith("he") || locale.startsWith("iw") //$NON-NLS-1$ //$NON-NLS-2$
|| locale.startsWith("ur")) { //$NON-NLS-1$
return true;
}
return false;
|| locale.startsWith("ur")); //$NON-NLS-1$
}

// Return true if the URI is of the form /<context>/nav/*
Expand Down
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